Affiliation:
1. Beijing National Laboratory for Molecular Sciences (BNLMS) Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education College of Chemistry Peking University Beijing 100871 China
2. State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 China
3. University of Chinese Academy of Sciences Beijing 100049 China
Abstract
AbstractIn dinitrogen (N2) fixation chemistry, bimetallic end‐on bridging N2 complexes M(μ‐η1 : η1‐N2)M can split N2 into terminal nitrides and hence attract great attention. To date, only 4d and 5d transition complexes, but none of 3d counterparts, could realize such a transformation. Likewise, complexes {[Cp*Cr(dmpe)]2(μ‐N2)}0/1+/2+ (1–3) are incapable to cleave N2, in contrast to their Mo congeners. Remarkably, cross this series the N−N bond length of the N2 ligand and the N−N stretching frequency exhibit unprecedented nonmonotonic variations, and complexes 1 and 2 in both solid and solution states display rare thermally activated ligand‐mediated two‐center spin transitions, distinct from discrete dinuclear spin crossovers. In‐depth analyses using wave function based ab initio calculations reveal that the Cr‐N2‐Cr bonding in complexes 1–3 is distinguished by strong multireference character and cannot be described by solely one electron configuration or Lewis structure, and that all intriguing spectroscopic observations originate in their sophisticate multireference electronic structures. More critical is that such multireference bonding of complexes 1–3 is at least a key factor that contributes to their kinetic inertness toward N2 splitting. The mechanistic understanding is then used to rationalize the disparate reactivity of related 3d M(μ‐η1 : η1‐N2)M complexes compared to their 4d and 5d analogs.
Funder
National Natural Science Foundation of China
Natural Science Foundation of Beijing Municipality
Cited by
1 articles.
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