ISSN:0260-1818    

DOI:10.1039/b516521k

出版商:RSC    

年代:2005

数据来源: RSC

ISSN:0260-1818    

DOI:10.1039/b516522a

出版商:RSC    

年代:2005

数据来源: RSC

摘要:

In this the 101st Volume in the series ofAnnual Reports, Section A, the vitality of inorganic chemistry is once again demonstrated in the separate reports covering developments by periodic group and by special topics. The reports endorse the perception of the strength of inorganic chemistry, not only in its own right, but in its work at the interface with other branches of chemistry and with other disciplines. Indeed, the thinking across boundaries seems to be a particular aspect of much of the work reported in this Volume and points to an expectation that continued endeavours by inorganic chemists will be at interfaces and boundaries. This is reflected in some new chapters which highlight interdisciplinary areas of inorganic chemistry which are particularly topical, such as inorganic compounds as pharmaceuticals, the photophysical properties of metal complexes and assemblies, and computational methods in inorganic chemistry. It is hoped that the coverage of special topics such as these will complement the more traditional element-by-element coverage to provide a concise summary of the most significant recent developments in inorganic chemistry which is as up-to-date as possible.

ISSN:0260-1818    

DOI:10.1039/b414981p

出版商:RSC    

年代:2005

数据来源: RSC

摘要:

1IntroductionThis chapter follows the usual pattern with emphasis on the organometallic and coordination chemistry of Groups 1 and 2 published in 2004.Reviews have appeared on s-block compounds with oxygen donor ligands, such as alkoxides, aryloxides, enolates, carboxylates and β-diketiminates,1the formation of Grignard reagents,2electrides stabilised by alkali metal loaded zeolites3and metal β-diketiminates together with the preparation and structure of some newansa-bridged compounds of lithium.4Alkali metal salts of 1-phenyl-1H-1,2,3,4-tetrazole-5-thiolate [M(C6H5N4CS)] (M = Li–Cs) exhibit a variety of coordination modes with MSCN (M = K, Rb or Cs) rings and M⋯Ph (M = Rb or Cs) interactions present.5A series of alkali metal 3-hydroxyphenolates have been prepared and structurally characterized.6Complexes of the alkali metals Na–Cs derived from 2-phenylaminopyridine (LH) have been prepared in the presence of 12-crown-4, 15-crown-5 and 18-crown-6 ethers to give separated ion pairs [M(crown)2][L] and contact ion pairs [ML(crown)] in which L acts as a bidentate ligand. Several interesting structures including the polymeric potasside [K(18-crown-6)K(L2)] were observed. Most of the separated ion pairs contained parallel rings but the [Rb(12-crown-4)2] complex showed a bent geometry and density functional calculations suggested this effect to be inherent.7Reduction of 1-chloro-2,3,4,5-tetraethyl-arsole and -stibole with Na–Cs in dme or tmen yielded the base-stabilised arsolides or stibolides. All form one-dimensional polymers apart from [Na(tmen)AsC4Et4]2and all exhibit only η5-coordination except the sodium complexes which also show η1-coordination.8The vinylidene phosphine (PPrn2)C&z.dbd;CH2reacted with lithium, sodium or potassium to give the corresponding bis(diphosphinomethanide) complexesviaSchlenk dimerization. When the PPh2derivative was used, reaction with potassium led to P–C bond cleavage as reported in last year’s Annual Report.9The preparations and X-ray structures of some 2,3-pyrazyl-linked bis(1-azaallyl) complexes, [M2{{N(SiMe3)C(But)C(H)}2C4H2N2-2,3}(thf)n]2(M = Li or Na,n= 2; M = K,n= 3)10and of [Li(15-crown-5)(L)] (L = Ph2EPNPEPh2, E = S or Se), [Rb(18-crown-6)(L)] (E = O, S or Se) and [Cs(18-crown-6)(L)] (E = O, S or Se) have been reported. Since 18-crown-6 ether is unable to satisfy the coordination requirements of rubidium and caesium, rare M–E bonds are formed in a six-membered ring.11Deprotonation of (dipp)P&z.dbd;C(4-MeC6H3)N(H)dipp with LiBunin thf yields the monomer [(dipp)PC(4-MeC6H3)NLi(thf)3(dipp)] whereas with KN(SiMe3)2the polymer [K(thf)0.5N(dipp)C(4-MeC6H3)P(dipp)K(thf)0.5]∞is formed.12The structures of some metallated derivatives of 2-(Ar),6-(2,6-diisopropylanilido)pyridine (Ar = dmp or trip) reveal three-coordinate lithium centres and potassium polymers (through K⋯Ar/anilido interactions).13As part of a study of the reactivity ofN-heterocyclic carbene complexes in Lewis acidic metal-catalysed processes the preparation and structure of the lithium (dimer) and magnesium (monomer) derivatives of C{N(CH2CH2NHBut)CHCHNR} (R = Butor mes) have been reported.14A theoretical study of lithium bonding has suggested a mechanism similar to that proposed for hydrogen bonding to account for the blue shift in the X–Li stretching frequency of X–Li⋯Y species.15The ligand exchange mechanism in [LiL4]+(L = H2O or NH3) has been studied using density functional calculations.16Reaction of Mg(AsF6)2and XeF2in anhydrous HF afforded [Mg(XeF2)4][AsF6]2and [Mg(XeF2)2][AsF6]2; both cations are octahedral with Mg⋯F interactions.17

ISSN:0260-1818    

DOI:10.1039/b408039b

出版商:RSC    

年代:2005

数据来源: RSC

摘要:

1IntroductionThis review covers the literature published in 2004. Due to space limitations it is not exhaustive; focusing on what the author considers to be significant contributions to the field in 2004. Descriptions of scientific results are kept to a minimum, and the reader is directed to the original paper for more information. The overall approach to this section is similar to that used by previous authors. The inorganic and organometallic aspects of boron chemistry have been reviewed, while complexes bearing boron-containing counterions and tris-pyrazolyl type borate ligands have not been included, unless the focus of the chemistry is towards boron.

