Di- and trinuclear Co^IIcomplexes of a bis-β-diketone ligand with variable conformation: structure and magnetic studies

Abstract

The bis-b-diketone-phenol ligand H 3 L reacts with Co(OAc) 2 to become part of di-or trinuclear complexes in various conformations, depending on the nature of the co-ligand present in the reaction. Thus, the following series of complexes have been synthesized: [Co 2 (HL) 2 (Solv) 4 ] (Solv = py, 1; MeOH, 2), [Co 2 (HL) 2 (LL) 2 ] (LL = bpy, 3; bpya, 4; Ph 2 bpy, 5; phen, 6) and [Co 3 (HL) 3 ] (7), of which 1, 3, and 7 have been crystallographically characterized. The solvent-controlled interconversion between the trinuclear complex and dinuclear complexes 1 or 2 has been demonstrated. The distortion of the Co II coordination geometry within 1, 3, and 7 has been evaluated through Continuous Shape Measures, whereas their magnetic data have been treated with models that include spin-orbit coupling effects.

Double‐CO32− Centered [CoII5] Wheel and Modeling of Its Magnetic Properties

“…Nevertheless, it can be expanded to include more metal ions and the coupling between them. [42,43] Complex 1 exhibits five nonequivalent Co II ions, which could, for simplicity, be treated using average values of the spin-orbit coupling parameters. However, the system contains metals with coordination numbers five and six.…”

Designed Topology and Site‐Selective Metal Composition in Tetranuclear [MM′⋅⋅⋅M′M] Linear Complexes

“…[11,12] The new ligands have provided access to a number of tri-and . Complexes 1, 2, 3 and 4 exhibit antiferromagnetic interactions between pairs of metals within each cluster, leading to S = 0 spin ground states, except for the latter cluster, which features two quasiindependent S = 1 tetranuclear linear complexes of 3d metals with interesting or unprecedented features, such as asymmetric trinuclear helicates, [13,14] the first mixed-valence Mn chain with the Mn III /Mn III /Mn II sequence [15] or M 4 strings (Mn, Ni). [16,17] In some cases, the aggregation of M 4 chains have produced other architectures, such as [M 4 ] 2 dimers [18] or [M 4 ] n polymers.…”

“…[36] For this purpose, numerical procedures will be carried out in due time and will involve the full diagonalisation of a matrix as obtained from a Hamiltonian containing both SOC and exchange coupling. [14] The results for 3 ([Cu 2 ] 2 ) indicate that the Cu II ions are pairwise strongly coupled; at 300 K the c M T product is 0.9 cm 3 K mol…”

Poly[[bis[μ-1,2-bis(4-pyridyl)ethene]bis(trichloroacetato)cadmium(II)] monohydrate]

“…Self-assembly processes involving metal ions and organic ligands directed by either metal coordination or hydrogen bonds have attracted much attention in the field of supramolecular chemistry and current coordination chemistry (Batten, et al,1998;Moler, et al, 2001;Moulton, et al, 2001;Kim, et al, 2002;Evans, et al, 2002). The use of rigid or flexible spacer ligands is of considerable interests in recent years owing to their potential as building blocks for supramolecular assemblies (Sauvage, et al,1995;Fujita, et al, 2001;Aromí, et al, 2006) and their ability to act as optical sensors and heterogeneous catalysts (Yoo, et al, 2003;Takizawa, et al, 2003;Hong, et al, 2004;Kitagawa, et al, 2004;Hong, et al, 2005;Han, et al, 2006). In our attempt to investigate the design and control of the self-assembly of coordination polymers with the rigid bridging ligands, we have employed Cd II to develop a new polymeric complex with the ligand 1,2-bis(4-pyridyl)ethene.…”

“…For supramolecular assemblies, see: Sauvage & Hosseini (1995); Fujita et al (2001); Aromí et al (2006). For optical sensors and heterogeneous catalysts, see: Yoo et al (2003); Takizawa et al (2003); Hong et al (2004); Kitagawa et al (2004); Hong et al (2005); Han et al (2006).…”