EFFECT OF COORDINATION ON THE STRUCTURE OF TRIS(N,N-DIMETHYLAMINOMETHYL)PHOSPHINE OXIDE

Crystals of tris(NN-dimethylaminomethyl)phosphine oxide (tmpo) are hex agonal, space group P6(3): a = 8.723(5), c = 10.636(5) angstrom, Z = 2 , R = 0.039 for 384 observed reflections. The complex [Co(tmpo)2(H2O)2 ](ClO4)2, forms orthorhombic crystals, space group Pbca, a = 19.16(1), b = 10.576(2), c = 17.043(4) angstrom, Z = 4, R = 0.069 for 1 409 obs erved reflections. The molecule is centrosymmetric, with the Co atom l ying in the centre. The tmpo is coordinated through the oxygen atom an d one of the nitrogen atoms. The coordination of the ligand brings abo ut very small changes in the bond lengths and angles except for the P = O bond. The coordinated water molecules play a major part in the str ucture of [Co(tmpo)2(H2O)2](ClO4)2.