摘要:
The crystal structures of [ NMe,] [ (Me2AsO~{Mo0(02)2}2],[ NH4] [ (Ph2P02){MoO(O~2(H20)}] and their use as catalytic oxidants[NMe4I[(Ph2PO2)CMO0(02)2}21, [NBun,I[(Ph2P02){WO(02)2}21 andN. Melanie Gresley, William P. Griffith,* Bernardeta C. Parkin, Andrew J. P. White andDavid J. Williams *Inorgunic. and Chemical Crystallographic Research Laboratories, Department of Chemistry,Imperiul College of Science, Technology and Medicine, London S W7 2A Y, UKThe new heteropolyperoxometalate compounds [NMe,][(Me,AsO,){ MoO(O,),},] 1, [NMe,][(Ph,PO,)-fMoO(02),] '1 2, [NBu",][(Ph2P02)(WO(0,),j,13 and CNH41[(Ph2P02)(MoO(0,),(H20)}l 4 have beenisolated and their crystal structures determined. Compounds 1-3 are dinuclear, whilst compound 4 ismononuclear; in all four structures the metal centre(s) have essentially identical pentagonal-bipyramidalco-ordination geometries with a weak axial ligand trans to an 0x0 group.The utility of 3 as a catalyst for theoxidation of alkenes, alcohols and tertiary amines with hydrogen peroxide as cooxidant has been studied.Catalysis of the homogeneous oxidation of organic substratesby environmentally acceptable reagents such as hydrogenperoxide is of current interest.IP5 In this series of papers 132*6 wehave explored the use of molybdenum and, in particular,tungsten iso- and hetero-polyperoxo complexes as catalystsfor organic oxidations with hydrogen peroxide as cooxidant. Aprerequisite for such oxidations to be effective appears to be thepresence of an q',q'-peroxo moiety in which one of the oxygenatoms of a peroxo ligand, side-bonded to a metal atom, forms aweak bond to an adjacent metal atom.The presence of suchbonds was first demonstrated in 'Venturello's compound',[N(C,H 3)4]3[P04(WO(02)2}4].3 This will, with hydrogenperoxide as cooxidant, catalyse the epoxidation of alkane^,'^^the conversion of tertiary amines to N-oxides,' internal alkynesto the corresponding x,P-epoxy ketones, 7*8 allenes to a-alkoxyor x-hydroxy ketones,' alkenes to carboxylic acids, l o aniines tooximes and nitrones,' ' anilines to azoxynitroso- and nitro-benzenes '' and sulfides to sulfoxides and sulfones. 'We have been investigating the use of organo-phosphorusand -arsenic ligands in such heteropolyperoxo species with theaim of facilitating their attachment to solid-state supports.Here, we report the crystal structures of three new complexescontaining q ' , ~ '-linkages, [NMe,][(Me,AsO,)( MoO(O,),},]1, [NMe,][(Ph,PO,){ MoO(O,),},] 2 and [NBu",:I[(Ph,-PO,)(WO(O,),),] 3, and also the structure of a relatedmononuclear species [NH,][(Ph2P02)(MoO(0,)(H20)}] 4which contains only q2-peroxo groups.Although we havepreviously reported ' the existence of salts of [AsO,{WO-(0')' 1 ,I3 P, complex 1 is the first structurally characterisedexample of an arsenic-containing polyperoxometalate. In linewith our earlier observations, 1*2*6 we find that the tungsten-containing complex 3 is effective for alkene epoxidation,alcohol oxidation and the oxidation of tertiary amines, allwith hydrogen peroxide as cooxidant.Results and DiscussionPreparations and crystallographyPreparation and crystal structure of complex 1.The complexwas isolated as a bright yellow crystalline solid by reactingMoO,.H,O, H202, Na[Me,AsO,] and [NMe,]Cl in a water-t Studies on Polyoxo- and Polyperoxo-metalates. Part 4.'O(11)A\/0(231W O(211Fig. 1 Structure of the anion in complex 1ethanol mixture followed by cooling at 0°C for 3 d. Notungsten analogue could be obtained under similar reactionconditions using WO,-H,O.The crystal structure of complex 1, Fig. 1, shows the complexto have non-crystallographic C, symmetry about an axispassing through the arsenic atom and bisecting the vectorlinking the two molybdenum centres. Both of the metal ionshave distorted pentagonal-bipyramidal geometries, a least-squares fit of which had a root mean square (r.m.s.) deviation of0.02 8, for the co-ordinated atoms.The primary axial position oneach metal centre carries an 0x0 ligand. Four of the equatorialsites around each of the molybdenum atoms are