Increasing the Nuclearity of Magnetic Polyoxometalates. Syntheses, Structures, and Magnetic Properties of Salts of the Heteropoly Complexes [Ni3(H2O)3(PW10O39)H2O]7-, [Ni4(H2O)2(PW9O34)2]10-, and [Ni9(OH)3(H2O)6(HPO4)2(PW9O34)3]16-

Abstract

The rational synthesis and the structural and magnetic characterization of three different nickel clusters encapsulated in Keggin trivacant fragments are presented. The three complexes show how it is possible to increase the nuclearity of the clusters (from 3 and 4 to 9) by slightly changing the synthetic conditions. These three anionic clusters crystallize as mixed salts of K+ and Na+. The trimeric complex [Ni3(H2O)3PW10O39H2O]7- (Ni3) crystallizes in the triclinic space group P1 (a = 10.896(6) A, b = 12.869(5) A, c = 20.373(6) A, α = 94.67(6)°, β = 101.12(8)°, γ = 110.72(8)°, Z = 2) and presents a ferromagnetic triangular cluster. The tetranuclear complex [Ni4(H2O)2(PW9O34)2]10- (Ni4) crystallizes in the monoclinic space group P21/n (a = 11.824(5) A, b = 16.551(6) A, c = 21.074(5) A, β = 100.38(2)°, Z = 2) and presents a ferromagnetic rhomb-like cluster. The nonanuclear complex [Ni9(OH)3(H2O)6(HPO4)2(PW9O34)3]16- (Ni9) crystallizes in the monoclinic space group P21/c (a = 30.589(10) A, b = 12.521(6) A,...