Martin J. Mays

The reaction of Ru3(CO)12 and Os3(CO)12 with PH2Ph; the x-ray crystal structures of HRu3(CO)10(PHPh) and H2Ru3(CO)9(PPh)

Abstract Twelve new trinuclear complexes containing terminal PH 2 Ph, edge-bridging PHPh and/or capping PPh ligands have been isolated from the reaction of M 3 (CO) 12 (M = Ru or Os) with PH 2 Ph in refluxing solvents. HRu 3 (CO) 10 (PHPh) (IIIa) crystallises in the monoclinic space group P 2 1 / c with a = 8.761(3), b = 11.402(4), c = 22.041(7) A,β = 98.89(2)°, and Z = 4. The structure was solved by a combination of direct methods and Fourier difference techniques, and refined by blocked-cascade least squares to R = 0.027 for 3676 unique observed intensities. The X-ray analysis shows that one edge of the Ru 3 triangle is bridged by a hydride and the PHPh ligand, and that the phosphorus-bound hydrogen atom lies over the metal triangle and the phenyl group away from it. This provides an explanation for the ready formation of the capped species H 2 Ru 3 (CO) 9 (PPh) (Va) on pyrolysis of the edge-bridged complex as opposed to the previously reported conversion of HOs 3 (CO) 10 (NHPh) to an orthometallated derivative under similar conditions. An X-ray analysis of H 2 Ru 3 (CO) 9 -(PPh) (Va) confirms the capped geometry. the complex crystallises in the monoclinic space group P 2 1 / n with a = 9.323(4), b = 15.110(6), c = 45.267(15) A,β = 91.84(3)°, and Z = 12. the structure was solved and refined using the same techniques as described previously. The final residual R is 0.061 for 4839 reflections. Some reactions of Va show that the phosphorous cap is difficult to displace and stabilises the molecule with respect to decomposition to non-cluster species.

Chemistry of phosphido-bridged dimolybdenum complexes. Part 3. Reinvestigation of the reaction between [Mo2(η-C5H5)2(CO)6] and P2Ph4; X-ray structures of [Mo2(η-C5H5)2(µ-PPh2)2(CO)2], [Mo2(η-C5H5)2(µ-PPh2)2(µ-CO)], and trans-[Mo2(η-C5H5)2(µ-PPh2)2O(CO)]

The thermal reaction of [Mo2(η-C5H5)2(CO)2] with P2Ph2 in toluene gives [Mo2(η-C5H5)2(µ-PPh2)2-(CO)2] in high yield. An X-ray diffraction study shows a Mo–Mo double bond [2.712(2)A] symmetrically bridged by two PPh2 groups, with a planar Mo2P2 core. Under u.v. irradiation, further decarbonylation occurs to give [Mo2(η-C5H5)2(µ-PPh2)2(µ-CO)], in which two PPh2 groups and a carbonyl ligand bridge a Mo–Mo triple bond of length 2.515(2)A. Oxidation of either of these complexes gives cis- and trans-[Mo2(η-C5H5)2(µ-PPh2)2(CO)]; the structure of the trans isomer has been determined by X-ray diffraction. Protonation of [Mo2(η-C5H5)2(µ-PPh2)2(CO)2] occurs across the metal–metal bond to give [Mo2(η-C5H5)2(µ-H)(µ-PPh2)2(CO)2][BF4].

The Preparation and 13C nmr Spectra of some Trinuclear Osmium Complexes Containing an O-Alkylated Carbonyl Group.

Abstract The new osmium clusters [HOs 3 (CO) 9 (CNBu t )(COR)] (R = Me or Et) and [HOs 3 (CO) 9 (CNBu t )(COMe)] have been prepared via the alkylation of [HOs 3 (CO) 11 ] − . These clusters contain an O-alkylated carbonyl group and are structurally different from the isomeric bridging acyl complexes [HOs 3 (CO) 10 (COR)] which have been reported previously. The two isomers do not interconvert even at elevated temperatures. The 13 C nmr spectra of the new complexes are reported together with the 13 C spectrum of the analogous iron complex [HFe 3 (CO) 10 (COMe)]. Alkyl group ‘flipping’ and polytopal rearrangement of the M(CO) 4 and M(CO) 3 units are observed for M = Os and Fe but there is no scrambling of CO groups between metal centres on the nmr timescale.

