1978 1387Heteronuclear Cluster Systems. Part 13. t Synthesis of p-Diphenyl -phosphido-bridged Carbonylmetal Complexes, and Crystal Structureof 1.2-p-Carbonyl-1 ,I ,2,2,3,3-hexacarbonyl-I ,3 ;2,3-bis-p-diphenylphos-p h id o - trr'anguh - t r i co ba I tBy Jennifer C. Burt. Roland Boese, and Gunter Schmid," Fachbereich Chemie, The University, Lahnberge,3550 Marburg, West GermanyReaction of PPh,CI with Li[Co,(CO),,] or [CO,(CO)~] gives the new complex [Co,(CO),(pil:CO)(p-PPh,),] andthe known complex [(CO(CO)~(~-PP~,)),]. Both reactions appear to proceed via the intermediate species[Co(CO),(PPh,)] which may be trapped using [Fe,(CO)J as [CoFe(CO),(p,-PPh,)]. The crystal structure ofthe title complex has been determined by three-dimensional X-ray diffraction using Mo-K, radiation : a =19.271 (1 6).b = 11.870(3), c = 13.51 2(8) 8, @ = 99.36". Z = 4, space group P2Ja. R = 0.069 7. The threecobalt atoms form an isosceles triangle, two sides of which are bridged by PPh, groups (one symmetrically, theother asymmetrically) and the third side also unequally by a carbonyl group.THE preparation of the complex [{Co(CO),(PPh,)},],which is believed to contain doubly bridging diphenyl-phosphide groups, has been reported by several independ-ent research groups1-3. One synthetic method is thereaction of P,Ph, with [CO,(CO)~]. The parallel reactionof P,Me, with [Co,(CO),], however, gives only a clustercomplex formulated as [Co,(CO),(PMe,),] whose struc-ture has never been determined. Two suggestions weremade, (A) and (B).In (A) the phosphorus groups bridge* Present address : Fachbereich Chemie, The University,t Part 12 is ref. 12.Universit&tstrape, 4300 Essen 1, West Germany.R. G. Hayter, J . Amer. Chem. Soc., 1964, 86, 823.W. Hieber and H. Duchatsch, 2. Naturforsch., 1963, B18,1132.two cobalt atoms as in [{Co(CO),(p-PPh,)},] ; in (B) theyare triply bridging, and the phosphorus atoms adopt aco-ordination number of five.( A ) (B 1Phosphorus bridging three cobalt atoms has previouslybeen encountered for example in the cluster complexesW. Schweckendick, G.P., 1 072 244/1959.A. Vizi-Orosz, J . Organometallic Chew., 1976, 111, 611388 J.C.S. Daltonsolubility of (2). However, a very weak broad signal wasdetected a t ca. 18-19 p.p.m.which may be attributedto such a proton. The analogous complex [Co,(CO),-(PMe,),] probably has the same structure as (2), althoughthis has not been determined.1 Also, although the pre-vious molecule was shown to be diamagnetic, no conclu-sions were drawn as to whether it contained a cobalt-hydride bond, since no evidence for the hydride was[Co,(CO),P] and [Co,(CO),(PR)] .5 The structures ofthese complexes are believed to be based on a tetrahedralframework of C0,P. An X-ray crystallographic investi-gation of the structure of the analogous complex [CO,-(CO),S] has indeed shown this tetrahedral arrangementto be present.We now report the preparation of [ c o ~ ( c o ) ~ ( p c o ) -(PPh,),] and the determination of its structure by X -ray diffraction.In addition, related studies on carbonyl-cobalt-chlorodiphenylphosphine systems are presented.RESULTS AND DISCUSSIONThe reaction of [Co,(CO),] with PPh,C1 yields as majorproduct the orange crystalline complex [{Co(CO),(?