The interaction of molybdenum pentachloride with carbonyl compounds.

The reactions of MoCl(5), 1, with small amounts of a series of carbonyl compounds in a chlorinated solvent were investigated. The chloroiminium salts [ClCH=NEt(2)][Mo(O)Cl(4){O=C(H)NEt(2)}], 2a, and [ClC=NH(CH(2))(4)CH(2)][Mo(O)Cl(4){O=CNH(CH(2))(4)CH(2)}], 2b, were obtained by a selective 1 : 2 molar reaction of 1 with, respectively, N,N-diethylformamide or ε-caprolactam. Otherwise 1 reacted with tetra-N-alkyl ureas in a 1 : 2 ratio to give the Mo(IV) mononuclear complexes MoCl(4)(urea)(2) [urea = (Me(2)N)(2)CO, 3a; urea = (Et(2)N)(2)CO, 3b; urea = (EtPhN)(2)CO, 3c] in high yields. Addition of 2 equiv. of ketones to 1 resulted in clean formation of equimolar amounts of MoOCl(3)(O=CR(2)) (R = Me, 4a; R = Et, 4b; R = Ph, 4c) and R(2)CCl(2). Analogously 1,2-C(6)H(4)(Me)(CHCl(2)) was produced from MoCl(5) and ortho-tolyaldehyde. The reactions of 1 with 1H-indole-2,3-dione (isatin) took place with selective chlorination of the carbonyl function non-adjacent to the nitrogen: the complexes MoOCl(3)(3,3-dichloro-2,3-dihydro-1H-indol-2-one)(2), 5a, and MoOCl(3)(isatin)(3,3-dichloro-2,3-dihydro-1H-indol-2-one), 5b, were isolated depending on the stoichiometry employed. The X-ray molecular structures of 2b, 3b, 4b, 5a and 5b were ascertained.