Karen Marsden

Synthesis, structure and reactions of a dihapto-formaldehyde complex, Os(η2-CH2O)(CO)2(PPh3)2

Abstract Os(η 2 -CH 2 O)(CO) 2 (PPh 3 ) 2 results from direct reaction of formaldehyde with the zerovalent complex, Os(CO) 2 (PPh 3 ) 3 . The structure of Os(η 2 -CH 2 O)(CO) 2 (PPh 3 ) 2 was determined by X-ray crystallography. The crystals are triclinic, space group P 1 , a 18.739(2), b 11.157(1), c 9.986(1) A, α 116.70(1), β 93.20(1), γ 107.93(1)°, V 1727.69 A 3 , Z = 2, D m 1.55(2), D c 1.57 g cm −3 . Refinement of atomic parameters was by full-matrix least-squares methods, employing anisotropic thermal parameters for all non-hydrogen atoms except for the carbon atoms of the phenyl rings. The formaldehyde hydrogen atoms were located from difference electron density maps, other hydrogens were included in calculated positions. Final residuals were R = 0.047 and R w = 0.061 for 3508 unique observed reflections measured on an automatic diffractometer. The complex itself is monomeric, although interstices in the crystal lattice are occupied by hydrogen-bonded water dimers which fulfil a purely space-filling role. The osmium is bonded to two mutually trans triphenylphosphines, two carbonyls, and the η 5 -formaldehyde, in an arrangement which is best described as distorted octahedral. The geometry of the coordinated formaldehyde is characterised by OsO 2.039(7), OsC 2.186(8) and CO 1.584(11) A. The OsP bonds are equivalent at 2.372(2) and 2.378(2) A but the OsCO bond trans to the formaldehyde carbon 1.931(7) A is longer than that trans to the formaldehyde oxygen 1.907(7) A. Os(η 2 -CH 2 O)(CO) 2 (PPh 3 ) 3 has proved to be a useful synthetic precursor for stable formyl, hydroxymethyl, methoxymethyl, and halomethyl (CH 2 X, X  Cl, Br, I) complexes. The compounds Os(CHO)H(CO) 2 (PPh 3 ) 2 , Os(CH 2 OH)H(CO) 2 (PPh 3 ) 2 , Os(CH 2 OMe)Cl(CO) 2 (PPh 3 ) 2 and Os(CH 2 Cl)Cl(CO) 2 (PPh 3 ) 2 are illustrative of the many compounds which have been characterised. A general synthetic route to neutral formyl osmium complexes, Os(CHO)X(CO) 2 (PPh 3 ) 2 (X = halide or alkyl) has been developed from reaction of the cations [OsX(CO) 3 (PPh 3 ) 2 ] + with BH 4 − . Acetaldehyde also reacts with Os(CO) 2 (PPh 3 ) 3 forming Os(η 1 -C[O]CH 3 )H(CO) 2 (PPh 3 ) 2 . No reaction was observed with benzaldehyde, and trichloroacetaldehyde affords the cation, [OsCl(CO) 2 (PPh 3 ) 3 ] + .

Syntheses and structures of the chalcocarbonyl complexes OsCl2(CO) (CE) (PPh3)2 (E=S,Se,Te)

