Theoretical studies on the smallest fullerene: from monomer to oligomers and solid States

Hybrid B3LYP and density-functional-based tight-binding (DFTB) computations on the solid-state structures and electronic properties of the C(20) fullerene monomer and oligomers are reported. C(20) cages with C(2), C(2h), C(i), D(3d), and D(2h) symmetries have similar energies and geometries. Release of the very high C(20) strain is, in theory, responsible for the ready oligomerization and the formation of different solid phases. Open [2+2] bonding is preferred both in the oligomers and in the infinite one-dimensional solids; the latter may exhibit metallic character. Two types of three-dimensional solids, the open [2+2] simple cubic and the body-centered cubic (bcc) forms, are proposed. The energy of the latter is lower due to the better oligomer bonding. The open [2+2] simple cubic solid should be a conductor, whereas the bcc solids are insulators. The most stable three-dimensional solid-state structure, an anisotropically compressed form of the bcc solid, has a HOMO-LUMO gap of approximately 2 eV and a larger binding energy than that of the proposed C(36) solid.     

四苯基卟啉镍的电子结构及光谱研究

本文用INDO/CI方法计算了中位取代四苯基镍卟啉的电子结构与光谱。分子轨道能级表明平面型和垂直型的基态最高占有π轨道(a_(1w)和a_(2w))与次高占有轨道间有较大的能隙。计算的低激发态跃迁光谱表明,最低能量跃迁Q带和B带计算值与实验值符合较好,但N带与L带计算值偏高。算出的最低(nπ~*)跃迁出现在37000 cm~(-1)左右。     

Syntheses and Crystal Structures of Some CCo3 Clusters Containing PPh3 or dppm Ligands

Molecular structural determinations are reported for six Co₃C carbonyl cluster complexes containing tertiary phosphines, which have been isolated as by-products from a variety of reactions. Structural features are similar to those of related complexes already reported. Some discussion of apparent orientational preferences of the CH₂ group of dppm ligands, which appear to enter into H-bonding interactions with amido or carboxylate substituents, is given. Appropriate comparisons are made with unsubstituted analogues.     

Contribution to the techniques of enumeration ofKekulé structures

Four auxiliary classes of benzenoids are introduced, and formulas are given for their number ofKekulé structures (K). An enumeration method forK of different important classes of benzenoids is illustrated by examples. The utilization of essentially disconnected benzenoids is a special feature of the method.

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Ein Beitrag zur Methodik der Bestimmung möglicherKekulé-Strukturen

Zusammenfassung Es werden Hilfsklassen von benzenoiden Aromaten eingeführt und Formeln zur zahlenmäßigen Auswertung möglicherKekulé-Strukturen angegeben (K). Die Auswertungsmethode fürK wird an verschiedenen wichtigen Klassen benzenoider Verbindungen exemplarisch gezeigt. Die Verwendbarkeit essentiell abgekoppelter aromatischer Bauelemente ist eine spezielle Eigenschaft dieser Methode.

     

Syntheses and Characterizations of Two Palladium(II) Complexes of 5‐Mercapto‐1‐methyltetrazole

Reaction of PdCl₂(CH₃CN)₂ with the sodium salt of 5‐mercapto‐1‐methyltetrazole (MetzSNa) in methanol solution affords an interesting dinuclear palladium complex [Pd₂(MetzS)₄ ] ( 1 ). However, treatment of PdCl₂(CH₃CN)₂ with neutral MetzSH ligand in methanol solution produces a mononuclear palladium complex [Pd(MetzSH)₄]Cl₂ ( 2 ). Both complexes were characterized by IR, ¹HNMR, UV‐Vis spectroscopy as well as X‐ray crystallography. Single‐crystal X‐ray diffraction analyses of two complexes lead to the elucidation of the structures and show that 1 possesses an asymmetric structure: one Pd atom is tetracoordinated by three sulfur atoms and one nitrogen atom to form PdS₃N coordination sphere, the other Pd atom is tetracoordinated by three nitrogen atoms and one sulfur atom to form PdSN₃ coordination sphere. The molecules of 1 are associated to 1‐D infinite linear chain by weak intermolecular Pd···S contacts in the crystal lattice. In 2 , the Pd atom lies on an inversion center and has a square‐planar coordination involving the S atoms from four MetzSH ligands. The two chloride ions are not involved in coordination, but are engaged in hydrogen bonding.     

Cyano-bridged bimetallic complexes of copper(II) with tetracyanonickelate(II). Crystal structure of [Cu(dpt)Ni(CN)4]

Five new complexes of composition [Cu(dpt)Ni(CN)₄] (1) (dpt=dipropylenetriamine), [Cu(dien)Ni(CN)₄]·2H₂O (2) (dien=diethylenetriamine), [Cu(N,N′-dimeen)Ni(CN)₄]·H₂O (3) (N,N′-dimeen=N,N′-dimethylethylenediamine), [Cu(N,N-dimeen)Ni(CN)₄]·H₂O (4) (N,N-dimeen=N,N-dimethylethylenediamine) and [Cu(trimeen)Ni(CN)₄] (5) (trimeen=N,N,N′-trimethylethylenediamine) have been obtained by the reactions of the mixture of Cu(ClO₄)₂·6H₂O, appropriate amine and K₂[Ni(CN)₄] in water and have been characterized by IR and UV–Vis spectroscopies and magnetic measurements. The crystal structure of [Cu(dpt)Ni(CN)₄] (1) has been determined by single-crystal X-ray analysis. The structure of 1 consists of a one-dimensional polymeric chain ---Cu(dpt)---NC---Ni(CN)₂---CN---Cu(dpt)--- in which the Cu(II) and Ni(II) atoms are linked by CN groups. The nickel atom is four coordinate with four cyanide-carbon atoms (two cyano groups are terminal and two cyano groups (in cis fashion) are bridged) in a square-planar arrangement and the copper atom is five coordinate with two cyanide-nitrogen and three dpt-nitrogen atoms, in a distorted square-pyramidal arrangement. The temperature dependence of magnetic susceptibility (2–300 K) was measured for compound 1. The magnetic investigation showed the presence of a very weak antiferromagnetic interaction (J=−0.16 cm⁻¹) between the copper atoms within each chain through the diamagnetic Ni(CN)₄ ²⁻ ions.     

