Trinuclear coordination assemblies of low-spin dicyano manganese(II) (S = 1/2) and iron(II) (S = 0) phthalocyanines with manganese(II) acetylacetonate and tris(cyclopentadienyl)lanthanidesстатья
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Аннотация:The reaction of Mn(II)Pc, Fe(II)Pc or Fe(II)PcCl16 with KCN in the presence of cryptand[2.2.2] yielded dicyanocomplexes {cryptand(K+)}2 {M(II)(CN)2(macrocycle(2−))}(2−)·XC6H4Cl2 (M = Mn and Fe, X = 1 and 2) that were used for the preparation of trinuclear assemblies of the general formula {cryptand(K+)}2 {M(II)(CN)2Pc·(ML)2}(2−)·nC6H4Cl2 (M(II) = Mn(II) and Fe(II); n = 1, 4 and 5). These assemblies were formed via coordination of two manganese(II) acetylacetonate (ML = Mn(II)(acac)2, S = 5/2), tris(cyclopentadienyl)gadolinium (ML = Cp3Gd(III), S = 7/2) or tris(cyclopentadienyl)neodymium (ML = Cp3Nd(III), S = 3/2) units tothe nitrogen atoms of bidentate cyano ligands. The N(CN)–Mn{Mn(II)(acac)2} bond is 2.129(3) Å long butthe bonds are elongated to 2.43–2.49 Å for tris(cyclopentadienyl)lanthanides. {Cryptand(K+)}2{MnII(CN)2Pc·(MnII(acac)2)2}2−·5C6H4Cl2 (2) contains three Mn(II) ions in different spin states (S = 5/2 and 1/2). Strong antiferromagnetic coupling of spins observed between them with the exchange interaction (J) of −17.6 cm(−1) enables the formation of a high S = 9/2 spin state for{Mn(II)(CN)2Pc·(Mn(II)(acac)2)2}(2−) dianions at 2 K. The estimated exchange interaction between Mn(II) (S = 1/2) and Gd(III) (S = 7/2) spins in {Mn(II)(CN)2Pc·(Cp3Gd(III))2}(2−) is only −1.1 cm(−1), and in contrast to 2, nearly independentGd(III) and Mn(II) centers are formed. As a result, no transition to the high-spin state is observed in{Mn(II)(CN)2Pc·(Cp3Gd(III))2}(2−). The {Mn(II)(CN)2Pc·(Cp3Nd(III))2}(2−) and{Fe(II)(CN)2Pc·(Cp3Nd(III))2}(2−) dianions withCp3Nd(III) show a decrease of χMT values in the whole studied temperature range (300–1.9 K). A similar behaviour was found previously for pristine Cp3Nd(III) and Cp3Nd(III)·L complexes (L = alkylisocyanide ligand).