3 The Transition Elements By F. A. HART and P. THORNTON Department of Chemistry Queen Mary College Mile End Road London El 4NS J. NEWBERY Department of Chemistry Goldsmiths' College New Cross London SE14 6NW Part I Scandium Yttrium the Lanthanides and the Actinides By F. A. Hart 1 Scandium A variety of reduced scandium halides are now known. The system sc CS3SC2C19 -csscc13 700 "C has been investigated and the shiny blue product found to have the hexagonal perovskite CsNiCl structure. This is similar to the Cs3Sc2C19 structure but with all Sc positions filled. Non-stoicheiometric phases exist between the two end-structures.' 2 Yttrium and the Lanthanides It is remarkable that much .more work has been done this year on the lanthanides than on the actinides.Beginning with the lower oxidation states solutions of Sm12 or Yb12 may easily be made by the quantitative reaction THF Sm(or Yb) + ICH2CH21-Sm(or Yb)12 + C2H4 The solids may be isolated as THF adducts; the solutions may be used for a variety of organic reductions.' The new compounds YC1 YBr Y2C13 and Y2Br3 have been made by heating Y with YCl or YBr at 1000-1150 K in tantalum capsules. They join the growing number of low-valent lanthanide halides which mostly contain metal octahedra with bridging halide ions. Y2C13 contains joined Y6Cls clusters with Y-Y = 3.266 3.638 3.694 A.' Several MO phases previously reported have proved to be highly contaminated with C H or N. A report has now appeared which describes the synthesis of pure face-centred cubic NdO and SmO by reaction of M203with metal.Golden yellow SmO (a = 4.943A) and NdO (a = 4.994A) are prepared at 1000 "C and pressures at or above 50 kbar. They show metallic conduction. No K. R. Poeppelmeir J. D. Corbett T. P. McMullen D. R. Torgeson and R.G. Barnes Inorg. Chem. 1980 19 129. 'P. Girard J. L. Namy and H. B. Kagan J. Am. Chem. SOC., 1980,102,2693. H. Mattausch J. B. Hendricks R. Eger J. D. Corbett and A. Simon Inorg. Chem. 1980.19 2128. 157 F. A. Hart J Newbery and P. Thornton reaction was observed for thulium; YbO made similarly has been previously rep~rted.~ Eu" is attracting attention because of its interesting fluorescent proper- ties arising from the 4f5d -+4f7transition. Eu2B204 and M(Eu)B204 (M = Sr or Ca) have been prepared by high-pressure synthesis and characterized.Thus Eu203 reacts with boron and H3B03 at 1000 "C during 3 h in vacuo to give Eu2B204. Further heating at 600-900 "C and 8-25 kbar gave various phases characterized by X-ray powder data. The best phosphor was Sr0.99E~0.01B204 which emits at 395 nm with 60% quantum efficiency at 313 nm excitation. The wavelength of the emission is strongly affected by the geometry of the ligand field.5 Complexes of EuC12 with crown ethers give a very intense emission at 433-467 nm the wavelength depending on the complex when irradiated in methanol at about 320 nm. Emission is up to 620 times more intense than the uncomplexed salt6 Turning from lower to higher oxidation states 2-5.5 mol dm- aqueous M,CO (M = K or Cs) 1mol dmP3 in KOH containing CeCI, PrCI, or TbC1 (0.1- 0.01 mol dm-3) was electrolytically oxidized for 3 h or oxidized by ozone.This procedure gave remarkable stable solutions of yellow Pr4' (A,, 283 nm) dark reddish-brown Tb4' (A,, 365 nm) and of course Ce4'. The alkaline medium provided considerable stabilization