Synthesis and structures of platinum diphenylacetylene and dithiolate complexes bearing diphosphinidenecyclobutene ligands (DPCB-Y)
作者:Yumiko Nakajima、Mitsuharu Nakatani、Kyohei Hayashi、Yu Shiraishi、Ryo Takita、Masaaki Okazaki、Fumiyuki Ozawa
DOI:10.1039/c0nj00118j
日期:——
A series of platinum complexes of the type [Pt(D)(A)] having two kinds of π-conjugated ligand systems with donor and acceptor properties are prepared, using p-substituted diphenylacetylenes (tolan-X; X = OMe, H, CF3), 1,2-benzenedithiolato (bdt) and 1,3-dithia-2-thione-4,5-dithiolato (dmit) as π-donor ligands (D), and 1,2-diaryl-3,4-bis[(2,4,6-tri-tert-butylphenyl)phosphinidene]cyclobutenes (DPCB-Y; diaryl = 2C6H4-p-Y (Y = OMe, H, CF3), biphenyl-2,2′-diyl) as π-acceptor ligands (A). The electronic structures of the resulting complexes are examined in detail to investigate π-orbital interaction occurring in DPCB-Y complexes with a low-coordinate phosphorus ligand. The 31P NMR chemical shifts are highly sensitive to the Pt–P distances of the complexes, and linearly correlated with the bond lengths. The UV-vis absorption spectra of [Pt(tolan-X)(DPCB-Y)] display π–π* transitions in the visible region, which are shifted to longer wavelengths as the electron-donating ability of X and electron-withdrawing ability of Y increase, respectively. The complex [Pt(tolan-OMe)(DPCB-CF3)] with a donor–acceptor combination of substituents exhibits particularly low-energy absorption. The absorption is further red-shifted for [Pt(bdt)(DPCB-phen)] and [Pt(dmit)(DPCB-phen)] having dithiolates as strong π-donor ligands.
一系列类型为[Pt(D)(A)]的铂配合物被合成,具有两种具有给体和受体性质的π共轭配体系统,使用p取代的二苯乙炔(tolan-X;X = OMe、H、CF3)、1,2-苯并二硫醇盐(bdt)和1,3-二硫-2-硫酮-4,5-二硫醇盐(dmit)作为π给体配体(D),以及1,2-二芳基-3,4-双[(2,4,6-三叔丁基苯)膦烯]环丁烯(DPCB-Y;二芳基 = 2C6H4-p-Y(Y = OMe、H、CF3),联苯-2,2′-二基)作为π受体配体(A)。对所得配合物的电子结构进行了详细研究,以探讨在低配位磷配体的DPCB-Y配合物中发生的π轨道相互作用。31P NMR化学位移对配合物的Pt–P距离高度敏感,并与键长呈线性相关。配合物[Pt(tolan-X)(DPCB-Y)]的紫外-可见吸收光谱在可见区域显示π–π*跃迁,随着X的给电子能力和Y的吸电子能力的提高而向更长波长移动。具有给体-受体取代基组合的配合物[Pt(tolan-OMe)(DPCB-CF3)]显示出特别低的能量吸收。对于具有二硫醇盐作为强π给体配体的[Pt(bdt)(DPCB-phen)]和[Pt(dmit)(DPCB-phen)],吸收进一步红移。