Kirill Yu. Monakhov

Anionic N‐Heterocyclic Carbene Ligands from Mesoionic Imidazolium Precursors: Remote Backbone Arylimino Substitution Directs Carbene Coordination

(Comments from the Editor: The first cover of this journal to originate from France features a molecule that was synthesized in Strasbourg by an international team of chemists from China, Germany, Italy, and France under the leadership of P. Braunstein. Their work analyzes the bonding in novel bis(NHC) Cu(I) and Ag(I) complexes in which the aryl spacer between the NHC ligands is in close proximity to the metal. However, proximity does not always imply bonding!)

Heptabismuthate [Bi7I24]3–: a main group element anderson-type structure and its relationships with the polyoxometalates.

We describe the unique structural and electronic arrangement in the heptanuclear polyiodobismuthate [Bi(7)I(24)](3-) which displays striking similarities with the Anderson-type structures found in polyoxometalates. This main group element anion is part of the complex [Bi(OAc)(2)(thf)(4)](3)[Bi(7)I(24)] (1) which has been characterized by X-ray crystallography. We investigated the structure, stability, and bonding of [Bi(7)I(24)](3-) using relativistic dispersion-corrected density functional theory in combination with a quantitative energy decomposition and electron localization function analysis in order to better understand the main features of this isopolyanion. A comparative analysis of the properties of [Bi(7)I(24)](3-) and previously reported high-nuclearity [Bi(n)X(3n+m)](m-) anions, in the gas phase and in solution, has been performed, in the latter case to track the macroscopic solvent effects. [Bi(7)I(24)](3-) is the largest building block in the class of trianionic iodobismuthates and the sole heptanuclear framework in the family of iodobismuthates.

A comparative synthetic, magnetic and theoretical study of functional M4Cl4 cubane-type Co(II) and Ni(II) complexes

We describe the synthesis, structures, and magnetochemistry of new M4Cl4 cubane-type cobalt(II) and nickel(II) complexes with the formula [M(μ3-Cl)Cl(HL·S)]4 (1: M = Co; 2: M = Ni), where HL·S represents a pyridyl-alcohol-type ligand with a thioether functional group, introduced to allow subsequent binding to Au surfaces. Dc and ac magnetic susceptibility data of 1 and 2 were modeled with a full spin Hamiltonian implemented in the computational framework CONDON 2.0. Although both coordination clusters 1 and 2 are isostructural, with each of their transition metal ions in a pseudo-octahedral coordination environment of four Cl atoms and N,O-donor atoms of one chelating HL·S ligand, the substantially different ligand field effects of Co(II) and Ni(II) results in stark differences in their magnetism. In contrast to compound 1 which exhibits a dominant antiferromagnetic intramolecular coupling (J = -0.14 cm(-1)), 2 is characterised by a ferromagnetic coupling (J = +10.6 cm(-1)) and is considered to be a single-molecule magnet (SMM), a feature of special interest for future surface deposition studies. An analysis based on density functional theory (DFT) was performed to explore possible magnetostructural correlations in these compounds. Using a two-J model Hamiltonian, it revealed that compound 1 has four positive and two (small) negative J(Co···Co) isotropic interactions leading to a S(HS) = 6 ground state. Taking into account the magnetic anisotropy, one would recover a M(S) = 0 ground state since D > 0 from computations. In 2, all the J constants are positive and, in this framework, the zero-field splitting energy characterising the axial anisotropy was estimated to be negative (D = -0.44 cm(-1)). The computational results are consistent with compound 2 being an SMM.

Supramolecular Recognition Influences Magnetism in [X@HVIV8VV14O54]6− Self-Assemblies with Symmetry-Breaking Guest Anions

Mixed-valence polyoxovanadates(IV/V) have emerged as one of the most intricate class of supramolecular all-inorganic host species, able to encapsulate a wide variety of smaller guest templates during their self-assembly formation process. As showcased herein, the incorporation of guests, though governed solely by ultra-weak electrostatic and van der Waals interactions, can cause drastic effects on the electronic and magnetic characteristics of the shell complex of the polyoxovanadate. We address the question of methodology for the magnetochemical analysis of virtually isostructural {V(IV/V) 22 O54 }-type polyoxoanions of D2d symmetry enclosing diamagnetic VO2 F2 (-) (C2v ), SCN(-) (C∞v ), or ClO4 (-) (Td ) template anions. These induce different polarization effects related to differences in their geometric structures, symmetry, ion radii, and valence shells, eventually resulting in a supramolecular modulation of magnetic exchange between the V(3d) electrons that are partly delocalized over the {V22 O54 } shells. We also include the synthesis and characterization of the novel [V(V) O2 F2 @HV(IV) 8 V(V) 14 O54 ](6-) system that comprises the rarely encountered discrete difluorovanadate anion as a quasi-isolated guest species.

Synthesis and structure of Tri- and octaindium compounds

The reactions of InCp* with alkali metal silanides M(thf)(n)SiRPh(2) (R = Me, Ph) resulted in the triindanate [(Ph(3)Si)(3)In-In-In(SiPh(3))](-) with a linear arrangement of In atoms and the octaindium clusters [(In(8)(SiPh(3))(8)](m-) (m = 0, 2) amongst others, which were characterized by X-ray crystallography. The neutral cluster has a bisphenoidal core similar to that of B(8)Cl(8), whilst the anionic one adopts a distorted square antiprismatic structure. In addition, the tri- and octaindium compounds were studied by DFT calculations.