occupied bytwo bidentate peroxo groups, the fifth site in each case beingfilled by an oxygen atom from the dimethylarsinate ligand. Oneof the peroxo groups on each metal ion is of the non-bridgingq2-type, whereas the other [0( 14)-O( 15), O(24)-0(25)] isinvolved in bridging between Mo(1) and Mo(2) in an q2,q'fashion. The consequence of these secondary axial interactions(depicted by broken bonds in Fig. 1) is not a lengthening ofeither peroxide bond (which remain at ca.1.47 8, with an anglesubtended at the 'parent' molybdenum atom of around 44") butJ. Chem. Soc., Dalton Trans., 1996, Pages 2039-2045 203Table 1 Selected bond lengths (A) and angles (") for complexes 1 4x-O( 1 )x-O(2)x-cM( 1 to( 1)M(2)-0(2)M( 1)-O( 1 1)M( 1 )-O( 12)M( 1)-O( 13)M( 1 )-O( 14)M( 1 )-O( 1 5 )M( 1 FO(25)M (2)-O( 2 1 )M(2)-O(22)M( 2)-O( 23)M( 2)-O( 24)M( 2)-O( 25)M ( 2 t 0 ( 15)O( 12)-O( 13)O( 14)-O( 1 5 )O(22)-O(23)O(24)-O(25)M( 1 )-O( 1 )-XM(2)-0(2)-XO( 1 2 j-M( 1 kO( 1 3)O( 14)-M( 1 )-O( 1 5 )0(22)-M(2 j-O( 23)0(24)-M(2)-0(25)O( 1 1 )-M( 1 )-O( 25)0(21)-M(2)-0( 15)1" 2 b1.700(4)1.691(4)1.874(6), 1.901(6)2.007(4)2.020(4)1.67 1 (4)1.923(4)1.928(4)1.920(4)2.426(4)1.653(5)1.928(4)1.91 5(4)1.922(4)2.005(4)2.439(4)1.458(5)1.480(6)1.466(6)1.997(4)1.457(7)132.6(2)129.4(2)44.5( 2)43.7(2)45.3(2)43.8( 2)170.7(2)168.1(2)1.525(2)1.524(2)1.781(2), 1.776(2)2.043( 2)2.029(2)1.668(2)1.9 16(2)1.9 1 O(3)1.922(2)1.98 1 (2)2.478(2)1.657(2)1.920(3)1.914(3)1.9 19(2)1.977(2)2.534(2)1.468(4)1.468(3)1.463(4)1.470( 3)133.58( 13)137.06( 13)45.1 l(12)44.1 5( 1 0)44.87( 12)44.32( 10)170.49( 1 1 )171.65(11)3'1.501(9)1.502(9)1.763(10), 1.769(13)1.925(9)2.036( 9)dddddddddddddddd1 40.3( 7)136.9(5)dddddd4b1.536(2)1.488(2)d2.0 1 6( 2)1.670(2)1.936(2)1.930(2)1.936(2)1.947(2)2.368(2)----~-~1.469( 3)1.474( 3)-~1 40.6 1 ( 1 3)44.65( 10)44.62( 9)-~-179.93( 10)-M = Mo, X = As.M = Mo, X = P. ' M = W, X = P. Values for major occupancy orientation only. Values unreliable due to disorder (seetext). ' Aqua ligand.an increase in the bond length to the parent molybdenumcentres of the bridging oxygen atoms O(15) and O(25)1.922(4) and Mo(2)-O(25) 2.005(4) A]. The bridging bondlengths to the second metal atoms [0(15)-Mo(2) 2.439(4) andO(25)-Mo( 1) 2.426(4) A] are comparable with those found in(C6H 1 3141 3 [Po4 (Wo(0z)z 141 and "Bun,] 2 [(PO3(OH))-{WO(Oz)2)2].14 The angles between the peroxo groups are ca.127" whilst those between the peroxo groups and the bridgingarsinate donor atoms are in the range 108 to 112".* In eachcase, the molybdenum centres are displaced towards the 0x0ligand relative to the plane of the five equatorial oxygen atomsby 0.40 and 0.41 8, for Mo(1) and Mo(2) respectively.+ Theangles between the axial ligands are 171" [for Mo(l)] and 168"[for Mo(2)].The geometry at arsenic is tetrahedral, with angles in therange 107-1 15" with virtually identical arsenic-oxygen bondlengths [As-O(1) 1.700(4) and As-O(2) 1.691(4) A].There areno significant intermolecular interactions other than normalvan der Waals. A comparison of selected bond lengths andangles for this and the structures of complexes 2, 3 and 4 isgiven in Table 1.[Mo( 1)-O( 14) 1.920(4), Mo( 1)-O( 15) 1.997(4), M0(2)-0(24)CNM~~~ZC(P~PO~)(M~O(O~)~(HZ~)) (MoO(O2)2) 21, "-Preparation and crystal structure of complex 2.The complexwas isolated as a bright yellow crystalline solid by reactingMo03*H20, H20z, Ph,PO(OH) and [NMeJCl in a water-ethanol mixture followed by cooling at 0 "C for 3 d. Atetrabutylammonium salt was also synthesised.The X-ray analysis of complex 2, Fig. 2, reveals a structure* Considering each peroxo group as a unidentate ligand associated witha trigonal-bipyramidal geometry around each metal centre.t The five equatorial co-ordinated oxygen atoms are coplanar to within0.11 A for both Mo( 1) and Mo(2).no mQ oz 01131O(21 - vO(22l a6 O(211Fig. 2 Structure of the anion in complex 2that is geometrically virtually identical with that of 1, but withthe dimethylarsinate unit being replaced by a diphenylphosphi-nate. Both molybdenum centres have pentagonal-bipyramidalgeometries, a