Inclusion of relativistic effects into ZDO methods. IV. Relativistic CNDO/1

A relativistic, four-component version of the CNDO (complete neglect of differential overlap) method is introduced. This method spans the class of zero-differential-overlap approximation and it utilizes a nonempirical parametrization based on results of atomic Dirac-Fock calculations. The spin-orbit splitting is included implicitly using the relativistic basis set which distinguishes Slater-type functions of the lower and higher component spinors. The method is applicable to closed-shell as well as to open-shell systems. The actual version used is the R -CNDO /1_χ with a variable scaling approach. Applications to molecular geometries, ionization potentials, and energies of spin-orbit splitting are demonstrated for AH, AH₂, AH₃, MH, InX, and HgI₂ molecules at the self-consistent-field level as well as in the second order of the many-body perturbation theory.     

Inclusion of relativistic effects into ZDO methods. I. A quasi-relativistic CNDO/1

A version of the CNDO /1 method has been outlined that includes dominant relativistic effects. The method utilizes a nonempirical parametrization based on atomic Dirac–Fock calculations. The goal of this QR -CNDO /1 method lies in its applicability to molecules consisting of arbitrary atoms (z = 1–118). Applications to molecular geometries and ionization potentials for 50 molecules are presented.     

Inclusion of relativistic effects into ZDO methods. III. A. Quasi-relativistic INDO/1 version

The quasi-relativistic CNDO /1 method for molecular orbital calculations has been extended to the INDO /1 version where all monocentric repulsion integrals are taken into account. This version has been applied to calculate molecular geometries of MX_n-type molecules, with the central atom belonging to from the second to seventh period. Properties of hypothetical superheavy elements (Z = 110–117) have been predicted. Transition metal complexes of the MCl-type (M = Ni, Pd, Pt, and ePt) have been investigated from the point of view of spin-state and configuration stability.     

Inclusion of relativistic effects into ZDO methods. V. Effect of core and polarization functions in bonding of first-group elements

Electronic structure and geometry of XY diatomics (X, Y = H, Na, K, Rb, Cs, Cu, Ag, and Au) have been studied by nonempirical versions of ZDO methods which account for major relativistic effects. Influence of the basis set size is investigated for these systems exhibiting the bonding controlled by the [(n ? 1)d¹⁰]ns¹[np⁰] ? [(n ? 1)d¹⁰]ns¹[np⁰] interactions; [] are optical.     

Thermal degradation of transition metal carbonyl complexes. Part II

The thermal degradation of three monosubstituted hexacarbonyl complexes, M(CO)₅py (where M=Cr, Mo, and W; py=pyridine) has been studied by thermogravimetry (TG) and differential scanning calorimetry (DSC) and their results reported. It was found that for each of the three complexes studied, the starting material M(CO)₆ was formed which immediately sublimed unchanged with or without concomitant loss of carbonyl (CO) ligands to give the first large weight loss step. This was closely followed by the volatilisation of the pyridine ligands and at higher temperatures the loss of further CO ligands. The enthalpy changes associated with the above-mentioned steps are reported. The conversion of M(CO)₅py to M(CO)₆ and other products was confirmed by the analysis of residue after pyrolysis in a tube furnace under conditions similar to those observed in TG experiments.

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Zusammenfassung Der thermische Abbau von drei monosubstituierten Hexacarbonylkomplexen der allgemeinen Formel M(CO)₅py (mit M=Cr, Mo und W; py=Pyridin) wurden mittels TG und DSC untersucht. Von jeder der drei Komplexe wird die Ausgangssubstanz M(CO)₆ erhalten, die sofort unverändert mit oder ohne gleichzeitigem Verlust an Carbonyl (CO)-Liganden sublimiert und die erste große Gewichtsverluststufe ergibt. Diesem Schritt folgt gleich die Verflüchtigung des Pyridinliganden und bei höheren Temperaturen die Abgabe weiterer CO-Liganden. Die mit den genannten Schritten einhergehenden Enthalpieveränderungen werden mitgeteilt. Die Umwandlung von M(CO)₅py zu M(CO)₆ und anderen Produkten wurden durch Analyse des Rückstandes nach der Pyrolyse in einem Röhrenofen unter ähnlichen Bedingungen wie in den TG-Versuchen bestätigt.

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()₅, M=, , =. , , , . , . . , .

