IODINATION REACTIONS OF ICOSAHEDRAL PARA-CARBORANE AND THE SYNTHESIS OF CARBORANE DERIVATIVES WITH BORON-CARBON BONDS

Reaction of closo-1,12-C2B10H12 (para-carborane) with 2 molar equiv of ICl in the presence of catalytic quantities of AlCl4 affords closo-1,12-C2B10H10I2 as a mixture of isomers. The 2,9- (2), 2,3- (3), and 2,7-isomers (4) have been isolated and characterized. Reaction of closo-1,12-C2B10H11-2-I (1) with PhMgBr or 2 with RMgBr (R = Me, Ph) in the presence of PdCl2(PPh(3))(2) and CuI gives high yields of closo-1,12-C2B10H11-2-Ph (6) and closo-1,12-C2B10H10-2,9-R(2) (7, R = Me; 8, R = Ph), respectively. Reaction of 1 with HC=CPh in the presence of PdCl2(PPh(3))(2) and pyrrolidine yields closo-1,12-C2B10H11-2-C=CPh (9). Reaction of 1 or 2 with HC=CSiMe(3) under the same conditions affords closo-1,12-C2B10H11-2-C=CSiMe(3) (10) and closo-1,12-C2B10H11-2,9-(C=CSiMe(3))(2) (12) which react with fluoride ion to give closo-1,12-C2B10H11-2-C=CH (11) and closo-1,12-C2B10H11-2,9-(C=CH)(2) (13), respectively. The structures of 1, 3, 4, closo-1,12-C2H2B10I10 (5), and 8 have been determined by crystallographic studies. Crystallographic data are as follows: For 1, monoclinic, space group C2/c, a = 10.824(2) Angstrom, b = 9.439(1) Angstrom, c = 21.414(3) Angstrom, beta = 102.121(4)degrees, Z = 8, R = 0.035; for 3, orthorhombic, space group Pmnb, a = 12.868(1) Angstrom, b = 14.144(2) Angstrom, c = 7.069(1) Angstrom, Z = 4, R = 0.038; for 4, monoclinic, space group C2/c, a = 25.039(1) Angstrom, b = 8.1129(4) Angstrom, c = 14.3300(7) Angstrom, beta = 122.567(1)degrees, Z = 8, R = 0.050; for 5, triclinic, space group P ($) over bar 1, a = 7.796(1) Angstrom, b = 9.882(2) Angstrom, c = 16.681(3) Angstrom, alpha = 91.550(6)degrees, beta = 100.271(6)degrees, gamma = 110.854(5), Z = 2, R = 0.060; for 8, orthorhombic, space group Pcab (Pbca ($) over bar cba), a = 8.7706(8) Angstrom, b = 10.559(1) Angstrom, c = 18.081(2) Angstrom, Z = 4, R = 0.067.