N. G. Naumov

Octahedral rhenium(III) chalcocyanide cluster anions: Synthesis, structure, and solid state design

The review summarizes data on synthesis and structure of rhenium chalcocyanide cluster onions [ Re6X8(CN)6]4-f (X = S, Se, Te) belonging to a new class of inorganic compounds. Two main groups of such compounds are considered: salts with an island structure and polymer compounds. Various factors governing the type of structure and the dimensionality of the polymer compounds are analyzed, including the nature of the chalcogen atom in the cluster anion, preferable coordination of the transition metal cation, and the size of additional charge-compensating cations. Crystal-chemical approaches to design of complex salts based on octahedral rhenium chalcocyanide cluster anions are formulated.

Inorganic Coordination Polymers Based on Chalcocyanide Cluster Complexes

The paper reports results of experiments involving design of inorganic coordination polymers based on tetrahedral and octahedral chalcocyanide cluster complexes as building blocks. Various approaches to designing three‐dimensional, layered, and chain‐like structures are discussed. Structures of various types are described, and prospects of further studies in this field are outlined.

Primitive cubic packing of anions in Cs4[Re6Te8(CN)6]· 2H2O and Ba2[Re6Te8(CN)6] · 12H2O crystals

Crystal structures of Cs4[Re6Te8(CN)6]·2H2O (1) and Ba2[Re6Te8(CN)6]· 12H2O (2) are determined. Crystals 1 are orthorhombic, a = 14,282(1), b = 12.910(1), c = 18.040(1) Å, Vcell = 3326.3(8) Å3, space group Pbcn, Z = 4, dcalc = 5.715 g/cm3, R(F) = 0.0482 for 3193 Fhkl > 4σ(F). Crystals 2 are triclinic, a = 9.671(3), b = 9.697(4), c = 11.039(4) Å, α = 89.86(3), β = 72.34(3), γ = 82.46(3)∘, Vcell = 977.2(6) Å3, space group P1, Z = 1, dcalc = 4.733 g/cm3, R(F) = 0.0490 for 3226 Fhkl > 4σ(F). In both structures, the [Re6Te8(CN)6]4− anions form a distorted primitive cubic packing with distances between the centers 9.02-9.63 Å in 1 and 9.70-11.04 Å in 2. The Cs+ cations in 1 lie near the face centers of the cubes formed by the onions. In 2, cation pairs (Ba2+)2 bonded to two solvate water molecules are formed; the pairs lie at the centers of the anion cubes. In structures 1 and 2, there are shortened contacts between the tellurium atoms belonging to the neighboring anions (3.75-4.09 and 3.95-4.22 Å, respectively).

Hexacyano octahedral metallic clusters as versatile building blocks in the design of extended polymeric framework and clustomesogens

Using self-assembling processes to generate hybrid organic inorganic materials allows the control of their structuration at the nanometric scale. We describe in this work the synthesis, liquid crystal and photo-physical properties of [M6Qi8(CN)a6]n− (M = Mo, Re; Qi = Br, Se; n = 2, 3 or 4) cluster anionic units containing clustomesogens. A new and efficient synthetic route was developed to synthesize the [Mo6Bri8(CN)a6]2− building block that is stable in water solution and that could be crystallized as the porous [trans-Cd(H2O)2][Mo6Bri8(CN)a6]. Hybrids were obtained by a metathesis reaction with a specifically designed organic cation. Their self-assembling abilities can be tailored by playing with the charge of the inorganic building blocks going from a nematogenic behaviour, which is particularly rare for ionic mesomorphic material, to the formation of layered structures. The intrinsic properties (luminescence or magnetism) of transition metal clusters are well retained in the hybrid matrices. The nanostructuration of the material influences its ability to emit light despite the isotropy of the emissive nanocluster. Finally, we demonstrate that the magnetic [Re6Se8CN6]3− can be reduced into the luminescent [Re6Se8CN6]4− upon heating at 150 °C. These hybrid materials show promising prospects in the field of luminescent material.

