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Reaction of ArSNᆖC(py)2 [Ar = 2,4-dinitrophenyl, (O2N)2C6H3] with CuCl2·2H2O in DMF yielded the tetranuclear complex [Me2NH2][Cu4Cl6{py2CO2}{py2C(OH)O}] (1) through metal-catalysed hydrolysis of both DMF and the thiazyl chain. Notably direct reaction of dipyridylketone (py2CO) with CuCl2·2H2O in DMF yielded the mononuclear pseudo-octahedral complex [CuCl2(py2C(OH)2)(DMF)]·DMF (2) in which the 1,1-gem diol, py2C(OH)2 acts as a tripodal ligand. Heating of 2 in DMF/MeOH promoted aggregation and formation of the polymer [Cu2Cl3{py2(OMe)O}]∞ (3). The structures of 1–3 were determined by X-ray diffraction. [ABSTRACT FROM AUTHOR]

Abstract: The metal-templated synthesis of the bimetallic macrocyclic complex {CoII(N3O2)Cl(OH2)}2·2Cl·H2O (2) containing two N3O2 macrocyclic binding pockets was achieved from the metal-templated Schiff-base condensation of 2,2′-6,6′-tetracetyl-4,4′-bipyridine together with 3,6-dioxaoctane-1,8-diamine. Slow diffusion of (2) with K4[Fe(CN)6] in a (1:1) mixture of methanol and water afforded the 1-D coordination polymer [{Co(N3O2)(OH2)}2{Fe(CN)6}]⋅5H2O (5) whose structure was determined by X-ray diffraction. The polymer comprises two covalently tethered pentagonal bipyramidal Co(II) macrocycles both axially coordinated to a single [Fe(CN)6]4− unit in a zig-zag arrangement, highlighting the versatility of this family of dimeric building blocks for the self-assembly of higher order structures. Magnetic studies on (2) reveal that the ions exist as isolated S =3/2 spin systems with no first-order spin–orbit coupling, but with significant axial zero field splitting (D =23cm−1, g iso =2.37), indicating that the back-to-back N3O2 macrocyclic ligand does not offer an efficient magnetic exchange pathway. The magnetic response of (5) in the high temperature region (T >50K) is identical to (2) indicating dominant zero field splitting effects. However, on further cooling an upturn in χT is consistent with weak ferromagnetic exchange (J/k =+7.8K) via the [Fe(CN)6]4− bridging unit, affording weakly-coupled CoII dimer units within the polymer chain of (5). [Copyright &y& Elsevier]

Knowledge of the spin-density distribution in the dithiadiazolyl radical ring (DTDA) constitutes a major step towards the understanding of the magnetic and electronic properties of the rich magnetism of DTDA derivatives. The p-O2N·C6F4·CNSSN⋅ radical was chosen as the most favourable CNSSN⋅ derivative to study the spin distribution in this kind of free radical by polarised neutron diffraction. Spin-density maps obtained for the p-O2N·C6F4·CNSSN⋅ radical show that almost all the spin density is localised on the sulphur and nitrogen atoms of the CNSSN⋅ ring. A small negative spin density on the carbon atom of the CNSSN⋅ ring and a negligible spin density over the rest of the radical are observed, in good agreement with ab initio calculations. [Copyright &y& Elsevier]