TETRA- TO HEPTA- COORDINATION IN DIMETHYL METHYLPHOSPHONATE CATIONIC METAL COMPLEXES

Dimethyl methylphosphonate (DMMP) cationic complexes with metal perchlorates of the types [M(DMMP)4]2+ (M Ni, Cu), [M(DMMP)5]2+ (M Mg, Fe), [M(DMMP)6]2,3+ (M Al(III), Cr(III), Mn(II), Fe(III)), [M(DMMP)4(H2O)2]2+ (M Co, Zn) and [Ce(DMMP)6 (ClO4)]2+ have been prepared and characterized by means of spectral, magnetic conductance and, in certain cases, X-ray powder diffraction studies. Infrared evidence indicates that coordination occurs through the phosphoryl oxygen and conductance measurements justify the formulations given above. Ligand-field symmetries assigned to the complex cations are as follows: tetracoordinated, intermediate between distorted Td and D4h; pentacoordinated, close to square pyramidal; hexacoordinated, lower than Oh. The ability of DMMP to form higher-coordinated complexes than other organophosphoryl compounds is discussed in terms of the favorable steric characteristics arising from the presence of methyl and methoxy groups in this molecule. © 1969.