of the tetrapositive ions; Eofor Ce3'/Ce4' being only +0.05 V.' Much the greatest quantity of work has of course been upon the tripositive lanthanides and we begin with the solution studies. Enthalpies of solution for MBr (M = La-Er) and of Er metal and ErC1 in aqueous HCl have led to standard enthalpies of formation of MBr, ErCl, and Er3+(aq).8*9 Solutions of LaC1 in aqueous methanol in varied proportions were studied by '39La and 35Cl n.m.r.As methanol replaces water an increasing degree of La-C1 inner-sphere co-ordination occurs. There is rapid chloride exchange by a displacement process.1o Photoinduced electron transfer between Ce3+(aq) and Cu2'(aq) in sulphate solution has been studied by microsecond flash excitation techniques. The resulting Ce4' and Cu' complexes rapidly undergo reverse electron transfer. The primary photochemical process is bimolecular collision involving the lowest-energy 4f -P 5d excited state of Ce3'." The kinetics of the ligand-exchange reactions between Ce3' complexes of edta and diethylenetriaminepenta-aceticacid (dtpa) and the reactions of the cor- responding Tb3' system have been studied spectrophotometrically. For Tb3' the exchange takes place by both an H'-catalysed dissociative mechanism and by an associative pathway whereas for the Ce3' complexes the latter mechanism only is effective." Emission titrations have been used to investigate the adduct formation between several Eu3' P-diketonates and phosphate esters.Log K values range from 1.41 to 3.47 in CC14.13 Stability constants have been determined in aqueous solution J. M. Leger N. Yacoubi and J. Loriers Inorg. Chem. 1980 19 2252. K.-I. Machida G.-Y. Adachi J. Shiokawa M. Shimada and M. Koizurni Znorg. Chem. 1980 19,983. G.-Y. Adachi K. Tornokiyo K. Sorita and J. Shiokawa J. Chem. SOC.,Chem. Commun. 1980,914. D. E. Hobart K. Sarnhoun J. P. Young V. E. Norvell G. Marnantov and J. R. Peterson Inorg. Nucl. Chem. Lett. 1980 16 321.C. Hurtgen and D. Brown J. Chem. SOC.,Dalton Trans. 1980 70. J. Fuger L. Morss and D. Brown J. Chem. SOC.,Dalton Trans. 1980 1076. lo D. C. McCain J. Znorg. Nucl. Chem. 1980,42 1185. l1 R. P. Asbury G. S. Harnmond P. H. P. Lee and A. T. Poulos Inorg. Chem. 1980 19 3461. '' E. Brucker and I. Banyai J. Inorg. Nucl. Chem. 1980 42,749. l3 H. G. Brittain Inorg. Chem. 1980 19 640. The Transition Elements for complexation between Ce3+ Eu3+ Tm3' and Am3' and all three chloroacetates. Log K for any cation varies linearly with pK values of the anions.14 Various types of chiral interactions in aqueous lanthanide shift reagents leading to spectral resolution of enantiomeric substrates or to assignment of chirality have been Selection rules based on L S J quantum numbers and including perturbation by crystal-field effects and spin-orbit coupling have been developed in order to quantify factors governing the magnitudes of the chiroptical properties associated with f-f transitions in lanthanide complexes.l6 The correlation between luminescence lifetimes and numbers of co-ordinated water molecules has been further used to investigate solutions of Eu3+ and Tb3+ in malic acid. There are stepwise changes in the co-ordination environment of the metal ion as the pH is raised.17 A direct measurement of anisotropic magnetic susceptibilities can be obtained from the 2Hn.m.r. spectra of