-PPh,)),] ( l ) , thus providing an alternative route to thiscomplex. The i.r. spectrum, which correlates well withthat reported by Hayter,l and the elemental analysissupport this formulation. The 31P n.m.r. spectrum inbenzene shows a singlet 61.7 p.p.m. downfield from H,PO,.This indicates a small increase in electron density on thephosphorus atom relative to PPh,C1 (80.5 p.p.m.) .'The dark green-black crystalline cluster complex[ c o ~ ( c o ) ~ ( ~ ~ c o ) (p-PPh,),] (2) is also produced in the re-action of [Co,(CO),] with PPh,Cl. The complex ismoderately stable in air in the solid state.Its i.r. spec-trum shows a very complex pattern in the carbonyl-stretching region indicating a general lack of symmetryin the molecule. The presence of at least one bridgingcarbonyl group is indicated by a band a t 1 856 cm-l.An X-ray crystallographic analysis shows the structureof (2) to be based on an isosceles triangle of cobalt atomseach of which bears two terminal carbonyl ligands.Diphenylphosphide groups bridge the two longer sidesof the triangle and a carbonyl group the third side. Itis interesting to note that the environments of Co(1) andco(3) are very different. As may be seen from Figures(a) and ( b ) , Co(1) has an approximately octahedral ar-rangement of ligands, whereas co(3) may be consideredto have a pentagonal-pyramidal environment.Thisdifference is also shown by comparison of the bridgingligands. The P(2) bridge is rather asymmetric, whereasP(l) symmetrically bridges Co(1) and Co(2). The bridg-ing carbonyl ligand is also markedly asymmetric, beinglocated nearer to Co( 1). The analysis further reveals thepresence of two peaks of electron density in the apparentgap in the base of the pyramid round co(3). Thiselectron density is evidently the cause of the very differ-ent environments of Co(1) and co(3). The structurecould not be refined further, so that it cannot be de-termined whether a hydrogen atom occupies this posi-tion.Attempts to locate a metal hydride in the n.m.r.spectrum were inconclusive, despite phosphorus-decoup-ling and Fourier-transform techniques, due to the low5 L.Marko and B. Markb, Inorg. Chim. Acta, 1975, 14, L39.6 C. H. Wei and L. F. Dahl, Inorg. Chem., 1967, 6, 1229.K. Moedritzer, L. Maier, and L. C. D. Groenweghe, J . Chem.S. A. Fieldhouse, B. H. Freeland, C. D. M. Mann, and R. J.and Eng. Data, 1962, 7, 307.O'Brien, Chem. Comm., 1970, 181.Environments of (a) Co(1) and ( b ) c o ( 3 ) in [Co,(CO),(p-CO)-(p-PPh,),] ( 2 ) . . (c) Molecular structure of (2). One phenylgroup of P(1) is omitted for clarityfound in the 1H n.m.r. spectrum. As Hayter indicated,lsuch a signal may be overlooked due to coupling to phos-phorus.The reaction of PPh,C1 with the salt L~[CO,(CO)~,]whose proposed structure is shown in (C), was alsostudied. The same two products (1) and (2) were againfound.In contrast, the reaction of the complex ion withSiMe,Cl,g NMe,*BH,I,g [Ti(~p),Cl,]~~ (cp = q-C5H5), orMeCOBr l1 results in attack at the oxygen atom of the>C-0- group with retention of the C0,C cluster frame-work and formation of the complexes [Co,(CO),(COR)][R = SiMe,, BH,(NMe,), Ti(cp),Cl, or C(O)Me]. Thesolvent[c~,(co),,l- 'T--- [CO(CO),I- + [CO,(CO)~L~I (1)reaction reported here suggests that in toluene [CO,-(CO),,]- dissociates in an equilibrium reaction (1) (L =9 C. D. M. Mann, A. J. Cleland, S. A. Fieldhouse, B. H. Free-land, and R. J. O'Brien, J . Organometallic Chem., 1970, 24, C61.10 G. Schmid, V. Batzel, and B. Stutte, J .Organometallic Chem.,1976, 113, 67.11 V. Batzel and G. Schmid, Chem. Ber., 1976, 109, 33391978 1389solvent) to the reactive [Co(CO),]- and solvent-stabilised0- L i + I[C0,(C0)61~(C)Assuming that [Co(CO),]- ions are the reactive speciesin toluene solutions of Li[Co,(CO),,], then the initialproduct in the reaction with PPh,Cl is probably [Co-(CO),(PPh,)]. The nucleophilic character of the phos-phorus atom in this complex then causes room-temper-ture dimerisation accompanied by displacement of[Co(CO),]- anions are the reactive species in solutions ofWCO~(CO)IOI -The i.r. spectrum of (3) exhibits absorptions for ter-minal carbonyl groups but none in the bridging-carbonylregion. The mass spectrum shows a parent ion a t m/e496, and peaks corresponding to stepwise loss of sevencarbonyl groups.A field-desorption mass spectrumalso gave the molecular ion as m/e 496, and so confirmedthe presence of only seven and not the expected eightcarbonyl groups. After total decarbonylation the[CoFe(PPh,)]+ ion appears to fragment further to[CoFeP]+. Loss of the phosphorus atom completes thedecomposition. Alternative fragmentation patterns for(3) are also in evidence and the ions [Co(PPh,)]+,[Fe(CO),]+, and Fe+ may be identified.On the basis of the mass and i.r. spectra and micro-analysis a structure for (3) is proposed in which the di-phenylphosphide ligand acts formally as a three-electronPh [ /p\(OC)4Co C1'"/ [ (OC)~CO'PPh2 3t- 1 r(iii \0liil -11 - C O(3)(1 1 ( 2 )SCHEME (2) PPh,Cl; (ii) [Fe,(CO),] ; (iii) [Co,(CO),L,] or [Co,(CO),]carbon monoxide.If PPh,Cl is added to a solution ofLi[Co,(CO),,] at (-25 "C no appreciable gas evolutionoccurs, although reaction proceeds, and it appears thatthe species [Co(CO),(PPh,)] may be stable at low tem-peratures. In fact at -50 "C a small amount of redsolid believed to be [CO(CO)~(PP~,)] may be isolated, butrapid decomposition occurs at > -25 "C cven in an inertatmosphere.The complex [CoFe(CO),(p-PPh,)] (3) was preparedby treatment of [Fe,(CO),] with a toluene solution ofLi[Co,(CO),,] and PPh,Cl at -78 "C. The yield ob-tained by adding [Fe,(CO),] to a reaction mixture ofNa[Co(CO),] and PPh,Cl at -78 "C is considerably higherthan from Li[Co,(CO),,].This is further evidence thatdonor, bridging the two metal atoms. The cobalt atombears three carbonyl groups and the iron four. Ametal-metal bond is necessary to satisfy the electronicrequirements of the two metals.Varying yields of a third product may also be isolatedfrom the reaction of PPh,C1 with Li[Co,(CO),,]. The i.r.spectrum l2 and elemental analysis surprisingly indicatethe molecular formula [{Co(CO),),PPh] (4). The possi-bility that this product is formed from an impurity ofPPhCl, in the PPh,C1 is unlikely since reaction solutionsfrom which (4) may be isolated at lower