Polyhedral-Based Nonlinear Optical Materials. 3. Synthetic studies of Cyclopentadiene-and Cycloheptatriene-Substituted Polyhedral Compounds: Synthesis of 1,12-[(C_7H_7)C_2B_(10)H_(10)(C_5H_3Me_2)] and Related Species

摘要

The synthesis and characterization of a series of new olefin-substituted closo-1,12-[C_2B_(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_7H_7)-12-(H)-C_2B_(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_7H_7)-12-(C_5H_4-1-(OH)-3,4-(CH_3)_2-C_2B_(10)H_(10)) (5) in good yield. Acidic dehydration of 5 quantitatively converted it into the simple bis-olefin cage compound [1-(1-C_7H_7)-12-(C_5H_3,3,4-(CH_3)_2-C_2B_(10)H_(10)) (6). Finally, thermal treatment of 6 in refluxing toluene was employed to prepare the isomerized cycloheptatriene compound [1-(4-C_7H_7)-12-(C_5H_3-3,4-(CH_3)_2)-C_2B_(10)H_(10)] (7) in hih 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 (~1H, ~(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 P1 with cell constants a = 6.6807(3) A, b = 10.2939(3) A, c = 10.3962(4) A, #alpha# = 89.342(2), #beta# = 74.610(2), #gamma# = 83.373(2), 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), Z = 4, R1 = 0.0761 (wR2 (all data) = 0.2050).