Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 13. Synthesis of platinumirontungsten tri-metal compounds with µ3-tolylidyne groups; crystal structures of [FePtW(µ3-CR)(CO)5(PMePh2)2(η-C5H5)] and [FePtW(µ3-CR)(CO)6(PEt3)(η-C5H5)](R = C6H4Me-4)

Abstract

The dimetal compounds [PtW(µ-CR)(CO)2(PR′3)2(η-C5H5)](R = C6H4Me-4, PR′3= PMe3, PMe2Ph, PMePh2, or PEt3) react with [Fe3(CO)9] in tetrahydrofuran at room temperature to afford trimetal complexes [FePtW(µ3-CR)(η-CO)(CO)5(PMe2Ph)2(η-C5H5)], [FePtW(µ3-CR)(CO)5(PMePh2)2(η-C5H5)], and [FePtW(µ3-CR)(CO)6(PR′3)(η-C5H5)](PR′3= PMe3, PMePh2, or PEt3). The reaction involving [PtW(µ-CR)(CO),(PEt3)2(η-C5H5)] also gave the non-iron containing compound [Pt2W(µ3-CR)(CO)4(PEt3)2(η-C5H5)]. Pathways for the formation of these heteronuclear trimetal complexes are discussed, and n.m.r. data (1H, 31 P-{1H}, 13C-{1H}) are reported for the dynamic platinumirontungsten species which contain a µ3-CFePtW core. X-Ray diffraction studies on [FePtW(µ3-CR)(CO)5(PMePh2)2(η-C5H5)] and on [FePtW(µ3-CR)(CO)6(PEt3)(η-C5H5)] confirm that the molecular skeleton is the same for both; the Pt atom in the former carries two PMePh2 ligands whereas in the latter it carries one terminal CO and one PEt3 ligand. Interesting differences in detailed structure are revealed, however. The Fe–Pt bond lengths are similar [2.556(2) and 2.542(3)A] for [FePtW(µ3-CR)(CO)5(PMePh2)2(η-C5H5)] and [FePtW(µ3-CR)(CO)6(PEt3)(η-C5H5)] respectively, but the Fe–W and Pt–W bond lengths are significantly different [2.694(2)versus 2.784(3), and 2.883(1)versus 2.775(1)A]. The Pt–W bond in [FePtW(µ3-CR)(CO)5(PMePh2)2(η-C5H5)] is among the longest so far observed. These differences, and those between the bonds of the µ3-CR ligand, are discussed. In the pentacarbonyl species the two P–Pt distances differ, that trans to the µ3-C atom [2.331(4)A] being notably longer than the other [2.289(3)A]. Both molecules are chiral and both crystallise in non-centrosymmetric space groups. Crystals of [FePtW(µ3-CR)(CO)5(PMePh2)2(η-C5H5)] are monoclinic, space group P21(no. 4) with Z= 2 in a unit cell of dimensions a= 10.005(2), b= 17.240(3), c= 12.928(4)A, β= 115.98(2)°, and the structure has been refined to R 0.050 for 4 490 reflections. Crystals of [FePtW(µ3-CR)(CO)6(PEt3)(η-C5H5)] are orthorhombic, space group Pna21(no. 33) with Z= 4 in a unit cell of dimensions a= 16.106(5), b= 8.958(5), c= 18.429(7)A, and the structure has been refined to R 0.050 for 2 703 reflections.