temperaturesyield only (1) at room temperature. A mechanism forthe reaction may be suggested (see Scheme) in which the12 J. C . Burt and G. Schmid, preceding paper1390 J.C.S.Daltonproposed intermediate [Co(CO),(PPh,)] follows an altern-ative mode of decomposition eliminating PPh,.EXPERIMENTALMicroanalyses were either by the central analytical di-vision of the Department of Chemistry, Philipps-Universi-tat, Marburg, or by the A. Bernhardt MikroanalytischesLaboratorium , Elbach, West Germany. Infrared spectrawere recorded on a Perkin-Elmer 457 spectrometer andcalibrated using polystyrene. The Fourier-transform 31Pn.m.r. spectrum was obtained on a Varian XL 100 spectro-meter, using H3PO4 as external standard, the mass spectrumof (3) on a Varian CH7 machine.All the operations were carried out under an atmosphere ofdry nitrogen. Solvents were dried and saturated with nitro-gen by distilling over potassium (toluene), Li[AlH,] (di-ethyl ether or light petroleum), or sodium diphenylketyl(tetrahydrofuran).The samples of PPh,Cl, [Co,(CO),], and[Fe,(CO) 9] were obtained commercially. The salts Na-[Co(CO),] l3 and Li[(Co,(CO),,] were prepared according toliterature methods.A toluene solution(10 cm3) of PPh,Cl (0.6 cm3, 710 mg, 3.23 mmol) was addeddropwise to a stirred toluene solution (40 cm3) of [Co,(CO),](1.0 g, 2.92 mmol) at room temperature. Slow evolution ofcarbon monoxide immediately commenced. After stirringfor 18 h the orange-red reaction mixture was filtered. Lightpetroleum (20 cm3) was added to the filtrate, precipitating asolid which was recrystallised from toluene-light petroleumand identified as [(Co(CO),(p-PPh,)),] (l), 410 mg (21%),m.p.148-150 "C (Found: C, 54.6; H, 3.20; Co, 18.05.Calc. for C,,H,,Co,O,P,: C, 54.9; H, 3.05; Co, 18.0%);v(C0) a t 2 045w, 1 995vs, and 1 968 (sh) cm-l in Nujol mull.The remaining toluene-light petroleum solution was re-duced in volume to 5 cm3 and another 15 cm3 of light petro-leum were added. After standing overnight a t 0 "C, green-black crystals of 1,2-p-carbonyl-l, 1,2,2,3,3-hexacarbonyZ-formed, 60 mg (4y0), m.p. 160-162 "C (Found: C, 50.25;H, 2.70. Calc. for C3,H,,Co30,P,: C, 50.05; H, 2.70%);v(C0) a t 2 OBOm, 2 034m, 1995 (sh), 1 983vs, 1977vs,1 962s, 1 852s, and 1 815w cm-l in Nujol mull.A toluene solution (10 cm3)of PPh,Cl (0.5 cm3, 600 mg, 2.73 mmol) was added dropwiseto a stirred toluene solution (40 cm3) of Li[Co,(CO),,] (pre-pared from [Co,(CO),]; 1.0 g, 2.92 mniol), at 0 "C.Afterstirring for 15 min a t 0 "C, the evolution of carbon monoxideceased. The red-brown reaction mixture was allowed torewarm to room temperature and was filtered. Additionof light petroleum (25 cm3) to the filtrate precipitated anorange solid which was recrystallised from toluene-lightpetroleum to give (1) (100 mg, 5%). The remaining solutionwas reduced in volume to 20 cm3, cooled t o 0 "C, and lightpetroleum (20 om3) added. Green-black crystalline (2)precipitated slowly overnight, 30 m g (2%) (Found: C,49.8; H, 2.75%).Preparation of p-Diphenylphosfihido-tricarbonylcobalttetracarbonyliron (Co-Fe) (3) .