Ag(I)/V(V) heterobimetallic frameworks generated from novel-type {Ag2(VO2F2)2(triazole)4} secondary building blocks: a new aspect in the design of SVOF hybrids.

A series of new silver(I)-containing MOFs Ag(2)(tr(2)ad)(2)(2) (1), [Ag(2)(VO(2)F(2))(2)(tr(2)ad)(2)]·H(2)O (2), [Ag(2)(VO(2)F(2))(2)(tr(2)eth)(2)(H(2)O)(2)] (3), and [Ag(2)(VO(2)F(2))(2)(tr(2)cy)(2)]·4H(2)O (4) supported by 4-substituted bifunctional 1,2,4-triazole ligands (tr(2)ad = 1,3-bis(1,2,4-triazol-4-yl)adamantane, tr(2)eth = 1,2-bis(1,2,4-triazol-4-yl)ethane, tr(2)cy = trans-1,4-bis(1,2,4-triazol-4-yl)cyclohexane) were hydrothermally synthesized and structurally characterized. In these complexes, the triazole heterocycle as an N(1),N(2)-bridge links either two adjacent Ag-Ag or Ag-V centers at short distances forming polynuclear clusters. The crystal structure of compound 1 is based on cationic {Ag(2)(tr)(4)}(2+) fragments connected in a 2D rhombohedral grid network with (4,4) topology. The neighboring layers are tightly packed into a 3D array by means of argentophilic interactions (Ag···Ag 3.28 Å). Bridging between different metal atoms through the triazole groups assists formation of heterobimetallic Ag(I)/V(V) secondary building blocks in a linear V-Ag-Ag-V sequence that is observed in complexes 2-4. These unprecedented tetranuclear {Ag(2)(VO(2)F(2))(2)(tr)(4)} units (the intermetal Ag-Ag and Ag-V distances are 4.24-4.36 and 3.74-3.81 Å, respectively), in which vanadium(V) oxofluoride units possess distorted trigonal bipyramidal environment {VO(2)F(2)N}¯, are incorporated into 1D ribbon (2) or 2D square nets (3, 4) using bitopic μ(4)-triazole ligands. The valence bond calculation for vanadium atoms shows +V oxidation state in the corresponding compounds. Thermal stability and photoluminescence properties were studied for all reported coordination polymers.