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首页> 外文期刊>Organometallics >Coordination and reactivity study of group 4 and 10 transition metal complexes of N-imidazol-2-ylidene-N′-p-tolylureate and thioureate ligands
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Coordination and reactivity study of group 4 and 10 transition metal complexes of N-imidazol-2-ylidene-N′-p-tolylureate and thioureate ligands

机译：N-咪唑-2-亚甲基-N'-对甲苯甲酸酯和硫脲酸酯配体的4和10组过渡金属配合物的配位和反应性研究

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摘要

The synthesis and isolation of N-imidazol-2-ylidene-N′-p-tolylureate and thioureate proligands is described. Titanium(IV), nickel(II), and palladium(II) complexes containing one or two equivalents of the ligand were prepared by transmetalation of the ureate or thioureate salts. The X-ray structure of titanium complexes corroborated our prediction based on spectroscopic data and showed the ureate binds in a bidentate fashion through the oxygen and nitrogen atoms of the isocyanate building block, leaving the imidazol-2-imine fragment uncoordinated. Carbon-nitrogen bond lengths indicate substantial electron delocalization from the imidazole ring to the ureate group. In contrast, the ligand adopts a different coordination mode and binds to nickel and palladium through the N_(imidazol-2-ylidene) and N_(p-tolyl) atoms. Surprisingly, despite the softer nature of sulfur, coordination of the thioureate was exclusively through the sulfur and nitrogen atoms of the isothiocyanate building block with all three metals studied. All complexes were tested for ethylene polymerization at ambient conditions using methylaluminoxane as cocatalyst. Titanium(IV) complexes were found to be the most active, with activities up to 60 kg PE mol~(-1) catalyst h~(-1).
机译：描述了N-咪唑-2-亚甲基-N'-对甲苯甲酸酯和硫脲酸酯配体的合成和分离。含有一或两当量配体的钛（IV），镍（II）和钯（II）配合物是通过对脲酸盐或硫脲酸盐进行金属化制备的。钛配合物的X射线结构证实了我们基于光谱数据的预测，并显示尿酸盐通过异氰酸酯结构单元中的氧和氮原子以双齿形式结合，而使咪唑-2-亚胺片段未配位。碳-氮键的长度表示从咪唑环到脲酸酯基团的大量电子离域。相反，配体采用不同的配位方式，并通过N_（咪唑-2-亚烷基）和N_（对甲苯基）原子与镍和钯结合。令人惊讶的是，尽管硫的性质较软，但硫脲酸酯的配位仅是通过异硫氰酸酯结构单元中的硫原子和氮原子与所研究的所有三种金属进行的。使用甲基铝氧烷作为助催化剂，在环境条件下测试了所有配合物的乙烯聚合反应。发现钛（IV）络合物活性最高，活性最高可达60 kg PE mol〜（-1）催化剂h〜（-1）。

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