Establishment of syntheses of metal-rich metallaborane clusters using borane-Lewis base adducts

本课题的目的是建立一种新的合成方法，利用我们最近开发的过渡金属络合物活化硼烷-路易斯碱加合物来合成具有大M/B比的金属硼烷。钌金属配合物与BH_3-THF反应，得到具有Ru_2B_3、Ru_2B_4、RuB_4骨架的簇合物，进一步与膦配体反应，得到具有较大M/B比的Ru_2B_2、RuB_3簇合物，BH_3-THF与[Cp^*RuCl]_4反应，得到巢式[Cp^*RuCl]_4簇合物。（Cp^*Ru（μ-H）}_2B_3H_7]（1）与BH_3-THF反应得到巢式-[（Cp^*Ru（μ-H）}_2B_4H_9]（2）。1与膦衍生物的反应经历了簇合物骨架的降解和重排，反应模式取决于膦的性质。在与PHPh_2或P（OPh）_3的反应中，1得到了六方结构的[（Cp^*_2Ru_2PR_3）（μ-H）_2B_3H_7]。与P（OR）_3反应，经脱氢重排得到巢式-[（Cp^*_2Ru_2（μ-P（OR）_2}（μ-H）_2B_3H_5（OR）]（4）。与强碱性的PR_3反应，生成[（Cp^*Ru）_2（μ-H）（PR_3）B_2H_5]（5），其中BH_3-PR_3被消除。与苯基膦反应得到[（Cp^*Ru）_2（μ-PR_2）（B_2H_2）]（6），同时伴有苯的消除和骨架的重排。核磁共振测定表明了6.在BH_3-THF体系中，[（C_6Me_6）RuCl_2]_2与配体C_6Me_6反应，得到了只含一个金属碎片的簇合物[（C_6Me_6）RuB_4H_<10>]（7）。7与PMe_3花生状-[（C_6Me_6）Ru（PMe_3）（B_3H_7）]（8）的反应伴随着BH_3-PMe_3的消除。这也表明簇与膦的反应为M/B比的改变提供了途径。

The purpose of this project was to establish new methods for the syntheses of metallaboranes with large M/B ratios using activation of borane-Lewis base adducts by transition metal complexes which we have developed recently. Reactions of organometallic ruthenium complexes with BH_3-THF gave cluster compounds with the Ru_2B_3, RU_2B_4, RuB_4 frameworks, and further reactions of these clusters with phosphines gave RU_2B_2, RuB_3 clusters with larger M/B ratios.The reaction of BH_3-THF with [Cp^*RuCl]_4 gave nido-[(Cp^*Ru(μ-H)}_2B_3H_7] (1), and 1 further reacted with BH_3-THF to give nido-[(Cp^*Ru(μ-H)}_2B_4H_9] (2). Reaction of 1 with phosphine derivatives underwent degradation and rearrangement of cluster frameworks, and the reaction modes depended on the nature of phosphines. In the reactions with PHPh_2 or P(OPh)_3 1 gave arachno-[(Cp^*_2Ru_2PR_3)(μ-H)_2B_3H_7] (3) adding phosphine to the basal metal. Reaction with P(OR)_3 underwent dehydrogenation rearragement to give nido-[(Cp^*_2Ru_2(μ-P(OR)_2}(μ-H)_2B_3H_5(OR)] (4). Reactions with PR_3, stronger bases gave [(Cp^*Ru)_2(μ-H)(PR_3)B_2H_5] (5) with elimination of BH_3-PR_3. Reaction using phenyl phosphines provided [(Cp^*Ru)_2(μ-PR_2)(B_2H_2)] (6) accompanied with benzene elimination and rearagement of the framework. NMR measurement showed the fraxional property of the cluster flamework of 6. Reaction of 5 with excess PR_3, underwent total degradation of the cluster to form mononuclear compounds, although 6 did not show any such reaction.Reaction of BH_3-THF and [(C_6Me_6)RuCl_2]_2 with a bulky ligand, C_6Me_6, afforded arachno-[(C_6Me_6)RuB_4H_<10>] (7) which contained only one metal fragment. Reaction of 7 with PMe_3 arachno-[(C_6Me_6)Ru(PMe_3)(B_3H_7)] (8) accompanied with the elimination of BH_3-PMe_3. This also shows that the reaction of the cluster with phosphine provides a route to the change of the M/B ratio.