Homo- and heterometallic coordination networks based on linear trinuclear Co(ii) units: syntheses, structures and magnetic properties?

RSC Advances Pub Date: 2015-02-23 DOI: 10.1039/C5RA00728C

Abstract

Two three-dimensional (3D) coordination networks, [Co3(1,4-BDC)3(L1)]∞ (L1 = N,N′-bis(3-pyridinyl)-1,4-benzenedicarboxamide; 1,4-H2BDC = 1,4-benzenedicarboxylic acid), 1, and [K2Co3(L2)4]∞ (H2L2 = 5-acetamidoisophthalic acid), 2, have been synthesized by hydrothermal reactions and characterized by single crystal X-ray crystallography. Complex 1 consists of linear trinuclear Co(II) centers, which are linked by the 1,4-BDC? and L1 ligands to form a rare (1 + 3) self-catenated 3D net with the new (36,410,511,6) topology, and complex 2 reveals a 3p–3d heterometallic coordination network based on linear trinuclear Co(II) and dinuclear K(I) centers bridged by the μ6-L2 ligands, forming a 4,4,8-connected trinodal net with the new (414·610·84)(42·64)(44·62) topology. The linear trinuclear Co(II) centers in 1 adopt the square pyramidal–octahedral–square pyramidal geometries, whereas those in 2 are tetrahedral–octahedral–tetrahedral. Both of the complexes exhibit paramagnetism that is consistent with the Curie–Weiss law between 60 and 300 K. The effective magnetic moments (〈μeff〉) of both complexes are larger than the estimated value of 6.71 μB/f.u., revealing the spin–orbit couplings that are invoked by the different distorted geometries of the linear trinuclear Co(II) centers. The dinuclear K(I) centers in 2 weaken the magnetic coupling, and reduce the antiferromagnetic ordering at 6 K.

Graphical abstract: Homo- and heterometallic coordination networks based on linear trinuclear Co(ii) units: syntheses, structures and magnetic properties
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