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The molecular structures and temperature-dependent magnetic susceptibility data for several new metal complexes of heterospin triplet ground-state biradical ligands are reported. The intraligand exchange interactions are found to be strongly ferromagnetic in nature, and generally greater in magnitude than the metal-ligand exchange.

Research has been conducted on the tris-bidentate ligand. The synthesis of this ligand has been carried out and its reaction with the paramagnetic acceptors in basic solution yielding trinuclear complexes has been studied and is described.

The molecular conformational and electron spin exchange coupling in an isostructural series of bis(semiquinone) complexes is examined. The relative amounts of ferro- and antiferromagnetic contributions to exchange coupling is controlled by molecular confrontation. The delocalization in the cross-conjugated, mixed-valent radical anions is found to be proportional to the ferromagnetic contribution to the exchange coupling in the biradical oxidation states.

The synthesis and the structure of a complex having a quartet ground state with three entirely different spin carriers, namely nitronyl nitroxide (NN), o-semiquinone (o-SQ) and cupric ion are presented. The results of X-ray structural characterization suggest a substantial interaction between the two spin carriers NN and 0-SQ.

A pioneering research on a self-assembly of the magneto-anisotropic module [Re(CN)7]3- with the Mn(III) complexes involving Salen type (N,N'-ethylenebis(salicylideneiminate)) Schiff base (SB) ligands was performed using the known [Mn(3MeOSalen)(H2O)2]2(ClO4)2.H2O (1) and the firstly synthesized [Mn2(5MeSalen)2OAc]PF6 (2). In the case of 1, a slow diffusion of the component solutions led to the ionic compound Ph4P[Mn(3MeOSalen)(H2O)2]2[Re(CN)7].6H2O (3). The direct mixing of the same solutions has resulted in the microcrystalline nearly insoluble solid [Mn(3MeOSalen)(H2O))4Re(CN)7]ClO4.1.5MeCN.6.5H2O, which is likely to comprise the pentanuclear clusters [(MnIII(SB)(H2O))4Re(CN)7]+. The use of 2 resulted in a 2D-network assembly of octanuclear clusters, [{(Mn(5MeSalen))6(H2O)2Re(CN)7}2Re(CN)7]Cl2(PF6).H2O (4), incorporating one Re-center in a pentagonal bipyramid coordination environment, while another has strongly distorted capped trigonal prism as a coordination polyhedron. The latter was observed for the first time for Re(IV) complexes. A synthetic challenge to obtain the 0D assemblies with Re:Mn ≥ 3 has yielded a hexanuclear complex [Mn(5MeSalen)H2O(i-PrOH)] [(Mn(5MeSalen))5H2O(i-PrOH)2Re(CN)7](PF6)2(OAc).2i-PrOH (5) being 1D chain via a bridging phenoxyl group. Owing to a low solubility of the final product, an addition of a bulk anion Ph4B- to the MeCN/MeOH solution of [Re(CN)7]3-and 1 in ratio 1:6 resulted in rhenium-free matter [Mn(3MeOSalen)(H2O)2][Mn(3MeOSalen)(H2O)MeCN](Ph4B)2.5MeCN (6). [ABSTRACT FROM AUTHOR]

The article presents a study which discusses synthesis and crystallographical evidence of pentagonal bipyramidal polyhedron of Heptacyanoosmate (IV) and mentions role of cyanide ligand in coordination chemistry.

The ligand exchange in (n-Bu4N)2OsIVCl6 (n-Bu4N = tetra-n-butylammonium) leads to the formation of the osmium(IV) heptacyanide, the first fully inorganic homoleptic complex of heptacoordinated osmium. The single-crystal X-ray diffraction (SC-XRD) study reveals the pentagonal bipyramidal molecular structure of the [Os(CN)7]3- anion. The latter being a diamagnetic analogue of the highly anisotropic paramagnetic synthon, [ReIV(CN)7]3- can be used for the synthesis of the model heterometallic coordination compounds for the detailed study and simulation of the magnetic properties of the low-dimensional molecular nanomagnets involving 5d metal heptacyanides. [ABSTRACT FROM AUTHOR]

Upon the interaction of the hydrated lanthanide(III) salts found in acetonitrile solution with a tripodal paramagnetic compound, 4,4-dimethyl-2,2-bis(pyridin-2-yl)-1,3-oxazolidine-3-oxyl (Rad), functionalized by two pyridyl groups, three neutral, structurally characterized complexes with diamagnetic polydentate ligands—[Dy(RadH)(hbpm)Cl2], [Yb2(ipapm)2(NO3)4], and [Ce2(ipapm)2(NO3)4(EtOAc)2]—were obtained. These coordination compounds are minor uncolored crystalline products, which were formed in a reaction mixture due to the Rad transformation in a lanthanide coordination sphere, wherein the processes of its simultaneous disproportionation, hydrolysis, and condensation proceed differently than in the absence of Ln ions. The latter fact was confirmed by the formation of the structurally characterized product of the oxazolidine nitroxide transformation during its crystallization in toluene solution. Such a conversion in the presence of 4f elements ions is unique since no similar phenomenon was observed during the synthesis of the 3d-metal complexes with Rad. [ABSTRACT FROM AUTHOR]

Two diradical complexes of the formula [LnRad2(CF3SO3)3] c (Ln(III) = Dy, Eu, Rad = 4,4-dimethyl-2,2-bis(pyridin-2-yl)-1,3-oxazolidine-3-oxyl) were obtained in air conditions. These are the first examples of diradical compounds of lanthanides and oxazolidine nitroxide. The complexes were characterized crystallographically and magnetically. Single crystal XRD analysis revealed that their coordination sphere is composed of three monodentate triflates and two tripodal Rad, which coordinate the central atom in a tridentate manner via two N atoms of the pyridine groups and the O atom of a nitroxide group. The LnO5N4 polyhedron represents a spherical capped square antiprism with point symmetry close to C4v. The data of static magnetic measurements are compatible with the presence of two paramagnetic ligands in the coordination sphere of the metal. [ABSTRACT FROM AUTHOR]

Structural and dynamical properties of the transition metal ions V[sup 2+] and Mn[sup 2+] in aqueous solution, resulting from combined quantum mechanical (QM)/molecular mechanical (MM) molecular dynamics (MD) simulations have been compared. The necessity of polarization functions on the ligand's oxygen for a satisfactory description of such ions in aqueous solution is shown using V[sup 2+] as test case. Radial distribution functions, coordination number distributions, and several angle distributions were pursued for a detailed structural comparison of the first hydration shells. Dynamical properties, such as the librational and vibrational motions of water molecules were evaluated by means of velocity autocorrelation functions. Approximative normal coordinate analyses were employed to calculate the rotational frequencies and vibrational motions around the three principal axes. The very low exchange rates for the first shell water exchanges only allow an investigation of the water exchange processes in the second shell, which take place within the picosecond range. [ABSTRACT FROM AUTHOR]