Atoms in Highly Symmetric Environments: H in Rhodium and Cobalt Cages, H in an Octahedral Hole in MgO, and Metal Atoms Ca-Zn in C20 Fullerenes

An atom trapped in a crystal vacancy, a metal cage, or a fullerene might have many immediate neighbors. Then, the familiar concept of valency or even coordination number seems inadequate to describe the environment of that atom. This difficulty in terminology is illustrated here by four systems: H atoms in tetragonal-pyramidal rhodium cages, H atom in an octahedral cobalt cage, H atom in a MgO octahedral hole, and metal atoms in C20 fullerenes. Density functional theory defines structure and energetics for the systems. Interactions of the atom with its container are characterized by the quantum theory of atoms in molecules (QTAIM) and the theory of non-covalent interactions (NCI). We establish that H atoms in H2Rh13(CO)243− trianion cannot be considered pentavalent, H atom in HCo6(CO)151− anion cannot be considered hexavalent, and H atom in MgO cannot be considered hexavalent. Instead, one should consider the H atom to be set in an environmental field defined by its 5, 6, and 6 neighbors; with interactions described by QTAIM. This point is further illustrated by the electronic structures and QTAIM parameters of M@C20, M=Ca to Zn. The analysis describes the systematic deformation and restoration of the symmetric fullerene in that series.

Crystal structure and Hirshfeld surface analysis of dichlorido(methanol-κO)bis(2-methylpyridine-κN)copper(II)

In the title complex, [CuCl2(C6H7N)2(CH3OH)], the copper atom is five-coordinated by two nitrogen atoms of 2-methylpyridine ligands, two chloro ligands and an oxygen atom of the methanol molecule, being in a tetragonal–pyramidal environment with N and Cl atoms forming the basal plane. In the crystal, complex molecules related by the twofold rotation axis are joined into dimeric units by pairs of O—H...Cl hydrogen bonds. These dimeric units are assembled through C—H...Cl interactions into layers parallel to (001).

Chirality Control in Crystalline Ni(II) Complexes of Thiophosphorylated Thioureas

Chirality control over the formation of Ni(II) complexes with chiral thiophosphorylated thioureas was achieved via breaking the symmetry of nickel coordination geometry by the introduction of the pyridine ligand, while centrosymmetric meso-complexes are formed from racemic ligands in case of square-planar nickel coordination. Centrosymmetric heterochiral arrangement is observed in crystals of ligands themselves through N–H⋅⋅⋅S hydrogen bonds in intermolecular dimers. Molecular homochirality in tetragonal pyramidal complexes is further transferred to supramolecular homochiral arrangement via key–lock steric interactions.

A CuII complex with an carbamoylcyanonitrosomethanide ligand formed in situ by the nucleophilic addition of water to dicyanonitrosomethanide: structure, spectral and magnetic properties

The complex (2,2′-biquinoline-κ2 N,N′)(carbamoylcyanonitrosomethanide-κ2 N,O)chloridocopper(II) acetonitrile monosolvate, [Cu(C3H2N3O2)Cl(C18H12N2)]·CH3CN or [Cu(ccnm)Cl(biq)]·acn (acn is acetonitrile, biq is 2,2′-biquinoline and ccnm is carbamoylcyanonitrosomethanide), (I), was prepared as a result of nucleophilic addition of water to the dicyanonitrosomethanide ion in the presence of CuII and biq. IR spectroscopy confirmed the presence of ccnm, biq and acn in (I). The solid-state structure consists of the neutral complex containing ccnm and biq ligands, coordinated to the CuII atom in a bidendate chelating manner, and a chloride ligand, resulting in a distorted tetragonal pyramidal coordination of CuII. The asymmetric unit is supplemented by one molecule of solvated acn which, along with the nitrile group of ccnm, serves as an acceptor in intermolecular hydrogen bonding, creating infinite chains along the b axis. Magnetic measurements revealed a paramagnetic behaviour with a very small Weiss temperature Θ = −0.32 K and high anisotropy of the g tensor (g x = 2.036, g y = 2.120 and g z = 2.205).

A supramolecular tetranuclear zinc(II) complex constructed from an asymmetrical Salamo-type ligand: synthesis, structure and fluorescence properties

The tetranuclear Zn(II) complex, [{ZnL(μ-OAc)Zn(CH3CH2CH2OH)}2], derived from an asymmetrical Salamo-type chelate ligand H3L (5-methoxy-6′-hydroxy-2,2′-[ethanedioxybis(nitrilomethylidyne)]diphenol) has been synthesized and structurally characterized by elemental analysis, IR spectrum, X-ray crystallography, UV/Vis and fluorescence spectra. The structure is made up of four Zn(II) atoms, μ2-coordinated acetate ions and two coordinated n-propanol molecules, and forms an infinite one-dimensional supramolecular structure via intermolecular C–H···π interactions. The four Zn(II) atoms are penta-coordinated and show slightly distorted trigonal bipyramidal and tetragonal pyramidal symmetries.

