Clément Sébastien, Aly Shawkat Mohammed, Fortin Daniel, Guyard Laurent, Knorr Michael, Abd-El-Aziz Alaa S, Harvey Pierre D
Département de chimie, Université de Sherbrooke, 2550 Boul. Université, Sherbrooke, PQ, Canada.
Inorg Chem. 2008 Dec 1;47(23):10816-24. doi: 10.1021/ic800811j.
The homodinuclear d9-d9 ClM(mu-dppm)2MCl2 complexes, 1 (M ) Pt) and 2 (M ) Pd) react with the conjugated and luminescent PCP-NC ligand (3, PCP ) [2.2]paracyclophane) to provide the corresponding d9-d9 terminal[ClPt(mu-dppm)2Pt(CNsPCP)]Cl (4) and d8-d8 A-frame [ClPd(mu-dppm)2(mu-CdNsPCP)PdCl] (5) isocyanide complexes, respectively. These two bimetallic complexes were characterized by IR, 1H, and 31P{1H} NMR and bychemical analysis. IR data (nu(CN) bridging vs terminal) reveal a terminal isocyanide bonding mode for 4 (2147cm(-1)) and an A-frame structure for 5 (1616 cm(-1)). The optical and emission properties of the free isocyanide 3as well as those of the homodinuclear complexes 4 and 5 were studied by UV-visible and luminescence spectroscopy and by photophysical measurements. The unexpected presence of simultaneous intraligand pipi* fluorescence and phosphorescence attributable to the organic PCP-NC ligand, as well as luminescence from the inorganic M2-bonded Pt2(mu-dppm)2 center arising from a lower energy excited LMCT state (ligand-to-metal-charge-transfer) for4 at 77 K, indicates a weak conjugation between the two chromophores and an absence of efficient singlet andtriplet energy transfers. For 5, only the fluorescence and phosphorescence bands of the PCP-NC ligand are observed [since the A-frame XPd(mu-dppm)2(mu-L)PdX (L ) isocyanide, X ) halide) is not luminescent], stressing that the NtC bridge exhibits modest electronic communication properties.
同双核d9 - d9 ClM(μ - dppm)2MCl2配合物，1（M = Pt）和2（M = Pd）与共轭发光的PCP - NC配体（3，PCP = [2.2]对环芳烷）反应，分别生成相应的d9 - d9端基[ClPt(μ - dppm)2Pt(CNsPCP)]Cl（4）和d8 - d8 A框架[ClPd(μ - dppm)2(μ - CdNsPCP)PdCl]（5）异氰化物配合物。这两种双金属配合物通过红外光谱、1H和31P{1H}核磁共振以及化学分析进行了表征。红外数据（ν(CN)桥连与端基）表明4的异氰化物为端基键合模式（2147cm(-1)），5为A框架结构（1616 cm(-1)）。通过紫外可见光谱、发光光谱和光物理测量研究了游离异氰化物3以及同双核配合物4和5的光学和发射性质。在77 K下，有机PCP - NC配体意外地同时存在配体内ππ*荧光和磷光，以及4中来自较低能量激发的LMCT态（配体到金属电荷转移）的无机M2键合Pt2(μ - dppm)2中心的发光，这表明两个发色团之间共轭较弱，且不存在有效的单重态和三重态能量转移。对于5，只观察到PCP - NC配体的荧光和磷光带[因为A框架XPd(μ - dppm)2(μ - L)PdX（L = 异氰化物，X = 卤化物）不发光]，强调了N≡C桥表现出适度的电子通讯性质。