lanthanide or actinide complexes of known structure. The method depends on quadrupole coupling of the 2H nuclei which splits absorption lines at high field owing to partial ordering of the molecules in the field." The n.m.r.spectra of aromatic substrates olefins or phosphines are well shifted by M(f~d)~ (M = Pr or Yb fod = C3F7COCHCOCMe3) in association with Ag(fod) or AgCF,COCHCOMe. Thus toluene has its aromatic hydrogen resonances shifted 4 p.p.m. and resolved with couplings well defined." This paper describes an important development of an earlier method.20 An interesting series of papers has appeared concerning the n.m.r. spectra of lanthanide aquo- and dipicolinato- complexes. The 'H shifts of the dipicolinate ligands arise from a dipolar mechanism alone. The resulting conformational analysis shows the tris-complexes to be nine-co- ordinate tricapped trigonal prismatic in the second half of the series but that ligand mobility may be present in the first half.The relaxation time of the water protons has been used to determine hydration number. Thus the bis(dipico1inato) complexes have three H20 co-ordinated also and the mono-complexes have six H20 co-ordinated. In the aquo-complexes the very short s) correlation times of the proton relaxation rates predominantly arise from the cationic electron-spin relaxation. 21-24 * H and 13C n.m.r. shift data have been used to study the solution structures of complexes between La3' Pr3+ Eu3+ and Yb3+ with ethylene-1,2- dioxydiacetate ethylene-1,2-dithiodiacetate and ethylene-1,2-diaminodiacetate ions. The sulphur atoms in the thio-ligand do not ~o-ordinate.~' Crown and cryptate ligands continue to provide interesting studies.Using a potentiometric method the stability constants of lanthanide ions with the cyclic polyether 4,4'(5')-di-t-butylbenzo-18-crown-6were determined in propylene carbonate showing log K = 5.14 (La3') decreasing to 2.51 (Lu3'). For the M2+ ions log K = 7.60 (Sm2') and 7.31 (Yb2') -a great increase over the tripositive l4 D. D. Ensor and G. R. Choppin J. Inorg. Nucl. Chem. 1980 42 1347. l5 J. Reuben J. Am. Chem. SOC.,1980,102 2232. l6 F. S. Richardson Inorg. Chem. 1980 19 2806. S. Salama and F. S. Richardson Inorg. Chem. 1980,19 629. P. J. Domaille J. Am. Chem. Soc. 1980 102 5392. l9 T. J. Wenzel T. C. Bettes J. E. Sadlowski and R. E. Sievers J. Am. Chem. SOC., 1980 102 5903. D. F. Evans J. N.Tucker and G. C. de Villardi J. Chem. SOC.,Chem. Commun. 1975,205. B. M. Alsaadi F. J. C. Rossotti and R. J. P. Williams J. Chem. SOC., Dalton Trans. 1980 597. *' B. M. Alsaadi F. J. C. Rossotti and R. J. P. Williams J. Chem. SOC.,Dalton Trans. 1980 813 23 B. M. Alsaadi F. J. C. Rossotti and R. J. P. Williams J. Chem. SOC., Dalton Trans. 1980 2147. B. M. Alsaadi F. J. C. Rossotti and R. J. P. Williams J. Chem. SOC.,Dalton Trans. 1980 2151. *' G. R. Choppin and L. Kullberg Inorg. Chem. 1980,19 1686. 160 F. A. Hart J. Newbery and P. Thornton state. A reversible one-electron reduction was shown with an anodic shift of the polarographic wave.26 A series of complexes M(NO,),( 12-crown-4) (M = La-Lu) has been reported together with PrC13( 12-crown-4) and the possibly sandwich-type complex Pr(C1O4),( 12-crown-4)2.Their magnetic moments are 343% lower than free-ion value^.