Synthesis, characterization and optical property of a new two-dimensional (2-D) copper halide coordination polymer [(1,10-phen)4][] (phen=phenanthroline)

Magnetostructural characterization of copper(II) hydroxide dimers and coordination polymers coordinated to apical isothiocyanate and cyanide-based counteranions

Five Cu(II) hydroxo-bridged complexes of the type [Cu2(μ-OH)2(L)2][A]x·yH2O (where L = 1,10-phenanthroline, A = NCS–, x = 2, y = 2 (1); L = 2,2′-bipyridine, A = NCS–, x = 2, y = 1 (2); L = 2,2′-bipyridine, A = [Au(CN)4]–, x = 2, y = 0 (3) and 2 (4); L = N,N,N′,N′-teteramethylethylenediamine, A = [Pt(SCN)4]2–, x = 1, y = 0 (5)) have been prepared and have been characterized by elemental analysis, IR and Raman spectroscopy, X-ray crystallography, and SQUID magnetometry. Complexes 1 and 2 consist of five-coordinate Cu(II) hydroxo-bridged dinuclear units bound to two NCS– anions in the apical positions, 3 and 4 are pseudo-polymorphs of a Cu(II) hydroxo-bridged dimer core with [Au(CN)4]– counteranions, and 5 is a coordination polymer of Cu(II) hydroxo-bridged dimers with trans-bridging [Pt(SCN)4]2– anions coordinated in the apical position of the five-coordinate Cu(II) centres. The magnetic susceptibility versus temperature for each system was measured, fit to obtain J-coupling values (which range from –0.37 to 17.8 cm−1), and qualitatively compared to known magnetostructural correlation parameters.

[Au(CN)4]- as Both an Intramolecular and Intermolecular Bidentate Ligand with [(tmeda)Cu(μ-OH)] Dimers: from Antiferro- to Ferromagnetic Coupling in Polymorphs

Two polymorphic products, [[Cu(tmeda)(mu-OH)}2Au(CN)4][Au(CN)4] (1) and [Cu(tmeda)(mu-OH)Au(CN)4]2 (2), were synthesized from {Cu(tmeda)(mu-OH)}(2)X(2) (tmeda = N,N,N',N'-tetramethylethylenediamine, X = ClO4-, BF4-) and 2 equiv of K[Au(CN)4], and their X-ray structures were determined. Both compounds have [Cu(tmeda)(mu-OH)}2(2+) dimers with [Au(CN)4]- units bound in the axial positions. However, in 1, two trans N-donor cyanides of each [Au(CN)4]- unit bind to adjacent copper(II) dimers, forming a 1-D chain, whereas complex 2 is molecular, with two mono-coordinated [Au(CN)4]- units. The 1-D polymorph 1 is formed from aqueous solution, while the molecular polymorph 2 is obtained with X = BF4- in methanol. The polymorphs have slightly different Cu-O-Cu angles, a key magnetostructural parameter, such that the 1-D chain 1, with an angle of 96.6(2) degrees, shows ferromagnetic interactions with 2J = +57.5 cm(-1) and g = 2.097, whereas the molecular complex 2, with an angle of 98.92(17) degrees, shows antiferromagnetic interactions with 2J = -143.6 cm(-1) and g = 2.047. A similar Cu(II) complex, [[Cu(tmeda)(mu-OH)]2Au(CN)4][ClO4].MeOH (3), was synthesized in methanol when X = ClO4-, in which the [Au(CN)4]- unit bridges the two Cu(II) centers within the dimer in an intramolecular fashion via cis N-donor cyanides. The average Cu-O-Cu angle of 98.4(2) degrees in 3 generates antiferromagnetic interactions with 2J = -64.8 cm(-1) and g = 2.214. Complexes 1-3 represent the first examples of [Cu(tmeda)(mu-OH)]2(2+) dimers with Cu-O-Cu angles under 100 degrees, thereby extending the range of 2J coupling constants for this moiety from 149 to 566 cm(-1). The switch to ferromagnetic interactions in 1 as a result of the coordinating, bridging [Au(CN)4]- anion suggests that cationic, dinuclear moieties that are typically antiferromagnetically coupled may, with an appropriate coordinating counterion, become ferromagnetic units.