Antiferromagnetic Mixed-Valence Cu(I)-Cu(II) Two-Dimensional Coordination Polymers Constructed by Double Oximato Bridged Cu(II) Dimers and CuISCN Based One-Dimensional Anionic Chains

One dinuclear CU(II) complex [Cu2L22(EtOH)(0.5)(CIO4)](CIO4) (1) has been synthesized by reacting an oxime-based tridentate Schiff base ligand, 3{2-(diethylamino)ethylimino]butan-2-one,oxime (HL2), with Cu-II(CIO4)2, whereas the reaction of another similar ligand, 3-[2-(dimethylamino)ethylimino]-butan-2-one oxime (HL1), and this ligand (HL2) with Cu-II(CIO4)(2) in the presence of NaSCN yielded two rare mixed-valenceCu(I)-Cu(II) two-dimensional (2D) coordination polymers, (2)(infinity)[{((Cu2L21)-L-II)}{Cu-4(I)(mu(1,1,3)-SCN)(2)(mu(1,1,3)-SCN)(4)}](n) (2) and (2)(infinity)[{((Cu2L22)-L-II)}{Cu-2(I)(mu(1,1,3)-SCN)(2)(mu(1,1,3)-SCN)(2)}](n) (3), respectively. The presence Railroad track-like 2D Sheet of SCN- during the synthesis of the complexes induces reduction of a part of the Cu(II) to Cu(I) giving rise to these two novel mixed-valence 2D coordination polymers 2 and 3. All three complexes have been structurally and magnetically characterized. In complex 1, the square pyramidal Cu(II) atoms are joined by the double oximato bridges. On the other hand, the railroad track-like 2D sheet of 2 and stair-like arrangement of the 2D layer of 3 have been constructed by the connection of one-dimensional (ID) anionic chains ([Cu-2(I)(SCN)(3)](n)(n-) in 2 and [Cu-I(SCN)(2)](n)(n-) in 3) through the cationic oximato bridged dinudear units ([(Cu2L21)-L-II](2+) in 2 and [(Cu2L22)-L-II](2+) in 3) via the sulfur atom of the thiocyanato ligand. In both complexes; Cu(I) and thiocyanato ligand form ID infinite chains, but their different stoichiometry and coordination environments around the copper centers result in different structures. Variable-temperature (2-300 K) magnetic susceptibility measurements show that complexes 1-3 exhibit a strong antiferromagnetic interaction between two Cu(II) ions via N,O oximato bridges with J values -549.6, -578.7, and -663.8 cm(-1), respectively.