Creation of Substitution Labile Pyrazolylborate Metal Complexes

(1)合成了双[二氢双（3，5-双（三氟甲基）吡唑基）硼酸]钴，并通过X射线单晶衍射确定了其结构。钴中心与四个吡唑基以正方形平面方式配位，与轴向位置的两个B-H基团配位，形成完全扭曲的八面体构型。这与已知的未取代的和3，5-二甲基取代的吡唑基硼酸酯衍生物形成鲜明对比，它们呈四面体构型。(2)合成了双（三苯基膦）[二氢双（3，5-R_2-吡唑基）硼酸酯]钌配合物（R=H，Me，CF_3），用X射线单晶衍射法测定了其结构。基于与CO的反应性，估计agostic相互作用的强度按Me> H * CF_3的顺序减小。(3)合成了双（三苯基膦）[二氢双（3，5-R_2-吡唑基）硼酸酯]铑配合物（R=H，Me，CF_3），用X射线单晶衍射法测定了其结构。铑中心以正方形平面的方式与四个吡唑基配位。在这些配合物中没有观察到B-H-Rh的agostic相互作用。(4)合成了3-烯丙基和茚基[氢化三（3，5-R_2-吡唑基）硼酸酯]钯配合物（R=H，Me，CF_3），用X射线单晶衍射法测定了其结构。用核磁共振谱研究了它们在溶液中的流动行为。

(1) Bis[dihydrobis(3,5-bis(trifluoromethyl)pyrazolyl)borate]cobalt was prepared and the structure was determined by X ray crystallographic analysis. The cobalt center is coordinated to four pyrazolyl groups in a square planner manner and to two B-H groups at the axial positions forming totally a distorted octahedral configuration. This is in marked contrast to those of known non-substituted and 3, 5-dimethyl substituted pyrazolylborate derivatives which appear inn a tetrahedral configuration Similar nickel complex having a B-H-M agostic interaction was prepared.(2) Bis(triphenylphosphine)[dihydrobis(3,5-R_2-pyrazolyl)borate]ruthenium hydrides (R=H, Me, CF_3) were prepared and the structures containing a B-H-Ru agostic interaction were determined by X ray crystallography. Based on the reactivity with CO, strength of the agostic interaction was estimated to decrease in the order, Me> H * CF_3.(3) Bis(triphenylphosphine)[dihydrobis(3, 5-R_2-pyrazolyl)borate]rhodium complexes (R=H, Me, CF_3) were prepared and the structures were determined by X ray crystallographic analysis. The rhodium centers are coordinated in a square planner manner to the four pyrazolyl groups. No B-H-Rh agostic interactions were observed in these complexes.(4) eta^3-Allyl and indenyl[hydrotris(3,5-R_2-pyrazolyl)borate]palladium complexes (R=H, Me, CF_3) were prepared and the structures were determined by X ray crystallographic analysis. Their fluxional behavior in solution were studied by NMR spectroscopy.