Adjustment of dimensionality in covalent frameworks formed by Co2+ and rhenium cluster chalcocyanide [Re6S8(CN)6]4-

Abstract The synthesis and X-ray structure of a new cluster compound (Pr4N)2Co[Re6S8(CN)6] · 6H2O is reported. It crystallizes in orthorhombic symmetry, P212121 space group with four formula units per unit cell. The following parameters were found: a = 17.942(9) A, b = 17.979(4) A, c = 16.344(8) A, V=5272 0rA3, ρcalc=2.607 g cm−1; final R=0.0331. The compound was prepared by interaction of layered Cs2Co[Re6S8(CN)6] · 2H2O with aqueous solution of Pr4NBr. This interaction results in cleavage of covalently linked {Co(H2O)2Re6S8(CN)6}2α2− sheets and in formation of isolated fragments {Co(H2O)5Re6S8(CN)6}u2−. Heating of (Pr4N)2Co[Re6S8(CN)6] · 6H2O results in elimination of two water molecules and in formation of (Pr4N)2Co[Re6S8(CN)6] · 4H2O containing infinite -Co(H2O)4-NC-Re6S8(CN) 4-CN-Co(H2O)4-chains.

23-Electron Re6 metal clusters: syntheses and crystal structures of (Ph4P)3[Re6S8(CN)6], (Ph4P)2(H)[Re6Se8(CN)6]·8H2O, and (Et4N)2(H)[Re6Te8(CN)6]·2H2O

The cluster anions [Re6X8(CN)6]34– (X = S, Se, or Te) containing 23 cluster valence electrons in the Re6 octahedron were synthesized and isolated as salts with organic cations. The crystal structures of the (Ph4P)3[Re6S8(CN)6], (Ph4P)2(H)[Re6Se8(CN)6]·8H2O, and (Et4N)2(H)[Re6Te8(CN)6]·2H2O clusters were solved by X-ray diffraction analysis. Removal of one electron has virtually no effect on the geometry and interatomic distances in the cluster anion but leads to a substantial change in the electronic spectrum and to an increase in stretching vibration frequencies νCN compared to those of the [Re6X8(CN)6]4– anions.

Colloidal solutions of niobium trisulfide and niobium triselenide

Exfoliated nanomaterials, such as graphene and related few-layered materials, are now widely studied for electronic devices, electrodes and composites, so it is desirable to demonstrate exfoliation of a wider number of layered materials. We have shown that bulk niobium trichalcogenides NbS3 and NbSe3 may be stably dispersed in a number of common organic solvents by ultrasonic treatment. The most concentrated dispersions are obtained in alcoholic media (up to ∼0.443 g L−1). The colloids contain thin well-crystallized nanoribbons of NbS3 and NbSe3. Filtration or spraying of the colloids produces strongly textured thin films with good conducting properties.

Unusual H-bonding in novel cyano-cluster polymeric hydrates [(H){Ln(H2O)4}{Re6S8(CN)6}]·2H2O (Ln = Yb, Lu)

X-Ray studies and (1)H NMR measurements for novel cyano-bridged polymers [(H){Ln(H(2)O)(4)}{Re(6)S(8)(CN)(6)}]*2H(2)O (Ln = Yb, Lu) reveal temperature dependence of proton localization: acid protons are trapped between nitrogen atoms at low temperatures, but can be transferred to the water sublattice at higher temperatures; this transfer resulted in intermolecular proton exchange.

Framework polymers based on octahedral chalcocyanide cluster [Re6Q8(CN)6]4−/3− anions (Q = Se, Te) and [Nd(Bipy)n]3+ Complexes (n = 1, 2)

AbstractInteraction of salts of the cluster anions {Re [Re6Q8(CN)6]4−/3− (Q = Se, Te) with Nd salts in the presence of 2,2′-bipyridyl (Bipy) ligand brings about new coordination polymers: Pr4nN[{Nd(Bipy)(H2O)4} {Re6Se8(CN)6}] · 2H2O (I) (space group C2/c, a = 18.2918(16) Å, b = 14.9972(13) Å, c = 37.513(3) Å, β = 102.046(4)°, V = 10064.2(15) Å3, Z = 8), [{Nd(Bipy)2(H2O)} {Re6Se8(CN)6}] (II) (space group C2/c, a = 15.8668(3) Å, b = 13.5403(3) Å, c = 20.5189(4) Å, β = 110.135(1)°, V = 4138.89(15) Å3, Z = 4), and [{Nd(Bipy)(EtOH)(H2O)4}{Re6Te8(CN)6}] · EtOH (III) (space group