The niobaziridine-hydride functional group: synthesis and divergent reactivity

A multistep synthetic strategy enables the isolation of the niobaziridine-hydride complex Nb(H)(eta2-tBu(H)C=NAr)(NNp]Ar)2 (1, Np = neopentyl, Ar = 3,5-C6H3Me2), which functions as a reactive synthon for its tautomer, the three-coordinate, trisamide species Nb(NNp]Ar)3 (2). Treatment of 1 with various small molecules has demonstrated its capacity to effect two-electron reduction chemistry. Most noteworthy is the reaction between 1 and elemental phosphorus (P4), providing in high yield the bridging diphosphide complex (mu2:eta2,eta2-P2)Nb(NNp]Ar)3]2. However, unsaturated organic functionality including nitriles and aldehydes can insert into the Nb-H bond of 1, leaving the niobaziridine ring intact, thus demonstrating that dual pathways of reactivity are available to the niobaziridine-hydride functional group.