Reactions of P2Ph4 with alkyne-bridged dicobalt carbonyl complexes; crystal structures of [Co2{µ-C2(CO2Me)2}(µ-P2Ph4)(CO)4], [Co2{µ-PPh2CHCPhC(O)}(µ-PPh2)(CO)4] and [Co2{µ-PPh2C(O)CHCH}(µ-PPh2)(CO)3(PPh3)]

The reactions of P2Ph4 with a variety of substituted alkyne complexes [Co2(µ-RCCR′)(CO)6] in toluene give the complexes [Co2(µ-RCCR′)(CO)5(P2Ph4)]1(R = R′= CO2Me 1a or Ph 1b; R = Ph, R′= H 1c and [Co2(µ-RCCR′)(µ-P2Ph4)(CO)4]2(R = R′= Ph 2b; R = Ph, R′= H 2c. All three derivatives of type 1 are cleanly converted into 2 on thermolysis. An X-ray diffraction study of 2a reveals a square-planar Co2P2 core with the symmetrical alkyne perpendicular to the Co–Co bond. Further thermolysis of complexes 2 produces [Co2(µ-PPh2CRCR′)(µ-PPh2)(CO)4]3(R = R′= CO2Me 3a or Ph 3b and [Co2{µ-PPh2CRCR′C(O)}(µ-PPh2)(CO)4]4c(R = H, R′= Ph). The structure of 4c has been determined by X-ray analysis. The PPh2CHCPhC(O) ligand forms a five-membered metallacyclic ring incorporating one Co atom and is π-bonded to the other Co atom. Complexes 3a and 3b are partially converted into 4a(R = R′= CO2Me) and 4b(R = R′= Ph) on treatment with CO. This reaction is reversed by heating 4a and 4b in solution or, more slowly, on standing at room temperature. The parent acetylene complex [Co2(µ-HCCH)(CO)6] reacts with P2Ph4 differently from the substituted derivatives to give as the principal product [Co2{µ-PPh2C(O)CHCH}(µ-PPh2)(CO)4]5b. The structure of the PPh3 derivative of this complex, [Co2{µ-PPh2C(O)CHCH}(µ-PPh2)(CO)3(PPh3)]6d, has been determined by X-ray diffraction.

Preparation and Mössbauer spectra of some cyclopentadienyl iron complexes containing a chelating diphosphine ligand

Convenient methods of preparing complexes of the type (C5H5)Fe(dppe)X (dppe = Ph2PCH2CH2PPh2) are reported and some new complexes are described. The 57Fe and (for X = SnCl3 SnBr3 and Snl3) the 119Sn Mossbauer spectra of these complexes have been recorded, and are discussed in relation to the spectra of analogous C5H5Fe(CO)2X and C5H5Fe(CO)(L)X complexes (L = monodentate phosphine) which have been previously studied.

The reaction of diphenylphosphine, PPh2H, with an alkyne-bridged dicobalt carbonyl complex; the synthesis crystal structure and reactivity of the complex [CO2{μ-C(CO2Me)CHCO2Me}(μ-PPh2)(CO)4]

The reaction between [Co2(μ-C2(CO2Me)2)(CO)6] and diphenylphosphine gives the mono- and di-substituted complexes [Co2{μ-C2}(CO2Me)2(CO)6-n(PPh2H)n] [n = 1 (1), 2 (2)]. Thermolysis of (1) leads to phosphorus-hydrogen bond cleavage and formation of the phosphido-, vinyl-bridged complex [Co2{μ-C(CO2Me)CHCO2Me}(μ-PPh2(CO)4] (3) together with the trinuclear cobalt complex [Co3{μ-C2(CO2Me)2}(μ-PPh2(CO)7 (4). An X-ray diffraction study of 3 reveals that one of the methylcarboxylate substituents of the vinyl ligand is coordinated via oxygen to cobalt, forming an almost planar M-C-C-C-O five-membered metallacyclic ring. The reactions of (3) with a tertiary phosphine and with phenylacetylene are described.

Synthesis of phosphido-bridged ruthenium–manganese complexes; X-ray crystal structures of [RuMn(µ-H)(µ-PPh2)(η5-C5H5)(CO)5], [Ru2(µ-H)(µ-PPh2)(η5-C5H5)2(CO)2] and [RuMn2(µ-H)(µ-PPh2)2(η5-C5H5)(CO)9]

The complex [RuMn(η5-C5H5)(CO)7]1 has been synthesised in 70% yield from the reaction of [Ru(η5-C5H5)(CO)2I] with Na[Mn(CO)5]. Photolytic reaction of 1 with PPh2H gives the new complexes [RuMn(µ-H)(µ-PPh2)(η5-C5H5)(CO)5]2, [Mn2(µ-H)(µ-PPh2)(CO)7(PPh2H)]3, trans- and cis-[Ru2(µ-H)(µ-PPh2)(η5-C5H5)2(CO)2]4a and b, [RuMn2(µ-H)(µ-PPh2)2(η5-C5H5)(CO)9]5 and [RuMn2(µ-H)(µ-PPh2)2(η5-C5H5)(CO)8(PPh2H)]6 together with the known complexes [Mn2(µ-H)(µ-PPh2)(CO)8] and [Ru2(η5-C5H5)2(CO)4]. The crystal structures of 2, 4a and 5 have been determined. Structures are proposed for the other new complexes and the mechanism of the photolytic reaction of 1 with PPh2H is discussed.