-(a) A toluene solution (10cm3) of PPh,Cl (0.5 cm3, 600 mg, 2.73 mmol) was addeddropwise to a toluene suspension (40 cn13) of Li[Co,(CO),,]{prepared from [Co,(CO),]; 1.0 g, 2.92 mmol) a t -78 "C.Tetrahydrofuran (10 cm3) and [Fe2(CO)9] (500 mg, 1.37mmol) were then added and stirring continued for 1 h.Thel3 W. Hieber, 0. Vohler, and G. Braun, 2. Naturforsch., 1958,B13, 192.Reacti~ns.-[Co,(CO)~] with PPh,Cl.1,3 ; 2,3-bis-p-diphenyZphos~hido-triangulo-tricobalt (2)Li[Co,(CO),,] with PPh,Cl.mixture was allowed to warm slowly to room temperature,and was then filtered. Solvent was removed from the fil-trate, and the residue pumped in vucuo for 30 min to re-move [Fe(CO),] formed during the reaction. A light petro-leum extract (30 cm3) of the residue was then chrornato-graphed on silica gel.The first band eluted with lightpetroleum was evaporated to give a dark red solid. Thiswas recrystallised from light petroleum to give (3), 20 mg(lye), m.p. 78-80 "C (Found: C, 45.2; H, 1.90%; M 496.Calc. for C,,Hl,CoFe07P: C, 45.95; H, 2.00%; M 496);v(C0) a t 2 0 9 4 m , 2037vs, 2 0 0 7 ~ s ~ 2003s, 1 981w, and1 972m cm-1 in light petroleum.(b) A toluene solution (10 cm3) of PPh,Cl (0.2 om3, 200 mg,0.91 mmol) was added dropwise to a suspension of Na[Co-(CO),] (200 mg, 1.03 mmol) in toluene (45 cm3) and diethylether (5 cm3) a t -78 "C. After stirring for 1 h, [Fe,(CO),](250 mg, 0.69 mmol) was added. Stirring was continued for3 h a t -78 "C and then 24 h a t room temperature. Thereaction mixture was filtered, solvent removed, and theresidue pumped in vucuo for 30 min.This was then ex-tracted with light petroleum (40 cm3). After concentrationand cooling to - 30 "C for 2 d, a black solid was precipitated.Recrystallisation from light petroleum gave (3), 60 mg (12%)(Found: C, 46.15; H, 2.10%).Preparation of p-Phenylphosphinediyl-bis(tetracarbony1-cobalt) (4).-A toluene solution (10 cm3) of PPh,Cl (0.48 cm3,570 mg, 2.60 mmol) was added dropwise to a stirred toluenesuspension (40 cm3) of Li[Co,(CO),,] (from [Co,(CO),] ; 1.0g, 2.92 mmol} a t -78 "C. Stirring was continued for 30min. The resulting red solution was filtered a t - 60 "C, andthe solvent volume reduced to 5 cm3. Cooled light petro-leum was added, followed by stirring a t -30 "C. Somesolid was precipitated and discarded, and the liquid layerdecanted.More light petroleum (30 om3) was added anda second portion of solid was precipitated. This was re-crystallised from toluene-light petroleum a t room tempera-ture to give orange (4), 60 mg (5y0), m.p. 95 "C (decomp.)(Found: C, 37.7; H, 1.80; Co, 25.7; P, 7.05. Calc forC,,H,Co,O,P: C, 37.35; H, 1.10; Co, 26.2; P, 6.90%).Crystal Structure of Conzplex (2) .-A single crystal of[Co,(CO),(p-CO)(p-PPh,),] with dimensions 0.20 x 0.18 x0.3 mm was selected and orientated inside a thin-walledcapillary. The crystal was then mounted on an automaticfour-circle diffractometer (Philips PW 1100, graphite mono-chromator, 03-2 0 scan, Mo-K, radiation) equipped with apeak searching program.Crystal data. C3,H,,Co307P,, M = 743.27, Monoclinic,U = 3 050 A3, 2 = 4, D, = 1.869 g cmP3, F(000) = 1 507.9,space group P2,/a, p(Mo-K,) = 16.6 cm-l.Theobserved systematic absencesof h0l for h = 2n + 1,Oh0 for K = 2n + 1, and hOO for h = 2n + 1 uniquely indi-cated the space group t o be P2,/a, which was subsequentlyconfirmed by the successful refinement of the resultingstructure. A total of 3 725 independent reflections wascollected within the range of 1 < 8 < 20" for f h f k I and8 = 20-22" for & hkl.The time of measurement perreflection was 40 s with 2 x 5-s background. Of thesereflections, 1 815 were set below an observation limit of Fmin.