Theoretical Study of Structure, Bonding, and Electronic Behavior of Low-Valent Bismuth Cyclopentadienyl and Pentamethylcyclopentadienyl Half-Sandwich Compounds

The correlations between structural and electronic properties of the bismuth cyclopentadienyl complexes of the types [(C(5)R(5))(n)Bi(n)](q+) (where R = H, Me; n = 1, q = 2; n = 1-4, q = 0) and (C(5)R(5))BiX(2) (where R = H, Me; X = Cl, Br, I) were studied with quantum-chemical calculations. The influence of the ligand, significant variations in the Bi-C bond lengths, haptotropic shifts with distortion of the C(5)R(5) ring, Jahn-Teller splitting, interstabilization effects, and the role of the lone pairs on p-block element-unalkylated or peralkylated cyclopentadienyl ring interactions were examined to obtain qualitative and quantitative pictures of the intramolecular C(5)R(5)-Bi interactions. Our theoretical investigations of monovalent and trivalent bismuth cyclopentadienyl complexes give an insight into the geometric and electronic structures, the relative stabilities and further behavior of this kind of compounds.

A thioether-decorated {Mn11Tb4} coordination cluster with slow magnetic relaxation

The oxidation reaction of manganese(II) acetate tetrahydrate with terbium(III) nitrate hexahydrate in acetonitrile in the presence of 4-(methylthio)benzoic acid (Hbza·SMe) afforded a polynuclear [MnIII11TbIII4O9(OH)5(bza·SMe)18(NO3)2(H2O)6(OMe)2] complex (1) with a {Mn5Tb2O6}-bridged double-{TbMn3O4}-cubane structure. This antiferromagnetically coupled, neutral molecule is decorated in the periphery with structurally exposed thioether groups which can be used as anchors to metallic surfaces. Compound 1 is potentially a single-molecule magnet (SMM), exhibiting slow relaxation of the magnetisation up to 3 K. While 1 is not thermally stable, the coordination cluster remains stable in various Lewis base-type organic solvents like THF and acetone.

Thioether-terminated nickel(II) coordination clusters with {Ni6} horseshoe- and {Ni8} rollercoaster-shaped cores

We report two polynuclear nickel(II) compounds whose supramolecular structures are controlled by small inorganic templating anions and π-conjugated Schiff-base ligands (L·SMe3− and HL·SMe2−) with peripheral, structurally exposed methylthioether groups. The central component of the compound [Ni6(L·SMe)3(CO3)(MeOH)6(THF)2]Cl·2MeOH (1, monoclinic space group P2/c) displays a horseshoe-shaped {Ni6} core templated by μ6-CO32− moiety due to the fixation of atmospheric carbon dioxide. According to thermogravimetric analysis, compound 1 retains the structural integrity of its carbonate-bonded metal core [Ni6(L·SMe)3(CO3)]+ up to ca. 390 °C. In the crystal lattice, compound 1 features an one-dimensional hydrogen-bonded chain structure [{CO3 ⊂ Ni6}⋯Cl⋯{CO3 ⊂ Ni6}]∞. The structure of the compound [Ni8(HL·SMe)2(L·SMe)2(OH)4(MeCN)4(H2O)4](NO3)2·11MeCN·2PhCN (2, triclinic space group P) consists of a dicationic crown-like {Ni8} metallamacrocycle hosting two NO3− anions in the upper and lower cavities. The {Ni6} complex is characterised by antiferromagnetic exchange interactions, whereas {Ni8} reveals predominantly ferromagnetic exchange coupling between the spin-1 Ni(II) centres. The presence of terminal thioether anchoring groups at the periphery of complex 1, coupled with high thermal stability and solubility in several common organic solvents, renders this compound an interesting candidate for molecular surface-deposition from solution using electrospray ionisation mass spectrometry approach and, possibly, for supported-transition metal complex heterogeneous catalysis.

Supramolecular 3d–4f single-molecule magnet architectures

The nanosized self-assemblies {[{LnIII}{H2O⊂CrLn}]2(H2O)} (Ln = Dy, 1 and Tb, 2) based on new 3d-4f mixed-metal coordination topologies are formed via extensive intramolecular hydrogen bonding that is directed by enclosed water molecules. Compounds 1 and 2 show single-molecule magnet characteristics manifested by hysteresis loops up to 1.6 K (Ueff = 8.3 cm-1) and 1 K (Ueff = 3.4 cm-1), respectively.

Synthesis and Crystal Structure of a “FeBi” Cluster Compound with Noncovalent Low-Valent Bi···πArene Interactions

We describe the synthesis and structural characterization of the unprecedented [Bi4Fe3(CO)9] cluster, the low-valent Bi atoms of which are involved in the types of previously not identified intermolecular Bi···π(arene) and ΔBi···π(arene)interactions. Different coordination modes of arene rings bound to Bi atoms were determined.