The Group VI nucleophiles HE− (E = O, S, Se, Te) react with the electrophilic dichlorocarbene ligand in the complex OsCl2(CCl2)(CO)(PPh3)2 to form the corresponding chalcocarbonyl derivatives OsCl2(CO)(CE)(PPh3)2. OsCl2(CO)-(CTe)(PPh3)2 is the first reported tellurocarbonyl complex, and the compounds OsCl2(CO)(CE)(PPh3)2 constitute the first complete series of chalcocarbonyl complexes. H2O, H2S and H2Se also react with the dichlorocarbene complex to yield the corresponding chalcocarbonyl derivatives OsCl2(CO)(CE)(PPh3)2, although OsCl2(CO)(CTe)(PPh3)2 cannot be formed this way. The thiocarbonyl, dichlorocarbene complex OsCl2(CCl2)(CS)(PPh3)2 gives tractable products with H2O, H2S and H2Se, and in this way the mixed chalcocarbonyl compounds OsCl2(CS)(CE)(PPh3)2 can be isolated. X-ray crystal structure determinations have been carried out on the complexes OsCl2(CO)(CS)(PPh3)2, OsCl2(CO)(CSe)(PPh3)2 and OsCl2(CO)(CTe)(PPh3)2. The CS and CSe complexes are isostructural and crystallise in space group P1, with two molecules in unit cells of dimensions: CS a 12.837(1), b 14.302(1), c 10.452(1) A, α 92.45(1), β 97.42(1), γ 99.86(1)°; CSe a 12.846(3), b 14.341(3), c 10.462(4) A, α 92.26(2), β 97.67(2), γ 99.76(1)°. The CTe complex crystallises in space group P21/n, with four molecules in a cell of dimensions a 14.211(3), b 18.084(4), c 14.857(3) A, β 113.29(2)°. The coordinated CTe ligand in OsCl2(CO)(CTe)(PPh3)2 displays similar overall structural features to the other coordinated chalcocarbonyl ligands in that the OsCTe angle is ca. 180° and the OsCTe and CTe bonds are very short. For each of the complexes the OsCE bond length is shorter than the OsCO bond length in the same molecule, although only for the thiocarbonyl complex is the difference significant. The trans-influence of the chalcocarbonyl ligands increases in the order CO < CS ≤ CSe < CTe.

Synthesis and some reactions of a terminal carbyne complex of osmium. Crystal structures of Os(CR)Cl(CO)(PPh3)2 and Os(C[AgCl]R)Cl(CO)(PPh3)2

Abstract The reaction of two equivalents of LiR (R = p-tolyl) with the dichlorocarbene complex OsCl2(CCl2)(CO)(PPh3)2 gives the carbyne complex Os(CR)Cl(CO) (PPh3)2 (I) in good yield. X-ray crystal structure determination shows that I is mononuclear with an OsC distance of 1.78(2) A. The OsC bond reacts with electrophiles rather than nucleophiles. Thus, HCl adds to give the alkylidene complex OsCl2(CHR)(CO)(PPh3)2, Cl2 forms OsCl2(CClR)(CO)(PPh3)2 and sulphur, selenium and tellurium react to yield to corresponding dihapto-chalcoacyls Os(η2-C[X]R)Cl(CO)(PPh3)2 (X = S, Se, Te). Group Ib metal halides also add to the OsC bond to form the adducts Os(C[M X]R)Cl(CO)(PPh3)2 (MX = CuI, AgCl, AuCl). The X-ray crystal structure determination of Os(C[A gCl]R)Cl(CO)(PPh3)2 (II) suggests that this complex can be considered as a dimetallacyclopropene derivative. Crystals of I are monoclinic, space group P21/n, a 17.030(2), b 12.774(1), c 18.315(3) A, β 107.96 (1)°, V 3793.2 A3, Z = 4, Dm 1.53(1), Dc 1.54. Crystals of II are monoclinic, space group P21/n, a 13.021(2), b 23.714(2), c 12.999(2) A, β 90.556(2)°, V 4013.7 A3, Z = 4, Dm 1.705(5), Dc 1.695. The structures were solved by conventional heavy-atom methods, and refined by full-matrix least-squares employing anisotropic thermal parameters for all non-hydrogen atoms except for the carbon atoms of the phenyl rings. Phenyl hydrogen atoms were included in calculated positions. Final residuals R were 0.040 and 0.037, respectively.

