The reaction of the cluster complexes [Pt3(μ-CO)3(PR3)3] (PR3 = PPh3
 1, PPh2Bz  2, PCy3
 3 and PiPr3
 4) with dialkyl acetylenedicarboxylate, Râ²O2CCCCO2Râ² (Râ²Â = CH3 or tBu) have been examined under various conditions. At low temperature the alkyne reacts quantitatively giving the unstable adducts [Pt3(CO)3(PR3)3(μ3-alkyne)]. The stereochemistry of the intermediate [Pt3(CO)3(PPh3)3(μ3-tBuO2CCCCO2tBu)] 5
has been deduced from low temperature 195Pt-1H}, 31P-1H} and 13C-1H} NMR spectra. At higher temperature a fluxional process renders two of the three platinum atoms equivalent on the NMR timescale. At room temperature the alkynes convert the starting clusters 1â4 to the stable dinuclear complexes [Pt2(CO)2(PR3)2(μ-Râ²O2CCCCO2Râ²)] (Râ²Â = CH3, PR3 = PPh3
 6; R = tBu, PR3 = PPh3
 7; PPh2Bz  8; PCy3
 9 and PiPr3
 10) in which the alkyne coordination has the CâC bond collinear with the PtâPt bond (6 and 7) or perpendicular to the PtâPt axis (9 and 10). The stereochemistry of these two types of dinuclear complexes has been established by NMR and IR studies and confirmed by X-ray diffraction analyses of 8 and 9.
簇配合物的反应 [Pt3(μ-CO)3(PR3)3] (PR3=PPh3
1、PPh2Bz 2、
PCy3
3 和 PiPr3
4) 与
乙炔二
甲酸二烷基
酯一起,在各种条件下对 R−O2CCCCO2R−(R−=
CH3 或 tBu)进行了研究。在低温下,
炔烃定量反应,生成不稳定的加合物 [Pt3(CO)3(PR3)3(μ3-
炔烃)]。
中间体的立体
化学 [Pt3(CO)3(PPh3)3(μ3-tBuO2CCCCO2tBu)] 5
由低温 195Pt-1H}、31P-1H} 和 13C-1H} NMR 谱推导出来。在较高温度下,流变过程使得三个
铂原子中的两个在核磁共振时间尺度上等效。在室温下,
炔烃将起始簇 1–4 转化为稳定的双核配合物 [Pt2(CO)2(PR3)2(μ-R–O2CCCCO2R–2)] (R–2= , PR3=PPh3
6; R=tBu, PR3=PPh3
7; PPh2Bz 8;
PCy3
9 和 PiPr3
10) 其中炔配位的 C–C 键与 Pt–Pt 键共线(6 和 7)或垂直于 Pt–Pt 轴(9 和 10)。这两种双核配合物的立体
化学已通过 NMR 和 IR 研究确定,并通过 8 和 9 的 X 射线衍射分析得到证实。