Alan Dobson

Coordination, oligomerisation and transfer hydrogenation of acetylenes by some ruthenium and osmium carboxylates: Crystal and molecular structures of bis(trifluoroacetato)carbonyl-(methanol) bis(triphenylphosphine)ruthenium(II) and (1,4-diphenylbut-1-en-3-yn-2-yl)trifluoroacetato-(carbonyl) bis(triphenylphosphine)ruthenium(II)

Abstract The hydrides [MH(O2CCF3)(CO)(PPh3)2] (M = Ru or Os) react with disubstituted acetylenes PhCCPh and PhCCMe to afford vinylic products [M{C(Ph)CHPh}(O2CCF3)(CO)(PPh3)2] and [M{C(Ph)CHMe}(O2CCF3)(CO) (PPh3)2]/[M{C(Me)CHPh}(O2CCF3)(CO)(PPh3)2] respectively. Acidolysis of these products with trifluoroacetic acid in cold ethanol liberates cis-stilbene and cis-PhHCCHMe respectively thus establishing the cis-stereochemistry of the vinylic ligands. The complexes [M(O2CCF3)2(CO)(PPh3)2] formed during the acidolysis step undergo facile alcoholysis followed by β-elimination of aldehyde to regenerate the parent hydrides [MH(O2CCF3)(CO)(PPh3)2] and thereby complete a catalytic cycle for the transfer hydrogenation of acetylenes. The molecular structure of the methanol-adduct intermediate, [Ru(O2CCF3)2(MeOH)(CO)(PPh3)2] has been determined by X-ray methods and shows that the coordinated methanol is involved in H-bonding with the monodentate trifluoroacetate ligand [MEO-H---OC(O)CF3; O...O = 2.54 A]. The hydrides [MH(O2CCF3)(CO) (PPh3)2]react with 1,4-diphenylbutadiyne to afford the complexes [M{C(CCPh)CHPh} (O2CCF3)(CO)(PPh3)2]. The ruthenium product, which has also been obtained by treatment of [RuH(O2CCF3)(CO)(PPh3)2] with phenylacetylene, has been shown by X-ray diffraction methods to contain a 1,4-diphenylbut-1-en-3-yn-2-yl ligand. The osmium complexes [Os(O2CCF3)2(CO)(PPh3)2], [OsH(O2CCF3)(CO)(PPh3)2] and [Os{C(CCPh)CHPh}(O2CCF3)(CO)(PPh3)2] all serve as catalysts for the oligomerisation of phenylacetylene. Acetylene reacts with [Ru(O2CCF3)2(CO)(PPh3)2] in ethanol to afford the vinyl complex [Ru(CHCH2)(O2CCF3)(CO)(PPh3)2].

Coordination, Oligomerisation and Transfer Hydrogenation of Acetylenes by Some Ruthenium and Osmium Carboxylato Complexes: Crystal and Molecular Structure of (1,4-Diphenylbut-1-en-3-yn-2-yl)trifluoroacetato(carbonyl) bis(triphenylphosphine)ruthenium(II)

Abstract The complexes (MH(O2CCF3) (CO) (PPh3)2] and (M(O2CCF3)2(CO)(PPh3)2] (M = Ru or Os) react with terminal and internal acetylenes to afford oligomerisation and hydrogenation products, respectively, together with vinylic complexes, including the ruthenium species [Ru(C4HPh2)(O2CCF3)(CO) (PPh3)2], which has been shown by x-ray diffraction methods to contain a 1,4-diphenylbut-1-en-3-yn-2-yl ligand.

Complexes of the platinum metals. Part V. Perfluorocarboxylato-derivatives

Perfluorocarboxylic acids, RFCO2H (RF= CF3, C2F5, or C6F5), react with hydrido(triphenylphoshine) or low-oxidation-state triphenylphosphine complexes of the platinum-group metals to yield a wide range of perfluorocarboxylato-derivatives. Products which have been prepared in this manner include [RuCl(OCOCF3)(CO)(PPh3)2], [Ru(OCORF)2(CO)(PPh3)2], [Ru(OCORF)2(CO)2(PPh3)2], [RuH(OCOCF3)(PPh3)3], [OsCl(OCORF)(CO)(PPh3)3], [OsH(OCORF)(CO)(PPh3)3], [Os(OCORF)2(CO)(PPh3)2], [OsH(OCORF)(CO)2(PPh3)2], [Os(OCORF)2(CO)2(PPh3)2], [OsH(OCOCF3)(PPh3)3], [Rh(OCORF)(PPh3)3], [Rh(OCORF)(CO)(PPh3)2], [IrH(OCORF)2(CO)(PPh3)2], and [Ir(H)2(OCORF)(PPh3)3]. The new complexes have been characterised and, where possible, their stereochemistry has been determined by i.r. and n.m.r. spectroscopy. The occurrence of a rapid intramolecular exchange between uni- and bi-dentate perfluorocarboxylate ligands in the complexes [M(OCORF)2(CO)(PPh3)2](M = Ru or Os) has been established by observation of temperature-dependent 19F n.m.r. spectra for the trifluoroacetate derivatives. Mechanisms involving oxidative addition of perfluorocarboxylic acids to the precursors, and subsequent reductive elimination of dihydrogen, are proposed for the reactions discussed. The tendency for unidentate perfluorocarboxylate ligands situated trans to strong σ-donor ligands to undergo alcoholysis is reported.