= a(F) = 6.5, and another eight reflections having small 8,being shaded by the primary beam stop, were also omittedfrom the least-squares refinement.No absorption correc-tion was applied.A Fourier synthesis based on the best E map provided thelocations of the cobalt and phosphorus atoms. These wereu = 19.271(16), b = 11.870(3), c == 13.512(8) A, p = 99.36"1978isotropically refined in a full-matrix calculation to R 0.33,within two cycles using the SHELX-76 program. Adiff erence-Fourier map revealed all the non-hydrogen atoms.The phenyl carbon atoms were refined as rigid groups, eachas a regular hexagon of carbon atoms having a fixed C-CCo(l)-C0(2)Co( 1)-P( 1)Co( 2)-P( 1)c o (2)-P (2)c o (1 )-c ( 1)CO(2)--c(2)Co (2)<0 (3)c0(3)-CO( 1)CO (3) -P( 2)CO (1)-C (6)CO( 1)-c (4)CO (2)-c (5)CO( 3)-c( 3)TABLE 1Bond lengths (A) in the molecule[c03(c0)6(p-c0) (p-PPh2)212.57 1 (3) Co(3)-C( 7)2.584(3) c ( 1)-0( 1)2.482(3) c (2)-0 (2)2.163(4) c (31-0 (3)2.174 (4) C(4)-0(4)2.170(4) C(5)-0(5)2.2 10 (4) c (6k-O (6)1.792( 17) c (71-0 (7)1.792(17) P(l)--C(8)1733(16) P (2) -c (20)1 823(15) P( 1)-C( 14)1.729( 19) P ( 2)-C (26)1.780( 19) (C-C) ring1.824( 17)1.128( 21)1.186 ( 19)1.139(23)1.148( 19)1.160 (24)1.115(20)1.097(22)1.838(4)1.819(4)1.850(4)1.825 (4)1.395 (fixed)TABLE 2Angles (") in the molecule[ c 0 3 ( c 0 ) 6 ( ~ - c 0 ) (pL-Pp11!2)21Co( l)-C0(2)-Co (3)Co(3)-Co( 1)-C0(2)c o (2)-Co( 1)-C( 1)c o (2)-co (1)-c (4)C0(2)-Co( 1)-P( 1)CO (2)<0 (3)-c0 (1)c0(2)<0( l)-c(6)C0(3)-Co(l)-c(1)CO (3)-c0 ( l)<( 4)CO (3)-Co ( 1)-C (6)Co(3)-Co( 1)-P( 1)P(1)-Co(1)-C(1)P( 1)-Co( 1)-c(4)c ( 1)-co (1)-c (4)Co( 1)-co (2)-c(5)c o (1)-co (2)-C( 2)c o (3)-co (2)-c (5)c o (3)-co (2)-C( 2)P( l)-Co(2)-P(2)P( 1)-Co( 2)-c (2)P( 2)-co (2)-c (2)Co( 1)-P( 1)-C0(2)c o ( 1)-P( 1 )-c (8)Co(l)-P(l)-C(14)c o (2)-P( 1 )-c (8)c o (2)-P( 1 )-c ( 14) c (1 4)-P ( 1 )-c (8)P(l)-Co( 1)-C(6)C( l)-Co( 1)-C(6)C ( 6)-Co ( 1) -C ( 4)57.5( 1)61.0(1)61.5(1)92.0(5)1 1 5.1 (4)136.5 (5)53.8(1)88.4(6)56.4 (5)157.8( 5)88.3( 1)142.0( 5)106.7 (6)95.1(6)101.9( 7)102.8( 7)101.8( 7)146.1(6)93.0 (6)12 1.5( 6)129.1( 6)138.2 (2)1 10.5 (5)105.4 (5)72.7(1)1 18.3 (2)12 1.6( 2)1 20.9 (2)1 19.5 (2)103.0( 2)(C-C-C) phenyl ring 120 (fixed)c o (2)-co (3)-c (3)c o (2)-co (3)-c (4)C0(2)-Co(3)-C( 7)c o (2)-Co( 3)-P( 2)c o (1 )-co (3)-c (3)Co( 1)-Co( 3)-C( 7)P (2)-co (3)-C( 3)P( 2)-co (3)-C( 4)C( 3)-co (3)-C( 7)C( 3)-co (3)-C( 4)C( 7)-co (3)-C( 4)P ( 1) -co ( 2) -c (5)P( 2)-co (2)-c (5) c (2)-Co(2)-C (5)Co( 1)-C( 4)-co( 3)CO ( 1)<0 (3)-c (4)CO ( 1)<0 (3)-P( 2)P( 2)<0( 3)-C( 7)CO (1)-C( 4)-O( 4)CO (3)-C (4)-0 (4)144.8( 6)104.7 (4)1 10.6( 5)53.1( 1)1 18.0( 6)125.2(5)106.4(1)1 OO.O( 5)15 1.2 (5)106.2(5)97.9( 8)90.5(6)98.7(7)93.1(6)97.2(6)l06.0(8)77.8(4)149.3( 1.4)132.4 (1.3)45.9(5)Co(3)-P( 2)-C0 (2) 72.3 (1)CO (3)-P (2)-C (20) 1 