Small molecule activation of nitriles coordinated to the [Re6Se8](2+) core: formation of oxazine, oxazoline and carboxamide complexes

摘要

Novel oxazine, oxazoline and carboxamide cluster complexes were prepared when different nucleophilic oxygen species reacted with nitriles coordinated to the Lewis acidic [Re6Se8](2+) cluster core. Reaction of ICH2CH2O- (generated in situ) with [Re6Se8(PEt3)(5)(NCR)]A(2) (1A(2) (R = Me) and 2A(2) (R = Ph) where A = BF4-), leads to the formation of [Re6Se8(PEt3)(5)(2-methyloxazoline)](2+) (3(2+)) and [Re6Se8(PEt3)(5)(2-phenyloxazoline)](2+) (4(2+)). Similarly, reaction of BrCH2CH2CH2O- with the same nitrile complexes, 1A(2) and 2A(2) (where A = BF4- or SbF6-) leads to the corresponding oxazine complexes, [Re6Se8(PEt3)(5)(2-methyloxazine)](2+) (5(2+)) and [Re6Se8(PEt3)(5)(2-phenyloxazine)](2+) (6(2+)). In addition, reaction of 2(BF4)(2) with KOH leads to the formation of the carboxamide complex, [Re6Se8(PEt3)(5)(phenylcarboxamide)](BF4) (7(BF4)). The neutral oxazine and oxazoline ligands can be removed using either heat or UV irradiation; UV irradiation was found to be more efficient at ligand removal as indicated by the shorter reaction times. The relative coordination strength of the neutral N-donor ligands was determined by these reaction times. X-ray structure determinations of 5(BF4)(2) and 7(BF4) are also reported.