Complexes of the platinum metals. Part 25. Reactions of ruthenium and osmium nitrosyls [MH(NO)(PPh3)3] and [M(NO)2(PPh3)2] with perfluorocarboxylic acids: X-ray crystal structure determination of nitrosyl(trifluoroacetato)(trifluoroacetohydroximato-OO′)bis(triphenylphosphine)osmium(II)–dichloromethane (1/1)

Ruthenium and osmium hydridonitrosyl complexes, [MH(NO)(PPh3)3], react with perfluorocarboxylic acids RCO2H (R = CF3 or C2F5) to afford the products [Ru(O2CR)3(NO)(PPh3)2] and [OsH(O2CR)2(NO)(PPh3)2] respectively. The reaction intermediates [RuH(O2CR)2(NO)(PPh3)2] and [OsH2(NO)(PPh3)3]+ have been detected in solution by 1H and 31P-{1H} n.m.r.; the latter species has been isolated and characterised as the tetraphenylborate salt. The ruthenium dinitrosyl complex [Ru(NO)2(PPh3)2] reacts with the acids RCO2H in boiling toluene or 2-methoxyethanol to afford the products [Ru(O2CR)3(NO)(PPh3)2]. The corresponding osmium complex [Os(NO)2(PPh3)2] reacts with the same acids in boiling 2-methoxyethanol and boiling toluene to yield the hydrides [OsH(O2CR)2(NO)(PPh3)2] and the novel hydroximate derivatives [[graphic omitted]R}(O2CR)(NO)(PPh3)2] respectively. Possible mechanisms for these reactions are discussed. The X-ray crystal structure of [[graphic omitted]CF3}(O2CCF3)(NO)(PPh3)2]·CH2Cl2 has been determined. The crystals are triclinic, space group P, with a= 12.709(3), b= 22.694(8), c= 9.662(3)A, α= 118.28(3), β= 113.59(3), γ= 59.66(4)°, and Z= 2. The structure has been refined to R(F)= 0.051 and R′(F)= 0.049 for 4 730 observed reflections. The complex contains six-co-ordinated osmium(II) bound to a chelate O,O′-trifluoroacetohydroximate(2–) ligand, a unidentate trifluoroacetate ligand, a linear nitrosyl group, and a pair of mutually cis triphenylphosphine ligands.

New nitrosyl(perfluorocarboxylato) complexes of the platinum metals

Abstract Perfluorocarboxylic acids (R F COOH) (R F = CF 3 ,C 2 F 5 and (for Rh) C 6 F 5 ) react with the species [M(NO) 2 (PPh 3 ) 2 ] (M = Ru, Os) and [M′(NO)(PPh 3 ) 3 ] (M′ = Rh, Ir) to yield new nitrosyl complexes [Ru(OCOR F ) 3 (NO)(PPh 3 ) 2 ], [OsH(OCOR F ) 2 (NO)(PPh 3 ) 2 ], [Os(OCOR F )(NO) 2 (PPh 3 ) 2 ][OCOR F ], [Ir(OCOR F )(NO)(PPh 3 ) 2 ][OCOR F ] and [Rh(OCOR F ) 2 (NO)(PPh 3 ) 2 ].

Complexes of the platinum metals. Part 23. Synthesis of the nitrosyl carboxylate complexes [M(O2CR)2(NO)(PPh3)2](M = Rh or Ir; R = CF3, C2F3, or C6F5): crystal and molecular structures of the trifluoroacetate derivatives [M(O2CCF3)2(NO)(PPh3)2]

The rhodium complex [Rh(NO)(PPh3)3] reacts with perfluorocarboxylic acids, RCO2H, in the presence of dioxygen to afford emerald green complexes [Rh(O2CR)2(NO)(PPh3)2](R = CF3, C2F3, or C6F5) in good yield. In contrast, the corresponding iridium precursor, [Ir(NO)(PPh3)3] reacts with the same acids under aerobic or anaerobic conditions to yield brown complexes [Ir(O2CR)2(NO)(PPh3)2]. The trifluoroacetate derivatives have been examined by X-ray diffraction methods and shown to possess dissimilar structures. Crystals of the rhodium complex are monoclinic, space group Cc, with a= 12.593(2), b= 15.466(3), c= 20.479(3)A, β= 100.03(4)°, and Z= 4. The structure, which has been refined to R= 0.06 for 2 918 observed reflections, consists of tetragonal-pyramidal molecules with angular apical nitrosyl ligands and trans phosphine ligands. Crystals of the iridium complex (solvated with one molecule of acetone) are orthorhombic, space group Pbcn, with a= 19.171(2), b= 22.684(3), c= 20.169(3)A, and Z= 8. The structure, which has been refined to R= 0.081 for 3 791 observed reflections, consists of trigonal-bipyramidal molecules with linear equatorial nitrosyl groups and axial trans phosphine ligands. The angle subtended at the iridium by the co-ordinated oxygen atoms of the unidentate trifluoroacetate ligands is remarkably small [75.0(6)°]. Preliminary calculations performed using a steric energy calculation computer program, EENY2, suggest that in each case the structure adopted corresponds to a stereochemical energy minimum.