From achiral ligands to chiral coordination polymers: spontaneous resolution, weak ferromagnetism, and topological ferrimagnetism

Using the achiral diazine ligands bearing two bidentate pyridylimino groups as sources of conformational chirality, five azido-bridged coordination polymers are prepared and characterized crystallographically and magnetically. The chirality of the molecular units is induced by the coordination of the diazine ligands in a twisted chiral conformation. The use of L(1) (1,4-bis(2-pyridyl)-1-amino-2,3-diaza-1,3-butadiene) and L(2) (1,4-bis(2-pyridyl)-1,4-diamino-2,3-diaza-1,3-butadiene) induces spontaneous resolution, yielding conglomerates of chiral compounds [Mn(3)(L(1))(2)(N(3))(6)](n) (1) and [Mn(2)(L(2))(2)(N(3))(3)](n)(ClO(4))(n).nH(2)O (2), respectively, where triangular (1) or double helical (2) chiral units are connected into homochiral one-dimensional (1D) chains via single end-to-end (EE) azido bridges. The chains are stacked via hydrogen bonds in a homochiral fashion to yield chiral crystals. When L(3) (2,5-bis(2-pyridyl)-3,4-diaza-2,4-hexadiene) is employed, a partial spontaneous resolution occurs, where binuclear chiral units are interlinked into fish-scale-like homochiral two-dimensional (2D) layers via single EE azido bridges. The layers are stacked in a heterochiral or homochiral fashion to yield simultaneously a racemic compound, [Mn(2)(L(3))(N(3))(4)](n) (3a), and a conglomerate, [Mn(2)(L(3))(N(3))(4)](n).nMeOH (3b). On the other hand, the ligand without amino and methyl substituents (L(4), 1,4-bis(2-pyridyl)-2,3-diaza-1,3-butadiene) does not induce spontaneous resolution. The resulting compound, [Mn(2)(L(4))(N(3))(4)](n) (4), consists of centrosymmetric 2D layers with alternating single diazine, single EE azido, and double end-on (EO) azido bridges, where the chirality is destroyed by the centrosymmetric double EO bridges. These compounds exhibit very different magnetic behaviors. In particular, 1 behaves as a metamagnet built of homometallic ferrimagnetic chains with a unique "fused-triangles" topology, 2 behaves as a 1D antiferromagnet with alternating antiferromagnetic interactions, 3a and 3b behave as spin-canted weak ferromagnets with different critical temperatures, and 4 also behaves as a spin-canted weak ferromagnet but exhibits two-step magnetic transitions.     

The electrostatic potential generated by topological atoms. II. Inverse multipole moments

Quantum chemical topology defines finite atoms, whose bounded electron density generates a well-defined electrostatic potential. A multipole expansion based on spherical tensors provides a potential that is formally convergent outside the divergence sphere. Part I of this series [P. L. A. Popelier and M. Rafat, Chem. Phys. Lett.376, 148 (2003)] showed that a continuous multipole expansion expands the convergence region, thereby allowing the electrostatic potential to be evaluated at short range. Here, we propose a different method, based on "inverse" multipole moments, enabling an expansion that converges everywhere. These moments are defined by inverse (i.e., negative) powers of the magnitude of the position vector describing the electron density inside the atom. We illustrate this technique on nitrogen in N(2), oxygen in H(2)O, and oxygen in the phenolic group of the amino acid tyrosine. The proposed method constitutes a considerable advance over the method presented in Part I.     

Synthesis of some pyridylamino-1,4-disubstituted phthalazines

Two general procedures involving the condensation of phthalonitrile or 1,3-diiminoisoindoline with various aminopicolines, followed by ring expansion with hydrazine to the corresponding phthalazine are described. Syntheses are reported of 1, 4-di(3′-methyl-2′-pyridyl) aminophthalazine, 1,4-di(5′-methyl-2′-pyridyl)aminophthalazine, and 1,4-di(4′, 6′-dimethyl-2′-pyridyl)aminophthalazine.     