least-squares fit of which, compared with thatobserved in I , has a r.m.s. deviation of only 0.03 A.In commonwith 1, there are both q2- and q2,q1-peroxo groups on eachmetal ion, the latter [0(14)-O( 15) and O(24)-0(25)] exhibitinga lengthening of the parent Mo-0 bond in a fashion analogousO(24) 1.919(2) and Mo(2)-O(25) 1.977(2) A], see Table 1.The geometry at phosphorus shows only small deviationsfrom tetrahedral, with angles in the range 106-1 14"; the twoto I [M0(1)-0(14) 1.922(2), Mo(l)-0(15) 1.981(2), Mo(2)-2040 J. Chem. Soc., Dalton Trans., 1996, Pages 2039-204(4 (b)Structures of ( a ) the major occupancy conformer and (6) the enantiomer of the minor occupancy conformer of the anion in complex 3 Fig.3P-0 distances are the same [P-0(1) 1.525(2) and P-0(2)1.524(2) 141. Again, there are no significant intermolecularinteractions.Preparation and crystal structure of complex 3. The complexwas isolated as a colourless crystalline solid by reactingW0,-H20, H202, Ph,PO(OH) and [NBu",]Cl in a water-ethanol mixture followed by cooling at 0°C for 2 months.Despite many attempts with other cations, only thetetrabutylammonium salt could be isolated.The X-ray analysis of complex 3 reveals a disorderedstructure, the major occupancy component of which has anoverall geometry [Fig. 3(a)] essentially the same as that of themolybdenum analogue 2. The minor occupancy conformer,which is present with 45% occupancy, has a geometry for thetungsten co-ordination spheres which is virtually unchanged.Between both conformers, the two tungsten centres, thephosphorus and the bridging W-0-P oxygen atoms areoverlaid.but the peroxo and 0x0 ligands are enantiomeric withrespect to the major occupancy conformation. The equivalenceof these two conformers can be visualised by taking theenantiomer of the minor occupancy conformer, Fig. 3(h), theonly difference between the two geometries then being areversal (or mirroring) of the pitch of the two phenyl rings. Thisdisorder precludes discussion of the fine detail of the co-ordination geometries, and only the pertinent bond lengths andangles are summarised in Table 1.Despite this disorder, theq ',q '-linked pentagonal-bipyramidal co-ordinations are de-finitive. There are, again, no significant intermolecularinteractions .Preparation and crystal structure of complex 4. The complexwas isolated as a bright yellow crystalline solid by reactingMoO,-H,O, H,O,, Ph,PO(OH) and NH,Cl in a water-ethanol mixture followed by cooling at 0 "C for 3 d. Despitemany attempts with other cations, only the ammonium saltcould be isolated. Reactions were attempted under similarconditions using WO,-H,O in place of MoO,-H,O, but notungsten analogue could be obtained.The X-ray analysis of complex 4 reveals that a minimalchange in the nature of the cation (from NMe,' in 2 to NH4+here) results in a dramatic change in the resultant complex(i.6..from dinuclear in 2 to mononuclear in 4), Fig. 4. Themolybdenum atom again has pentagonal-bipyramidal geometrywith the primary axial site occupied by an 0x0 ligand and theYh u- CFig. 4 Structure of the anion in complex 4equatorial positions filled by two q2-peroxo groups and adiphenylphosphinate oxygen atom. The secondary axialposition, in the absence of any q2,q1 interaction, is occupied byan aqua ligand. The Mo-OH, distance of 2.368(2) A is typicalof that observed in other molybdenum and tungsten diperoxospecies. 1,1 The overall co-ordination geometry again differslittle from that observed in the dinuclear molybdenum andtungsten species 1, 2 and 3 (see Table 1).As expected, the P-O( 1) distance [I .536(2) A] is significantlylonger than P-0(2) [ 1.488(2) 813, the latter retaining its doublebond character.An analysis of the packing of the molecules reveals that theNH,' cation plays, together with the aqua ligand, a major rolein the determination of the solid-state superstructure.TheNH,+ cation is almost promiscuous in its nature, distributingits favours equally, forming N-H 0 hydrogen bonds tophosphinato 0x0 [0(2)], peroxo [0( 13)], aqua [0(25)] and0x0 [0( 1 l)] oxygen atoms of adjacent molecules (depicted, bylinks a, b, c and d respectively, in Fig. 5). One of the hydrogenatoms of the aqua ligand is linked to one of the peroxo oxygenatoms [0( 15)] of a centrosymmetrically related anion, whilstthe other links to the phosphinato 0x0 oxygen atom [0(2)] ofa lattice-translated anion (in a), depicted, by links e and fJ.Chem. SOC., Dalton Trans., 1996, Pages 2039-2045 204Table 2 Vibrational spectroscopic characteristics (cm ')' of complexes 1 4Complex v(M=O) v ( 0 - 0 ) Va5ym(M20) vaymCM(0)211 975vs 873vs b 5902 968vs 872vs 757s 591s3 970vs 846vs 736s 578s4 962vs 87111s ~~ 581sRaman data in italics (relative intensities in parentheses). I, Band obscured by the cacodylate ion.978( 10) 8 70( 9) 748( 3 ) 586(4)970( 10) 8 79( 8 ) 752( 3 ) 592(4)970( 10) 859( 9) 704( 3 ) 5 78( 4 )956( Z0) 875(6) - 577(2)v,ymCM(0)21549s5S6( 3)540s533(5)539s537(5)553s538( 3 )c4Fig. 5 Part of the extended hydrogen bonding in the structure ofcomplex 4, showing the environment of the ammonium cation.Hydrogen bonding geometries; N - .- 0 and H - - - 0 distances (A) andN-H . 0 angle ("), a, 2.83, 1.94, 166; b, 2.85, 2.21, 128; c, 2.98, 2.15,153; d, 3.10,2.22,166; 0 - - - 0 and H . - 0 distances (A) and O-H - 0angle("), e, 2.75, 1.85, 174; f, 2.71, 1.81, 172respectively, in Fig. 5. The combination of these hydrogen-bonding interactions produces extended sheets, two complexesthick, that extend in the crystallographic a and b directions.Vibrational and 31P-(1H) NMR spectroscopyThe infrared and Raman spectra of complexes 1-4 (Table 2)show features comparable to those observed for "Me4],-( 0 2 ) 2 ) 4 ] 3 - [M = Mo or W, X = P or As]., Bands near970 cm ' are assigned as v(M=O), those between 845 and 880cm ' as v(0-0) of the q2-peroxo ligands and those around580 and 535 cm-I as asymmetric and symmetric [M(O,)]stretches, respectively. Our assignments are based on thoseestablished by us for Venturello's complex.2 In addition tobands due to the counter ions, NMe,+ and NBu",+, and thediphenylphosphinic acid, P=O stretches appear near 1080 cm- '.Bands due to the cacodylate ligand, [Me,AsO,]-, obscure theasymmetric (M20) and [M(O,)] stretches.The 31P-{ 'H) NMR spectra of complexes 2 and 3 in CD,CNshow sharp bands at 6 49.3 and 5 1.9 respectively, the latter withpoorly resolved ' 83W satellites.The solid-state 31P-{ 'H}spectrum of 2 shows a sharp peak at 6 48.0, whilst that of 3shows two peaks at 6 52.7 and 53.9. This splitting probablyreflects the disorder found in the crystal structure, but itnevertheless seems likely that 2 and 3 have essentially the samestructures in solution as in the solid state.Unfortunately thecomplexes were not sufficiently soluble to allow the Ramanspectra of solutions to be recorded. The solid-state NMRspectrum of 4 shows two sharp peaks at 6 33.2 and 30.5, butunfortunately solution spectra could not be obtained due to thelow solubility of the complex.The NMR spectra of solutions of complexes 2 and 3 inCD3CN with added H202 show broad bands at 6 49.1 (2) and46.7 (3), and sharp bands at 28.7 (2) and 30.1 (3). The sharpbands increase in intensity as the concentration of H,O, isincreased. It seems likely that for 2 the 6 49.1 band arises from[(Ph PO,) { WO(02) 2 } 2 { WO(02 12 (H 2 0 ) ) 1 and C(X0,) { MO-the monoanionic species [(Ph,P02){MoO(02)2),] - and the6 28.7 band from [(Ph2P0,){MoO(0,),(H,0))]~, the anion of4.If this is so, then the sharp 6 30.1 band of 3 could arise fromthe otherwise unknown tungsten analogue of the monomer 4.Epoxidation of cyclic and linear alkenesIn the presence of the phase-transfer cation [N(C,H, ,),]Cl in a1 : 1 (cation :complex) ratio (this was found to be the optimumratio), complex 3 will cleanly catalyse the epoxidation of anumber of cyclic and linear alkenes in a biphasic 15% H,02-benzene mixture at 75 "C (Table 3). The epoxidation of smallring cycloalkenes over 3 h is less effectively carried out incomparison with those of larger ring cycloalkenes. Theepoxidations are slightly less efficient than those catalysed