Xu Bao-Hua, Peng Xu-Qing, Li Yi-Zhi, Yan Hong
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University-Jin Chuan Group Ltd., Nanjing, Jiangsu 210093, China.
Chemistry. 2008;14(30):9347-56. doi: 10.1002/chem.200801136.
The reaction of the 16e half-sandwich complex [CpCo(S2C2B10H10)] (1S; Cp: cyclopentadienyl) with ethynylferrocene in CH2Cl2 at ambient temperature leads to [CpCo(S2C2B10H9)-(CH2CFc)] (2S; Fc: ferrocenyl) and 1,2,4-triferrocenylbenzene. In 2S, B substitution occurs at the carborane cage in the position B3/B6 with the formation of a C-B bond. In the presence of the protic solvent MeOH, 2S loses a CpCo fragment to generate [(CH2CFc)(S2C2B10H9)] (3S). On the other hand, 2S can take a free CpCo fragment to form [(CpCo)2(S2C2B9H8)-(CHCFc)] (4S) containing a nido-C2B9 unit. In sharp contrast, [CpCo-(Se2C2B10H10)] (1Se) does not react with the alkyne in CH2Cl2, but in MeOH [(CHCFc)(Se2C2B10H10)] (5Se) is generated without the presence of a CpCo unit. The reaction of 1 with dimethyl acetylenedicarboxylate at ambient temperature leads to insertion compounds [CpCo(E2C2B10H10){(MeO2C)-C=C(CO2Me)}] (6S, E=S; 6 Se, E=Se). Upon heating, 6S rearranges to two geometrical isomers [CpCo(S2C2B10H9){(MeO2C)C=CH(CO2Me)}] (7S) and [CpCo(S2C2B10H9){(MeO2C)-CHC(CO2Me)}] (8S). In both, B-H functionalization takes place at the carborane cage in the position B3/B6, but 7S is a 16e complex with an olefinic unit in a Z configuration, and 8S is an 18e complex containing an alkyl B-CH group. Further treatment of 7 S with dimethyl acetylenedicarboxylate at ambient temperature affords two B-disubstituted complexes at the carborane cage in the positions of the B3 and B6 sites, that is, [CpCo(S2C2-B10H8){(MeO2C)C=CH(CO2Me)}2] (9S) and [CpCo(S2C2B10H8){(MeO2C)-CHC(CO2Me)}{(MeO2C)C=CH-(CO2Me)}] (10S). Compound 9S is a 16e complex with two olefinic units in E/E configurations, whereas 10S is an 18e species containing both an olefinic substituent and an alkyl B--CH unit. The reaction of 7S with methyl acetylenemonocarboxylate at ambient temperature leads to the sole 16e compound [CpCo(S2C2B10H8){CH=CH(CO2Me)}-{(MeO2C)C=CH(CO2Me)}] (11S). In contrast, 6Se does not rearrange. All new complexes 2S-4S, 5Se, 6Se, and 7S-11S were characterized by NMR spectroscopy (1H, 11B, 13C) and X-ray structural analyses were performed for 2S-4S, 5Se, 6Se, and 7S-9S.
16电子半夹心配合物[CpCo(S2C2B10H10)]（1S；Cp：环戊二烯基）在室温下于二氯甲烷中与乙炔基二茂铁反应，生成[CpCo(S2C2B10H9)-(CH2CFc)]（2S；Fc：二茂铁基）和1,2,4-三二茂铁基苯。在2S中，硼取代发生在碳硼烷笼的B3/B6位，形成C-B键。在质子溶剂甲醇存在下，2S失去一个CpCo片段生成[(CH2CFc)(S2C2B10H9)]（3S）。另一方面，2S可以接受一个游离的CpCo片段形成含有巢式-C2B9单元的[(CpCo)2(S2C2B9H8)-(CHCFc)]（4S）。形成鲜明对比的是，[CpCo-(Se2C2B10H10)]（1Se）在二氯甲烷中不与炔烃反应，但在甲醇中生成不含CpCo单元的[(CHCFc)(Se2C2B10H10)]（5Se）。1在室温下与乙酰基二甲基乙炔二羧酸酯反应生成插入化合物[CpCo(E2C2B10H10){(MeO2C)-C=C(CO2Me)}]（6S，E = S；6Se，E = Se）。加热时，6S重排为两种几何异构体[CpCo(S2C2B10H9){(MeO2C)C=CH(CO2Me)}]（7S）和[CpCo(S2C2B10H9){(MeO2C)-CHC(CO2Me)}]（8S）。在这两种异构体中，硼氢化官能化都发生在碳硼烷笼的B3/B6位，但7S是一个具有Z构型烯烃单元的16电子配合物，而8S是一个含有烷基B-CH基团的18电子配合物。在室温下用乙酰基二甲基乙炔二羧酸酯进一步处理7S，在碳硼烷笼的B3和B6位得到两种硼二取代配合物，即[CpCo(S2C2-B10H8){(MeO2C)C=CH(CO2Me)}2]（9S）和[CpCo(S2C2B10H8){(MeO2C)-CHC(CO2Me)}{(MeO2C)C=CH-(CO2Me)}]（10S）。化合物9S是一个具有E/E构型两个烯烃单元的16电子配合物，而10S是一个同时含有烯烃取代基和烷基B-CH单元的18电子物种。7S在室温下与甲基乙炔单羧酸酯反应生成唯一的16电子化合物[CpCo(S2C2B10H8){CH=CH(CO2Me)}-{(MeO2C)C=CH(CO2Me)}]（11S）。相比之下，6Se不发生重排。所有新配合物2S - 4S、5Se、6Se和7S - 11S均通过核磁共振光谱（1H、11B、13C）进行了表征，并对2S - 4S、5Se、6Se和7S - 9S进行了X射线结构分析。
