Chemistry of vinylidene complexes. XXIV. A new μ-vinylidene complex containing RePt core, and platinum-bound carbonyl ligand. Spectroscopic, structural and electrochemical study

Abstract

The novel heterobinuclear μ-vinylidene complex [Cp(CO) 2 Re(μ-C=CHPh)Pt(PPh 3)(CO)] (1) was isolated from the reaction mixture of [Cp(CO) 2 Re(μ-C=CHPh)Fe(CO) 4 ] and Pt(PPh 3) 4 for the first time. Alternative high-yield synthetic approaches to 1 were developed including the reactions of [Cp(CO) 2 Re(μ-C=CHPh)Pt(PPh 3) 2 ] (2) with Co 2 (CO) 8 and Rh(acac)(CO) 2. The complex was characterized by IR and 1 H, 13 C and 31 P NMR spectroscopy, a molecular structure of 1 was determined by X-ray diffraction analysis. The electrochemical behavior of the new complex was studied by cyclic voltammetry at platinum or glassed carbon electrodes and by dc polarography at a dropping mercury electrode.

Chemistry of vinylidene complexes. XXV. Synthesis and reactions of binuclear µ-vinylidene RePt complexes containing phosphite ligands. Spectroscopic, structural and electrochemical study

“…The 13 C NMR spectra of 1a-3c contain broad resonances or sharp singlets (1a, 1b, and 2a) in the narrow interval 200-203 ppm that were assigned to the two Re-bound CO ligands. The coalescence of the two CO resonances can be explained by a site exchange of two carbonyl groups of the [Cp(CO) 2 Re] fragment and observed earlier [27][28][29][32][33][34]. The presence of the platinum coordinated carbonyl group in the 13 C NMR spectra of 1c-3c is indicated by signals around 199 ppm with characteristic J PtC coupling about 1224 Hz The 31 P NMR spectra of type a and b complexes show two signals corresponding to two non-equivalent phosphorus nuclei (Table 1).…”

“…So in complexes 1a-3a one of the Pt-bound P(OR) 3 ligand were replaced by CO, whereas in complexes of type b replacement of phosphine ligand at the Pt atom occurred.Such reactivity of the complexes reflects the high transinfluence of the bridging vinylidene ligand. The chemistry of the obtained tricarbonyl complexes is identical to previously synthesized complex 5 [29]. For example, the Pt-bound CO ligand in 1c-3c can be readily substituted upon addition of different nucleophiles like triphenylphosphine to give complexes Cp(CO) 2 RePt(-C=CHPh)(PPh 3 )L [L = P(OPr i ) 3 (1b), P(OEt) 3 (2b), P(OPh) 3 (3b)], or phosphites to regenerate initial complexes 1a, 2a, and 3a in high yields.…”

“…We also investigated possibility of substitution of phosphorous ligands at the platinum atom in the obtained binuclear vinylidenes by carbon monoxide. Previously, RePt and MnPt complexes of the type [Cp(CO) 2 MPt(μ-C=CHPh)(PPh 3 )(CO)] (M = Re (5), Mn) were prepared by the reaction of [Cp(CO) 2 MPt(μ-C=CHPh)(PPh 3 ) 2 ] (M = Re (4), Mn) and Co 2 (CO) 9 [23,29]. Following this strategy, we prepared a series of RePt μ-vinylidene complexes with the platinum-bound CO ligands Cp(CO) 2 RePt(-C=CHPh)(CO)L [L = P(OPr i ) 3 (1c), P(OEt) 3 (2c), P(OPh) 3 (3c)] in high yields (Scheme 3).…”

“…The presence of the platinum coordinated carbonyl group in the 13 C NMR spectra of 1c-3c is indicated by signals around 199 ppm with characteristic J PtC coupling about 1224 Hz The 31 P NMR spectra of type a and b complexes show two signals corresponding to two non-equivalent phosphorus nuclei (Table 1). 31 P NMR signal assignment was made on the basis of previously published works [27,29,35]. The signal with a larger coupling constant is assigned to the ligand trans to the rhenium and the signals with a smaller J PtP coupling is assigned to the ligand trans to the µ-C=CHPh.…”

“…In our previous works we reported a preparation of the binuclear Cp(CO) 2 Re(μ-C=CHPh)M(PPh 3 ) 2 μ-vinylidene complexes through the reaction of the rhenium vinylidene Cp(CO) 2 Re=C=CHPh and M(PPh 3 ) 4 (M= Pt, Pd) [26]. The possibility of substitution of both PPh 3 groups by chelate diphosphine ligands or one PPh 3 group by carbonmonoxide in these binuclear complexes was demonstrated [27][28][29].…”