byPO,){ WO(O,),} { WO(O,),(H,O))] ' under similar reactionconditions.The oxidation of linear primary alkenes, carried outfor 20 h, gave a low yield of epoxide, though the yields werehigher for longer chain alkenes. The presence of the phenylrings clearly has some effect on the catalytic ability as complex3 is not as efficient as the other dinuclear tungsten complexreported, [NBu",],[{ PO,(OH)){WO(O,),),]. l 4 Neumannand Miller,16 however, have recently shown that quaternaryammonium salts of [PO,( W0(02),j ,I3 - can be attached uiaphenyl groups to silica particles. It is therefore of interest todesign complexes (as has been done here) in which organoligands, for example phenyl groups, are bound to the hetero-atom as possible anchor points for attachment of the catalyststo surfaces such as silica.The molybdenum complexes 1 and 2, in the presence ofa stoichiometric amount of phase-transfer agent, will alsocatalyse alkene epoxidation, though far less efficiently than 3.This often appears to be the case with oxidations usingmolybdenum and tungsten complexes in which H,O, is thecooxidant.' The mononuclear complex 4, which contains onlyq2-peroxo groups, is an even poorer catalyst than either 1 or2 for the epoxidation of cyclic alkenes.either CN(CbH 1 3)413cp04{ w0(02)2 )4] Or CNMe,I,C(Ph-Oxidation of primary and secondary alcohols and tertiaryaminesWhen complex 3 is used as a catalyst for the oxidation ofprimary and secondary alcohols under the same conditions asdescribed above for the epoxidation of cyclic alkenes, goodyields of aldehyde and ketone respectively are obtained (Table4).As the size of the ring of the secondary cyclic alcohols isincreased, the yield of ketone increases. The oxidation oftertiary amines catalysed by 3 was also successfully carriedout and good yields of the corresponding N-oxides obtained(Table 5 ) ; these reactions were typically carried out at 90 "Cin a biphasic 15% H,O,-toluene mixture for 5 h. Again themolybdenum complexes 1 and 2 are not as efficient as 3 forthese transformations. Complex 3 is a better oxidation catalystalcohols in respect of yields though not turnovers, and isthan ~ N M e , I , C ( P h P O , ) ~ W O ( ~ 2 ~ 2 ) ~ ~ ~ ~ ~ 2 ~ 2 ( H 2 ~ for2042 J.Chem. SOC., Dalton Trans., 1996, Pages 2039-204Table 3 Epoxidation of cyclic and linear alkenes by [NBu", ][(Ph,- Table 5 Oxidation of tertiary amines by [NBu",][(Ph,PO,){WO-PO,) I WO(0,)Z ; 2 1 3 * (02)2}213*SubstrateCyclopenteneCyclohexeneCyclohepteneCycloocteneCyclododeceneHept- 1 -eneOct- 1 -eneProductCyclopentene oxideCyclohexene oxideCycloheptene oxideCyclooctene oxideCyclododecene oxide1,2-Epoxyheptane1,2-EpoxyoctaneYield (%) [turnover]16 [24]67 [ l o l l85 [ 128130 [45]23 [35]8 [I218 [I21Non- 1 -ene 1,2-Epoxynonane 31 [47]Dec- 1 -ene I ,2-Epoxydecane 32 [48]Undec- 1 -ene 1,2-Epoxyundecane 34 [ 5 11Dodec- I -ene 1,2-Epoxydodecane 35 [53]* Reactions were carried out in a benzene-peroxide system refluxing at75 "C for 3 h for cyclic alkenes and 20 h for linear alkenes.Table 4 Oxidation of primary and secondary alcohols by "Bun,]-[(Ph,PO,) ; WO(o,),; 21 3 *SubstrateRen7yl alcohol2-Methylbenzyl alcohol4-Methylbenzyl alcoholCyclopentanolCyclohexanol2-Methylcyclohexanol3-Methylcyclohexanol4-MethylcyclohexanolCycloheptanolCyclooctanolMenthol1 -PhenylethanolProductBenzaldeh y de2-Methylbenzaldehyde4-Meth ylbenzaldehydeCyclopentanoneCyclohexanone2-Methylcyclohexanone3-Methylcyclohexanone4-MethylcyclohexanoneCycloheptanoneCyclooctanoneMenthoneAcetophenoneYield (:4)[turnover]76 [I 14176 [114]85 [ 128137 [56]55 [83]72 [I08163 [95]59 [89]91 [I37153 [SO]85 [I28194 [I411* Reactions were carried out in a benzene-peroxide system refluxing at75 "C for 3 h.ConclusionIn the previous paper in the series' we intimated that thepresence of q2,q'-peroxo groups is a key feature in determin-ing the catalytic oxidation properties of heteropolyperoxocomplexes containing an organic phosphonate.Here we havedemonstrated this principle to hold for the simpler dinucleararsinate and phosphinate species 1-3. It is still not