SYNTHESIS AND CHARACTERIZATION OF A NEW SERIES OF ZINC PHOSPHITES
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Several new zinc phosphites have been synthesized in aqueous solution by reactions of Zn2+ with H3P03 and either Na+, K+, or Ba2+. The structures were determined by single-crystal X-ray diffraction techniques. Zn(H2PO3)23H2O; R3 a = 21.128 (2) , c = 7.769 (6) , V = 3003 (2) 3, Z = 18, R(F) = 0.073 for 494 observations (I > 3(I)), 82 variables. Zn2(HPO3)2-(H2O)4H2O: P, a = 7.670 (2) , b = 9.454 (1) , c = 7.554 (1) , = 90.83 (1), = 92.90 (1), y = 88.54 (2), V= 546.9 (2) 3, Z = 2, R(F) = 0.022 for 1430 observations ( I > 3(I)) 175 variables. Zn3Na2(HPO3)4: Pnma, a= 8.331 (2) , b = 12.243 (2) , c = 12.669 (1) , V = 1292.2 (6) 3, Z = 4, R(F) = 0.038 for 704 observations (I > 3(I)), 103 variables. Zn3K2(HPO3)4: P21/c,a = 12.373 (2) , b = 13.635 (2) , c = 8.571 (2) , = 90.24 (1), V= 1445.9 (4) 3, Z = 4, R(F) = 0.037 for 1525 observations ( I > 3(I)), 206 variables. Zn3Ba(HPO3)4(H2O)6: C2/c, a = 22.707 (2) , b = 5.302 (3) , c = 15.029 (1) , = 105.28 (1), V= 1745 (1) 3, Z = 4, R(F) = 0.054 for 1530 observations (I> 3(I))t141 variables. Each of the five structures is a new type with the Zn atoms in either octahedral or tetrahedral coordination bridged by phosphite groups to produce a framework of zinc and phosphorus-centered oxygen polyhedra. Several of the frameworks have open channels lined with phosphite H atoms or coordinated water molecules. In some cases, these polyhedra are bridged by alkali-metal or alkaline-earth-metal ions to produce different frameworks. The exact nature of each structure is highly dependent on the identity of the second metal as each adopts a different coordination environment. The coordination numbers of the Na+, K+, and Ba2+ ions are 6, 7, and 12, respectively. The role of the alkali and alkaline-earth metals in the structures is discussed, and the phosphite structures are compared with similar known phosphates. 1989, American Chemical Society. All rights reserved.