     

Self consistent modified extended Hückel (SC-MEH) calculations on heavy metal systems. I. Platinum(II) tetragonal planar complexes with and without relativistic effects

The Self Consistent Modified Extended Hückel molecular orbital method had been applied to several square planar complexes of platinum (II). Calculations including both the limited 5d, 6s, 6p and extended 5s, 5p, 5d, 6s, 6p starting bases for platinum were made. It is shown that in PtCl ₄ ^2– both the nuclear quadrupole moment and minimum total energy vs. bond distance are calculated to be in good agreement with experiment, only with the extended platinum AO basis.Specific inclusion of relativistic parameters via a pseudo-relativistic approximation are shown to have a significant effect on the energy molecular energy levels, however no meaningful rationalization can be made without the simultaneous inclusion of ligand field parameters as well.Supported in part by a grant made available through the Cancer Association of Greater New Orleans. Use of the facilities of the Computer Research Center of the University of New Orleans is gratefully acknowledged.     

QTAIM study of transition metal complexes with cyclophosphazene-based multisite ligands II. Cobalt(II) complexes

[(CoLCl)CoCl₃], [(CoMeLCl)CoCl₃], [(CoLBr)CoBr₃], [CoLBr]⁺ and [CoMeLBr₂] complexes, L = hexakis(2-pyridyloxy)cyclotriphosphazene, MeL = hexakis(4-methyl-2-pyridyloxy)cyclotriphosphazene, in the most stable high spin states are investigated at DFT level of theory using hybrid B3LYP functional. The exchange coupling parameter evaluated using a broken symmetry treatment increases with the ligands mass. Electron density is evaluated in terms of QTAIM (Quantum Theory of Atoms-in-Molecule) topological analysis of electron density. The bonds of central Co atoms with phosphazene nitrogens are shorter, stronger and more polar than with the aromatic pyridine nitrogens and their higher ellipticities may be explained by the π contribution from the phosphazene ring. The atomic charges of phosphazene nitrogens are ca. twice more negative than at the pyridine ones.     

Thermal behaviour of transition metal complexes of dithiocarbazic esters. II

A thermal study (simultaneous TG and DTA measurements) was carried out on the dithiocarbazic ester complexes M[N³CH₂R₁N²C¹(S)SCH₃]₂, where M=Ni, Pt; R₁=C₆H₅. The following disproportionation reaction occurs in the solid state: II is formed through deprotonation of the CH₂ group bound to N³, whereas III is formed through protonation of N³.The influence of inductive and/or steric effects on the mechanism of this reaction is discussed, taking into account the electrochemical and X-ray data on the complexes Pt[NRNC(S)SR']₂ with differentR substituents: R=H, Ph, CH₂Ph, CH₂C₅H₁₁, CH(CH₃)₂, C(CH₃)₃; R=CH₃, CH₂Ph.These results accord with the behaviour of the same complexes in solution.

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Zusammenfassung Dithiokarbamidsäureesterkomplexe M[N³CH₂R₁N²C¹(S)SCH₃]₂ mit M=Ni, Pt und R₁=C₆H₅ wurden thermisch untersucht. Im festen Zustand spielt sich folgende Disproportionierungsreaktion ab: II wird durch Deprotonierung der an N³ gebundenen CH₂ Gruppe und III durch Protonierung des Atoms N² gebildet. Unter Zuhilfenahme der elektrochemischen und Röntgendaten der Komplexe Pt[NRNC(S)SR']₂ mit verschiedenen Substituenten R: R=H, Ph, CH₂Ph, CH₂C₅H₁₁, CH(CH₃)₂, C(CH₃)₃ und R=CH₃ bzw. CH₂Ph wurde der Einfluß von induktiven und/or sterischen Effekten auf den Reaktionsmechanismus diskutiert. Diese Ergebnisse stehen in Übereinstimmung mit dem Verhalten der Komplexe in Lösung.

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M[N³CH₂R₁N²C¹(S)SCH₃]₂, M= Ni, Pt,R ₁=C₆H₅. : II CH₂ , N³, III N². () , Pt[NRNC(S)SR]₂, R= , aR= . .

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We thank prof. A. La Ginestra for many helpful discussions on the various aspects of this work.     