Free radical ring expansion and chain extension of 1,3-diketones

Free radical-promoted one carbon ring expansion and chain extension of 1,3-diketones including 1,3-diarylpropane-1,3-diones and 2-aroyl-3,4-dihydro-2H-naphalen-1-one to generate corresponding 1,4-diketones are described.     

Invariance properties of the multipole expansion with respect to the choice of the coordinate system

The physical interpretation of intermolecular interactions is usually based on the well-known multipole expansion of the inverse of the interparticle distance. The interaction energy is then interpreted as a sum of terms arising from the interaction of various multipole moments of both systems. It is supposed that the interaction energy calculated via the truncated multipole expansion generally depends on the choice of local coordinate systems through the coordinate dependence of the multipole moments. In this paper we prove that each term of the multipole expansion given in the form ∑_{k = 1} C_k/R^k is invariant with respect to identical translations and arbitrary rotations of the local coordinate systems. The invariant form of the convergence criterion of the multipole expansion is given and discussed.     

Polarisable multipolar electrostatics from the machine learning method Kriging: an application to alanine

We present a polarisable multipolar interatomic electrostatic potential energy function for force fields and describe its application to the pilot molecule MeNH-Ala-COMe (AlaD). The total electrostatic energy associated with 1, 4 and higher interactions is partitioned into atomic contributions by application of quantum chemical topology (QCT). The exact atom–atom interaction is expressed in terms of atomic multipole moments. The machine learning method Kriging is used to model the dependence of these multipole moments on the conformation of the entire molecule. The resulting models are able to predict the QCT-partitioned multipole moments for arbitrary chemically relevant molecular geometries. The interaction energies between atoms are predicted for these geometries and compared to their true values. The computational expense of the procedure is compared to that of the point charge formalism.     

Practical expressions for the two-center multipole expansion of r

An explicit and transparent deduction of a conventional expression for the two-center multipole expansion of the Coulomb potential, r, in terms of spherical harmonics, is perfomed. An intermediate expression in the deduction is shown to be well suited for transformation into a Cartesian representation. Practical formulas are produced that allow for safe and efficient implementations in computer programs. Electrostatic interactions between two pairs of point charges are computed and the importance to include the higher multipole interactions is stressed. © 1995 John Wiley & Sons, Inc.     

Solution self-assembly, spontaneous deprotonation, and crystal structures of bipyrazolate-bridged metallomacrocycles with dimetal centers

A series of nanosized cavity-containing bipyrazolate-bridged metallomacrocycles with dimetal centers, namely, {[(bpy)M]8L4}(NO3)8 [L=3,3',5,5'-tetramethyl-4,4'-bipyrazolyl, Pd, Pt; 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene), Pd; and 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbiphenyl, Pd], {[(phen)M]8L4}(NO3)8 [L=3,3',5,5'-tetramethyl-4,4'-bipyrazolyl, Pd, Pt; 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene, Pd; and 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbiphenyl, Pd], {[(bpy)Pd]6L3}(NO3)6 [L=1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,], {[(phen)Pd]6L3}(NO3)6 [L=1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,], {[(bpy)Pd]4L2}(NO3)4 [L=1,3-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene, and 1,2-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,], and {[(phen)Pd]4L2}(NO3)4 [L=1,3-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene, and 1,2-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,] (where bpy=2,2'-bipyridine and phen=1,10-phenanthroline) have been synthesized through a directed self-assembly approach that involves spontaneous deprotonation of the 1H-bipyrazolyl ligands in aqueous solution. These complexes, with weak Pd(II)...Pd(II) or Pt(II)...Pt(II) interactions, have been characterized by elemental analysis, 1H and 13C NMR, cold-spray ionization or electrospray ionization mass spectrometry, UV-visible spectroscopy, and luminescence spectroscopy. Complexes and have also been characterized by single-crystal X-ray diffraction analysis.     

Über die Synthese von 7-Chlor-1,3-dihydro-thieno[3,2-e]1,4-diazepin-2-onen

The preparation of 7-chloro-1,3-dihydro-5-phenyl-thieno-[3,2-e]-1,4-diazepin-2-one (8 a) and 7-chloro-5-(2-chlorophenyl)-1,3-dihydro-thieno[3,2-e]1,4-diazepin-2-one (8 b) as well as the methylation in position 1 are described.     