Migratory-insertion reactions involving the thiocarbonyl ligand. dihapto-thioacyl complexes from the rearrangement of arylthiocarbonyl complexes of osmium(II). Structure of Os(η2-CSR)(η1-O2CCF3)(CO)(PPh3)2

Abstract Reaction of HgR 2 with OsHCl(CS)(PPh 3 ) 3 yields red, five-coordinate, OsRCl-(CS)(PPh 3 ) 2 (R = p -tolyl). From this have been derived the compounds OsRX(CS)(PPh 3 ) 2 with X = Br, I, S 2 CNEt 2 , O 2 CMe, O 2 CCF 3 . These compounds add an additional ligand, MeCN, CO or CNR to form colourless, six coordinate arylthiocarbonyl complexes, which undergo migratory-insertion reactions to form red, dihapto -thioacyl complexes. The crystal structure of a representative example, Os(η 2 -CSR)(η 1 -O 2 CCF 3 )(CO)PPh 3 ) 2 has been determined. The red equant crystals are orthorhombic, space group P 2 1 2 1 2 1 , a 11.584(1), b 19.184(2), c 18.90(1) A, V 4199 A 3 , Z  4. The structure was solved by conventional heavy-atom methods and refined by full-matrix least-squares employing anisotropic thermal parameters for all non-hydrogen atoms except the carbon atoms of the triphenylphosphines. The final R factor is 0.057 for 2868 observed reflections. The coordination geometry in the monomeric complex is that of an octahedron distorted by the constraints of the ligands. The triphenyl phosphine ligands are mutually trans ; the equatorial plane contains carbonyl, monohapto -trifluoroacetate, and dihapto -thioacyl ligands. Bond distances and angles are OsP 2.405, 2.407(4) A; POsP 173.9(1)°; OsCO 1.83(2) A; Os-O (trifluoroacetate) 2.206(11) A; OsC (thioacyl) 1.91(2); OsS 2.513(6); CS 1.72 A. The CS bond length implies a reduction in bond order from 2.0 to approx. 1.5 upon coordination to the metal. The η 2 -thioacyl ligand in Os(η 2 -CSR)Cl(CNR)(PPh 3 ) 2 is methylated with methyl triflate and further reaction with LiCl produces the thiocarbene complex OsCl 2 (C[SMe]R)(CNR)(PPh 3 ) 2 .

Rearrangement of σ-aryl-thiocarbonyl complexes to dihapto-thioacyl complexes. : Structure of Os[η2-C(S)R](η1-O2CCF3)(CO)(PPh3)2

Abstract Octahedral osmium complexes of the type OsRX(CS)L(PPh 3 ) 2 (R  p -tolyl; X  Cl, Br, I or O 2 CCF 3 ; L  CO or CNR), which have adjacent R and CS ligands, undergo rearrangement to dihapto -thioacyl complexes Os[η 2 -C(S)R]XL(PPh 3 ) 2 , and the X-ray structure determination of a representative example Os[η 2 -C(S)R] (η 1 -O 2 CCF 3 ) (CO) (PPh 3 ) 2 , is reported.

Rhodium(III) and iridium(III) olefin complexes containing the tridentate ligand 1,6-bis(diphenylphosphino)-trans-hex-3-ene: crystal and molecular structure of trichloro-1,6-bis(diphenylphosphino)-trans-hex-3-eneiridium(III).

Abstract The olefin complexes RhCl3(BDPH), RhClBr2(BDPH), IrCl3(BDPH), IrClBr2(BDPH), IrCl(CH3)I(BDPH), IrHCl2(BDPH) and IrHBr2(BDPH); BDPH = 1,6-bis(diphenylphosphino)-trans-hex-3-ene, have been prepared by oxidative-addition reactions of RhCl(BDPH) and IrCl(BDPH) and characterised by I.R. and 1H NMR spectra. A single crystal X-ray determination of the structure of IrCl3(BDPH) shows the crystals to be orthorhombic, a = 16.1636(13), b = 20.2927(7), c = 17.1916(6)A, Z = 8, space group Pbca, ϱobs = 1.76, ϱcalc = 1.77 g cm−3. The structure was solved by conventional methods and refined by use of full-matrix least-squares equations to final residuals R = 0.041 and Rw = 0.052 for 2926 observed reflections. The complex is monomeric with an octahedral coordination geometry consisting of the tridentate olefin(phosphine)2 BDPH ligand (arranged such that the phosphorus atoms are mutually trans, and the three chloride ligands. Distances observed are Ir-P 2.382, 2.389(2)A, Ir-Cl 2.358, 2.387 (trans to olefin), 2.371(2)A, Ir-C(olefin) 2.274, 2.277(10)Af, C=C 1.352(14)A. The olefin is inclined at an angle of 28° to the Ir, P(1), P(2), Cl(2) plane. The structure is compared and contrasted with the known structures of IrCl(BDPH) and IrH2Cl(BDPH).

