This critical review presents a comprehensive study of transition-metal carboxylate clusters which may serve as secondary building units (SBUs) towards construction and synthesis of metal–organic frameworks (MOFs). We describe the geometries of 131 SBUs, their connectivity and composition. This contribution presents a comprehensive list of the wide variety of transition-metal carboxylate clusters which may serve as secondary building units (SBUs) in the construction and synthesis of metal–organic frameworks. The SBUs discussed here were obtained from a search of molecules and extended structures archived in the Cambridge Structure Database (CSD, version 5.28, January 2007) which included only crystals containing metal carboxylate linkages (241 references).

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Secondary building units, nets and bonding in the chemistry of metal–organic frameworks

Synthesis of 3d metallic single-molecule magnets

Jaguar is an ab initio quantum chemical program that specializes in fast electronic structure predictions for molecular systems of medium and large size. Jaguar focuses on computational methods with reasonable computational scaling with the size of the system, such as density functional theory (DFT) and local second-order Moller–Plesset perturbation theory. The favorable scaling of the methods and the high efficiency of the program make it possible to conduct routine computations involving several thousand molecular orbitals. This performance is achieved through a utilization of the pseudospectral approximation and several levels of parallelization. The speed advantages are beneficial for applying Jaguar in biomolecular computational modeling. Additionally, owing to its superior wave function guess for transition-metal-containing systems, Jaguar finds applications in inorganic and bioinorganic chemistry. The emphasis on larger systems and transition metal elements paves the way toward developing Jaguar for its use in materials science modeling. The article describes the historical and new features of Jaguar, such as improved parallelization of many modules, innovations in ab initio pKa prediction, and new semiempirical corrections for nondynamic correlation errors in DFT. Jaguar applications in drug discovery, materials science, force field parameterization, and other areas of computational research are reviewed. Timing benchmarks and other results obtained from the most recent Jaguar code are provided. The article concludes with a discussion of challenges and directions for future development of the program. © 2013 Wiley Periodicals, Inc.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/qua.24481

Jaguar: A high-performance quantum chemistry software program with strengths in life and materials sciences

The distribution of distances from atoms of a particular element E to a probe atom X (oxygen in most cases), both bonded and intermolecular non-bonded contacts, has been analyzed. In general, the distribution is characterized by a maximum at short E⋯X distances corresponding to chemical bonds, followed by a range of unpopulated distances – the van der Waals gap – and a second maximum at longer distances – the van der Waals peak – superimposed on a random distribution function that roughly follows a d3 dependence. The analysis of more than five million interatomic “non-bonded” distances has led to the proposal of a consistent set of van der Waals radii for most naturally occurring elements, and its applicability to other element pairs has been tested for a set of more than three million data, all of them compared to over one million bond distances.

/pdf/a-cartography-of-the-van-der-waals-territories-4rxnfp59yz.pdf

A cartography of the van der Waals territories

Structure and magnetism of coordination polymers containing dicyanamide and tricyanomethanide

Polynuclear NiII and MnII azido bridging complexes. Structural trends and magnetic behavior