ISSN:0260-1818    

DOI:10.1039/b418479n

出版商:RSC    

年代:2005

数据来源: RSC

摘要:

1IntroductionArticles of general, fundamental, or comparative interest across trielide chemistry published last year include reviews of phosphanido- and arsanido-cage compounds with Al–In,21and a short review of trielide–trielide donor–acceptor bonding.22Fundamental studies include a report of emission spectra of Ga, In and Tl (M) atoms in solid hydrogen. There was significant evidence for MH production at 3.5 K. Irradiation at 193 nm appears to induce MH2and MH3production in all cases.23Insertions of Mt (Mt = Al, Ga) atoms into SiH4in argon matrices were seen to give, initially, Mt(κ2-H2SiH2) associates, which result in insertion to give HMtSiH3and, ultimately, MtSiH3, according to spectral evidence. In the case of Ga2‘molecules’,24there is evidence of the formation of HGa(μ2-H3Si)Ga.25Similar reactions to the above with SnH4result in HMtSnH3, however irradiation with visible light induces likely tautomerisation to dihydrido-bridged species H2Mt(μ-H)2Sn; furthermore, the Ga2dimer seems to afford a cluster-type product Ga2(μ-H)4Sn in contrast to the silane product above.26Complexes of oep with Al(iii), Ga(iii) and In(iii) were studied and properties compared down the group.27A synthetic and structural study of trielide complexes of the heterocycle {cyclo-CH2SCH2SCH2NCH3} (L) was conducted: complexes characterised structurally were [LAlMe2Cl], [LAlCl3], [LAlBr3], [L2InCl3], the salts [LH][AlCl4], [LH][GaCl4] and [HL2][AlBr4], and also the B congeners [LH][BF4] and [LH]2[Cl][BCl4].28The first four complexes mentioned often possess a degree of intramolecular dipolar interaction between the trielide substituents and ligand hydrogen atoms.28Another synthetic–structural comparison revealed an interesting anomaly: the 1-aminoindan-2-ol ligand (Hain) has two chiral centres, which persist in its complexes. The Al examples [AlMe2(μ-κ1∶κ2-ain)]2(of various chiral permutations) are dimeric, along with their In congeners. However [GaMe2(ain)] is simply monomeric.29The imine {(mes)N&z.dbd;P(Ph)2}2CH2proved, on deprotonation, a good ligand for both {GaCl2} and {AlI2} centres affording both an unusual ligand donor set.30Two rare examples of the occurrence of a {(M2F6)(O3PC)2} structural unit, where M is a trivalent metal, emerged, namely the novel kindred inorganic–organic hybrid structures [(H3NCH2CH2NH3)2{Al2F6(O3PCH2CH2PO3)}] and [(H3NCH2CH2NH3){Ga2F4(O3PCH2CH2PO3)}].31A series of heterometallic and metalloid coordination gold compounds were reported, often containing the trielides. Sometimes these are found in the counterions, as in [Au10S4{Ph2P(CH2)5PPh2}4][InCl5], part of the complex itself, as in [Au4(SeInCl3)2{Ph2P(CH2)5PPh2}2] or [Au2(TeInCl3){Ph2P(CH2)6PPh2}]2, or both, as in [Au8Se4In{Ph2P(CH2)2PPh2}4][InCl4]3.32Rather varied chemistry emerged from a rather simple ligand system: complexes of organoaluminiums and organogalliums with R2NO−ligands (R = Me, Pri) display different means of aggregation.33Simplest of all is the centrosymmetric 6-member cycle. In contrast, [Pri2Al(μ-ONMe2)]2is a 4-membered {AlOAlO} cycle, reflecting the preference of the Al for the harder donor atom. Additional steric strain in [But2Al(μ-ONMe2)]2is insufficient to promote a structural change to a 6-membered ring or a dimer, the most interesting variation occurring in the asymmetric [But2Ga(μ-ONMe2)]2. This latter structure possesses a 5-membered cycle, one Me2NO−ligand binding through N and O, and the other through O only.33Finally, a theoretical study comparing Lewis acidities of AlH3with GaH3(and BH3) towards XH3(X = N, P, As) by DFT was conducted and seemed to find unusually short Ga–H bonds.34Stabilities of the putative GaAs5and InAs5intermetallics were investigated by theoretical means, with a view to assessment of these GaCp*or InP5analogues as transport agents in GaAs and InAs production.35The study concluded that such molecular structures might exist at temperatures around 900 °C.

