Gong Lei, Chen Zhening, Lin Yumei, He Xumin, Wen Ting Bin, Xu Xin, Xia Haiping
State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P.R. China.
Chemistry. 2009 Jun 15;15(25):6258-66. doi: 10.1002/chem.200900214.
Treatment of HC[triple bond]CC(CH3)(OH)CH=CH2 with [OsCl2(PPh3)3] in dichloromethane yielded the eta2-olefin-coordinated osmacycle [Os{CH=C(PPh3)C(=CH2)-eta2-CH=CH2}Cl2(PPh3)2] (9). Transformations of osmacycle 9 by treatment with benzonitrile under various conditions have been investigated. Reaction of 9 with excess benzonitrile at room temperature afforded the dicationic osmacycle [Os{CH=C(PPh3)C(=CH2)-eta2-CH=CH2}(PhCN)2(PPh3)2]Cl2 (11) by ligand substitution, which reacted further to the intramolecularly coordinated eta2-allene complex [Os{CH=C(PPh3)C(CH3)=(eta2-C=CH2)}(PhCN)2(PPh3)2]Cl2 (12). In contrast, heating a chloroform solution of 9 to the reflux temperature in the presence of excess benzonitrile generated osmabenzene [Os{CHC(PPh3)C(CH3)CHCH}(PhCN)2(PPh3)2]Cl2 (14). Complexes 11, 12 and 14 are in fact isomers. In the absence of excess benzonitrile, the isolated dicationic 12 and 14 readily dissociate the benzonitrile ligands in solution to produce the neutral complex [Os{CH=C(PPh3)C(CH3)=(eta2-C=CH2)}Cl2(PPh3)2] (13) and the monocationic osmabenzene [Os{CHC(PPh3)C(CH3)CHCH}Cl(PhCN)(PPh3)2]BPh4 (15), respectively. Mechanisms for the formation of osmabenzene 14 from 11 and 12 are proposed based on DFT calculations.
在二氯甲烷中，用[OsCl₂(PPh₃)₃]处理HC≡CC(CH₃)(OH)CH=CH₂，得到η²-烯烃配位的锇杂环化合物[Os{CH=C(PPh₃)C(=CH₂)-η²-CH=CH₂}Cl₂(PPh₃)₂]（9）。研究了在各种条件下，用苯甲腈处理锇杂环化合物9的转化反应。9与过量苯甲腈在室温下反应，通过配体取代得到二价阳离子锇杂环化合物[Os{CH=C(PPh₃)C(=CH₂)-η²-CH=CH₂}(PhCN)₂(PPh₃)₂]Cl₂（11），该化合物进一步反应生成分子内配位的η²-丙二烯配合物[Os{CH=C(PPh₃)C(CH₃)=(η²-C=CH₂)}(PhCN)₂(PPh₃)₂]Cl₂（12）。相反，在过量苯甲腈存在下，将9的氯仿溶液加热至回流温度，生成锇苯[Os{CHC(PPh₃)C(CH₃)CHCH}(PhCN)₂(PPh₃)₂]Cl₂（14）。实际上，配合物11、12和14是异构体。在没有过量苯甲腈的情况下，分离得到的二价阳离子12和14在溶液中很容易解离苯甲腈配体，分别生成中性配合物[Os{CH=C(PPh₃)C(CH₃)=(η²-C=CH₂)}Cl₂(PPh₃)₂]（13）和一价阳离子锇苯[Os{CHC(PPh₃)C(CH₃)CHCH}Cl(PhCN)(PPh₃)₂]BPh₄（15）。基于密度泛函理论计算，提出了由11和12形成锇苯14的反应机理。