Crystal structures of (1,4,7,10-tetraazacyclododecane-κ4N)bis(tricyanomethanido-κN)nickel and (1,4,7,10-tetraazacyclododecane-κ4N)(tricyanomethanido-κN)copper tricyanomethanide

The structures of two mononuclear transition-metal complexes with tricyanomethanide (tcm−) and 1,4,7,10-tetraazacyclododecane (cyclen) ligands, [Ni(C4N3)2(C8H20N4)], (I), and [Cu(C4N3)(C8H20N4)](C4N3), (II), are reported. In the neutral complex (I), the nickel cation is coordinated by one cyclen ligand and two monodentate N-bound tcm−anions in a distorted octahedral geometry. The tcm−ligands are mutuallycis. The CuIIatom in (II) displays a distorted tetragonal–pyramidal geometry, with the four N-donor atoms of the cyclen ligand in the equatorial plane, and one tcm−anion bound through a single N atom in an axial site, forming a monocation. The second tcm−molecule acts as a counter-ion not directly coordinating to the copper cation. In both (I) and (II), extensive series of N—H...N and C—H...N hydrogen bonds generate three-dimensional network structures.

Diaqua(5-carboxybenzene-1,3-dicarboxylato-κO1)[8-ethyl-5-oxo-2-(piperazin-4-ium-1-yl)-5,8-dihydropyrido[2,3-d]pyrimidine-6-carboxylato-κ2O5,O6]zinc monohydrate

In the title compound, [Zn(C14H17N5O3)(C9H4O6)(H2O)2]·H2O, the complex molecule exists in a zwitterionic form. The ZnIIion exhibits a distorted tetragonal-pyramidal geometry, being coordinated by two O atoms from the zwitterionic 8-ethyl-5-oxo-2-(piperazin-4-ium-1-yl)-5,8-dihydropyrido[2,3-d]pyrimidine-6-carboxylate (L) ligand, one O atom from the 5-carboxybenzene-1,3-dicarboxylate dianion, [Hbtc]2−, and two O atoms from two aqua ligands. In the crystal, N—H...O and O—H...O hydrogen bonds link the components into a three-dimensional structure. The crystal packing exhibits π–π interactions between the aromatic rings, with centroid–centroid distances in the range 3.466 (3)–3.667 (3) Å.

Self-assembled hydrogen-bonded coordination networks in two copper(II) carboxylates with 4-pyridylmethanol

The crystal and molecular structure of [Cu(nif)2(4-PM)2]·CH3OH (1) and [Cu(2-Clbz)2(4-PM)2(H2O)] (2), (where nif = niflumate anion, 2-Clbz = 2-chlorobenzoate anion and 4-PM is the 4-pyridylmethanol), have been determinated by X-ray crystallography. The Cu2+ cation in (1), is coordinated by two pairs of oxygen atoms from asymmetric bidentate niflumate anions and by a pair of pyridine nitrogen atoms from monodentate 4-pyridylmethanol ligands in trans position forming an extremely elongated bipyramid. The Cu2+ cation in (2), is coordinated by a pair of oxygen atoms from monodentate 2-chlorobenzoate anions, further by a pair of pyridine nitrogen atoms from monodentate 4-pyridylmethanol ligands and finally by a water oxygen atom forming a tetragonal-pyramidal coordination polyhedron. The molecules of both complexes in crystal structures are linked by O-H…O hydrogen bonds, which created a three-dimensional hydrogen-bonding networks. The Π-Π stacking interactions are also observed in crystal structures of complex 2. The spectral properties (IR and electronic spectra) of both complexes were also investigated.

Formation of the Complexes [Fe(H2BDI)3]X2 and [CpCr(H2BDI)2]X2 (X =OTf) fromthe Unusual Reactions of Benzil-bis(trimethylsilyl)diimine with CpML2Cl (M = Fe, L = CO; M = Cr, L = NO)

The reaction of CpML2Cl (M = Fe, L = CO; M = Cr, L = NO) with benzil diimine (H2BDI) (2) derived from benzil-bis(trimethylsilyl)diimine (Si2BDI) (1) in a 1 : 3 and 1 : 2 molar ratio in the presence of excess AgO3SCF3 (= AgOTf) resulted in the formation of the new cationic tris- and bisbenzildiimine complexes [Fe(H2BDI)3]X2 (3) and [CpCr(H2BDI)2]X2 (X = OTf) (4), respectively. The addition of AgO3SCF3 is necessary in both cases to abstract chloride. Unusual in the first case is the total replacement of ligands of CpFe(CO)2Cl and in the second case the oxidation of Cr(0) to Cr(III) leading to the formation of complexes 3 and 4, respectively, with the neutral bidentate diimine ligand 2. Complexes 3 and 4 were fully characterized by their IR, mass, 1H- and 13C-NMR spectra, as well as elemental analyses. The molecular structures determined by X-ray diffraction studies reveal a distorted octahedral tris-chelate configuration in 3 and a pseudo-tetragonal pyramidal one in 4.