Trinuclear coordination assemblies of low-spin dicyano manganese(ii) (S = 1/2) and iron(ii) (S = 0) phthalocyanines with manganese(ii) acetylacetonate, tris(cyclopentadienyl)gadolinium(iii) and neodymium(iii)

Abstract

The reaction of MnIIPc, FeIIPc or FeIIPcCl16 with KCN in the presence of cryptand[2.2.2] yielded dicyano-complexes {cryptand(K+)}2{MII(CN)2(macrocycle2−)}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{MII(CN)2Pc·(ML)2}2−·nC6H4Cl2 (MII = MnII and FeII; n = 1, 4 and 5). These assemblies were formed via coordination of two manganese(ii) acetylacetonate (ML = MnII(acac)2, S = 5/2), tris(cyclopentadienyl)gadolinium (ML = Cp3GdIII, S = 7/2) or tris(cyclopentadienyl)neodymium (ML = Cp3NdIII, S = 3/2) units to the nitrogen atoms of bidentate cyano ligands. The N(CN)-Mn{MnII(acac)2} bond is 2.129(3) Å long but the 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 {MnII(CN)2Pc·(MnII(acac)2)2}2− dianions at 2 K. The estimated exchange interaction between MnII (S = 1/2) and GdIII (S = 7/2) spins in {MnII(CN)2Pc·(Cp3GdIII)2}2− is only −1.1 cm−1, and in contrast to 2, nearly independent GdIII and MnII centers are formed. As a result, no transition to the high-spin state is observed in {MnII(CN)2Pc·(Cp3GdIII)2}2−. The {MnII(CN)2Pc·(Cp3NdIII)2}2− and{FeII(CN)2Pc·(Cp3NdIII)2}2− dianions with Cp3NdIII show a decrease of χMT values in the whole studied temperature range (300-1.9 K). A similar behaviour was found previously for pristine Cp3NdIII and Cp3NdIII·L complexes (L = alkylisocyanide ligand).