The reaction of H2Os3(CO)10 with trifluoroacetonitrile and the x-ray crystal structure of HOs3(CO)9(μ3-η2-HNCCF3)

Abstract The reaction of H 2 Os 3 (CO) 10 with CF 3 CN in hexane at 80°C leads to two isomeric products. The isomer constituting the major product contains a 1,1,1-tri-fluoroethylidenimido ligand which bridges one edge of the Os 3 triangle via the nitrogen, atom and may be formulated as (μ-H)Os 3 (CO) 10 (μ-NC(H)CF 3 ) (I). The minor product, formulated as (μ-H)Os 3 (CO) 10 (μ-η 2 -HNCCF 3 ) (II), contains a 1,1,1-trifluoroacetimidoyl ligand which is also edge-bridging, being N-bonded to one Os atom and C-bonded to the other. Thermolysis of I and II in solution results in loss of a CO group in each case to give (μ-H)Os 3 (CO) 9 − (μ 3 -η 2 -NC(H)CF 3 ) (III) and (μ-H)Os 3 (CO) 9 (μ 3 -η 2 -HNCCF 3 ) (IV), respectively, which, it is proposed, are structurally related to I and II, but with the CN group coordinated also to the third Os atom in place of a CO group. In the case of IV this proposal has been confirmed by an X-ray crystallographic analysis. The compound crystallises in space group C 2/ c with a = 14.258(7), b = 13.486(10), c = 18.193(8) A, β = 92.68(4)°, and Z = 8. The structure was solved by a combination of direct methods and Fourier difference techniques, and refined by full-matrix least squares to R = 0.054 for 2489 unique observed diffractometer data. Reaction of I with Et 3 P gives a 1 : 2 adduct which is formulated as (μ-H)Os 3 (CO) 10 [μ-NC(H)(CF 3 )PEt 3 ] (V) on the basis of NMR evidence.

Chemistry of phosphido-bridged dimolybdenum complexes. Part 5. Synthesis and protonation of a phosphido-bridged dimolybdenum complex containing a terminal alkyne ligand: X-ray crystal structures of [Mo2(µ-PPh2)2(CO)(η-C2Me2)(η-C5H5)2] and [Mo2(µ-Co)(µ-PPh2){µ-Ph2PC(Me)CHMe}(η-C5H5)2][BF4]

The reaction between the alkyne complex [Mo2(µ-C2Me2)(CO)4(η-C5H5)2] and P2Ph4 in refluxing toluene affords a 42% yield of [Mo2(µ-PPh2)2(CO)(η-C2Me2)(η-C5H5)2]. An X-ray diffraction study has revealed that the but-2-yne ligand is co-ordinated to only one molybdenum atom, and that the molecule contains a planar Mo2(µ-PPh2)2 unit with a formal Mo–Mo double bond of length 2.865(1)A. Several other minor products are discussed in relation to the proposed mechanism of the reaction. Reaction of the terminal alkyne complex with HBF4·OEt2 causes a structural rearrangement in which the protonated but-2-yne is inserted into one of the Mo–P bonds to give a bridging Ph2PC(Me)CHMe vinylphosphine ligand; the structure of the product has been confirmed by X-ray diffraction.

Co-ordinated phospholes from the coupling of alkynes with bridging phosphido ligands: the crystal and molecular structures of [Co2{µ-η2:η2′-C4(CO2Me)4PPh2}(µ-PPh2)(CO)4], [Mn2(η4-C4H4PPh2)(µ-PPh2)(CO)6], and [Mn2(µ-η5-C4H4PPh2)(µ-PPh2)(CO)5]

Reaction of µ-phosphido complexes with alkynes can lead to complexes with quaternised phosphole ligands; by this means a cobalt complex, [Co2{µ-η2:η2′-C4(CO2Me)4PPh2}(µ-PPh2)(CO)4], and a manganese complex, [Mn2(η4-C4H4PPh2)(µ-PPh2)(CO)6], in which the phosphole adopts respectively a terminal and a bridging mode, have been prepared and characterised by X-ray analysis as has related manganese complex, [Mn2(µ-η5-C4H4PPh2)(µ-PPh2)(CO)5].