MOLYBDENUM-CARBON FUNCTIONALITIES SUPPORTED BY A QUADRIDENTATE SCHIFF-BASE LIGAND - THE REACTIVITY OF (SALICYLIDENE)-O-PHENYLENEDIAMINATO]MOLYBDENUM(IV)

The parent compounds trans-[Mo(salophen)Cl-2] 1 [salophen = N,N'-bis(s alicylidene)-o-phenylenediamine dianion] and trans-[Mo(tbsalophen)Cl-2 ] 2 [tbsalophen = (3,5-di-tert-butylsalicylidene)-o-phenylenediamine d ianion] were obtained from the corresponding Schiff bases and [MoCl4(M eCN)(2)]. The alkylation of 1 proceeded very differently depending on the alkylating agent. The reaction with (PhCH2)(2)Mg led to the format ion of trans-[Mo(salophen)(PhCH2)(2)] 3, containing two alkyl groups a t the metal, while with Mg(mes)Br (mes = 2,4,6-Me3C6H2) arylation occu rred both at the imino carbons and at the metal, via a rather complex mechanism. Reduction of 1 led to an intermediate Mo(salophen), which w as intercepted by PhCCPh. The plausible intermediate metallocycloprope ne rearranged with the migration of one of the carbons to an imino gro up and dimerization of the monomeric unit. The salophen ligand display ed a bridging bonding mode in the dimer, containing a Mo=Mo fragment a nd two bridging vinyl functionalities. The proposed structures are sup ported by three X-ray analyses.