^' Lanthanide nitrates form three types of complex with 18-crown-6 (L) [M(N03)3L] [M(N0,)2Ll,[M(N03),l and [M(N03),(H20),].L. The structures of the first and third types have been reported. Thus [M(NO,),L] (M = La or Nd) show 12-co-ordination whereas in the third type (M = Gd) the 18-crown-6 is not co-ordinated to the nine-co-ordinate Gd3+ ion but is hydrogen-bonded to the co-ordinated water m01ecules.~~-~~ Complexes of lanthanide perchlorates with 18-crown-6 and di- tetra- and hexa-thia-18-crown-6 have been reported. They are M(C104),L(H20),(MeCN) (M = La Ce Pr Nd Sm Eu Ho or Yb x = 0 or 1 y = 0 l; or 2). The X-ray structure of [La(C104)2(H20)(dithia-18-crown-6)1C10 shows both S atoms co-ordinated (La-S = 3.030,3.045 A) and one bidentate and one unidentate c104-ion in the 10-co-ordinate complex cation.31 In an informative paper containing much thermodynamic data cyclic voltammetry has been used to investigate redox behaviour of Eu3' and Yb3+ 2,2,1- and 2,2,2-crj-ptates in water.The reduction is reversible with the M3' complexes being less stable than the M2+ because of enthalpy differences. The redox couple decreased from 626 mV for the aqueous Eu3' ion to 205 mV for the Eu3' complex with the 2,2,2-cryptate. Dis- sociation kinetics showed marked acid catalysis.32 Turning to papers purely or mainly concerned with X-ray crystal structures Lu(OH) is difficult to crystallize but crystals may be obtained by digestion of a gel with 9.7N-NaOH at 158 "C for 30 h.The structure shows a three-dimensional array has of octahedra with Lu-0 = 2.243 A.33 c~La(S0~)~irregularly nine-co-ordinated La (La-0 = 2.480-2.801 The P-diketonate Gd(aca~)~(H~O)~ is dimeric with Gd co-ordinated to six 0from the diketonate anions two 0from water molecules and an 0 from a diketonate anion 'belonging' to another Gd3+ ion. The repulsion energy of this (bidentate)3(unidentate)3type of co-ordination is con~idered.~~ The hydrated nitrate [La(NO3),(H2O),].H2O is 11-co-ordinate with La-OOitrate= 2.617-2.875 8 and La-O,,,, = 2.526-2.668 A.36 The somewhat similar salt K2[La(N03)5(H20)2] has slightly distorted icosahedral co-ordination of La with La-Onitrate = 2.595-2.791 A and La-O,,,, = 2.697 Another nitrato-complex (P~,As),[Eu(NO,)~] has ten-co-ordina-tion in a distortsd bicapped square-antiprismatic configuration with the mean Eu-0 = 2.48 The structures of [M{P(C6H,,)2S2}3] (M = Dy or Lu) have been 26 J.Massaux J. F. Desreux C. Delchambre and G. Duyckaerts Inorg. Chem. 1980 19 1893. " J.-C. G. Bunzli and D. Wessner Inorg. Chim. Acta 1980 44 L55. 28 J. D. J. Backer-Dirks J. E. Cooke A. M. R. Galas J. S. Ghotra C. J. Gray F. A. Hart and M. B. Hursthouse J. Chem. SOC., Dalton Trans. 1980 2191. 29 J.-C. G. Bunzli B. Klein and D. Wessner Inorg. Chim. Acta 1980 44 L147. 30 G. Bombieri G. de Paoli F. Benetollo and A. Cassol J. Inorg. Nucl. Chem. 1980,42 1347. 31 M. Ciampolini C. Mealli and N. Nardi J.Chem. Soc. Dalton Trans. 1980 376. 32 E. L. Yee 0.A. Gansow and M. J. Weaver J. Am. Chem. SOC.,1980,102 2278. 33 D. F. Mullica and W. 0.Milligan J. Inorg. Nucl. Chem. 1980 42 223. 34 N. Bukovec V. KauEiE and L. GoliE Acta Crysiallogr. 1980 B36 129. 35 M. C Favas D. L. Kepert B. W. Skelton and A. H. White J. Chem. SOC.,Dalton Trans. 1980,454. 36 B. Eriksson L. 0.Larsson L. Niinisto and J. Valkonen Inorg. Chem. 1980 19 1207. 37 B. Eriksson L. 0.Larsson L. Niinisto and J. Valkonen Acta Chem. Scand. Ser. A 1980 34 567. J.