Investigation of the interaction of olefin-bonded transition metal complexes by gas chromatography. II. Phosphine complexes of Cu(II)

Summary Packings consisting of chemically bonded diphenylphosphine complexes with CuCl₂ and CuBr₂ were synthesized and their retention parameters determined. The packings investigated are capable of specific interactions with electron-donating compounds and are characterized by particularly high selectivity in relation to cis and trans isomers allowing their complete separation.Part 1: see ref. [1]     

Inclusion compounds of cucurbit[8]uril with noble metal polyamine complexes

Inclusion compounds of the macrocyclic cavitand cucurbit[8]uril (CB[8]) with the ruthenium(iii) bis(ethylenediamine) complex {trans-[Ru(en)₂Cl₂]@CB[8]}Cl·27.5H₂O (1), the gold(iii) diethylenetriamine complex {[Au(dien)Cl]@CB[8]}Cl₂·11H₂O (2), and the gold(iii) and platinum(ii) cyclam complexes (H₃O)₅{[Au(cyclam)]@CB[8]}Cl₈·18H₂O (3) and {[Pt(cyclam)]_0.11(H₂cyclam)_0.89@CB[8]}Cl₂·16H₂O (4), respectively, where cyclam is the tetraazamacrocyclic ligand, were synthesized. The inclusion compounds were synthesized both directly starting from CB[8] and the metal complexes with polyamines (en or dien) and by the two-step method with the use of the cyclic polyamine ligand (cyclam) pre-included into the cavity of the macrocycle. The inclusion compounds were characterized by X-ray diffraction (1, 2, and 4), IR spectroscopy, electrospray ionization mass spectrometry, UV-Vis spectroscopy, and thermogravimetric analysis.     

Ethylene polymerization catalysts from supported organotransition metal complexes. II. Chromium alkyls

Another class of organochromium compounds, beta-stabilized chromium alkyls, has been synthesized and tested for catalytic activity in ethylene polymerization. Although not active alone, these compounds do exhibit remarkable activity when reacted with a partially dehydroxylated high surface area carrier. The best supports seem to be fluorided alumina or the aluminophosphates, depending on the particular chromium alkyl being tested. The worst was always silica. Both divalent and tetravalent chromium alkyls were tested and found to have high catalytic activity. Comparisons of activity and polymer structure were made between these compounds and previously studied organochromium compounds with pi-bonded ligands.     

Inclusion of p‐sulfonatothiacalix[4]arene and its metal complexes

As a new member of the water‐soluble calixarene family, p‐sulfonatothiacalix[4]arene possesses unique properties resulting from its inherent structural characteristics. In our recent research, we have investigated the self‐assembly of bowl‐like p‐sulfonatothiacalix[4]arenes with or without transition‐metal ions in the presence of suitable guests. We have obtained a series of compounds with different structural motifs, such as capsules, tetranuclear clusters, and molecular clefts. In addition, p‐sulfonatothiacalix[4]arenes show good inclusion abilities and can capture different guests by utilizing their hydrophobic cavities through supramolecular interactions. Even when a cone‐like conformation is fixed, the p‐sulfonatothiacalix[4]arene can also splay its opposite aromatic rings apart to adjust its cone‐like conformations from C_4v to C_2v and even lower symmetries. All of these show that it is a good candidate for the research of inclusion phenomena. © 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 155–168; 2009: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.200800033     

Platinum group metal functionalized phosphine complexes. Part 1: Phosphinoamide ruthenium(II) complexes

Summary Three new bifunctional phosphinoamide ligands of the type Ph₂PCH₂C(O)NHR (R = H, HDPA; Me, MDPA; Ph, PDPA) were prepared and characterized. Their ruthenium(II) complexes prepared from two different precursors, RuCl₂-(DMSO)₄ and RuCl₂(PPh₃)₃, are of similar composition and correspond to the formula, [RuCl(L)₂(P-O)₂]Cl (L = DMSO/PPh₃; phosphinoamide). However, RuCl₃-(AsPh₃)₂(MeOH) reacts with the phosphinoamide to yield a reduced product of the cis-RuCl₂(P-O)₂ type. The ligands and complexes were characterized by mass, i.r. and n.m.r. spectroscopy. Possible stereochemistries for the complexes are proposed.     

Solvent effects on piezochromism of transition metal complexes

We report solvent effects on the piezochromic behaviour of wavelengths of maximum absorption for metal-to-ligand charge-transfer (m.l.c.t.) bands of several molybdenum–diimine–carbonyl and titanium or vanadium–cyclopentadienyl or ethylmaltolate–thiocyanate complexes. These and previously published data are collated in an attempt to establish a pattern for solvent effects on piezochromism of m.l.c.t. bands. Strategies for the design of compounds and complexes for use in establishing a clear pattern for such effects are outlined.