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

The reaction of C(NMe2)(4) (1) with M(CO)(6) (M = Cr, W) in THF solution le ads 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 o btained; 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 b etween anion and cation exist, and the cations are disordered. The structur e of 4 shows two independent molecules. The compounds were further characte rized by IR and NMR spectroscopy.