Synthesis, molecular structures and EPR spectra of the paramagnetic cuboidal clusters with Mo3S4Ga cores

Electron precise [Mo3(l3-S)(l-S)3(diphos)3Br3]Br (diphos = dppe, dmpe) incomplete cuboidal clusters with six cluster skeletal electrons (CSE) were converted into paramagnetic cuboidal [Mo3(GaBr)(l3-S)4- (diphos)3Br3] clusters by treatment with elemental Ga. The new heterobimetallic complexes with nine CSE possess a doublet ground state with the unpaired electron density delocalized over the three molybdenum atoms

New NIR-emissive tetranuclear Er(III) complexes with 4-hydroxo-2,1,3-benzothiadiazolate and dibenzoylmethanate ligands: synthesis and characterization

New tetranuclear heteroleptic complexes [Er4(dbm)6(O-btd)4(OH)2] (1) and [Er4(dbm)4(O-btd)6(OH)2] (2) (O-btd = 4-hydroxo-2,1,3-benzothiadiazolate and dbm = dibenzoylmethanide) and their solvates with toluene, THF and CH2Cl2 were prepared using two synthetic approaches. The structures of the products were confirmed by single-crystal X-ray diffraction. Magnetic properties of 1 and 2 are in good agreement with X-ray data. The effective magnetic moment (μeff) values at 300 K for 1 and 2 corresponds to a system of 4 non-interacting Er(III) ions in the ground state 4J15/2 with g = 6/5. At ambient temperature and upon excitation with λexc = 450 nm, complexes 1 and 2 exhibit luminescence at ∼1530 nm, i.e. in the near infra-red (NIR) region. The luminescence intensity grows with increasing the number of the (O-btd)−ligands in the complexes. This observation suggests (O-btd)− as a new efficient antenna ligand for the lanthanide-based NIR luminescence

Assembly of Mn(III) Schiff Base Complexes with Heptacyanorhenate (IV)

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)

Crystal structure of a Zn complex with terephthalate and 1,6-bis(1,2,4-triazol-1-yl)hexane

A new zinc coordination polymer with rigid benzene-1,4-dicarboxylate (bdc) and flexible 1,6-bis(1,2,4-triazol-1-yl)hexane (btrh), namely poly[[(μ2-benzene-1,4-dicarboxylato)[μ2-1,6-bis(1,2,4-triazol-1-yl)hexane]zinc] dimethylformamide monosolvate], [Zn(C8H4O4)(C10H16N6)]·C3H7NO, was synthesized. According to the single-crystal XRD analysis, the product crystallizes in the P-1 space group and has a layered structure. Analysis of the layered structure reveals {Zn(bdc)} chains which are connected by pairs of btrh ligands. The layers are packed tightly perpendicular to the [1-22] direction, separated by one non-disordered dimethylformamide solvent molecule per formula unit. According to thermogravimetric analysis, the product completely loses this solvent at 453 K; the desolvated compound is stable up to 503 K. As a result of the lack of hydrogen-donor groups, hydrogen bonds are not observed in the structure of the complex; however, an intermolecular C—H...π contact of 3.07 Å occurs

A Series of Lanthanide Complexes with Keggin-Type Monolacunary Phosphotungstate: Synthesis and Structural Characterization

The coordination of rare-earth metal ions (Ln3+) to polyoxometalates (POM) is regarded as a way of modifying and controlling their properties, such as single-molecular magnetism or luminescent behavior. The half-sandwich complexes of Ln3+ with monolacunary Keggin POMs (Ln3+/POM = 1:1) are of particular interest, since the Ln3+ retains its ability to coordinate extra ligands. Thus, the knowledge of the exact structures of 1:1 Ln/POM complexes is important for the development of reliable synthetic protocols for hybrid complexes. In this work, we isolated three 1:1 Gd3+/POM complexes of the general formula Cat4Gd(PW11O39)·xH2O (Cat = K+ or Me4N+). Complex (Me4N)2K2[Gd(H2O)2PW11O39]·5H2O (1) is polymeric, revealing a layered structural motif via bridging Gd3+ and K+ ions. Complexes (Me4N)6K2[Gd(H2O)3PW11O39]2·20H2O (2) and (Me4N)7K[Gd(H2O)3PW11O39]2·12H2O (3) are classified as dimeric; the difference between them consists of the different crystal packing of the polyoxometalates, which is induced by a variation in the cationic composition. Isostructural complexes have also been characterized for praseodymium, europium, terbium and dysprosium. The coordination number of Ln3+ (8) persists in all the compounds, while the binding mode of the POM varies, giving rise to different architectures with two or three H2O co-ligands per Ln3+. However, whatever the particular structure and exact composition, the {Ln(PW11O39)} moieties are always involved in bonding with each other with the formation either of polymeric chains or dimeric units. In water, these aggregates can dissociate with the formation of [Ln(H2O)4PW11O39]4-. This behavior must be taken into account when choosing L for the design of hybrid {Ln(L)POM} complexes