ISSN:0260-1818    

DOI:10.1039/b408108k

出版商:RSC    

年代:2005

数据来源: RSC

摘要:

1ReviewsThe past year has seen an upswing in the number of interesting and important reviews covering Group 14 chemistry. An issue ofJournal of Organometallic Chemistryhas appeared commemorating the award of the 2002 Main Group Chemistry Prize to Professor Robert West, famed silicon chemist and alpinist, which is very welcome if a little tardy.1The role of coordinating species such as phosphine oxides, sulfoxides and DMF in the enhancement of the reactivity of allyl silanes has been reviewed.2Recent developments in the area of molecular attachment on silicon surfaces has been reviewed with particular reference to the selectivity of attached reagents.3The chemistry of M(ii) species with M(14)–E bonds (M(14) = Si, Ge, Sn; E = N, O, S) has been reviewed as has the role of intramolecular bonds in the stabilisation of monomeric low-valent species, an area which has been the subject of some considerable discussion in recent years.4In a related vein, the chemistry of phosphasila- and germa-allenes (2,4,6-But3C6H2–P&z.dbd;C&z.dbd;ER2, where E = Si or Ge, R2= Ph, Trip; E = Ge, R = mes) has been reviewed. The complexes themselves typically dimerise above −40 °C although the sterically crowded germanium complex can be isolated as a monomer at room temperature. The reaction and structural characteristics of these compounds and others in the same family are shown to be close to those of carbon allenes.5The under-explored area of first-row transition-metal phyllosilicates has been comprehensively reviewed in an account that surveys both the established literature and also the more recent developments in the area of materials chemistry. The emphasis is on the magnetic properties of these transition-metal complexes, in part as this is the main interest of the authors of the review and in part because this is a very important new application for this family of compounds.6Silsesquioxanes have a developed role as ligands for transition metals inspired by the similarity between such complexes and silica-immobilised transition-metal ions. A range of complexes comprising two silsesquioxanes on each ion have been prepared in a recent increase in activity accelerated by the report of the synthesis of lithium derivatives of silsesquioxanes which are useful reagents in transmetallation reactions.7The application of aluminium-based melts in the synthesis of the commercially important material silicon carbide has been surveyed8as have photoemission and synchrotron radiation studies of silicon carbide surfaces9and the growth of silicon carbide by vapour deposition techniques.10,11The stability and structure of species with positively charged silicon centres has been reviewed.12The role of organosilicon reagents in the Hosomi–Sakurai reaction has been reviewed13and, in a similar vein, the application of silicon and germanium reagents in the Stille coupling reaction has been surveyed.14While there have been advances in both of these areas there is still plenty of scope for further development and it is to be hoped that surveys such as these that highlight the potential of the area can be instrumental in stimulating further expansion in these useful and important reaction protocols. New syntheses of organosilicon compounds by direct reaction of elemental silicon with either organohalides or unsaturated hydrocarbons and hydrogen chloride have been reviewed15as have synthetic routes to Group 14 nitrides.16The continuing interest in the semiconducting and electronic properties of pure and doped silicon and carbon clathrates has prompted a review of recent developments.17A timely survey of the area of stable metalloaromatic M(14) compounds, such as sila- and germa-benzene and -naphthalenes has appeared dealing with the synthesis and characterisation of these materials along with a theoretical treatment of their aromaticity.18The inadvertent chemistry of silicon grease, which is largely comprised of (Me2SiO)n, with a range of polar organometallic reagents has been surveyed. There are in the literature a number of examples of compounds that are adventitiously formed in very high yield. As an example of the kind of chemistry that can happen, the recrystallisation of K[In(H)(np)3] in apparatus with silicon grease sealant gives [(Me2SiO)7K](K)3[{In(H)(np)3}]4where the potassium is complexed by a heptasiloxane cyclic polyether. In reaction chemistry, treatment of Me2GaCl with Li[But2As] gives Li16[(OSiMe2OSiMe2OSiMe2OSiMe2O)2(OSiMe2OSiMe2O)2Cl4] in 48% yield with respect to lithium, a product with a cubane-type structure comprising a condensed ring motif. This review reports on the reaction behaviour of something that is added to almost all reactions carried out in synthetic chemistry but which is never really thought of as a possible reactant. It is a salutary thought that many reactions essayed the world over may “go wrong”, giving unrecognised products, because of the unanticipated participation of silicon grease.19

ISSN:0260-1818    

DOI:10.1039/b408111k

出版商:RSC    

年代:2005

数据来源: RSC

摘要:

