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Access to Stable Metalloradical Cations with Unsupported and Isomeric Metal–Metal Hemi‐Bonds
Author(s) -
Zheng Xin,
Wang Xingyong,
Zhang Zaichao,
Sui Yunxia,
Wang Xinping,
Power Philip P.
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201503392
Subject(s) - chemistry , cobalt , metal , crystallography , metal carbonyl , crystal structure , triple bond , inorganic chemistry , polymer chemistry , double bond , organic chemistry
Abstract Metalloradical species [Co 2 Fv(CO) 4 ] .+ ( 1 .+ , Fv=fulvalenediyl) and [Co 2 Cp 2 (CO) 4 ] .+ ( 2 .+ , Cp=η 5 ‐C 5 H 5 ), formed by one‐electron oxidations of piano‐stool cobalt carbonyl complexes, can be stabilized with weakly coordinating polyfluoroaluminate anions in the solid state. They feature a supported and an unsupported (i.e. unbridged) cobalt–cobalt three‐electron σ bond, respectively, each with a formal bond order of 0.5 (hemi‐bond). When Cp is replaced by bulkier Cp* (Cp*=η 5 ‐C 5 Me 5 ), an interchange between an unsupported radical [Co 2 Cp* 2 (CO) 4 ] .+ ( anti ‐ 3 .+ ) and a supported radical [Co 2 Cp* 2 (μ‐CO) 2 (CO) 2 ] .+ ( trans ‐ 3 .+ ) is observed in solution, which cocrystallize and exist in the crystal phase. 2 .+ and anti ‐ 3 .+ are the first stable thus isolable examples that feature an unsupported metal–metal hemi‐bond, and the coexistence of anti ‐ 3 .+ and trans ‐ 3 .+ in one crystal is unprecedented in the field of dinuclear metalloradical chemistry. The work suggests that more stable metalloradicals of metal–metal hemi‐bonds may be accessible by using metal carbonyls together with large and weakly coordinating polyfluoroaluminate anions.