The structural, chemical, and electrical properties of a number of transition-metal bisdithiolenes and tetrathiolenes are studied through qualitative MO and band structure calculations. The formation of metal-metalor metal-sulfur-bonded dimers of bisdithiolenes is found to depend on a delicate balance of several factors: sulfur lone-pair repulsion between the monomers, size and occupation of the transition metal’s d orbitals, and steric repulsions between substituents in the dithiolene ligands. Regular stacks of transition-metal bisdithiolenes are predicted to be unstable toward Peierls distortions for integral oxidation states. The sulfur lone-pair repulsions are responsible for the slippage of the stacks as well as for the sliding of neighboring stacks, giving rise to triclinic crystals. The resulting stacking pattern can produce mixing of the u and K sulfur lone pairs, hence two dimensionality in the electrical conductivity. An isolobal analogy allows one formally to replace carbon-carbon double bonds by a metal atom, providing the orbital foundation of a structural and electrical analogy between transition-metal bisdithiolenes and tetrathiofulvalene derivatives. The coordinative ability of the simplest tetrathiolene, ethylenetetrathiolate (ett), is analyzed. Of the two coordination modes available for this ligand, the dithiolene-like mode is found to be more stable than the dithiocarbamate-like one both for discrete and polymeric compounds. But the dithiocarbamate coordination mode should be accessible. A likely structural candidate for the polymers M(ett) is a planar ribbon; a band composed of the metal d,, and a ligand K orbital shows dispersion due to through-bond coupling and could account for one-dimensional electrical conductivity. Alternative oneand two-dimensional structures for the as yet unknown compounds M2(ett) and M3(ett) are also studied. While much has been learned about transition-metal dithiolenes,’ an interesting remaining intellectual challenge is the attainment of that degree of the understanding of their structural and electronic properties that could give rise to the design and synthesis of low-dimensional materials with metallic or semiconducting properties. The mode of association of metal dithiolenes is the subject of this work. The metal bisdithiolenes 1 (R = H, CN, CF3, and Ph; n = 0, 1, and 2) are planar compounds which may appear in the crystal state as isolated units,2 as dimers with metal-sulfur bond^,*^,^*^ n2a, metal-metal bonded dimer^,^ 2b, or as partially oxidized stacks featuring metal-metal bonds and different degrees of pairing distortion.6 Much less is known about the analogous compounds

Dimerization and stacking in transition-metal bisdithiolenes and tetrathiolates

Hexanuclear Manganese(III) Single-Molecule Magnets

μ4 end-on coordination (through the N atom) of the pseudohalogeno ligands X- =N3- and NCO- has been observed in the isostructural nonanuclear CoII cages with the general formula [Co9 {(2-C5 H4 N)2 CO2 }4 (O2 CMe)8 X2 ]; this mode is imposed by the trapping of anions X- into cavities formed inside the cage. The change of X- modulates the magnetic behavior of the cage from antiferromagnetic coupling to a ferrimagnetic high-spin ground state.

Unique Single-Atom Binding of Pseudohalogeno Ligands to Four Metal Ions Induced by Their Trapping into High-Nuclearity Cages

Tridentate/tetradentate Schiff base ligands L1 and L2, derived from the condensation of o-vanillin or pyridine-2-aldehyde with N,N-dimethylethylenediammine, react with nickel acetate or perchlorate salt and azide, cyanate, or thiocyanate to give rise to a series of dinuclear complexes of formulas [Ni(L1)(μ1,1-N3)Ni(L1)(N3)(OH2)]·H2O (1), {[Ni(L1)(μ1,1-NCS)Ni(L1)(NCS)(OH2)][Ni(L1)(μ-CH3COO)Ni(L1)( NCS) (OH2)]} (2) {[2A][2B]}, [Ni(L1)(μ1,1-NCO)Ni(L1)(NCO)(OH2)]·H2O (3), and [Ni(L2-OMe)(μ1,1-N3)(N3)]2 (4), where L1 = Me2N(CH2)2NCHC6H3(O-)(OCH3) and L2 = Me2N(CH2)2NCHC6H3N. We have characterized these complexes by analytical, spectroscopic, and variable-temperature magnetic susceptibility measurements. The coordination geometry around all of the Ni(II) centers is a distorted octahedron with bridging azide, thiocyanate/acetate, or cyanate in a μ1,1 mode and μ2-phenolate oxygen ion for 1−3, respectively, or with a double-bridging azide for 4. The magnetic properties of the complexes were studied by magnetic sus...

Crystal structure and magnetic interactions in nickel(II) dibridged complexes formed by two azide groups or by both phenolate oxygen-azide, -thiocyanate, -carboxylate, or -cyanate groups.

Ramon Vicente

Papers

Polynuclear NiII and MnII azido bridging complexes. Structural trends and magnetic behavior

Dimerization and stacking in transition-metal bisdithiolenes and tetrathiolates

Hexanuclear Manganese(III) Single-Molecule Magnets

Unique Single-Atom Binding of Pseudohalogeno Ligands to Four Metal Ions Induced by Their Trapping into High-Nuclearity Cages

Crystal structure and magnetic interactions in nickel(II) dibridged complexes formed by two azide groups or by both phenolate oxygen-azide, -thiocyanate, -carboxylate, or -cyanate groups.