1 NitrogenThe fixation of nitrogen continues to be attracting considerable interest and reviews covering recent advances in this area using transition metals and the interaction of substrates with nitrogenase have been published.3,4The structure of the MoFe cluster in nitrogenase, and the mechanism of N2reduction by this enzyme have been reinvestigated by DFT in the light of new crystallographic data.5The calculations support the assignment of the “light atom” at the centre of the metal cluster as being nitrogen. A series of ruthenium complexes with sulfur- and phosphorus-containing ligands have been prepared and their potential as models for nitrogenase has been explored.6,7A complementary theoretical study into the activation of terminally-bound dinitrogen in dinuclear Fe(ii) and Ru(ii) complexes has also appeared.8A comprehensive theoretical study into the reductive cleavage of the N&z.dbd;N bond in the cluster [(η5-C5H5)2Mo2(μ-SMe)3(μ-η1:η1-HN&z.dbd;NPh)]+has shown that the Mo–Mo δ-orbital plays a crucial role in this cleavage.9An extremely thorough structural and mechanistic study into the cleavage of a range of nitrogen–nitrogen double bonds in tungsten alkoxide complexes has been published.10Reduction of the Ti(iii) precursor (η5-C5H3-1-3-{SiMe3}2)2TiCl with sodium amalgam under one atmosphere of N2gives the paramagnetic dimeric dinitrogen complex [(η5-C5H3-1-3-{SiMe3}2)2Ti]2(μ2-η1,η1-N2)],1.11Reaction of1with organic azides RN3(R = SiMe3, Mes) gives N2and imido complexes [(η5-C5H3-1-3-{SiMe3}2)2Ti(&z.dbd;NR)]. The mechanism of the reaction of the dinitrogen unit in (η5-C5Me4H)2Zr)2(μ-η2∶η2-N2) has been probed by an elegant theoretical and deuterium labelling study and indicates the importance of a 1,2-addition process.12The dinitrogen in the zirconium complex ([P2N2]Zr)2(μ-η2∶η2-N2) has been shown to undergo C–N bond forming reactions with terminal aryl alkynes RC&z.tbd;CH to give2.13The N–N bond in hydrazine may be cleaved by the cluster [(η5-C5Me5Ru)3(μ-H)6] to give an imido-containing cluster which reacts with hydrogen to generate ammonia.14A solid-state NMR study of the labelled complex Mo15N[N(But)Ar]3(Ar = 3,5-Me2C6H3), prepared from15N2, has been reported.15The chemistry of the unlabelled material with Lewis acids was also described. The [TpW(CO)2]+fragment has been shown to support, and allow for the interconversion of, a wide range of nitrogen-based ligands.16Furthermore the activation of N2by metal complexes for use in organic synthesis has been reviewed.17The activation of ammonia by the iron clusters Fen+(n= 1–20) has been studied using Fourier transform ion cyclotron resonance mass spectrometry.18Addition of ammonia is observed in the cases whenn> 4; in the cases wheren= 4 addition of ammonia and dehydrogenation was observed. The interactions of the clusters with both nitrogen and hydrogen were also studied.The cation [NH3Cl]+has been prepared (as the BF4, AsF6and SbF6salts) by employing (Me3Si)2NCl as a masked form of the explosive and unstable NH2Cl.19Therefore, reaction of (Me3Si)2NCl with HF at low temperature results in thein situgeneration of NH2Cl and when the reaction is performed in the presence of a Lewis acid, such as BF3, then [NH3Cl]+is isolated from the reaction. The salt is stable under an inert atmosphere, but when exposed to moisture liberates NH2Cl.A chiral NPPN chelating ligand has been prepared by a rather remarkable reaction sequence.20Deprotonation of DippNHP(Ph)NRC(R′)&z.dbd;CR (R = But, R′ = Bun; R = Cy, R′ = But) with BunLi or AlMe3results in the formation of Li[DippNP(Ph)P(Bun)PhNDipp]·OEt2and AlMe2[DippNP(Ph)P(Me)PhNDipp], respectively. Both species were characterised by X-ray crystallography: the mechanism of this reaction is thought to proceedviathe elimination of the amidate Li[NRCR′NR]. The synthesis of a series of homoleptic azaallyl complexes has been reported and their structures commonly exhibit a fluxional η3-CCN bonding mode.21Homoleptic titanium aza-butadiene complexes have also been reported.22The use of 1-azaallylic anions in the synthesis of heterocycles has been reviewed.23A new generation of calix[3]arenes which employ boron and nitrogen as building blocks have been reported.24The calix[3]arenes act as hosts for a wide range of small molecule guests.There has been continued interest in the use of nitrogen-rich compounds as high energy materials and a review of group 15 and 16 polyazide compounds has appeared.25The synthesis of salts of the N5+ion has also been reported.26Perhaps most remarkable are the species [N5][P(N3)6] and [N5][B(N3)4] with nitrogen contents of 91.2 and 95.7%, respectively. Unsurprisingly, these compounds are extremely sensitive to mild shocks and explode on warming to room temperature. Furthermore the azides As(N3)nand Sb(N3)n(n= 3 or 5) have been prepared, in the cases wheren= 5 subsequent reaction with ionic azides such as [PPh4]N3to give [PPh4]M(N3)6(M = As or Sb) has also been described.27,28The enthalpies of formation of a range of polynitrogen compounds have been calculated and, as predicted, the salt [N5][N3] was shown to be extremely unstable.29The preparation of azide-substituted nitrogen-rich ring systems, such as3, has also been reported.30This material is, relatively, less friction-sensitive than cyanuric azide.The first example of an isolable selenium azide, N3Se(2-{Me2NCH2}C6H4, has been reported.31Crucial to the stability of this molecule is the pendant amino arm that coordinates to the selenium. Theoretical investigations into the mechanism of formation of N5−,32the nitrogen-rich sulfides SN5, SN6,33and the possible structures of Nn(n= 14, 16, 18, 24, 30, 36) have appeared.34–36Salts of the anion CS2N3−have also been characterised and a theoretical investigation into the compounds CE2N3−(E = S, Se, Te) performed.37A review of the chemistry of tetrazines has been published,38as has a theoretical study into tri-s-triazines39and triazidotri-s-triazine.40Quaternisation ofN-aminoazoles may be used to give salts such as4.41In this case the enthalpy of formation of the salts was also determined. The results indicated that the perchlorate salts have a higher energy of combustion than nitrate salts and that tetraazolium salts have higher enthalpy of formation than their triazolium analogues. An improved synthesis and a single-crystal X-ray structure of 3,6-diaza-1,2,4,5-tetraazine (C2N10) have been reported. This species was subsequently used for the generation of nitrogen-rich carbon nitrides and carbon nanospheres.42Soluble salts of the anions [RNSN]−and [NCN]2−have been prepared by reaction of [K(18-crown-6][OBut] with [RNSNSiMe3] and [Me3SiNSNSiMe3], respectively. The structures of the salts were determined by single-crystal X-ray diffraction and were also probed by DFT calculations.43The structure of the former anion is probably best described as being [RN−–S&z.tbd;N].A fascinating new, nitrogen-rich ferrocene derivative containing 12 nitrogen atoms and four ferrocene units has been prepared.44Four guanidine groups link the ferrocene units together. Differential pulse voltammetry experiments indicate that there is electronic coupling between the iron centres that is mediated by the nitrogen-rich bridges.

