CRYSTAL-CHEMISTRY OF MG2P2O7.NH2O, N = 0,2 AND 6 - MAGNESIUM OXYGEN COORDINATION AND PYROPHOSPHATE LIGATION AND CONFORMATION

The crystal structure of the hexahydrate has been determined and is compared with the known structures of the dihydrate and two forms of the anhydrous compound. Comparisons among the structures provide some insight as to the structural role of Mg2+ as a cofactor in the ATP-ADP hydrolysis reactions of bioenergetics. Crystal data for dimagnesium pyrophosphate hexahydrate: Mg2P2O7.6H2O, M(r) = 330.66, monoclinic, P2(1)/n, a = 7.189 (2), b = 18.309 (8), c = 7.665 (5) angstrom, beta = 92.360 (14)-degrees, V = 1008.1 angstrom3, Z = 4, D(x) = 2.18 mg mm-3, F(000) = 680, mu = 0.609 mm-1 for lambda(Mo K-alpha) = 0.7107 angstrom. R(absolute value of F) = 0.047 for 937 data.