-C. G. Bunzli B. Klein G. Chapuis and K. J. Schenk J. Inorg. Nucl. Chew 1980 42 1307. The Transition Elements 161 determined in order to extend the series of known structures (those for M = Pr or Sm are known). The angle of twist of the three bidentate ligands in the trigonal structure can be related to the ligand bite angle.39 The template condensation of 1,2-diaminoethane with (CF3)2C(OH)CH2COMe in the presence of Ce(N03)3-6H20 in ethanol in air gives a bis-complex of the dianion (CF3),C(O-)CH,C(Me)=NCH2CHzN=C(Me)CH~C(O-)C(CF3)~com-(L).The plex [CeIVL2] shows approximate square-antiprismatic co-ordination to four N at 2.607-2.641 and 4 0 at 2.196-2.230 A."" Organo-lanthanide work this year has been mainly concerned with cyclo- pentadienyl complexes particularly of Yb2+. A number of solvated red EuZ+and red or green YbZ+ bis(pentamethylcyclopentadieny1) complexes have been prepared from EuC13 or YbC12 and NaC,Me in THF. The structure (X-ray) of [Yb(C,Me,),(THF)].$(toluene)shows two v5rings and one THF molecule to be co-ordinated (Yb-0 = 2.41 A; Yb-C av.= 2.66 A)."' The reaction of MeC5H5 with Yb(hex-3-yne) gives Yb(MeC5H4),THF which contains chains of Yb atoms bridged by methylcyclopentadienyl groups (Yb-CC,e,,,,,I = 2.76 8 av.; Yb-Cbrldge = 2.89 av.). This compound may also be produced by hydrogen reduction of (MeC5H4),Ybhle; in this case there is evidence for an unstable Yb3+ hydrido-c~mplex."~ Reduction of [{Yb(q -C5H4SiMe3),Cl}2] in THF by Na/Hg gives purple diamagnetic Y 3(C5H4SiMe3),(THF), which can be desolvated. The crystal structure shows two q5-rings (Yb-C = 2.75 A av.) and two co-ordinated THF molecules (Yb-0 = 2!.41 8,a~.)."~ Treatment of Yb metal with C5MeSI and LiI in ether gave Li[Yb"'(C,Me5)13] which spontaneously changed into purple Li[Yb"(C5Me5)12].44 When treated with LiC5Me5 in pentane-THF NdCl gave purple Li(THF),(C5Me5)2NtIC12; this compound probably has a dichloro-bridged ~tructure."~ 3 The Actinides There seems to be a slightly reduced level of activity in this area this year.Starting with thorium the X-ray crystal structure of ThC14(Ph2S0)4 shows dodecahedra1 co-ordination with C1 at the B sites and 0at the A sites (Th-C1 = 2.759,2.757 A; Th-0 = 2.46A; SOTh = 130° 135°).46 Some 2,2'-bipyridyl 1,l'-dioxide (L) complexes of thorium have been reported. They are Th(NO,),L ThX4L3 (X = C1 or Br) Th14L4 and Th(NCS)4L.47 The cyclo-octatetraene (cot) complex Th(cot) reacts with ThC14 in THFto give [ThCl,(cot)(THF),] which is a very air-sensitive compound which adopts two crystalline forms differing only in the molecular packing.The Th is co-ordinated to an q8-cot ring (Th-C = 2.69-2.75 A) two Cl(2.686 A) and two 39 A. A. Pinkerton and D. Schwarzenbach J. Chem. SOC.,Dalton Trans. 1980 1300. 40 J. H. Timmons J. W. L. Martin A. E. Martell P. Rudolf A. Clearfield J. H. Arner S. J. Loeb and C. J. Willis Inorg. Chem. 1980 19 3553. 41 T. D. Tilley R. A. Andersen B Spencer H. Ruben A. Zalkin and D. H. Templeton Inorg. Chem. 1980,19,2999. 42 H. A. Zinnen J. J. Pluth and W J. Evans J. Chem. Soc. Chem. Commun. 1980,810. 43 M. F. Lappert P. L. W. Yarrow J. L. Atwood R. Shakir and J. Holton J. Chem.SOC.,Chem. Commun. 1980,987. 44 P. L. Watson J. Chem. SOC.,Chcm. Commun. 1980 652. 4s A. L. Wayda and W.J. Evans Irorg. Chem. 1980,19,2190. 46 C. E. F. Rickard and D. C. Wodlard Acta Crystallogr. 