Reactions of 2,4-hexadiyne-1,6-diol with [H₂Os₃(CO)₉(PR₃)] clusters. Cyclization of the diyne and reversible exchange of the phosphine ligands between different positions of the “Os₃C₃” framework

Abstract

Reactions between unsaturated [H(2)Os(3)(CO)(9)(PR(3))] clusters (PR(3)= PPh(3), P(4-CF(3)-C(6)H(4))(3), PEt(3)) and 2,4-hexadiyne-1,6-diol have been studied. It was found that the diyne ligand easily reacts with all these complexes to give [HOs(3)(CO)8(PR3)-[mu3, eta1:eta3:eta1)-(CH(3)-C-C=CH-CH=C-O)]] complexes (V, VI and VII, respectively) containing the "Os3C3" pentagonal pyramid cluster framework. This structural pattern is formed through the diyne cyclization, dissociation of a CO ligand and eventual coordination of the cyclized organic moiety to the osmium triangle in the [mu3, eta1:eta3:eta1) manner. In the case of the PEt(3) substituted cluster the second hydride transfer onto the organic fragment occurs to afford the nonhydride [Os(3)(CO)(8)(PR3)[mu3), eta1:eta2:eta1)-(CH(3)-CH-C=CH-CH=C-O)]] cluster, VIII, containing distorted pentagonal pyramid framework with a broken Os-C bond. Heating V, VI of VII and in hexane solutions results in formation of the regioisomers (Va, VIa and VIIa) with the phosphine ligand located at adjacent osmium atoms across the Os-Os bond bridged by the coordinated organic fragment. The most probable mechanism of the isomerization includes reversible phosphine migration between these metal centres. Solid-state structure of V, Va, VI, VIIa and VIII have been established by single crystal X-ray diffraction. A general mechanistic scheme for the diyne ligand cyclization and cluster framework transformations is suggested and discussed.

Reactions of diphenylpyridylphosphine with H2Os3(CO)10 and H4Ru4(CO)12, P–C bond splitting in the coordinated ligand and isolation of the oxidative addition products

“…Its 31 P chemical shift fits well to that found earlier for the adduct (2.81 ppm [7]) and the IR characteristics are very close to those revealed for analogous H 2 Os 3 (CO) 10 (j 1 -PR 3 ) clusters [39,40] that testifies in favour of terminal coordination of diphenylpyridylphosphine to one of the osmium atoms bridged by the hydride ligands. Heating of the adduct in boiling hexane for 1.5 h gives (l-H) 2 Os 3 (CO) 8 (l 3 ,j 2 -PhP-(2-C 5 H 4 N))(Ph) (1) together with substantially smaller amount of (l-H)Os 3 (CO) 9 (l 3 ,j 2 -PhP(2-C 5 H 4 N)) (2).…”

New Method for Intramolecular Cyclization of Osmium-Coordinated Diynes Avoiding Os3(μ-H)2(CO)10 as Starting Material

“…The organic ligand, containing a furan ring moiety, bridges the closed Os 3 triangle and can be viewed as forming a pseudoallylic interaction with the Os(1) atom and two σ interactions with the Os(2) and Os(3) atoms, thus providing 5e toward the cluster electron count; thus, the clusters have a total of 48e, which is the number expected for an electron-precise triangular cluster containing three metal−metal bonds. The cluster framework,”Os 3 C 3 ”, which is arranged into a pentagonal pyramid with three carbon and two osmium atoms in the basal plane, has also been observed in other related compounds. ,,, The Os−Os bond lengths range from 2.8019(2) to 2.9752(2) Å. The longest bond is located in the basal plane and is bridged by the hydride ligand.…”

“…Summarizing, the results of the studies published to date seem to indicate that [Os 3 (μ-H) 2 (CO) 10 ] is uniquely suited as a template for diyne cyclizations, ,,, and therefore reactions of 1,3-diynes with non-hydride trinuclear osmium and ruthenium clusters do not lead to cyclizations. ,,, …”

Group 15 ligand migration in the heteronuclear clusters RuOs3(μ-H)2(CO)12(EPh3) (E=P, As, Sb)

“…The solvent used was deuterated chloroform unless otherwise stated. Chemical shifts reported are referenced to that for the residual proton of the solvent for 1 out with the GNMR program [5]. Mass spectra were obtained on a Finnigan MAT95XL-T spectrometer in an m-nitrobenzyl alcohol matrix.…”

“…Ligand migration involving triorganophosphine (PR 3 ) ligands has sometimes been invoked in the fluxional behaviour of organometallic compounds [1][2][3]. However, there are very few examples in the literature in which activation parameters and standard free energy values for PR 3 migration are available.…”