ABSTRACT
The synthesis and characterization of a series of new olefin-substituted closo-1,12-[C(2)B(10)H(12)] compounds is described. The reaction of deprotonated closo-1,12-dicarbadodecaborane with 7-methoxycycloheptatriene yields the cycloheptatriene-substituted carborane compound, closo-[1-(1-C(7)H(7))-12-(H)-C(2)B(10)H(10)] (3). Deprotonation of 3 with butyllithium and subsequent reaction with 3,4-dimethyl-2-cyclopenten-1-one was found to yield the bis-olefin-substituted carbinol compound [1-(1-C(7)H(7))-12-(C(5)H(4)-1-(OH)-3,4-(CH(3))(2))-C(2)B(10)H(10)] (5) in good yield. Acidic dehydration of 5 quantitatively converted it into the simple bis-olefin cage compound [1-(1-C(7)H(7))-12-(C(5)H(3)-3,4-(CH(3))(2))-C(2)B(10)H(10)] (6). Finally, thermal treatment of 6 in refluxing toluene was employed to prepare the isomerized cycloheptatriene compound [1-(4-C(7)H(7))-12-(C(5)H(3)-3,4-(CH(3))(2))-C(2)B(10)H(10)] (7) in high yield. These compounds represent the first metal-free cyclopentadiene and bis-olefin large cluster species reported in which the C(5) ring is attached directly to the cage. The complete characterization of products by multinuclear NMR ((1)H, (11)B, and (13)C), infrared, UV-visible, and mass spectroscopic analyses is presented. The X-ray crystal structures of 3 and 7 are also reported. X-ray data for 3: triclinic system, space group P&onemacr; with cell constants a = 6.6807(3) A, b = 10.2939(3) A, c = 10.3962(4) A, alpha = 89.342(2) degrees, beta = 74.610(2) degrees, gamma = 83.373(2) degrees, Z = 2, R1 = 0.0487 (wR2 (all data) = 0.1272). X-ray data for 7: monoclinic system, space group P2(1)/c with cell constants a = 7.7207(7) A, b = 15.8730(14) A, c = 15.5493(13) A, beta = 99.146(2) degrees, Z = 4, R1 = 0.0761 (wR2 (all data) = 0.2050).
