Structure, stacking interactions and magnetism of compounds with oxalate-bridged dinuclear CuIICuII and CuIINbV units

Supramolecular motifs and solvatomorphism within the compounds [M(bpy)3]2[NbO(C2O4)3]Cl·nH2O (M = Fe2+, Co2+, Ni2+, Cu2+and Zn2+; n = 11, 12). Syntheses, structures and magnetic properties

“…The metastable, obviously thermodynamically less favoured, needle-like monoclinic crystals [M(bpy 2+ and Zn 2+ ) formed first, which, if left in solution, slowly transformed into the more stable orthorhombic compounds crystallizing with one more crystal water molecule. For copper(II) only the orthorhombic complex was obtained, which co-crystallized in solution with the previously reported [{Cu(bpy 11 The complexes obtained are rather insoluble in water and common organic solvents.…”

“…From the above mentioned ranges for these distances it is evident that for compounds 2-6 and 8 (including both types of cations), the fluctuation is not larger than 0.05 A ˚, showing that the tetragonal distortion is very small. However, in the B cation of 7 (Cu 2+ ion) the two trans bonds Cu(2)-N(8) and Cu(2)-N (11) [with the values of 2.205(5) and 2.243(5) A ˚, respectively; ligand numbering as in Fig. 1a] are significantly larger than the other four [2.057(5)-2.085(5) A ˚], thus indicating a tetragonal elongation in the direction Tetragonal distortion of coordination octahedra of Cu 2+ ions is usually attributed to the Jahn-Teller effect, the natural tendency of the complexes with orbitally degenerate ground states to transform themselves spontaneously into energetically more favourable distorted conformations without orbital degeneration.…”

μ-Oxalato-bis[bis(2,2′-bipyridine)manganese(II)] bis(perchlorate) 2,2′-bipyridine solvate

“…molecular. The cationic unit is similar to those seen in analogous Zn (Sun et al, 2009), Cu (Jurić et al, 2007), and Cr (Chen et al, 2005) complexes. As shown in Fig.…”

“…For general background tointeractions, see: Janiak (2000). For structures containing similar cations, see: Chen et al (2005); Jurić et al (2007); Sun et al (2009).…”

From a square core to square opening: structural diversity and magnetic properties of the oxo-bridged [CrIIINbV] complexes

“…, introduced by our group, forms heterometallic complexes with different transition metal centres, through the bridging oxalate group (μ-C 2 O 4 ), 4,5 except in the reaction with chromium(III) precursor when oxo-bridged (μ-O) complexes are formed. 6,7 In our previous work we reported heterotetranuclear compound [Cr 2 (bpy) 4 (μ-O) 4 Nb 2 (C 2 O 4 ) 4 ]•3H 2 O (bpy = 2,2'bipyridine) which crystallizes in the orthorhombic Pcab space group and contains a square shaped {Cr 2 (μ-O) 4 Nb 2 } core, exhibiting relatively strong antiferromagnetic coupling between two chromium(III) ions (J = -12.77 cm -1 ) mediated by two diamagnetic -O-Nb V -O-bridges. 6 The occurrence of this unexpected magnetic exchange interaction between two paramagnetic metal centres [separated more than 7.4 Å by three diamagnetic atoms, one of which is a metal ion of niobium(V)] inspired us to investigate the effect of different ancillary ligands, i.e.…”