Strongly Luminescent Palladium(0) and Platinum(0) Diphosphine Complexes

The synthesis, structure, and photoluminescence of palladium(0) and platinum(0) complexes containing biarydiphosphines, biphep (biphep = 2,2‘-bis(diphenylphosphino)-1,1‘-biphenyl) and binap (binap = 2,2‘-bis(diphenylphosphino)-1,1‘-binaphthyl) have been studied. X-ray structure analysis of [Pt(biphep)2] revealed the distorted-tetrahedral geometry of the complex. The photophysical properties of the three complexes [Pd(biphep)2], [Pt(biphep)2],
and [Pd(binap)2] were investigated and compared with that of the previously reported [Pt(binap)2] complex. The
[Pd(biphep)2] complex shows the strongest luminescence with a high quantum yield (38%) and a long lifetime (3.2
μs) in a toluene solution at room temperature. The luminescence should be due to metal-to-ligand charge transfer
excited states. At room temperature, radiative rate constants of the four complexes show similar values. The
difference in the luminescent properties should reflect the different nonradiative rate constants of the complexes.
The temperature-dependence of the luminescence spectra and lifetime of the complexes were also discussed.

本研究针对含联芳基双膦配体的零价钯与零价铂配合物的合成、结构及光致发光性能展开系统探究，所涉及的配体包括联苯双膦（biphep，即2,2'-双(二苯基膦基)-1,1'-联苯）与联萘双膦（binap，即2,2'-双(二苯基膦基)-1,1'-联萘）。对配合物[Pt(biphep)₂]开展X射线晶体结构分析后发现，该配合物呈现扭曲四面体几何构型。本研究对三种配合物[Pd(biphep)₂]、[Pt(biphep)₂]及[Pd(binap)₂]的光物理性能进行了表征，并与已报道的[Pt(binap)₂]配合物展开对比分析。在室温甲苯溶液中，[Pd(biphep)₂]配合物展现出最强的发光性能，具备较高的量子产率（38%）与较长的发光寿命（3.2 μs）。该发光行为应归因于金属到配体的电荷转移激发态。室温条件下，四种配合物的辐射跃迁速率常数数值相近，而发光性能的差异则反映了各配合物不同的非辐射跃迁速率常数。此外，本研究还探讨了配合物发光光谱与寿命的温度依赖性。