Tricarbonyl[1,1,1-tris(dimethylphosphinomethyl)ethane]chromium(0), -molybdenum(0) and -tungsten(0) complexes

The structures of chromium(0)-, molybdenum(0)- and tungsten(0)-tricarbonyl complexes containing the tripodal tridentate phosphine ligand 1,1,1-tris(di methylphosphinomethyl)ethane (tdmme) (systematic name: (2- [(dimethylphosph ino)methyl] -2-methyl-1, 3-propanediyl)bis(dimethylphosphine)), were determ ined by X-ray diffraction studies. The M-C (M = Cr, Mo and W) bond lengths in the complexes, [M(C11H27P3)(CO)(3)], are noticeably shorter than those i n the corresponding hexacarbonyl complexes owing to the trans influence of tdmme being weaker than that of CO. The Mo-P bond lengths in the tdmme comp lex are slightly shorter than those in the analogous 1,1,1-tris(diphenylpho sphinomethyl)ethane and 1,5,9-tris(isopropyl)-1,5,9-triphosphacyclododecane complexes, indicating the smaller steric requirement of tdmme.