Diazene Complexes of Copper: Synthesis, Spectroscopic Analysis, and Electronic Structure

✍ Scribed by Kiyoshi Fujisawa; Nicolai Lehnert; Yoko Ishikawa; Ken-ichi Okamoto

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 239 KB
• Volume: 116
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/ange.200460415

✦ Synopsis

Diazene is a very interesting molecule as a result of its ability to stereoselectively reduce some unsaturated organic substrates (probably via the cis isomer) [1] as well as its relevance in biological nitrogen fixation. Evidence from X-ray analyses, [2] spectroscopic studies, [3] and density functional calculations [4] suggests that HN=NH (1,2-diazene) is a metal-bound intermediate in nitrogenase turnover. Diazene is extremely unstable in its free state and undergoes a bimolecular decomposition above À150 8C to give N 2 and N 2 H 4 . [5] Its stability is greatly enhanced, however, when its lone pairs are coordinated to transition metals. The general importance of nitrogen fixation has resulted in many research groups having tried to make model complexes with coordinated diazene, dinitrogen, or hydrazine ligands; the corresponding transition-metal-diazene complexes have been synthesized by Sellmann [6] amongst others. [7,8] However, in the case of Cu, only three crystal structures-a complex of a 1,2-disubstituted diazene ([Cu 2 Cl 2 (MeN=NMe)] n ) [9] and two hydrazine complexes ([CuCN(N 2 H 4 )] n

[10a]

Scheme 1. Synthesis of complexes 1 and 2.