Coordination Chemistry, Saarland University, Campus C4.1, D-66123 Saarbrücken, Germany.
Inorganic and General Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 1, D-91058 Erlangen, Germany.
J Am Chem Soc. 2022 May 25;144(20):8897-8901. doi: 10.1021/jacs.2c02818. Epub 2022 May 16.
Whereas triplet-nitrene complexes of the late transition metals are isolable and key intermediates in catalysis, singlet-nitrene ligands remain elusive. Herein we communicate three such palladium terminal imido complexes with singlet ground states. UV-vis-NIR electronic spectroscopy with broad bands up to 1400 nm as well as high-level computations (DFT, STEOM-CCSD, CASSCF/NEVPT2, EOS analysis) and reactivity studies suggest significant palladium(0) singlet-nitrene character. Although the aliphatic nitrene complexes proved to be too reactive for isolation in analytically pure form as a result of elimination of isobutylene, the aryl congener could be characterized by SC-XRD, elemental analysis, IR-, NMR spectroscopy, and HRMS. The complexes' distinguished ambiphilicity allows them to activate hexafluorobenzene, triphenylphosphine, and pinacol borane, catalytically dehydrogenate cyclohexene, and aminate ethylene via nitrene transfer at or below room temperature.
虽然三重态氮烯配合物是晚期过渡金属的可分离的、催化中的关键中间体，但单重态氮烯配体仍然难以捉摸。本文报道了三种具有单重态基态的钯末端亚氨基配合物。具有 1400nm 宽带的紫外可见近红外电子光谱以及高级计算（DFT、STEOM-CCSD、CASSCF/NEVPT2、EOS 分析）和反应性研究表明，它们具有显著的零价钯单重态氮烯特性。尽管由于异丁烯消除，脂肪族氮烯配合物由于太活泼而无法以分析纯形式分离，但芳族同系物可以通过 SC-XRD、元素分析、IR、NMR 光谱和 HRMS 进行表征。这些配合物的独特的两性允许它们在室温或更低温度下通过氮烯转移活化六氟苯、三苯基膦和频哪醇硼烷、催化脱氢环己烯和胺化乙烯。