1980 B36 292. 47 R. K. Agarwal A. K. Srivastava and T. N. Srivastava J. Znorg. Nucl. Chem. 1980 42 1347. I? A. Hart J. Newbery and P.Thornton THF (Th-0 = 2.57 A). The complex may be converted into T~(BH,),(CO~).,~ The pentamethylcyclopentadienyl (mcp) neopentyl (np) complex Th(mcp),(np)Cl pre- pared by reaction of Li(np) with Th(mcp),C12 shows some interesting reactions. It reacts with CO in toluene to give the pale yellow complex (1) (a = 2.37 A b = 1.18A c = 2.44 A),which is converted in toluene at 100"Cinto the colourless (2). However excess CO reacts with (1) to give the dark purple (3) which has a remarkable bridging enedione diolate ligand.,' mcP mcP /CM% I p,tJ I /O\ mcp-Thy-C-np mcp-Th /c=c\ H IH C1 c1 Turning now to uranium there has been little work on U3+ but the first crystal structure of a hydrated U3+ salt has appeared.The compound is NH4U(SO4),(H20), which can be manipulated in air. The U3+ ion is linked to two bidentate and to two unidentate ions and to three H20 (U-Osulphate = 2.37-2.60& U-Owater = 2.47-2.56 A). It is isostructural with the corresponding La-Tb compound^.^^ A few papers have appeared on U4+ compounds. The rather unstable UI has at length yielded half an X-ray-quality crystal. It is not isomorphous with ThI or UBr but has chains of edge-sharing octahedra with U-I = 2.92A (terminal) and 3.08,3.11 A (bridging). The structure was determined by both X-ray and neutron diffra~tion.~'Non-aqueous methods are superior for making U4+ tetrakis(diketonates) which can give poor yields from aqueous preparations.Various complexes have been prepared by admixture of UCl in ethanol with the P-diketone in toluene followed by removal of solvent under reduced pressure.52 In solutions of U(acac) or U(dbm), irradiation at the charge-transfer wavelengths causes reduction to U3+ as a primary process followed by thermal reoxidation to U4+ with abstraction of halogen from the solvent. Irradiation at f -+ f transition wavelengths in the presence of oxygen gives the uranyl bi~(diketonate),'~ The complex (Et4N)4[U(NCS)8] may be converted into (Et4N)[U(NCS)5(bipyridyl)2] 48 A. Zalkin D. H. Tempieton C. Le Vanda and A.Streitweiser Znorg. Chem. 1980 19 2560. 49 P. J. Fagan J. M. Manriquez T. J. Marks V. W. Day S. H. Vollmer and C. S. Day J. Am. Chem. SOC. 1980,102,5393. 50 J. I. Bullock M. F. C. Ladd D. C. Povey and A. E. Storey Znorg. Chim. Acta 1980 43 101. J. H. Levy J. C. Taylor and A. B. Waugh Znorg. Chem. 1980,19 672. '* V. L. De Vito and D. W. Wester J. Znorg. Nucl. Chem. 1980 42 1719. 53 S. Sostero 0.Traverso L. Magon P. Zanella and G. Scribona J. Chem. Soc.,Dalton Trans. 1980,1324. The Transition Elements 163 which is nine-co-ordinate with U-NNcs = 2.61-2.65 8 and U-Nbipy = 2.61-2.65 The glycolate [U(02CCH20H)4(H20)2] is a ten-co-ordinate distorted bicapped square antiprism where the anion co-ordinates through one carboxyl oxygen atom and the hydroxy-group with U-0 = 2.5498 (water) 2.404 and 2.3828 (carboxyl) and 2.411 and 2.506 8 (hydroxyl)." The 'H n.m.r.spectrum of (Ph4As)2[U(dipicolinate)3]in Me2S0 and CDCI3 shows over a range of tempera- tures that the dipolar and contact contributions to the paramagnetic shifts are of a similar magnitude. The contact effect is caused by spin delocalization in the u-A full report has now appeared of the reaction of LiCH2CH2PPh2 with UCI(C~HS)~, giving [{Ph2P(CH)CH2}2U2(C5H5)41.57 Reaction of UF with SbF gives UF5.2SbF5 which on being heated is converted into UF5.SbFS the crystal structure of which shows dodecahedra1 co-ordination of uranium by fluorine in the SbFS-bridged structure with U-F = 2.306-2.658 A (bridge) and 1.924-1.984 8,.