CHARACTERIZATION OF THE BISMUTH(III) BROMIDE-[2.2]-PARACYCLOPHANE (2/1) ADDUCT

The 2:1 charge-transfer molecular complex between bismuth bromide and [2.2]paracyclophane has been prepared and investigated by means of thermogravimetric, electronic and IR spectra and resistivity measurements. The X-ray structure was also determined: monoclinic, space group P2(1)/c, a = 7.896(3), b = 14.198(6), c = 10.803(8) angstrom, beta = 101.27(5)-degrees, Z = 2 and R = 0.0457. The structure is built up by polymeric linear chains of BiBr3 units interlayered by centrosymmetric hydrocarbon molecules. Two bromine atoms bridge adjacent metal atoms so that the co-ordination is very distorted octahedral with three short [2.595(3)-2.676(3) angstrom] and two longer bridging [3.325(3), 3.402(2) angstrom] Bi-Br bonds; the sixth site is occupied by a benzene ring of the [2.2]paracyclophane molecule. The complex shows high stability and characteristic electrical properties of a semiconductor at 25-degrees-C.