clear, how-ever, why the presence or absence of such linkages should havesuch a marked effect on the catalytic efficacy, though we havediscussed possible reasons for this earlier.'Complexes 1-4 all have essentially identical distortedpentagonal-bipyramidal geometries with two equatorial peroxogroups, a short axial 0x0 ligand and a significantly longer transSubstratePyridine-2-carboxylic acidNicotinic acidIsonicotinic acidPyridine-2,3-dicarboxylic acidPyridine-2,5-dicarboxylic acidPyridine-2,6-dicarboxylic acidPyridine-3,4-dicarboxylic acidYield of N-oxide (%) [turnover]58 [87]72 [ 108157 [86]71 [I07127 [41]86 [I29185 [I281* Reactions were carried out in a toluene-peroxide system refluxing at90 "C for 5 h.of which were refined anisotropically.The phenyl rings instructures 2 4 were refined as optimised rigid bodies. All C-Hhydrogen atoms were placed in idealised positions, assignedisotropic thermal parameters, U(H) = 1.2Ue,(C) [U(H) =1.5Ue,(C-Me)] and allowed to ride on their parent carbonatoms.' In 4, the positions of the ammonium and aqua hydrogenatoms were determined from a AFmap and refined isotropicallysubject to N-H and O-H distance constraints (0.90 A).Refinement in all cases was by full-matrix least squares basedon F2. Computations were carried out on 50 MHz 486DX PCcomputers using the SHELXTL PC program system.'Atomic coordinates, thermal parameters and bond lengthsand angles have been deposited at the Cambridge Crystallo-graphic Data Centre (CCDC). See Instructions for Authors,1996, Issue 1. Any request to the CCDC for this material shouldquote the full literature citation and the reference number186/9.GeneralInfrared spectra of the solids were measured over the range4000400 cm-' using KBr discs on a Perkin-Elmer 1720Fourier-transform spectrometer, Raman spectra of the solids(as powders in melting-point tubes) on a Perkin-Elmer 1760XFT-IR instrument fitted with a 1700X NIR FT-Ramanaccessory using a Nd : YAG laser (1064 nm excitation).TheNMR spectra were obtained on a JEOL ESX 270 spectrometer(31P, 109.25 MHz) as CD3CN solutions, using external H3PO4as reference. The gas chromatography data were obtained on aPerkin-Elmer Autosystem instrument using a Perkin-Elmerstainless steel column (2 m) packed with 5% Carbowax 20M onChromasorb WHP AW (DCMS treated). Microanalyses werecarried out by the Microanalytical Laboratories at ImperialCollege.The trioxides Mo03-H20 and W03-H20 were obtained fromBDH and Fluka Chemie AG, respectively.Hydrogen peroxidewas obtained from BDH as a 30% wjv aqueous solution andwas used as supplied. Diphenylphosphinic acid and cacodylicacid (dimethylarsinic acid) were both obtained from Aldrich.Syntheses"Me,] [(Me,AsO~{MoO(O,),},] I . Hydrated molybdenumtrioxide, Mo03-H20 (0.72 g, 5.0 mmol), was suspended inaxial M-0 bond; the latter arises from an q2,q1-peroxo linkagein complexes 1-3 and an aqua ligand in 4.ExperimentalX-Ray crystallographyA summary of the crystal data, data collection and refinementparameters for compounds 1-4 is given in Table 6. All fourstructures were solved by direct methods and the majoroccupancy non-hydrogen atoms were refined anisotropically.In 3, the minor occupancy (45%) oxygen atoms were refinedisotropically.In 4, both phenyl rings were found to have welldefined, alternative, 50% partial occupancy orientations, allaqueous hydrogen peroxide solution (4 cm3. 30% wjv) and theresulting suspension stirred at 30 "C until a yellow solutionwas obtained. Upon cooling to ambient temperature, Na-[Me2As0,] (0.40 g, 2.5 mmol) in ethanol ( 5 cm3) was addedfollowed by dropwise addition of [NMe4]CI (0.27 g, 2.5 mmol)in water ( 5 cm3). Ethanol ( 5 cm3) was added and the mixturecooled to 4 "C. The bright yellow crystalline solid was filteredoff, washed with cold ethanol (2 x 5 cm3) and diethyl ether(10 cm3) and then air dried. Yield 1.2 g, 2.13 mmol (85%)(Found: C, 12.8; H, 2.9; N, 2.5. Calc. for CbHl,AsMo2NO12:C, 12.8; H, 3.2; N, 2.5%).J. Chem.SOC., Dalton Trans., 1996, Pages 2039-2045 204Table 6 Crystallographic data for complexes 1 4 '1 2 3 