ISSN:0260-1818    

DOI:10.1039/b408125k

出版商:RSC    

年代:2005

数据来源: RSC

摘要:

1Sulfur, selenium and telluriumThe interaction of Group 16 donors with dihalogen species received further attention in 2004. The first pseudohalogen adduct of a selenocarbonyl, generated from 1,3-dimethyl-4-imidazoline-2-selone and cyanogen iodide, was prepared,1the selenium–iodine separation [3.300(1) Å] in conjunction with DFT calculations suggesting that the selenium atom is in a partial hypervalent state. Diiodine adducts of 1,4-dimethylperhydro-1,4-diazepine-2,3-dithione and (SPPh2)2NH react with elemental mercury at room temperature to give neutral square planar Hg(ii) complexes with S2I2donor sets,2,3while the sulfur atoms of Group 8 bis(dithiolene) complexes can act as donors to diiodine,4comparisons between experimental and calculatedν(S–I) frequencies permit an evaluation of their strength. Two adducts of formula C48H32Br10Se8are available upon bromination of selenanthrene,5one product contains a linear Br4unit connecting selenium centres in adjacent molecules (4c–6e bond) whereas the other possesses a linear Se2Br5(7c–10e bond) unit. Lang and co-workers report that dimesityl ditelluride is oxidised by diiodine to give Mes(I)Te(TeMes2), the first aryltellurium(ii) halide complex stabilised by a Te–Te bond from a telluroether.6The mechanism of its formation involves disproportionation of the intermediate MesTeI to Mes(I)Te(TeMes2), MesTeI3and elemental tellurium. The interaction of 4,5-bis(bromomethyl)-1,3-dithiole-2-thione with iodine(i) monohalides generates adducts exclusively through the thione centre (S⋯I 2.534–2.597 Å), with the endocyclic sulfur atoms being uninvolved in S⋯halogen interactions.7Crystallographic and computational studies of organoselenides (2-YC6H4)SeX (Y = N or O donor, X = halogen or pseudohalogen) reveal the importance of non-bonded intramolecular Y→Se interactions in stabilising these low-valent compounds.8–10Poleschner and Seppelt have generated ArSeF by fluorination of Ar2Se2or ArSeSiMe3with xenon difluoride and used low-temperature77Se/19F NMR for characterisation.11Kläpotkeet al. isolated the first stable covalent selenium azide, (2-Me2NC6H4)SeN3, in near-quantitative yield by metathesis from the chloride using AgN3or NaN3,12as well as pseudohalogen derivatives of tellurium, notably Te(CN)x(x= 2 or 4) and Ph5TeN3.13,14The crystal structure of Te(CN)2is the first determination for a chalcogen cyanide. Binary azides of selenium, tellurium and the heavier Group 15 elements were also studied by Knapp and Passmore.15C6F5SeCl and C6F5SeLi are versatile precursors to new pentafluorophenylselenium(ii) compounds;16the chloride reacts with nitrogen nucleophiles or silylated chalcogen species to give compounds with Se–S, Se–N and Se–Se bonds, while Group 14 derivatives C6F5SeMMe3(M = Si, Ge, Sn or Pb) are produced from C6F5SeLi and Me3MHal.The selenium(ii) dialkanethiolates Se(SR)2(R = Me ortBu) undergo exchange of substituents with Se(ii) and Te(ii) dithiolates, and also with thiols if a catalytic amount ofp-toluenesulfonic acid is present.17Similarly, mixing dilute methanolic solutions of dimethyl trisulfide and diorganodiselenides at room temperature generates trichalcogenides containing either –SeS2–, –SSeS–, –Se2S–, –SeSSe– or –Se3– linkagesviachalcogenide exchange.18Branched isomers –Se–Se(&z.dbd;Se)– were also detected. In related work, the second example of a structurally characterised diorganotriselenide was reported.10Münchow and Steudel have synthesised sulfur-rich acyclic thiaalkanes by treatment of the titanocene thiolates [Cp2Ti(SSR′SS)] (R′ = CMe2or 1,1-C6H10) with Ph3CSCl, affording [Cp2TiCl(SSR′S3CPh3)], and quenching with electrophiles such as RSCl, SO2Cl2or SxCl2.19The thiaalkanes are stable for several weeks at 4 °C but undergo decomposition at higher temperatures. Oxidative coupling of phosphonodithioates [Fc(RO)PS2]−and [An(RO)PS2]−using KI/I2gives dithiophosphonodisulfides [P(S)–S–S–P(S) linkage], several of which were investigated crystallographically.20Disulfur monoxide, S&z.dbd;S&z.dbd;O, generated by the retro-Diels–Alder reaction of a sulfur-rich cycloadduct, rapidly disproportionates to S3and SO2.21In a separate study the decomposition of S2O to SO2, S3, S4and S5O, a process cited as relevant for understanding the chemistry occurring on Jupiter's moon Io, was probed by gas-phaseab initiocalculations at the G3X(MP2) level.22The rotational spectrum of thiozone, S3, obtained using high-resolution molecular beam FT microwave spectroscopy, discloses important structural data for the molecule [d(S&z.dbd;S) 1.917(1) Å, S–S–S 117.36(6)°].23During the reaction of the thioketeneS-oxidetBu2C&z.dbd;S&z.dbd;O with Lawesson's Reagent, sulfur atom transfer from the phosphorus compound affords a thiirane-2-thione in high yield