Reactions of nitridorhenium(V) and -osmium(VI) complexes with acylating agents

Abstract

Interaction of Re(N)L2 [L = N(PSPh2)2] 1 with (CF3CO)2O or RCOCl afforded air-sensitive acylimido-Re(V) complexes trans-Re[NC(O)CF3](OCOCF3)L2 2 or trans-Re[NC(O)R]ClL2 (R = CCl2H 3, CClH2 4, CH3 5), respectively. Treatment of 1 with (CX3CO)2O followed by recrystallization from CH2Cl2/hexane in air led to the formation of the corresponding parent imido complexes trans-Re(NH)(OCOCX3)L2 (X = F 6, Cl 7). The structure of 7 has been characterized by X-ray crystallography. The Re−N, average Re−S, and Re−O distances are 1.664(3), 2.441, and 2.116(3) Å, respectively. Deprotonation of 6 or 7 with Et3N gave 1. Recrystallization of 3 from CH2Cl2/hexane in air resulted in oxo-imido exchange and the isolation of the oxo-Re(V) species trans-Re(O)ClL2. Treatment of 1 with tosyl anhydride gave trans-Re(NH)(OTs)L2 (OTs = tosyl) 8. Reaction of [n-Bu4N][OsNCl4] with KL afforded trans-Os(N)ClL2 9, which has been characterized by X-ray crystallography. The Os−N, Os−Cl, and average Os−S bond distances in 9 are 1.64(1), 2.577(4), and 2.429 Å, respectively. Treatment of 10 with (CF3CO)2O, Ag(CF3CO2), or CF3CO2H resulted in chloride substitution and the formation of trans-Os(N)(OCOCF3)L2 10. The Os−N, Os−O, and average Os−S distances in 10 are 1.643(5), 2.271(4), and 2.419 Å, respectively. Treatment of 1 with [Ph3C]BF4 resulted in the isolation of trans-Re(NCPh3)(F)L2 11, presumably via the cationic tritylimido intermediate [Re(NCPh3)L2]+. Reaction of 9 with [Ph3C]BF4 led to chloride abstraction and the formation of five-coordinate [Os(N)L2]BF4 12. The Os−N and average Os−S distances in 12 are 1.646(5) and 2.364 Å, respectively.