4Chemical formulaA4Crystal systemSpace groupUIAblA44"PI"rl"uiA3zDJgp1rnrn-lF( 000)Colour, habitCrystal sizelmm28 Range/"Independent reflections ( Ri,JObserved reflections [IF,I > 40((Fol)]Absorption correctionMaximum, minimum transmissionNo. of parametersu, b in weighting schemeFinal R , (wR2)'Largest, mean AjoData : parameter ratioLargest difference peak, holele AC,H ,AsMo2NOl563.01Monoclinic14.098( 1 )10.3 18( 1)12.652(2)P2 1 lc113.324(7)1690.0(3)42.2133.4821096Yellow, blocks0.92 x 0.48 x 0.232955 (0.02)2587Empirical0.7736, 0.28831990.08 19, 1.50950.044 (0.1 15)-0.001, 0.00013.00.89, -0.875-50Cl ,H22Mo2NO, 2p643.20MonoclinicP2 I In11.203( 1 )18.023(2)1 I .419( 1 )97.095( 6)2288.1(4)41.8671.2271280Yellow, blocks0.80 x 0.37 x 0.234-504046 (0.02)3628Semi-empirical0.4543, 0.39932660.0365, 1.8 1230.028 (0.072)- 0.00 1, 0.00013.60.37, -0.41C28H,6N01 2pw2987.33TriclinicP i10.352(3)12.776( 1 )13.641(2)98.069( 9)100.89(2)91.77( 1 )1751.1(6)21.8736.667960Clear, prisms0.27 x 0.22 x 0.13&505578 (0.03)3272Semi-empirical0.663 1, 0.35984140.0457, 10.87300.060 (0.122)0.542, 0.0477.901.13, -1.54C, 2H,,MoN08P429.2Triclinic6.014( 1)8.671(2)15.328(3)87.90( 2)86.92(2)86.56( 2)796.3(3)I .7900.964432Yellow, blocks0.59 x 0.40 x 0.287 -502788 (0.02)2612Pi3 -2920.0388,0.77000.026 (0.071)8.95-0.006, 0.0010.43, -0.38a Details in common: Siemens P4/PC diffractometer, graphite-monochromated Mo-Ka radiation, o scans, room temperature, data corrected forLorentz and polarisation factors, refinement based on F2.w = o2(FO2) + (UP)' + hP. ' wR2 = (C[w(Fo2 - F , ' ) ' ] ~ C [ ~ ~ ( F , ' ) ' ] ) ~ .[NBu",] [(Me,As0,){MoO(0,),}2]. Hydrated molybdenumtrioxide, Mo03*H,0 (0.72 g, 5.0 mmol), was suspended inaqueous hydrogen peroxide solution (4 cm3, 30% w/v) and theresulting suspension stirred at 30 "C until a yellow solution.was obtained. Upon cooling to ambient temperature, Na-[Me,AsO,] (0.40 g, 2.5 mmol) in ethanol ( 5 cm3) was addedfollowed by dropwise addition of [NBu",]Cl(O.69 g, 2.5 mmol)in water ( 5 cm3).Ethanol ( 5 cm3) was added and the mixturecooled to 4 "C. The bright yellow crystalline solid was filteredoff, washed with cold ethanol (2 x 5 cm3) and diethyl ether (10cm3) and then air dried. Yield 1.1 g, 1 S O mmol (60%) (Found:C, 30.8; H, 5.5; N, 2.0. Calc. for C,,H,,AsMo,NO,,: C, 29.7;H, 5.8; N, 1.9%)."Me,] [ (Ph,PO,){MoO(O,),},] 2. Hydrated molybdenumtrioxide, Mo03-H20 (0.72 g, 5.0 mmol), was suspended inaqueous hydrogen peroxide solution (4 cm3, 30% w/v) and theresulting suspension stirred at 30 "C until a yellow solution wasobtained. Upon cooling to ambient temperature, Ph,PO(OH)(0.55 g, 2.5 mmol) in ethanol ( 5 cm3) was added followedby dropwise addition of [NMe,]C1(0.27 g, 2.5 mmol) in water( 5 cm3).Ethanol ( 5 cm3) was added and the mixture cooledto 4 "C. The bright yellow crystalline solid was filtered off,washed with cold ethanol (2 x 5 cm3) and diethyl ether (10cm3) and air dried. Yield 1.1 g, 1.63, mmol (65%) (Found: C ,29.8; H, 3.1; c 2 . 2 . Calc. for C,,H,,Mo,NO,,P: C, 29.9; H,3.5; N, 2.2%).[ NBu",] [(Ph,PO,){MoO(O,),},]. Hydrated molybdenumtrioxide, MOO,-H,O (0.72 g, 5.0 mmol), was suspended inaqueous hydrogen peroxide solution (4 cm3, 30% w/v) and theresulting suspension stirred at 30 "C until a yellow solution wasobtained. Upon cooling to ambient temperature, Ph,PO(OH)(0.55 g, 2.5 mmol) in ethanol ( 5 cm3) was added followedby dropwise addition of [NBu",]CI (0.69 g, 2.5 mmol) in water( 5 cm3).Ethanol ( 5 cm3) was added and the mixture cooledto 4 "C. The bright yellow crystalline solid was filtered off,washed with cold ethanoj (2 x 5 cm3) and diethyl ether (10cm3) and air dried. Yield'1.27 g, 1.56 mmol (62%) (Found: C,41.5; H, 5.3; N, 1.7. Calc. for C,,H,,Mo,NO,,P: C, 41.4; H,5.7; N, 1.7%).