Preparation and Reactivity of Hydrazine Complexes of Rhenium: Synthesis of 1,2‐Diazene (NH=NH) and Methyleneimine (CH2=NH) Derivatives

Abstract

AbstractThe hydrazine complexes [Re(RNHNH2)(CO)nP5−n]BPh4 [R = H, CH3, Ar; n = 1−4; P = P(OEt)3, PPh(OEt)2, PPh2OEt] were prepared by allowing the hydride species [ReH(CO)nP5−n] to react first with a Brønsted acid and then with hydrazine. The reaction of either [Re(NH2NH2)(CO)nP5−n]BPh4 or [Re(ArNHNH2)(CO)nP5−n]BPh4 with Pb(OAc)4 at −40 °C proceeds with the selective oxidation of the hydrazine ligand to yield either [Re(NH=NH)(CO)nP5−n]BPh4 or [Re(ArN=NH)(CO)nP5−n]BPh4. The oxidation of [Re(CH3NHNH2)(CO)nP5−n]BPh4 (n = 1, 2) with Pb(OAc)4 at −40 °C gives both [Re(CH3N=NH)(CO)nP5−n]BPh4 and [Re(η1‐NH=CH2)(CO)nP5−n]BPh4. Reduction reactions of both hydrazine and diazene complexes with Zn amalgam were also studied and yielded ammonia in moderate yield (20−25%). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)