Synthesis and crystal structures of tris(diethylamino)benzylphosphonium bromides: [(C2H5)(2)N](3)PCH2C6H5+Br-center dot CH3CN and [(C2H5)(2)N](3)PCH2C6H5+Br-3(-)

Tris(diethylamino)benzylphosphonium bromide, [(C2H5)(2)N](3)PCH2C6H5+ Br-. CH3CN (1), has been prepared by the reaction of tris(diethylamino)phosphine with benzylbromide in acetonitrile and its structure determined. The colorless crystals are monoclinic, space group P2(1)/n, Z = 4, a = 954.5(11), b = 2552(3), c = 1017.9(9) pm, beta = 92.27(8)degrees. The lattic contains Br- anions and [(C2H5)(2)N](3)PCH2C6H5+ cations. [(C2H5)(2)N](3)PCH2C6H5](+) Br-3(-) (2) has been obtained by treating compound 1 with equimolar quantities of elemental bromine in acetonitrile solution. The yellow-red crystals of 2 are monoclinic, space group P2(1)/n, Z = 4, a = 1065.1(4), b = 1952.9(2), c = 1201.7(2) pm, beta = 98.18(2)degrees, and comprise [(C2H5)(2)N](3)PCH2C6H5+ cations and linear Br-3(-) anions.