The interaction of molybdenum pentachloride with carbonyl compounds

The reactions of MoCl5, 1, with small amounts of a series of carbonyl compounds in a chlorinated solvent were investigated. The chloroiminium salts [ClCH=NEt2] [Mo(O)Cl-4{O=C(H)NEt2}], 2a, and [ClC-NH(CH2)(4)CH2][Mo(O)Cl-4{O-CNH(CH2)(4)CH2}], 2b, were obtained by a selective 1 : 2 molar reaction of 1 with, respectively, N, N-diethylformamide or epsilon-caprolactam. Otherwise 1 reacted with tetra-N-alkyl ureas in a 1 : 2 ratio to give the Mo(IV) mononuclear complexes MoCl4(urea)(2) [urea = (Me2N)(2)CO, 3a; urea = (Et2N)(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 MoOCl3(O=CR2) (R = Me, 4a; R = Et, 4b; R = Ph, 4c) and R2CCl2. Analogously 1,2-C6H4(Me)(CHCl2) was produced from MoCl5 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 MoOCl3(3,3-dichloro-2,3-dihydro-1H-indol-2-one)(2), 5a, and MoOCl3(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.