at room temperature.24Thecis-thiolate groups of a nickel(ii) complex with a macrocyclic N2S2ligand bind two sulfur dioxide molecules to give an adduct which is stablein vacuofor 12 h without SO2loss, although displacement occurs if a solution of the complex is purged with an inert gas.25Exposure of the adduct to dioxygen oxidises the bound SO2molecules to [SO4]2−.Under ambient conditions tellurium tetrahalides react with triphenylphosphine in thf to give [{(Ph3PO)2H}2][Te2X10] (X = Cl, Br) and [(Ph3PO)3(OH3)]2[TeI6], while from TeBr4a formally zwitterionic species Ph3PO(CH2)4TeBr4is also available, derived by ring-opening of the solvent.26Hexavalent organotellurium compounds TeAr6(Ar = Ph or 4-CF3C6H4) are formed in the reaction of TeCl4with four equivalents of ArLi in diethyl ether at −78 °C, pentaaryl halides TeAr5Hal (Hal = Cl or Br) were prepared by halogenating Li[TeAr5] intermediates with sulfuryl chloride or dibromine respectively.27DFT studies of the ring currents in chalcogen-containing monocycles were used to probe their aromaticity. Diatropic π-currents reinforced by σ-circulations were found in [S3N3]−, [S4N3]+, [S4N4]2+and [S5N5]+, but the currents were in opposition in the four-membered rings [S4]2+, [Se4]2+and S2N2, compatible with height profiles of calculated nucleus-independent chemical shifts.28The electronic and molecular structures of the square-planar 6π electron systems E2N2and [E4]2+(E = S, Se or Te) were also analysed by Suontamo and Laitinen.29The charge-density distribution of the sulfur imides MeS(NtBu)(NHtBu), (tBuN)2(ButNH)SCH2S(NHtBu)(NtBu)2, S(NtBu)2and S(NtBu)3were determined experimentally using high-resolution X-ray diffraction at 100 K and found to agree closely withab initiocalculations.30The authors concluded that in S(NtBu)2and S(NtBu)3the central planar SNxunits possess multicentre bonding whereas for the other molecules the sp3hybridisation of the nitrogen centres suggest that an S+–N−designation is more accurate. Potassium 18-crown-6 salts of [RNSN]−(R = Ad,tBu, SiMe3, Ph or 4-FC6H4) and [NSN]2−were synthesised by treatment of trimethylsilylated precursors with [K(18-crown-6)][tBuO] and studied crystallographically.31The bond lengths in the former suggest a thiazylamide form [R–N–S&z.tbd;N]−, rather than an [R–N&z.dbd;S&z.dbd;N]−(sulfur diimide) structure. The salts are thermally stable and very soluble in aprotic organic solvents. Thermal decomposition of Se(NAd)2in thf affordsinter aliaa new five-membered cyclic imide, Se3(NAd)2, a new ring size for a chalcogen imide (although the naked [Se3N2]+cation is also known).32Other products of the decomposition assigned by77Se NMR include Se3(NAd)3and two partially hydrolysed species, AdNSe(μ-NAd)2SeO and OSe(μ-NAd)2SeO. Anhydrous salts of 1,2,3,4-thiatriazole-5-thiolate, [CS2N3]−, were reported by Kläpotke and Crawford, including crystallographic analysis of the [NH4]+and [NMe4]+salts.33Also described were improved syntheses of the dipseudohalogen (CS2N3)2and the interpseudohalogen CS2N3CN, and calculations on the hypothetical [CSe2N3]−and [CTe2N3]−anions. New heterocyclic 1,3,2-dithiazolyl radicals were studied using variable temperature magnetic susceptibility measurements, X-ray crystallography and EPR spectroscopy.34–36Novel cyclic and linear polychalcogenide species were synthesised by several routes. Solvothermal methods afford [(AgI)2E6] (E = Se, Te), containing neutral E6rings stabilised in an AgI matrix,37[Se6]2−and [TeSe2]2−chains are generated from reactions involving manganese(ii) chloride, K2Se3and either Se or Te at 433 K.38Both [NEt4]2[Te3Se6] and [NEt4]2[Te3Se7] , which contain one-dimensional anionic chains of Te3Se5or Te3Se6rings, respectively, linked by selenium atoms, were prepared by reactions of [Ten]2−and [Sen]2−salts of ammonium cations in dmf at 293 K.39One-dimensional polymeric chains of [Te6]2+cations, comprising [Te5]2+rings joinedviasingle Te atoms, were generated by chemical vapour transport.40Computational studies by Krossing and Passmore provide evidence for the previously unknown 10π electron homocycle [S6]2+in solutions of [S8](AsF6)2in sulfur dioxide and propose that π*–π* transitions in this dication are responsible for the colour of solutions of S8in strong protonic acids.41The coordination chemistry of chalcogen donor ligands continue to attract attention. Recent developments in the chemistry of metal–sulfoxide complexes were reviewed by Alessio42and Calligaris.43Closely related to sulfoxides, sulfimides display similar coordinative versatility. Reaction of Ph2SNH with copper(ii) sulfate and sodium salts of trimesic acid (H3tma) gives two-dimensional networks [Cu3(Ph2SNH)6(tma)2] whose topologies (herring-bone, brick wall or honeycomb) vary with recrystallisation solvent.44[Cu(Ph2SNH)4][PF6]2crystallises in three