Synthesis and structural characterization of several dirhenium(III) compounds

Reaction between Re2(OAc)4Cl2 and N,N′-dicyclohexylbenzamidine (HDCyBA) under molten conditions yielded Re2(DCyBA)2Cl4 (1); reaction of [Bu4N]2[Re2Cl8] with N,N′-di(3-methoxyphenyl)formamidine (HDmAniF) resulted in Re2(DmAniF)2Cl4 (2); reaction of cis-Re2(OAc)2Cl4 with HDmAniF under reflux conditions resulted in cis-Re2(OAc)2(DmAniF)2Cl2 (3). Reaction between Re2(OAc)4Cl2 and α,α,α′,α′-tetramethyl-1,3-benzenedipropionic acid (H2esp) under reflux conditions led to Re2(esp)2Cl2 (4). Crystallographic studies of compounds 1–4 revealed Re–Re bond lengths of 2.1679(6), 2.1804(5), 2.2468(7), and 2.2304(6) Å, respectively, which are consistent with the presence of Re–Re quadruple bond. Also reported are electrochemical properties of compounds 1–4.