Transition metal complexes of (Schiff base)divalent Group 14 element species [(salen)M](n)=M '(CO)(6-n) (n=1, 2; M = Ge, Sn, Pb; M ' = Cr, W)

The syntheses, characterization, and reactivities of the new stable mono- a nd cis-disubstituted Group 14 metal(II) chromium and tungsten carbonyl comp lexes (salen)M=M'(CO)(5) [salen = 2,2'-N, N'-bis (salicylidene) ethylenedia mine; M' = Cr, M = Ge (4), Sn (5), Pb (6); M' = W, M = Ge (7), Sn (8), Pb ( 9)] and [(salen)M](2)=M'(CO)(4) [M' = W, M = Ge (10), Sn (11), Pb (12); M' = Cr, M = Sn (14), Ge (15)] are described. Complexes 4-9 were obtained in h igh yields by treatment of the M' (CO)(6).THF intermediates with the stable divalent species (salen)M-II [M = Ge (1), Sn (2), Pb (3)]. Direct irradiat ion of mixtures of (salen)M-II and M'(CO), resulted in formation of the mon osubstituted compounds 4-9 together with the disubstituted species 10-12, 1 4, and 15 in ratios depending on the nature of both M and M'. Pure complexe s 10-12 were obtained by two different synthetic approaches starting from t he (salen)M-II species or the (salen)M=M'(CO)(5) complexes. Each of the new complexes has been characterized by H-1- and C-13-NMR, and by Sn-119-NMR i n the case of 5, 8, 11, and 14, as well as by IR spectroscopy in all cases. The molecular structures of 5, 8, 11, and 14, determined by X-ray structur e analyses, reveal a pentacoordinated tin atom. The (in-chromium distances are among the shortest tin particular that in 5, 2.557 Angstrom) observed f or transition metal divalent tin complexes and the tin lies about 0.99 Angs trom above the plane defined by the O2N2 atoms of the salen ligand. All the se complexes have been found to be unreactive towards water and organic aci ds. Simple phosphane monosubstitution of carbonyl in 8 using Ph3P led to th e new complex 13, Reactions with 1,2-bis(diphenylphosphanyl)ethane and 3,5- di-tert-butyl-1,2-benzoquinone resulted in displacement of the divalent spe cies from the carbonyl complexes 5 and 8.