Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 3. Synthesis of bimetallic platinum–tungsten complexes with µ-tolylidyne groups; crystal structure of [PtW(µ-C·C6H4Me-p)(CO)2(PMe2Ph)2(η-C5H5)]

Abstract

The tungsten–carbyne complex [W(C·C₆H₄Me-p)(CO)₂(η-C₅H₅)] reacts with the compounds [Pt(C₂H₄)(PR₃)₂](PR₃= PMe₂Ph or PMe₃) to give the dimetal species [PtW(µ-C·C₆H₄Me-p)(CO)₂(PR₃)₂(η-C₅H₅)]. A related complex [PtWBr(µ-C·C₆H₄Me-p)(CO)₄(PMe₃)₂] is produced quantitatively from [W(C·C₆H₄Me-p)(Br)(CO)₄] and [Pt(C₂H₄)(PMe₃)₂]. In order to establish the molecular structure of this class of complex a single-crystal X-ray diffraction study was made on [PtW(µ-C·C₆H₄Me-p)(CO)₂(PMe₂Ph)₂(η-C₅H₅)], crystals of which are monoclinic, space group P2₁/c, Z= 4, in a unit cell with lattice parameters a= 12.212(11), b= 9.339(6), c= 26.125(24)Å, and β= 92.77(7)°. The structure has been refined to R 0.031 (R′ 0.029) for 3 803 reflections measured at 200 K for 2.9 ⩽ 2θ⩽ 55°(Mo-K_αX-radiation). In the molecule a Pt–W bond [2.751(1)Å] is bridged by a C·C₆H₄Me-p Group forming a ‘dimetallacyclopropene’ ring with Pt–C 1.997(9)Å and W–C 1.967(6)Å. The least-squares plane defined by the carbon atoms of the C·C₆H₄Me-p ligand is at 88.1° to the plane [graphic omitted]. The ¹H, ³¹P, and ¹³C n.m.r. spectra of the compounds are discussed in relation to their structures.