Incorporation of Thiophene Rings into Tri- and Tetraruthenium Clusters via Cyclometalation and C−P Bond Cleavage of the Ligand Diphenyl-2-thienylphosphine

Abstract

Diphenyl-2-thienylphosphine, Ph 2 PC 4 H 3 S (1), reacts with [Ru 3 (CO) 12 ] in refluxing toluene to give the compound [Ru 3 (µ 2 -H)(µ 3 -Ph 2 PC 4 H 2 S)(CO) 9 ] (2) (59%), cyclometalated at the thiophene ring, with smaller amounts of the cluster [Ru 3 (µ 2 -H)(µ 3 -Ph 2 PC 4 H 2 S)(CO) 8 (Ph 2 -PC 4 H 3 S)] (3) (10%), which is a substituted derivative of 2 and may also be formed by substitution at 2 with ligand 1. The single-crystal X-ray structure of cluster 2 shows that it contains the µ 3 -ligand Ph 2 PC 4 H 2 S bound through phosphorus to one Ru atom, through a σ-Ru-C bond to another and by an η 2 interaction to the third. There is a dynamic interchange between the σ and η 2 interactions of the thienyl group leading to NMR coalescence and a time-averaged plane of symmetry. The corresponding process would be nondegenerate in the substituted compound 3 (X-ray structure reported) and is quenched. Thermal treatment of cluster 2 with [Ru 3 (CO) 12 ] gave two tetranuclear clusters, [Ru 4 (µ 4 -PPh)(µ 4 -C 4 H 2 S)(CO) 11 ] (5) by elimination of benzene and the known cluster [Ru 4 (µ 4 -PPh)-(µ 4 -C 6 H 4 )(CO) 11 ] (6) by elimination of thiophene. Although compounds 5 and 6 are stoichiometrically equivalent, their single-crystal X-ray structures show that they adopt different geometries. The structure of 6 was shown to be the same as that reported previously for the compound derived from PPh 3 . Each has an approximate square of metal atoms capped on one side by µ 4 -PPh and on the other by µ 4 -thiophyne (C 4 H 2 S) or µ 4 -benzyne (C 6 H 4 ), respectively. The C 6 H 4 ligand is coordinated as a 6-electron donor, tilted with respect to the Ru 4 plane, with the coordinated C-C bond parallel to an Ru-Ru edge, whereas C 4 H 2 S is coordinated as a 4-electron donor, perpendicularly and diagonally across the Ru 4 plane in a manner related to known alkyne clusters of the type [Ru 4 (µ 4 -PPh)(µ 4 -alkyne)(CO) 11 ].

Syntheses and Fluxional Processes of Diphenyl(2‐thienyl)phosphane Derivatives of Triosmium Clusters

“…This is similar to that previously observed for [Ru 3 (µ-H)(CO) 9 {µ 3 -Ph 2 P(C 4 H 2 S)}]. [20] Unlike the ruthenium analogue, where the ortho-protons are fluxional at 20°C and only become static on the NMR timescale at -20°C, the ortho-protons of 5 were not fluxional at ambient temperature. The 31 P{ 1 H} NMR spectrum of 5 at 27°C displays a singlet at δ = -3.3 ( 1 J P-Os = 147 Hz) ppm, with a small change of shift to δ = -5.3 ppm at -80°C.…”

“…diphenyl(2-thienyl)phosphane] have therefore been used to bring the heterocycle into the coordination sphere of transition-metal clusters through the phosphane moiety of the ligand. [18][19][20] Treatment of diphenyl(2-thienyl)phosphane with [Ru 3 (CO) 12 ] has led to the incorporation of the thiophene ring into tri-and tetraruthenium clusters by cyclometallation and C-P bond cleavage of the ligand. [20] Here we report the reactions of [Os 3 10 ] with diphenyl(2-thienyl)phosphane, Ph 2 P(C 4 H 3 S), which have been undertaken in an effort to achieve C-P and C-S bond cleavage of the ligand.…”

“…Although IR spectra of isostructural Os and Ru clusters are not always comparable, the product was identified as the cyclometallated cluster [(µ-H)Os 3 (CO) 9 {µ 3 -Ph 2 P(C 4 H 2 S)}] (5) on the basis of the similarity of its IR spectrum to that of the known cluster [Ru 3 (µ-H)(CO) 9 {µ 3 -Ph 2 P(C 4 H 2 S)}]. [20] Mass spectrometric and microanalytical data were found to be consistent with the proposed formula. The 1 H NMR spectrum displays a doublet at δ = -18.0 ppm confirming the presence of a bridging hydrido ligand, which couples to one phosphorus atom (J P-H = 13.2 Hz).…”

Carbon-Hydrogen Bond Activation of Phenyldi(2- Thienyl)Phosphine at A Triruthenium Cluster Center

“…[5][6][7][8][9][10][11][12][13][14][15][16][17] In this context, the reactivity of thienylphosphines with triosmium and triruthenium clusters has been thoroughly examined in recent years. [10][11][12][13][14][15][16][17] The first report in this area was by Vahrenkamp et al in 1995 who documented the reaction of Ru 3 (CO) 12 with tri(2-thienyl)phosphine from which two simple tertiary phosphine substituted products [Ru 3 (CO) 10 12 and we demonstrated the reactivity of tri(2-thienyl)phosphine with [Ru 3 (CO) 10 (µ-dppm)] {dppm = bis(diphenylphosphino)methane}. [11][12] A worth of interesting reactivity pattern and structural features were obtained from those studies such as carbon-hydrogen and carbonphosphorous bond cleavage leading to cyclometalated µ 3 -R 2 P(C 4 H 2 S) (R = Ph, Th) and µ 4 -thiophyne ligands as well as carbon-sulfur bond cleavage leading to thiophene ring opening required for desulfurization.…”

“…[10][11][12][13][14][15][16][17] The first report in this area was by Vahrenkamp et al in 1995 who documented the reaction of Ru 3 (CO) 12 with tri(2-thienyl)phosphine from which two simple tertiary phosphine substituted products [Ru 3 (CO) 10 12 and we demonstrated the reactivity of tri(2-thienyl)phosphine with [Ru 3 (CO) 10 (µ-dppm)] {dppm = bis(diphenylphosphino)methane}. [11][12] A worth of interesting reactivity pattern and structural features were obtained from those studies such as carbon-hydrogen and carbonphosphorous bond cleavage leading to cyclometalated µ 3 -R 2 P(C 4 H 2 S) (R = Ph, Th) and µ 4 -thiophyne ligands as well as carbon-sulfur bond cleavage leading to thiophene ring opening required for desulfurization. The reactions of thienylphosphines with triosmium clusters also lead to the formation of both simple substitution and metalated product which were demonstrated by Nordlander and our research group.…”