CRYSTAL STRUCTURE OF DI-N-BUTYLARSINIC ACID

The crystal structure of di-n-butylarsinic acid has been determined from 1257 independent photographically recorded intensities. For convenience, a non-conventional triclinic cell, B1 was chosen, a = 8.38(2), b = 13.12(3), c = 10.39(2) Å, α = 91.5(5), β = 89.8(5), γ = 98.5(5)°, z = 4/cell, d(calcd.) = 1.31, d(measured) = 1.32 g/cc, R = 0.096 with unit weights, anisotropic temperature factors and no contribution of H-atoms included. The acid molecules are present as non-planar, H-bonded dimers across the centers of symmetry in the cell. The configuration around As is nearly tetrahedral, the average distance As-C = 1.95(2) Å, As-O(1) = 1.67(1), As-O(2) = 1.74(1) Å, O(1)-O′(2) = 2.47(2) Å, and the dihedral angle between O(1)-As-O(2) and O(1)-O(2)-O′(1)-O′(2) is 140.0(7)° with a chair configuration for the dimer ring. The average distance C-C = 1.55(5) Å, angle C-C-C = 110(2)°. The intra-dimer C-C contracts are ≧ 4.5 Å, while there are a number of inter-dimer distances close to 4 Å. © 1969.