different forms, two of which are polymorphic whereas the third is a pseudopolymorph, owing to solvent incorporation into the lattice.45The product distribution is primarily controlled by temperature, the forms differing in geometry at the copper centre and the nature of the supramolecular interactions.Cleavage of [FcP(S)(μ-S)]2with sodium ethoxide affords [FcP(OEt)S2]−, which forms mononuclear complexes with Group 10 metals,46while bis(phosphonodithioates) [M{S2P(OR)2}2] (M = Zn or Cd, R =iPr or Cy) react with 4,4′-bipyridyls to give coordination polymers with linear, zigzag or arched topologies.47,48Metal trithiophosphonates [(CyPS3)Li2·thf·tmen]2and [(CyPS3)Mg·thf2]2were prepared by metallating CyPH2with eithern-butyllithium in thf–tmen or dibutylmagnesium respectively, followed by addition of sulfur;49the molecules crystallise as dimer pairs with the three sulfur atoms of the anion coordinated to the alkali metal cations.Pyrazine-2,3-diselenolate (pds2−) reacts with PtCl2to give platinum(iv) species [Pt(pds)3]2−or [Pt2(pds)5]2−, depending upon the molar ratio of reagents used (3∶1 or 2∶1, respectively), while pulse field gradient spin-echo NMR experiments reveal the presence in solution of trimetallic species [{Pt(pds)3}{Pt(pds)2}2]2−derived from addition of [Pt(pds)2] to [Pt2(pds)5]2−.50Pds2−stabilises a mixed-valence two-dimensional coordination polymer CuI[CuIII(pds)2] in which the Cu(i) cations are coordinated by the nitrogen and selenium atoms from adjacent complex anions.51Obtained unexpectedly during electrocrystallisation of Na[CuIII(pds)2], CuI[CuIII(pds)2] is unique in its co-existence of Cu(i) and Cu(iii) centres without charge-transfer between them. Woollins and co-workers have investigated oxidative addition reactions of dichalcogen derivatives of naphthalene, acenaphthene and phenanthrene with Pt(0), Pt(ii) and Ir(i) complexes,52,53and an unusual 2-(arylmercapto)aryl mercaptan complex is isolable from the reaction of [RuCl(Tp)(cod)] with Ph2S2or (p-tolyl)2S2, the reaction pathway being dictated by the bulk of the Tp ligand and the high affinity of the RuTp fragment for the strong π-acceptor CO ligand.54The 1,5-diselenacyclooctane complexes [MCl3{[8]aneSe2}] (M = As, Sb or Bi) exhibit ladder structures composed of planar M2Cl6cores linked through thetrans-selenium atoms of the diselenoether ligands.55Whereas the arsenic adduct has an polymeric chain structure, the antimony compound is composed of discrete dimers. Cyanodithioimidocarbonate, [C2N2S2]2−, generates mononuclearS,S′-chelates with Pt(ii) and Pd(ii), while for Rh(i) and Ir(i) dimeric complexes are formed in which the sulfur atoms bridge two metal centres, producing cores with cubane-type geometries.56The monoanion of (tBuNH)3P&z.dbd;S forms four-memberedN,S-chelates at Rh(i) and Mo(vi) but for Ni(ii) an asymmetrical bis-chelate is found with the anion bound in hard (N,N′-) and soft (N,S-) modes.57A new ambidentate indene ligand with pendant thiophosphoryl and amine donors acts as anN,S-bidentate donor at Rh(i) in its neutral form, but upon deprotonation the indenyl anion binds to Rh(i) and Mn(i) centres inC,S-bidentate and η5-modes, respectively.58Transition metal clusters with bridging chalcogenide anions remain prominent. The undecanuclear complex [Cu11(μ9-Se)(μ3-Br)3{Se2P(OR)2}6] (R = Et,nPr oriPr) contains a nonacoordinate selenide in a tricapped trigonal prismatic geometry,59while [Zn4(μ4-Se){Se2P(OR)2}6] is the first Zn4tetrahedron stabilised by Se2−.60This cluster dissociates to monomeric and dimeric units in solution (VT31P NMR evidence), akin to the well-known dithiophosphate species, polymeric and selenide-free forms of this cluster were also reported by the same authors.61The orthoselenostannate anion, [SnSe4]4−, reacts with divalent metals to give [M4(μ4-Se)(SnSe4)4]10−(M = Zn, Cd, Hg or Mn), whereas from mercury acetate coordination polymers3∞{[Hg4(μ4-Se)(SnSe4)3]6−} and1∞{[Hg(SnSe4)]2−} are available.62Crystallographically characterised gold clusters constructed using bis(trimethylsilyl)selenium include [Au5Se2(PPh3)4]Cl, [(Au3Se)2(dpph)3]Cl2and [Au10Se4(dpppe)4][InCl5], constructed by edge-sharing of Au3(μ3-Se) tetrahedra.63Binuclear aluminium β-diketiminate complexes [(dike)Al(μ-E)2Al(dike)] (E = Se or Te) and [(dike)Al(μ-S3)2Al(dike)] have been structurally characterised. The μ-Se/Te species were prepared from reactions involving [Al(dike)H2] and elemental chalcogen in the presence of catalytic amounts of tertiary phosphine,64while for the polysulfide the conformation of the Al2S6ring differs from the octasulfur crown as the S3chains are staggered rather than eclipsed.65The first bimetallic telluroacyl complex, [WFe(μ-TeCTol)(CO)5Cp], was generated by reacting the alkylidene complex [WFe(μ-CTol)(CO)nCp] (n= 5 or 6) with elemental tellurium;66by contrast, μ-telluride