23.4 (2)CO( 3)-P( 2)-C( 26) 114.0( 2)CO (2)-P( 2)-C( 20) 1 18.5 (2)CO (2)-P( 2)-C(26) 125.6( 2)C(26)-P(2)-C(20) 102.5(2)bond length of 1.395 A.Thus it was only necessary to fur-ther refine the locations and orientations of the four pivotatoms within their ring. Three cycles lowered the R factorto 0.1064 with isotropic thermal motion. Block-matrixfour-cycle refinement of all the atoms including hydrogen incalculated positions (C-H 1.08 A) reduced R to 0.0697. Thethermal motion of all the hydrogen atoms was assumed to beequal and was refined to ~ i j 0.120 8 A2.All the attempts to locate an additional hydrogen atom* For details see Notices to Authors No. 7, J.C.S. Dalton, 1977,Index issue.1391(at a distance of ca. 1.63 A from a cobalt atom) failed. How-ever, a difference-Fourier map calculated using 951 reflec-tions within a small 8 range of 14.5" (Fmin.6.3, R 0.062)showed two strong peaks with respective electron densitiesof 0.5 and 0.4 e A-3 and several much lower peaks. Thehigher peak was located within a reasonable distance fromco(3) (1.7 A), but too near to P(2) (1.6 A), whilst the lowerpeak was 1.8 Thusneither peak could be identified as hydrogen. All theother peaks with electron density GO.25 e were within1.1 A of cobalt or phosphorus atoms.Scattering factors and anomalous dispersions for struc-ture-factor calculations were taken respectively from refs.14 and 15. Bond lengths and angles are given in Tables 1and 2, final positional parameters in Table 3. Structurefrom Co(3) and only 1.64 A from C(4).TABLE 3Final positional parametersX0.097 4(1)0.104 0(1)0.176 5(1)0.143 l(2)0.129 6(2)0.030 2(8)0.013 5(8)0.170 3(9)0.139 5(10)0.066 9(8)0.270 4(9)0.029 9(5)0.038 5(5)0.111 2(5)0.143 4(5)0.236 7(4)0.275 O(4)0.346 5(4)0.379 7(4)0.341 4(4)0.269 9(4)0.182 4(5)0.247 6(5)0.285 9(5)0.259 O(5)0.193 8(5)0.155 4(5)0.068 2(5)0.180 5(9)0,102 7(5)-0.002 2(5)-0.004 l(5)-0.050 7(5)-0.025 l(5)0.047 2(5)0.093 9(5)-0.013 2(6)-0.048 3(6)0.184 l(10)0.163 2(8)0.047 3(7)0.327 2(7)0.199 9(7)Y0.664 4(2)0.491 6(2)0.506 8(2)0.659 8(3)0.352 5(3)0.600 8(13)0.486 2(12)0.467 4( 13)0.678 8(14)0.435 2(13)0.806 9( 14)0.499 7(13)0.746 3(8)0.741 8(8)0.806 2(8)0.875 O(8)0.879 5(8)0.815 l(8)0.681 2(9)0.746 3(9)0.765 7(9)0.720 0(9)0.654 8(9)0.635 4(9)0.234 4(7)0.257 4(7)0.171 l(7)0.061 8(7)0.038 8(7)0.125 l(7)0.280 9(8)0.288 7(8)0.232 2(8)0.167 7(8)0.159 9(8)0.216 5(8)0.563 8(10)0.487 O ( 1 1 )0.440 l(13)0.731 7(10)0.399 O(12)0.895 4(10)0.492 9( 12)z0.304 O(2)0.369 2(1)0.168 O(3)0.294 9(3)0.362 7(11)0.155 3(12)0.497 l(14)0.407 7(12)0.092 6( 14)0.287 5(12)0.364 O(13)0.061 3(7)0.031 8(7)0.191 2(1)- 0.049 3( 7)-0.071 5(7)-0.100 9(7)0.009 6(7)0.169 9( 7)0.245 7(7)0.246 5(7)0.171 3(7)0.095 5(7)0.094 7(7)0.257 3(7)0.229 8(7)0.193 9(7)0.185 7(7)0.213 2(7)0.249 1 (7)0.363 l(7)0.330 2(7)0.381 7(7)0.466 O(7)0.499 O(7)0.447 5(7)0.399 4(10)0.129 O(10)0.578 5(11)0.472 3(8)0.025 7(1010.280 8(10)0.363 8(13)factors and thermal parameters are available as Supple-mentary Publication No.SUP 22314 (48 pp.).*Received, 10th November, 19771 [7/ 1983l4 P. A. Doyle and P. S. Turner, Acta Cryst., 1968, B24, 390.l5 D. T. Cromer and D. Libermann, J . Chem. Phys., 1970, 53,1891