(terminal).58 Remarkable new macrocyclic ligands with specific affinity for the UOZ2+ ion have been made.They are {-C(C02H)2(CH2)8-}3 and {-C(C02H)2C2H40C2H4- OCzH4-)3. The first ligand has log K = 16.4in aqueous solution the largest known for the UOZ2+ ion. When linked to a resin and immersed for four days in 5 1 Pacific Ocean water it extracted 6.85 pg of uranium (42%of that contained in the water).59 The X-ray structure of U02S04(urea)3 shows a close approximation to pentagonal- bipyramidal co-ordination with -U-0-SO2-0-U- in infinite chains and U-0 = 2.310-2.409 8 (urea) 2.380 and 2.407 8 (sulphate).60 Complexes have been described of U022+ with the ligands (4)and (5). These are converted into the uncharged complexes [U02L] [L = (6)or (7)] by the action of I R2 I R2 (4) R' = H R2 = 2-pyridyl (5) R' = H (6) R1absent R2 = 4-MeOC6H4C0 R2 = 2-pyridyl (7) R'absent R2 = 4-MeOC6H4C0 Some progress has been made in studies of the heavier actinides; Np(BH4) is similar to the Hf and Zr analogues in being 12-co-ordinated by tetrahedrally disposed terdentate BH4groups.It is very volatile (10 mmHg at 25 "C) and contrasts 54 R. 0.Wiley R. B. von Dreele and T. M. Brown Znorg. Chem. 1980,19 3351. '' N. W. Alcock T. J. Kemp S. Sostero and 0.Traverso J. Chem. SOC.,Dalton Trans. 1980 1182. 56 C. Miyake H. Sakurai and S. Imoto J. Inorg. Nucf. Chem. 1980,42 1725. 57 R. E. Cramer R. B. Maynard and J. W. Gilje Znorg. Chem. 1980,19,2564. 58 W. Sawodny and K. Rediess 2. Anorg. Allg. Chem. 1980,81,469. 59 I. Tabushi Y.Kobuke K. Ando M. Kishimoto and E. Ohara J. Am. Chem. SOC.,1980,102 5947. 6o H. Ruben B. Spencer D. H. Templeton and A. Zalkin Znorg. Chem. 1980 19 776. 61 G. Paolucci G. Marangoni G. Bandoli and D. A. Clemente J. Chem. SOC.,Dalton Trans. 1980,459. 62 G.Paolucci G. Marangoni G. Bandoli and D. A. Clemente J. Chsm. SOC., Dalton Trans. 1980 1304. F. A. Hart J. Newbery and P. Thornton with the Th Pa and U analogues which have e.g. UH2BH2Ubridges.63 Visible-u.v. spectra of Np species in aqueous nitric acid solution were not previously available in the open literature but have now been reported. Spectra of Np"' Np'" Np" and Np"' over the range 300-1400 nm are given. Owing to the coexistence of more than one species the spectra were deconvoluted digitally.64 249BkX (X = N P As or Sb) have been synthesized by heating 40 pg Bk (fromBkF4and Li) with excess P As or Sb at 540-690°C overnight in a quartz capillary.The nitride was made under different reaction conditions (1150 "C for 30 s). They all have the NaCl structure with a = 4.951,5.669,5.829 and 6.191 A re~pectively.~' Element 261104 has been synthesized by bombarding 248Cm with l80 ions. The recoil products were directed into a 'fast computer-controlled apparatus for performing chemical experiments' (a useful piece of equipment for any laboratory replacing scarce research students). The 26 1 104 was absorbed on a column containing a quaternary amine and showed in 12M-HCl complexation very similar to that of its homologue Hf.66