clusters were afforded when the bulkier 2,6-Me2C6H3substituent was present in the alkylidene fragment. In [Ta4Se9I8], obtained from Ta/Se/I2at 300 °C, the tantalum atoms form a square, with four Se2ligands bridging each Ta-Ta edge and one μ4-Se capping the Ta4unit.67Cyanide-terminated molybdenum clusters [Mo6Se8(CN)6]6−/7−and [Mo4Se4(CN)12]8−were prepared by treating Mo3nSe3n+2cluster compounds (n= 2–∞) with cyanide salts,68cuboidal heterobimetallic cages [Mo3CuSe4]4+/5+and [W3CuQ4]5+(Q = S or Se) were generated by reacting molybdenum and tungsten precursors with elemental copper,69while [Ru9S8(p-cymene)6]2+and [Ru5S4(p-cymene)4]2+were accessible from [Ru3S2(p-cymene)2(MeCN)3]2+using Na2S·9H2O and NaSH respectively.70The ruthenium clusters were considered to be potential hydrodesulfurisation catalysts, since Ru–S phases are more effective than Mo–Co–S systems.Lithium–tin imido heterocubane clusters containing terminal Sn&z.dbd;Se or Sn&z.dbd;Te bonds were prepared by chalcogenation of LiSn3N4cages using elemental selenium or tellurium respectively.71The monomeric stannane–thione and –selone [(Tbt)(Ditp)Sn&z.dbd;X] (X = S or Se), which are kinetically stabilised by the sterically demanding aromatic substituents, were prepared by dechalcogenating the tetrachalcogenastannolanes [(Tbt)(Ditp)Sn(E4)] with phosphines.72The X-ray structure of the stannaneselone reveals thatd(Sn&z.dbd;Se) = 2.373(3) Å supporting the view that the compound is structurally similar to a ketone, as is the case for the silicon and germanium analogues, a result further borne out by119Sn NMR spectra.An array of polychalcogenate-containing anions are accessible by solid-state synthetic methods. Heating B2S3and BaS at 1000 °C for 24 h affords [Ba7(BS3)4S] in which the Ba(ii) centres have eight or nine sulfide donors whereas the thioborate anions are not coordinated.73Ternary alkali selenophosphates A[PSe6] (A = K, Rb or Cs), available from A2Se/P2Se5/Se melts at 350 °C, contain one-dimensional chains of [PSe2(Se4)]−, in which the PSe2units are connectedvialinear [Se4]2−bridges.74A simple new route to crystalline metal polysulfides utilising boron sulfides was described.75In a fused silica ampoule a tube containing metal oxide was placed above another containing boron and sulfur powders. At temperatures exceeding 350 °C the boron sulfides formedin situare sufficiently volatile to react in gaseous form with the metal oxide. The generality of this procedure was demonstrated by the synthesis of sixteen d- and f-block metal sulfides; the authors also speculated thatin situformed boron selenides may behave in a similar capacity as a synthon for metal selenides. A new three-dimensional antimony sulfide framework with one-dimensional circular channels [Co(en)3][Sb12S19] was prepared solvothermally from sulfur, en, cobalt(ii) sulfide and antimony(iii) sulfide at 170 °C.76A kinetic study of the acid-dependent disproportionation of dithionate, [S2O6]2−, in the presence of dioxygen and a range of inorganic oxidants was conducted.77These investigations confirmed that [S2O6]2−is not directly oxidised but undergoes disproportionation and subsequent oxidation of the S(iv) species formed. Both Ce(iii) and iodide ions catalyse this autoxidation process. Addition of thiocyanate to an acidified aqueous solution of dichlorine rapidly generates an equilibrium mixture of thiocyanogen, (SCN)2and trithiocyanate, [SCN]3−.78The thiocyanogen subsequently decomposes to HSCN, H2SO4and HCN, a process followed by stopped-flow kinetics. The authors cite the relevance of these studies as delivering an insight into the physiological role of enzymes which catalyse thiocyanate oxidation.By using a very sterically bulky terphenyl substituent for stabilisation, anSe-nitrososelenol (Bpq)SeNO was prepared by treatment of (Bpq)SeH with either ethyl nitrite orS-nitrosoglutathione.79Although sensitive to dioxygen, (Bpq)SeNO is stable to water and is an important compound for developing our understanding of NO-mediated modifications of selenoproteins. An unusual carbocation [CS2Br3]+was isolated during the reaction of silver(i) salts with dibromine and carbon disulfide; the crystal structure of the cation as the [Al{OC(CF3)3}4]−salt reveals that the cation is planar at carbon and the C–S lengths are intermediate between single and double bond values.80

ISSN:0260-1818    

DOI:10.1039/b408130g

出版商:RSC    

年代:2005

数据来源: RSC

摘要:

1IntroductionThis chapter reviews the year 2004 literature for the elemental halogens and the noble gases, and compounds containing these elements in their positive oxidation states. As in previous years publications that involve halide, interhalide or oxohalide anions as counter ions are generally not described.

ISSN:0260-1818    

DOI:10.1039/b408298m

出版商:RSC    

年代:2005

数据来源: RSC