Synthesis and characterization of tungsten-cobalt, -rhodium, and -platinum compounds and the x-ray crystal structures of RhW(.mu.-CC6H4Me-4)(CO)2(PMe3)(.eta.5-C5H5)(.eta.5-C9H7) and PtW{.mu.-C(C6H4Me-4)C(O)}(CO)(PMe3)(.eta.4-C8H12)(.eta.5-C5H5)