Einkristalle von A?Nd2S3, U?Ho2S3, D?Er2S3 und E?Lu2S3 durch Oxidation reduzierter Chloride der Lanthanide mit Schwefel

Single Crystals of A? Nd₂S₃, U? Ho₂S₃, D? Er₂S₃, and E? Lu₂S₃ through the Oxidation of Reduced Lanthanide Chlorides with Sulfur The oxidation of reduced chlorides (MCl₂) or chloridehydrides (MClH_x) of the lanthanides with sulfur (850°C, 7 d, tantalum ampoule) usually results in the formation of their sesquisulfides (M₂S₃) as the main product. In the presence of appropriate fluxes (e. g., NaCl), they often are obtained as single crystals, and the flux appears to decide which modification is favourized. Single crystals of Nd₂S₃ , (from NdCl₂ + NaCl + S, 2 : 2 : 1, A-type: orthorhombic, Pnma (no. 62), Z = 4; a = 743.97(5), b = 402.78(3), c = 1551.96(9) pm, V_m = 70.015(8) cm³/mol, R , = 0.026, R_w = 0.023), Ho₂S₃ , (from Na_0.25HoClH_0.75 + S, 8 : 9, U type: orthorhombic, Pnma (no. 62), Z = 4, a = 1057.24(7), b = 384.48(4), c = 1041.15(7) pm, V_m = 63.716(9) cm³/mol, R , = 0.023, R_w = 0.020), Er₂S₃ , (from ErClH_0.67 + NaCl + S, 2 : 2 : 1, D type: monoclinic, P2₁/m (no. 11), Z = 6, a = 1744.18(9), b = 398.22(3), c = 1010.13(6) pm, β = 98.688(4)°, V_m = 69.610(7) cm³/mol, R = 0.031, R_w = 0.029) and Lu₂S₃ , (from LuClH_0.67 + NaCl + S, 2 : 2 : 1, E type: trigonal, R3 c (no. 167), Z = 6, a = 672.86(2), c = 1816.84(9) pm, c/a = 2.70, V_m = 71.497(6) cm³/mol, R = 0.023, R_w = 0.020) as well as more systematic general investigations (syntheses of the lanthanide sesquisulfides from the elements in the presence of NaCl as a flux in sealed tantalum containers at 850°C) are the main topic of the work presented here.     

A high-pressure mass spectrometric and density functional theory investigation of the thermochemical properties and structure of protonated dimers and trimers of glycine

A new modification of pulsed-ionization high-pressure mass spectrometry (PHPMS) has been used to perform equilibrium thermochemical studies for relatively nonvolatile biomolecules such as amino acids. Binding enthalpy and entropy changes have been measured for proton-bound clusters of glycine, which are in good agreement with both theoretical (DFT) results of this work and a previous blackbody infrared dissociation experiment. Experimental data indicate that a number of conformers of the proton-bound dimer of glycine may coexist in the explored temperature range (360-460 K). Several new, conceptually different isomers (two of them zwitterionic) have been found by DFT calculations, one of which is 7 kJ mol(-1) lower in energy than the structure previously reported to be the energy minimum.     

Diorganomorpholinometallane von Gallium und Indium – Monomer‐Dimer‐Gleichgewichte in Lösung

Diorganomorpholinometalates of Gallium and Indium – Monomer‐Dimer‐Equilibrium in Solution The reaction of Li[N(CH₂CH₂)₂O] (LiMorpholinate; Li(Morph)) with Me₂GaCl and Me₂InCl gives by salt‐elimination the diorganoamidometalates Me₂M(Morph) ( M = Ga: 1 ; M = In: 2 ), respectively. 1 and 2 were characterized by NMR and vibrational spectroscopy as well as by X‐ray structure determinations. According to this, centrosymmetrical dimers are present in the solid state while a monomer‐dimer equilibrium was assumed for the THF‐solution. Cryoscopic molecular weight determinations confirmed our assumptions.     

Concerning the Reaction of the Betain‐Like Compound O2CC(PPh3)2 with Tungsten‐Carbonyl Derivatives; Preparation and Crystal Structures of [(CO)5W{η1‐O2C2(PPh3)2}] and [(CO)4W{η2‐O2C2(PPh3)2}]

The carbodiphosphorane CO₂ adduct O₂CC(PPh₃)₂ ( 1a ) reacts with [(CO)₅W(THF)] and [(CO)₃W(NCEt)₃] to produce the complexes [(CO)₅W{η¹‐O₂CC(PPh₃)₂}] ( 2 ) and [(CO)₄W{η²‐O₂CC(PPh₃)₂}] ( 3 ), respectively. Whereas in 2 the betain‐like ligand is coordinated at the tungsten atom in a monodentate manner, in 3 it acts as a chelating ligand with formation of a WO₂C four‐membered ring. As a by‐product during the reaction with the acetonitrile adduct also some crystals of the hydrolysis product [HC(PPh₃)₂]₂[W₆O₁₉] · 3C₂H₄Cl₂ (4 · 3C₂H₄Cl₂) were isolated. All compounds could be characterized by X‐ray analyses and the usual spectroscopic methods.