Syntheses and structures of copper(I) complexes based on Cu(n)X(n) (X = Br and I; n = 1, 2 and 4) units and bis(pyridyl) ligands with longer flexible spacer

Self-assembly of four bis(pyridyl) ligands with longer flexible spacer: 1,4-bis(3-pyridylaminomethyl)benzene (L1), 1,4-bis(2-pyridylaminomethyl)benzene (L2), 1,3-bis(3-pyridylaminomethyl)benzene (L3) and 1,3-bis(2-pyridylaminomethyl)benzene (L4), and CuX (X = Br and I) leads to the formation of eight [Cu(n)X(n)]-based (X = Br and I; n = 1, 2, and 4) complexes, [Cu(2)I(2)L1(PPh(3))(4)] (1), [Cu(4)Cl(2)Br(2)(L4)(2)(PPh(3))(6)]·(CH(3)CN)(2) (2), [Cu(2)I(2)(L3)(2)] (3), {[Cu(2)Br(2)L2(PPh(3))(2)]·(CH(2)Cl(2))(2)}(n) (4), [CuIL1](n)·nCH(2)Cl(2) (5), [CuIL1](n) (6), [CuIL4](n) (7) and [Cu(2)I(2)L4](n) (8), which have been synthesized and characterized by elemental analysis, IR, TG, powder and single-crystal X-ray diffraction. Structural analyses show that the eight complexes possess an increasing dimensionality from 0D (1-3) to 1D (4) to 2D (5-8), in which 1 and 2 contain a CuX unit, 2-7 contain a Cu(2)X(2) unit and 8 contains a Cu(4)X(4) unit. Such evolvement indicates that the conformation of flexible bis(pyridyl) ligands and the participation of triphenylphosphine (PPh(3)) as a second ligand take an essential role in the framework formation of the Cu(i) complexes. Moreover, a pair of symmetry-related L3 ligands in complex 3 coordinate to the rhomboid Cu(2)I(2) dimer to form "handcuff-shaped" dinuclear structures, which are further joined together through intermolecular N-HI hydrogen bonds to furnish a 2D (4,4) layer. Although complexes 5 and 6 exhibit a similar 2D (4,4) layer constructed from L1 ligand bridging [Cu(2)I(2)](n) units, the different packing fashion of the layers leads to the formation of 3D porous frameworks of 5 and dense 3D frameworks of 6. The "twisted-boat" conformation of the Cu(4)I(4) tetramer unit in complex 8 has not been reported so far.     

由二茂铁基羧酸以及苯并咪唑基配体构筑的两个镉(II)配合物的合成、晶体结构及性质

使3-二茂铁-2-丁烯酸钠(FcC(CH3)＝CHCOONa, Fc＝(η5-C5H4)Fe(η5-C5H5))和1,3-二(1-H-苯并咪唑基)丙烷(L1)与Cd(II)在溶液中反应, 或使邻羧基苯甲酰二茂铁钠(o-FcCOC6H4COONa)和1,4-二(2-H-苯并咪唑基)丁烷(L2)与Cd(II)在溶液中反应, 分别得到了一维链状配位聚合物[Cd(h2-FcC(CH3)＝CHCOO)(L1)Cl]n (1)和单核环状配合物[Cd(h2-o-FcCOC6H4COO)(L2)(H2O)]•NO3•DMF•H2O (2). 采用红外、元素分析以及单晶衍射表征了这两个配合物的分子结构; 研究了它们的热性能以及在DMF溶液中的电化学性能.     

