Department of Chemistry, 6-335, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
Inorg Chem. 2010 Mar 15;49(6):3035-43. doi: 10.1021/ic902590u.
Halogen oxidation of Ir(I)Au(I)(dcpm)(2)(CO)X (dcpm = bis(dicyclohexylphosphino)methane, X = Cl, Br) and Ir(I)Au(I)(dppm)(2)(CN(t)Bu)(2)(2) (dppm = bis(diphenylphosphino)methane) furnishes the heretofore unknown class of d(7)-d(9) compounds comprising an Ir(II)Au(II) heterobimetallic core. A direct metal-metal bond is evident from a 0.2 A contraction in the intermetallic distance, as determined by X-ray crystallography. The photophysical consequence of iridium-gold bond formation, as elucidated by experimental and computational investigations, is an electronic structure dominated by a sigma --> sigma* transition that possesses significant ligand-to-metal charge transfer (LMCT) character. Accordingly, these compounds are non-emissive but photoreactive. Excitation of Ir(II)Au(II) complexes in the presence of a halogen trap prompts a net photoreductive elimination of halogen and the production of the two-electron reduced Ir(I)Au(I) species with about 10% quantum efficiency. The Ir(II)Au(II) complexes add to a growing library of d(7)-d(9) heterobimetallic species from which halogen elimination may be driven by a photon.
Ir(I)Au(I)(dcpm)(2)(CO)X（dcpm = 双(二环己基膦)甲烷，X = Cl，Br）和Ir(I)Au(I)(dppm)(2)(CN(t)Bu)(2)(2)（dppm = 双(二苯基膦)甲烷）的卤素氧化作用提供了以前未知的包含 Ir(II)Au(II)杂双金属核的 d(7)-d(9)化合物类。通过 X 射线晶体学确定，金属间距离的 0.2 A 收缩表明存在直接的金属-金属键。铱-金键形成的光物理后果，通过实验和计算研究阐明，是由具有显著配体-金属电荷转移（LMCT）特征的 sigma --> sigma* 跃迁主导的电子结构。因此，这些化合物是非发光但光反应性的。在卤素捕获剂存在下激发 Ir(II)Au(II)配合物会促使卤素的净光还原消除，并以约 10%的量子效率产生两电子还原的 Ir(I)Au(I)物种。Ir(II)Au(II)配合物加入了越来越多的 d(7)-d(9)杂双金属物种库，其中卤素消除可以由光子驱动。
