Five platinum(II) 1,2,4-triazolin-5-ylidene (tazy) complexes of the general formula [PtCl₂(DMSO)(R-tazy)] (1–5), bearing different N4 substituents (R = Dipp (1), Mes (2), Ph (3), Nap (4), and Bn (5)), have been successfully synthesized. The compounds have been fully characterized by means of ESI-MS mass spectrometry, NMR spectroscopy, elemental analysis, and X-ray diffraction analysis. The presence of two rotamers in complex 4 was elucidated using multinuclear magnetic resonance spectroscopy (¹H, ¹³C NMR) spectroscopy and theoretical calculations. The five complexes were tested for their catalytic activities in the hydration and hydrosilylation of phenylacetylene. Significant differences in catalytic performance were observed. In the hydration of phenylacetylene, only Markovnikov products were formed with yields ranging from poor to moderate with compound 3 performing the best. In the hydrosilylation reaction, both Markovnikov (α) and anti-Markovnikov (β-E) products were obtained. While complex 1 was not very active, reactions catalyzed by complex 5 show complete conversions. A detailed study on the steric and electronic properties of the five triazolinylidenes have been carried out to rationalize the different catalytic performances of their complexes.

中文翻译：

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铂（II）1,2,4-三唑啉-5-亚烷基配合物：立体电子对其在加氢反应中催化活性的影响

五铂（II）1,2,4-三唑-5-亚基（tazy）通式[氯铂酸的络合物₂（DMSO）（R-tazy）]（1 - 5），带有不同的取代基N4（R =迪普（1），Mes（2），Ph（3），Nap（4）和Bn（5））已成功合成。借助ESI-MS质谱，NMR光谱，元素分析和X射线衍射分析已对化合物进行了充分表征。使用多核磁共振波谱法阐明了复合物4中两个旋转异构体的存在（¹ H，¹³C NMR）光谱和理论计算。测试了五种络合物在苯乙炔的水合和硅氢化中的催化活性。观察到催化性能的显着差异。在苯乙炔的水合中，仅形成马尔可夫尼科夫产物，收率从差到中等，化合物3表现最好。在氢化硅烷化反应中，获得了马尔可夫尼可夫（α）和反马尔可夫尼可夫（β-E）产物。尽管配合物1不是很活泼，但是由配合物5催化的反应显示出完全的转化。已经对五个三唑啉的立体和电子性质进行了详细的研究，以合理化其配合物的不同催化性能。