A one-pot synthesis of 1,4-dithiins and 1,4-benzodithiins from ketones using the recyclable reagent 1,1′-(ethane-1,2-diyl)dipyridinium bistribromide (EDPBT)

A novel access to 1,4-dithiins and 1,4-benzodithiins from the corresponding ketones in one-pot using the recyclable reagent, 1,1′-(ethane-1,2-diyl)dipyridinium bistribromide (EDPBT) is described. This method is mild, simple, environmentally benign and is applied successfully for the ring expansion of 1,3-dithiolane to 1,4-dithiins and the ring expansion associated with aromatisation of cyclic ketones with or without double bonds in the ring. The main feature of this method is that EDPBT acts as a promoter in the formation of 1,3-dithiolane and as a reagent in the ring expansion step. The spent reagent can be recovered, regenerated and reused.     

Efficient implementation of the fast multipole method

A number of computational techniques are described that reduce the effort related to the continuous fast multipole method, used for the evaluation of Coulomb matrix elements as needed in Hartree-Fock and density functional theories. A new extent definition for Gaussian charge distributions is proposed, as well as a new way of dividing distributions into branches. Also, a new approach for estimating the error caused by truncation of multipole expansions is presented. It is found that the use of dynamically truncated multipole expansions gives a speedup of a factor of 10 in the work required for multipole interactions, compared to the case when all interactions are computed using a fixed multipole expansion order. Results of benchmark calculations on three-dimensional systems are reported, demonstrating the usefulness of our present implementation of the fast multipole method.     

1,4-Diazabuta-1,3-dien-N-Sulfinylamin-Nickel(0)-Komplexe

1,4-Diazabuta-1,3-Diene-N-Sulfinylamin Nickel(0) Complexes Synthesis, properties, and reactions of 1,4-diazabuta-1,3-diene-N-sulfinylamine nickel(0) complexes are described. The highly coloured and extremely air and moisture sensitive nickel(0) complexes have been characterized by means of i.r. and ¹H n.m.r.spectroscopy. The N-sulfinylamine ligands are η²-(S,N)-side on coordinated.     

Transferability of quantum topological atoms in terms of electrostatic interaction energy

Understanding atomic transferability is important to guide the design of a force field. Atoms in molecules are defined and computed according to the theory of quantum chemical topology (QCT). The electron density associated with such topological atoms is conveniently described by high-rank multipole moments. Here, we assess the transferability of atoms by means of their electrostatic interaction energy, using a convergent multipole expansion. The test systems are (H2O)3 and serine...(H2O)5. The effect of a varying electron density cutoff (i.e., truncating the atoms) is discussed and the effect of polarization is quantified.     

Syntheses,Crystal Structures and Fluorescence of Cadmium(II) Coordination Polymers with Pyrazine-1,4-dioxide, 2-Methylpyrazine-1,4-dioxide and Thiocyanate as Mixed Bridge Ligands

1 INTRODUCTION For a long time much research interest has been focused on the coordination polymeric compounds because such new coordination polymers may afford new materials with useful properties, such as catalytic activity, micro-porosity, electrical conduc- tivity, non-linear optical activity, magnetic coupling behavior and so on[1, 2]. Thiocyanate anion as well as pyrazine-1,4-dioxide and its derivatives belongs to very useful bridge ligands and many complexes[3, 4] with one of them e…     

Reactions of 2(3′-oxoalkyl)-1,3-cyclohexanediones with nitrogenous reagents

Condensed 1,4-dihydropyridines, which do not contain a substituent in position 4 and which are formed in the reaction of 2-(3-oxoalkyl)-1,3-cycohexanediones with ammonium acetate in acetic acid, undergo disproportionation. Pyridine bases are formed as the result of two competing reactions: disproportionation and oxidation of 1,4-dihydropyridines, intermediates in the heterocyclization of oxo-1,3-diketones with participation of the nitrogen atom, by air oxygen.N. G. Chernyshevskii Saratov State University Saratov 410026. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 647–651, May, 1994. Original article submitted April 22, 1994.     

Invariance properties of the multipole expansion

The calculations of long-range interaction energy are often based on multipole expansion. The truncated multipole expansion and interaction energy calculated with it are noninvariant with respect to an arbitrary choice of local coordinate systems. In this paper we show that truncated multipole expansion of form Σ C_kR^?k is “numerically” independent on a choice of local coordinate systems, if convergence conditions are satisfied.