Reactions of C(NMe2)4 with group 6 carbonyl compounds.: Crystal structures of [C(NMe2)3] [(CO)5CrC(O)NMe2], [C(NMe2)3]2[Mo2(CO)10] and [C(NMe2]3][(CO)4Mo(O2CNMe2)]

The reaction of C(NMe2)(4) (1) with M(CO)(6) (M = Cr, W) in THF solution leads to the anionic carbamoyl complexes [C(NMe2)(3)] [(CO)(5)MC(O)NMe2] (2a, M = Cr; 2c M = W). In the case of M = Mo the resulting complex 2b is not obtained; instead, the salts [C(NMe2)(3)](2)[Mo-2(CO) (10)] (3) and [C(NMe2)(3)] [(CO)(4)Mo(O2CNMe2)] (4) are isolated. The crystal structures of 2a, 3, and 4 are presented. In the salt-like compounds no interatomic contacts between anion and cation exist, and the cations are disordered. The structure of 4 shows two independent molecules. The compounds were further characterized by IR and NMR spectroscopy.