Two novel types of Ln2M2 clusters bridged by cyanide andcarboxylate simultaneously

Two novel complexes [Sm-2(AC)(2)(phen)(4)(H2O)(2){Fe(CN)(5)(NO)}(2)] 1 and [Dy-2(Ac)(2)(phen)(4)(H2O)(2){Fe(CN)(5)(NO)}(2)].8H(2)O 2 have been synthesized and structurally and magnetically characterized. Complex I crystallizes in the orthorhombic space group of Aba2 with a = 18.6179(3), b = 16.2001(3), c = 20.9875(4) Angstrom, and Z = 4, while complex 2 crystallizes in the monoclinic space group P2(1)/n with a = 12.0748(3), b = 27.3276(5), c = 22.9096(6) Angstrom, beta = 93.1001 (8)degrees, and Z = 4. A cyanide and carboxylate anions are bridging tetranuclear clusters, but exhibit different structural features. In 1, two [Fe(CN)(5)(NO)](2-) fragments connect the same Sm3+ cation in a [Sm-2(Ac)(2)] dimer unit to produce a T-shaped motif. In 2, two [Fe(CN)(5)(NO)](2-) fragments attach to the two different Dy3+ cations in a [Dy-2(Ac)(2)] dimer unit, leading to a U-shaped topology. Both examples represent novel structural types among tetranuclear Ln(2)M(2) clusters. (C) 2003 Elsevier Science (USA). All rights reserved.