Novel Layering of Aqua and Imidazolidinyl Phenolate Bridged Cationic [CuII2(μ-L)(μ-H2O)•H2O]2 Units Over CuINCS Based One-Dimensional Anionic Parallel Chains as Diamagnetic Coordination Framework Host

The hetero valence copper-based metal-organic framework structure {[Cu-2(II)(mu-L)(mu-H2O)center dot H2O][Cu-I-(1,3-NCS)(2)]}(n) (2) was constructed from the aqua-bridged (Cu-2) complex [Cu-2(mu-L)(mu-H2O)]ClO4 center dot 1.5H(2)O (1.1.5H(2)O) of the N4O3 coordinating heptadentate imidazolidinyl phenolate Schiff base ligand, H3L (2-(2'-hydroxyphenyl)-1,3-bis[4- (2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine). Thiocyanate coordination induced aqua bridge cleavage and reductive extrusion lead to the formation of Cu(NCS)(2)(-) anions as a molecular building block and generation of one-dimensional (1D) anionic chains as an extended coordination framework host in 2 and quantitatively replace all the ClO4- ions from 1 center dot 1.5H(2)O via anion metathesis. Once formed these chains trap the original [Cu-2] cationic units in a layer. The copper atoms of 2 are in a distorted square-pyramidal environments around I id copper ions and are held together by phenolate, imidazolidinyl, and aqua bridges at 3.29 angstrom intrametallic Cu-II center dot center dot center dot Cu-II separation. Within the anionic part the presence of two symmetric end-to-end thiocyanate bridges with Cu-I-SCN and Cu-I-NCS distances of 2.61 angstrom (av.) and 1.924 angstrom (av.), respectively, results in a Cu-I center dot center dot center dot Cu-I separation of 5.51 angstrom (av.) within the linear chain. The cationic part of 2 exhibits a weak ferromagnetic exchange interaction (J/k(B)=+13.0(5) K or J=+9.0cm(-1) and g=2.25(1)) between the two Cu-II ions (S=1/2) and implies that the complex possesses all S-T=1 spin ground state in good agreement with the M vs H data below 8 K.