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

One dinuclear Cu­(II) complex [Cu2L22(EtOH)0.5­(ClO4)]­(ClO4) (1) has been synthesized by reacting an oxime-based tridentate Schiff base ligand, 3-[2-(diethylamino)­ethylimino]­butan-2-one oxime (HL2), with CuII(ClO4)2, whereas the reaction of another similar ligand, 3-[2-(dimethylamino)­ethylimino]­butan-2-one oxime (HL1), and this ligand (HL2) with CuII(ClO4)2 in the presence of NaSCN yielded two rare mixed-valence Cu­(I)–Cu­(II) two-dimensional (2D) coordination polymers, 2∞[{(CuII2L12)}­{CuI4(μ1,3-SCN)2­(μ1,1,3-SCN)4}]n (2) and 2∞[{(CuII2L22)}­{CuI2(μ1,3-SCN)2­(μ1,1,3-SCN)2}]n (3), respectively. The presence 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 (1D) anionic chains ([CuI2(SCN)3]nn– in 2 and [CuI(SCN)2]nn– in 3) through the cationic oximato bridged dinuclear units ([CuII2L12]2+ in 2 and [CuII2L22]2+ in 3) via the sulfur atom of the thiocyanato ligand. In both complexes, Cu­(I) and thiocyanato ligand form 1D 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.