Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 9. Reactivity of the cations [MPt(µ-CC6H4Me-4)(CO)2(PR3)2(η-C5H5)]+(M = Mn or Re, Pr3= PMe3 or PMe2Ph) towards tertiary phosphines and the toluene-p-thiolate anion; X-ray crystal structures of [MnPt{µ-C(PMe3)C6H4Me-4}(CO)2(PMe3)2(η-C5H5)][BF4] and [MnPt(SC6H4Me-4){µ-C(PMe3)C6H4Me-4}(µ-CO)(CO)(PMe3)(η-C5H5)]

Abstract

The salts [MPt(µ-CC₆H₄Me-4)(CO)₂(PR₃)₂(η-C₅H₅)][BF₄](M = Mn or Re, PR₃= PMe₃ or PMe₂Ph), in which a tolylidyne group bridges the metal–metal bond, readily add a molecule of tertiary phosphine to form adducts, the ³¹P n.m.r. spectra of which suggest the formulation [MPt{µ-C(PR₃)C₆H₄Me-4}(CO)₂(PR₃)₂(η-C₅H₅)][BF₄]. This was confirmed by a single-crystal X-ray diffraction study on the compound M = Mn and PR₃= PMe₃, crystals of which are triclinic, with space group P and Z= 2 in a unit cell of dimensions a= 10.877(2), b= 10.230(2), c= 13.917(4)Å, α= 92.80(2), β= 95.28(2), and γ= 90.08(2)°. The structure has been determined by heavy-atom methods from automated diffractometer data for 2.9 ⩽ 2θ⩽ 50°, and refined to R 0.031 (R′ 0.034) for 4 845 reflections. The Mn–Pt bond [2.645(1)Å] is bridged by a C(PMe₃)C₆H₄Me-4 group, and semi-bridged by on CO ligand [MnCO 162.0(7)°]. In the three-membered ring [graphic omitted] the Mn–C separation of 2.107(5)Å is as expected for a σ bond and is thus significantly longer than the corresponding distance [1.829(8)Å] in the precursor [MnPt(µ-CC₆H₄Me-4)(CO)₂(PMe₃)₂(η-C₅H₅)][BF₄] which formally contains a CMn linkage. In the PMe₃ adduct the platinum atom is in an essentially planar environment [with Pt–µ-C 2.078(5)Å], while the plane [graphic omitted] is almost perpendicular to the plane defined by the atom µ-C and its ligated P and C atoms. Whereas the salt [PtRe(µ-CC₆H₄Me-4)(CO)₂(PMe₂Ph)₂(η-C₅H₅)][BF₄] reacts with Na[SC₆H₄Me-4] to give the expected product [PtRe{µ-C(SC₆H₄Me-4)C₆H₄Me-4}(CO)₂(PMe₂Ph)₂(η-C₅H₅)], the salts [MnPt(µ-CC₆H₄Me-4)(CO)₂(PR₃)₂(η-C₅H₅)][BF₄](PR₃= PMe₃ or PMe₂Ph) undergo an unusual reaction with this reagent to afford the compounds [MnPt(SC₆H₄Me-4){µ-C(PR₃)C₆H₄Me-4}(µ-CO)(CO)(PR₃)(η-C₅H₅)]. The structures of the latter species were revealed by their spectroscopic properties (i.r. and ³¹P n.m.r.) and confirmed by a single-crystal X-ray diffraction study on the compound with PR₃= PMe₃. Crystals are orthorhombic, space group Pca2₁ and Z= 4 in a unit cell of dimensions a= 19.482(4), b= 12.827(4), and c= 11.649(2)Å. The structure has been refined to R 0.031 (R′ 0.032) for 2 846 reflections (2.9 ⩽ 2θ⩽ 55°) measured at room temperature. The platinum atom is in a planar environment with distances Pt–PMe₃ 2.319(2), Pt–SC₆H₄Me 2.365(3), Pt–µ-C 2.132(8), and Pt–Mn 2.626(1)Å. The latter bond is bridged by a CO ligand which is essentially trans to the S atom [C–Pt–S 170.3(3)°], while µ-C is trans to PMe₃ on platinum [µ-C–Pt–P 168.6(3)°]. Within the [graphic omitted] ring, the Pt–µ-C separation [2.132(8)Å] is significantly longer and the Mn–µ-C separation [2.047(9)Å] shorter than the corresponding distances in [MnPt{µ-C(PMe₃)C₆H₄Me-4}(CO)₂(PMe₃)₂(η-C₅H₅)][BF₄].