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A series of heterometallic magnesium diruthenium(ii,iii) carbonates, namely K{Mg(H2O)6}2[Ru2(CO3)4Cl2]·4H2O (1), K2[{Mg(H2O)4}2Ru2(CO3)4(H2O)Cl]Cl2·2H2O (2), K[Mg(H2O)5Ru2(CO3)4]·5H2O (3) and K[Mg(H2O)4Ru2(CO3)4]·H2O (4), were synthesized from the reaction of Ru2(CO3)43− and Mg2+ in aqueous solution. Compound 1 is composed of ionic crystals with the Ru2(CO3)4Cl25− : Mg(H2O)62+ : K+ ratio of 1 : 2 : 1. Compound 2 consists of two dimensional layer structures, in which each octahedral environment Mg(H2O)42+ bonds to two [Ru2(CO3)4(H2O)Cl]4− units in a cis manner forming a neutral square-grid layer {Mg(H2O)4Ru2(CO3)4(H2O)Cl}n. For compound 3, one water molecule of each Mg(H2O)62+ is substituted by an oxygen atom of Ru2(CO3)43− forming [Mg(H2O)5Ru2(CO3)4]−, and then the neighboring Ru2 dimers are linked together by the rest of the two oxygen atoms of carbonates to form a layer structure {Mg(H2O)5Ru2(CO3)4}nn−. In compound 4, the neighboring squared-grid layers {Ru2(CO3)4}n3n−, similar to those in compound 3, are linked by each octahedral environment Mg(H2O)42+ in a cis manner forming the three-dimensional network {Mg(H2O)4Ru2(CO3)4}nn−. Compound 3 shows ferromagnetic coupling between Ru2 dimers, and a long-range ordering is observed below 3.8 K. Compound 4 displays a magnetic ordering below 3.5 K, and a systematic study of the size-dependent magnetic properties of compound 4 reveals that the coercivity of 4 has been improved with reduced sample particle size from the micrometer to the nanometer scale. [ABSTRACT FROM AUTHOR]

Two hetero-metallic carbonates, namely KCd(H2O)3Ru2(CO3)4·4H2O (1) and KCd(H2O)3Ru2(CO3)4·3.5H2O (2), have been synthesized in a neutral aqueous solution. Both of the 3D dimensional structured complexes contain mixed-valent diruthenium(ii,iii) carbonate paddlewheel cores of Ru2II,III(CO3)43− that are connected to each other in trans- or cis-modes by carbonate oxygen atoms, forming rectangular square-grid and isomeric parallelogram layers [Ru2(CO3)4]n3n− in 1 and 2, respectively. The reaction temperature is found to play an important role in directing the final products with particular topologies and their layered structural diversity is due to the various linking modes between the Ru2(CO3)43− units. The magnetic studies show that ferromagnetic interactions are propagated between the diruthenium units in both complexes 1 and 2 but their magnetic properties differ at low temperatures, in which the trans linking mode parallelogram layer [Ru2(CO3)4]n3n− in complex 2 leads to long-range magnetic ordering below 4.0 K. However, no Curie ordering down to 1.8 K is detected for complex 1 containing the isomeric rectangle square-grid layer linking in the cis mode. [ABSTRACT FROM AUTHOR]