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

The hydrazine complexes [Re(RNHNH 2 )(CO) n P 5− n ]BPh 4 [R = H, CH 3 , Ar; n = 1−4; P = P(OEt) 3 , PPh(OEt) 2 , PPh 2 OEt] were prepared by allowing the hydride species [ReH(CO) n P 5− n ] to react first with a Brønsted acid and then with hydrazine. The reaction of either [Re(NH 2 NH 2 )(CO) n P 5− n ]BPh 4 or [Re(ArNHNH 2 )(CO) n P 5− n ]BPh 4 with Pb(OAc) 4 at −40 °C proceeds with the selective oxidation of the hydrazine ligand to yield either [Re(NH=NH)(CO) n P 5− n ]BPh 4 or [Re(ArN=NH)(CO) n P 5− n ]BPh 4 . The oxidation of [Re(CH 3 NHNH 2 )(CO) n P 5− n ]BPh 4 ( n = 1, 2) with Pb(OAc) 4 at −40 °C gives both [Re(CH 3 N=NH)(CO) n P 5− n ]BPh 4 and [Re(η 1 ‐NH=CH 2 )(CO) n P 5− n ]BPh 4 . 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)