[NBu",] [ (Ph2P0,){WO(0,),},] 3. Hydrated tungsten triox-ide, WO,-H,O (1.25 g, 5.0 mmol), was suspended in aqueoushydrogen peroxide solution (4 cm3, 30% w/v) and the resultingsuspension stirred at 30 "C until a colourless solution wasobtained. The resulting solution was centrifuged to remove anyinsoluble material. Diphenylphosphinic acid (0.55 g, 2.5 mmol)in ethanol ( 5 cm3) was added followed by dropwise addition of[NBu",]C1(0.69 g, 2.5 mmol) in water ( 5 cm')).Ethanol ( 5 cm3)was added and the mixture cooled to 4°C. The colourlesscrystalline solid was filtered off, washed with cold ethanol(2 x 5 cm3) and diethyl ether (10 cm3) and air dried. Yield1.9 g, 2.22 mmol (89%) (Found: C, 34.4; H, 4.5; N, 1.4. Calc.for C,8H,,N012PW,: C, 34.1; H, 4.7; N, 1.4%).[ NH,] [ (Ph2P0,){Mo0(0~,(H20)}] 4. Hydrated molybde-num trioxide, Mo03-H,0 (0.72 g, 5.0 mmol), was suspended inaqueous hydrogen peroxide solution (4 cm3, 30% w/v) and theresulting suspension stirred at 30 "C until a yellow solution wasobtained. Upon cooling to ambient temperature Ph,PO(OH)(1.09 g, 5.0 mmol) in ethanol ( 5 cm3) was added followedby dropwise addition of NH,Cl (0.13 g, 5.0 mmol) in water( 5 cm3).Ethanol ( 5 cm3) was added and the mixture cooledto 4°C. The bright yellow crystalline solid was filtered off,washed with cold ethanol (2 x 5 cm3) and diethyl ether (10cm3) and air dried. Yield 1.6 g, 3.73 mmol (75%) (Found: C,33.4; H, 3.7; N, 3.3. Calc. for C,,H,,MoNO,P: C, 33.6; H, 3.8;N, 3.3%).General procedure for epoxidation of cycloalkenesThe catalyst 3 (0.1 mmol) and [N(C6H1 3)4]Cl (0.1 mmol) weredissolved in benzene (8 cm3) and the alkene (15 mmol) added.Hydrogen peroxide (15% w/v, 10 cm3) was added to the2044 J. Chern. SOC., Dalton Trans., 1996, Pages 2039-204benzene solution and the biphasic mixture refluxed at 75 "C for3 h. The resulting organic layer was then analysed by gaschromatography.General procedure for epoxidation of linear alkenesThe catalyst 3 (0.1 mmol) and [N(C,H, 3)4]CI (0.1 mmol) weredissolved in benzene (8 cm3) and the alkene (1 5 mmol) added.Hydrogen peroxide ( 1 5% wiv, 10 cm3) was added to thebenzene solution and the biphasic mixture refluxed at 75 "C for20 h.The resulting organic layer was then analysed by gaschromatography and/or H NMR spectroscopy.General procedure for oxidation of primary and secondaryalcoholsThe catalyst 3 (0.1 mmol) and [N(C,H,,),]CI (0.1 mmol) weredissolved in benzene (8 cm3) and the alkene (1 5 mmol) added.Hydrogen peroxide (15% wiv, 10 cm3) was added to thebenzene solution and the biphasic mixture refluxed at 75 "C for3 h. The resulting organic layer was then analysed by gaschromatography.General procedure for oxidation of tertiary aminesThe catalyst 3 (0.1 mmol) and [N(C,H,,),]Cl(O.l mmol) weredissolved in toluene (8 cm3) and the alkene ( 1 5 mmol) added.Hydrogen peroxide ( 1 5% wiv, 10 cm3) was added to the toluenesolution and the biphasic mixture refluxed at 90°C for 5 h.Upon cooling the solid was filtered off, washed with water ( 5cm3), diethyl ether (2 x 10 cm3) and air dried.The yield, IRspectrum and melting point of the product were recorded.AcknowledgementsWe thank the EPSRC for a postdoctoral fellowship to one of us(B. C. P.) and Solvay-Interox and the EPSRC for a CASE awardto N. M. G. The University of London Intercollegiate ResearchService is thanked for the Raman spectrometer and the EPSRCfor the X-ray diffractometer.We thank Patrick Barrie andDavid Butler of the University of London IntercollegiateResearch Service for running the solid-state NMR spectra, andBill Sanderson and Craig Jones of Solvay-Interox, Widnes forhelpful discussions.References1 W. P. Griffith, B. C. Parkin, A. J. P. White and D. J. Williams,J . Chem. Soc., Dalton Trans., 1995, 3131.2 A. C. Dengel, W. P. Griffith and B. C. Parkin, J . Chem. SOC., DaltonTrans., 1993, 2683.3 C. Venturello, R. D'Aloisio, J. C. Bart and M. Ricci, J. Mol. Catal.,1985,32, 107.4 W. P. Griffith, B. C. Parkin, A. J. P. White and D. J. Williams,J. Chem. Soc., Chem. Commun., 1995,2183; L. Salles, C. Aubry, F.Robert, G . Chottard, R. Thouvenot, H. Ledon and J.-M. Bregeault,New J. Chem., 1993, 17, 367; C. Aubry, G. Chottard, N. Platzer,J.-M. Bregeault, R. Thouvenot, F. Chauveau, C. Huet and H.Ledon, Znorg. 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ISSN:1477-9226
DOI:10.1039/DT9960002039
出版商:RSC
年代:1996
数据来源: RSC