The crystal and molecular structures of trans-di-μ-thioethyldinitrosylbis (pentahaptocyclopentadienyl) dimolybdenum, [(η5-C5H5) Mo(NO) (SC2H5)]2, and cis-di-μ-thioisopropyldinitrosylbis (pentahaptocyclopentadienyl) dimolybdenum, [(η5-C5H5)-Mo(NO) (SCH(CH3)2]

Abstract Structures of the title compounds have been determined from three-dimensional X-ray analyses using diffractometer data. Crystals of trans -[(η 5 -C 5 H 5 )Mo(NO) (SC 2 H 5 )] 2 are monoclinic, space group P 2 1 / c with Z = 2 in a unit cell of dimensions a = 7.924(1), b = 12.692(1), c = 9.510(1) A, β = 109.06(1)°. Full matrix least squares refinement has returned a final R factor of 0.034 for 1120 reflections for which I > 3σ(I). The analysis confirms that the molecule is a dimer, with molybdenum atoms bridged by sulphur atoms. The molecule is situated about a crystallographic centre of symmetry and thus the (MoS) 2 core is planar and the cyclopentadiene and nitrosyl ligands are in the trans configuration. The Mo-S distances are 2.398(2) and 2.400(2) A; the MoMo′ distance is 2.923(1) A. Crystals of cis -(η 5 -C 5 H 5 )Mo(NO) (SCH(CH 3 ) 2 )] 2 are orthorhombic, space group Im2a , with Z = 16 in a unit cell of dimensions a = 30.874(2), b = 14.849(3), c = 18.260(2) A. The structure is based on a clearly defined subcell for which c ′ = c 2 and Z ′ = 8. The structure has been solved in terms of this subcell only, and therefore is described as the average of the two halves of the cell. Refinement was terminated with R = 0.067 for 1487 reflections having I > 3σ(I). Within the subcell there are two independent molecules, one of which has space group required diad symmetry, and the other mirror symmetry. The two molecules are nevertheless very similar in geometry. In contrast to the ethyl complex, the disposition of ligands with regard to the planar (MoS) 2 core is cis .

Metal—olefin bonding. X-ray structures of trichloro-1,6-bis(diphenylphosphino)-trans-hex-3-enerhodium(III) and dichlorocarbonyl-1,6-bis(diphenylphosphino)-trans-hex-3-eneruthenium(II)

Abstract X-ray structures have been determined for the olefin-containing complexes RuCl3(BDPH) and RuCl2(CO)(BDPH); BDPH = 1,6-bis(diphenylphosphino)-trans-hex-3-ene. Both compounds crystallise in space group Pbca with eight molecules in unit cells of dimensions RhCl3(BDPH) a 16.109(8), b 20.359(12), c 17.194(4) A; RuCl2(CO)(BDPH) a 16.279(1), b 20.160(1), c 17.334(1) A. Least-squares refinement returned residuals, R, of 0.030 and 0.067 respectively. In the ruthenium complex the CO and one Cl ligand are statistically interchanged. Both complexes are characterised by weak metal—olefin bonding and a twisted olefin orientation. The geometries are compared with those in other IrI and IrIII complexes containing the BDPH ligand.

Unusual tetra- and penta-ruthenium complexes from linking of ethylidyne and vinylidene ligands

The complexes [Ru2(CO)2(μ-CO)(μ-CMe)(η-C5H5)2]− and [Ru2CO2(μ-CO)(μ-CCH2)(η-C5H5)2] react together to give [{Ru2CO)3(η-C5H5)2}2(μ-CMeCHCH)]+ and [{Ru3(CO)3(η-C5H5)3}(μ-CCH2CHC){Ru2(CO)3(η-C5H5)2}], each characterised by X-ray diffraction. The former results from ethylidyne-vinylidene linking followed by an alkylidyne to vinyl rearrangement.