Synthesis,Structure,and Reactivity of 13-Vertex Carboranes and 14-Vertex Metallacarboranes

摘要

Syntheses,properties,and synthetic applications of 13-vertex closo-and nido-carboranes are reported.Reactions of the nido-carborane salt [(CH_2)_3C_2B_(10)H_(10)]Na_2 with dihaloborane reagents afforded 13-vertex closo-carboranes 1,2-(CH_2)_3-3-R-1,2-C_2B_(11)H_(10)(R = H(2),Ph(3),Z-EtCH=C(Et)(4),E-~tBuCH= CH(5)).Treatment of the aracnno-carborane salt [(CH_2)_3C_2B_(10)H_(10)]Li_4 with HBBr_2 centre dot SMe_2 gave both the 13-vertex carborane 2 and a 14-vertex closo-carborane(CH_2)_3C_2B_(12)H_(12)(8).On the other hand,the reaction of [C_6H_4(CH_2)_2C_2B_(10)H_(10)]Li4 with HBBr_2 centre dot SMe_2 generated only a 13-vertex closo-carborane 1,2-C_6H_4(CH_2)_2-1,2-C_2B_(11)H_(11)(9).Electrophilic substitution reactions of 2 with excess MeI,Br_2,or I_2 in the presence of a catalytic amount of AlCl_3 produced the hexa-substituted 13-vertex carboranes 8,9,10,11,12,13-X_6-1,2-(CH_2)_3-1,2-C_2B_(11)H_5(X = Me(10),Br(11),I(12)).The halogenated products 11 and 12 displayed unexpected instability toward moisture.The 13-vertex closo-carboranes were readily reduced by groups 1 and 2 metals.Accordingly,several 13-vertex nido-carborane dianionic salts {nido-1,2-(CH_2)_3-1,2-C_2B_(11)H_(11)}{Li_2(DME)_2-(THF)_2}(13),[{nido-1,2-(CH_2)_3-1,2-C_2B_(11)H_(11)}{Na_2(THF)_4}]_n(13a),[{nido-1,2-(CH_2)_3-3-Ph-1,2-C_2B_(11)H_(10)}-{Na_2(THF)_4}]_n(14),[{nido-1,2-C_6H_4(CH_2)_2-1,2-C_2B_(11)H_(11)}{Na_2(THF)_4}]_n(15),and {nido-1,2-(CH_2)_3-1,2-C_2B_(11)H_(11)}{M(THF)_5}(M = Mg(16),Ca(17))were prepared in good yields.These carbon-atom-adjacent nido-carboranes were not further reduced to the corresponding arachno species by lithium metal.On the other hand,like other nido-carborane dianions,they were useful synthons for the production of super-carboranes and supra-icosahedral metallacarboranes.Interactions of 13a with HBBr_2 centre dot SMe_2,(dppe)NiCl_2,and(dppen)NiCl_2 gave the 14-vertex carborane 8 and nickelacarboranes [eta~5-(CH_2)_3C_2B_(11)H_(11)]Ni(dppe)(18)and [eta~5-(CH_2)_3C_2B_(11)H_(11)]Ni(dppen)(19),respectively.All complexes were fully characterized by various spectroscopic techniques and elemental analyses.Some were further confirmed by single-crystal X-ray diffraction studies.