Slow Magnetic Relaxation in Neutral <i>0D</i> and <i>1D</i> Assemblies of a Mn(III) Schiff Base Complex and Heptacyanorhenate(IV)

The first neutral 0D and 1D heterometallic assemblies based on orbitally degenerate heptacyanidorhenate(IV) were prepared and structurally characterized. An analysis of the magnetic data of polycrystalline samples showed that both compounds display slow magnetization relaxation at temperatures below 5 K. The very low temperature measurements of the magnetization on the single crystals demonstrate that for the 1D compound {[Mn(SB2+)Re(CN)7]·7H2O}n (1) and the 0D complex [Mn(SB2+)(H2O)Re(CN)7]·2H2O (2), the hysteresis loops open just below 2.2 and 1.8 K, respectively. Thus, heterometallic polymer 1 is the first single-chain magnet involving a pentagonal bipyramidal [ReIV(CN)7]3− synthon, and the binuclear complex 2 represents a single-molecule magnet

Synthesis, Crystal Packing Aspects and Pseudosymmetry in Coordination Compounds with a Phosphorylamide Ligand

This work reports the synthesis and crystal structure of new closely related coordination compounds, [ML2]·nTHF, where M is Zn or Mn; L is a phosphorylmethylamide derivative of benzothiadiazole; n = 1 (M = Zn) and 1, 2 (M = Mn); and THF is tetrahydrofuran. The zinc compound, 1·THF, crystallizes in a high-symmetry space group, I41/a, that is relatively rare for compounds with organic ligands. The corresponding manganese congener, 2·THF, with a similar crystal packing, features a pseudosymmetrical structure P21/c of the doubled volume of the unit cell as compared to 1·THF. The main difference between the structures lies in a different arrangement of solvate THF molecules, which likely modulates the crystal packing of the complexes. Another manganese solvatomorph, 2·2THF, reveals a fundamentally different crystal packing while exhibiting a similar geometry of the complex. We consider the problem of localization of solvate THF molecules and the types of their disorder by the example of compounds 1–2

Lanthanide Complexes with a Tripodal Nitroxyl Radical Showing Strong Magnetic Coupling

A series of isomorphous mononuclear complexes of Ln(III) ions comprising one stable tripoidal oxazolidine nitroxyl radical were obtained in acetonitrile media starting from nitrates. The compounds, [LnRad(NO3)3] (Ln = Gd, Tb, Dy, Tm, Y; Rad = 4,4-dimethyl-2,2-bis(pyridin-2-yl)-1,3-oxazolidine-3-oxyl), have molecular structure. Their coordination polyhedron, LnO7N2, can be described as a tricapped trigonal prism with symmetry close to D3h. The value of 23 cm-1 for the antiferromagnetic coupling Gd-Rad established from the DC magnetic and EPR data is a record strength for the complexes of 4f-elements with nitroxyl radicals. The terbium derivative displays frequency-dependent out-of-phase signals in zero field indicating single-molecule magnetic behavior with an effective barrier of 57 cm-1

Synthesis, Crystal Structure, and Luminescence of Cadmium(II) and Silver(I) Coordination Polymers Based on 1,3-Bis(1,2,4-triazol-1-yl)adamantane

Coordination polymers with a new rigid ligand 1,3-bis(1,2,4-triazol-1-yl)adamantane (L) were prepared by its reaction with cadmium(II) or silver(I) nitrates. Crystal structure of the coordination polymers was determined using single-crystal X-ray diffraction analysis. Silver formed two-dimensional coordination polymer [Ag(L)NO3]n, in which metal ions are linked by 1,3-bis(1,2,4-triazol-1-yl)adamantane ligands, coordinated by nitrogen atoms at positions 2 and 4 of 1,2,4-triazole rings. Layers of the coordination polymer consist of rare 18- and 30-membered {Ag2L2} and {Ag4L4} metallocycles. Cadmium(II) nitrate formed two kinds of one-dimensional coordination polymers depending on the metal-to-ligand ratio used in the synthesis. Coordination polymer [Cd(L)2(NO3)2]n was obtained in case of a 1:2 M:L ratio, while for M:L = 2:1 product {[Cd(L)(NO3)2(CH3OH)]·0.5CH3OH}n was isolated. All coordination polymers demonstrated ligand-centered emission near 450 nm upon excitation at 370 nm