Crystal structure of platinum(II) chloro(1,1,1-trifluoro-4-imino-2-pentanononate(hydrate)) [PtC1(ktf)H<Subscript>2</Subscript>O]

This paper reports on our study of the mixed-ligand Β-iminoketonate complex [PtCl(ktf)H₂O] including l,l,l-trifluoro-4-imino-2-pentanone as a ligand. An X-ray diffraction analysis was performed on a CAD-4 diffractometer (MoK_α radiation, Ω/2θ scan mode). Crystal data of PtClF₃O₂NC₅H₇: a =26.264(5), b =4.750(1), c =15.955(3) å, Β =108.16(3)?, V = 1891.3å₃, space group C2/c, Z = 8, d_calc = 2.82 g/cm³. The Pt atom has a distorted square planar environment. The Pt-Cl, Pt-O(H₂O), Pt-N, and Pt-O bonds are 2.29, 2.07, 1.97, and 1.98 å in length, respectively. The chelate angle is 93.7?. The environment of Pt is completed to pyramidal due to interactions with the C_α atom of the neighboring molecule at a distance of 3.57 å. The compound has a molecular structure. The molecules of the complex are stacked along the Y direction.     

Crystal and molecular structure of zinc(II) di-n-propyldithiocarbamate complexes with 2,2-bipyridyl and 1,10-phenanthroline

The structure of Zn[S₂CN(n-C₃H₇)2]₂(2,2’-Bipy) and Zn[S₂CN(n-C₃H₇)₂]₂Phen was determined by X-ray diffraction analysis (CAD-4 diffractometer, MoK_α radiation) for the monoclinic (a = 9.646, b = 20.978, c = 14.555 å; Β = 94.95?; Z = 4; space group P2₁/n) and orthorhombic (a = 18.621, b = 14.701, c = 10.676 å; Z = 4; space group Aba2) crystals. The structures consist of discrete monomer molecules packed with the aid of S...H-C and C...H-C hydrogen bonds and van der Waals interactions.     

Structure of 4,4′-butane-(1,4,7-three-p-tolylsulphonyl-1,4,7-three amine) diphthalonitrile

Abstract

The crystal structure of the title compound, C₄₁ H₃₅ N₇ O₆ S₃ was determined as monoclinic by single crystal X-Ray diffraction technique. The molecular structure was identified by IR, ¹H-NMR, ¹³C-NMR and elemental analysis. The crystal parameters of this compound are as follows: monoclinic P 2 1/n, a = 12.694(2) Å, b = 26.204(2) Å, c = 13.005(2) Å, β = 102.95(2)°, V = 4216.02(1) Å.³, Z = 4, Dx = 1.289 g/cm³, F(000) = 1704, λ (MoKα) = 0.71070 Å, μ = 0.2 mm^?1. The structure was solved by SHELXS-97 and refined by SHELXL-97. R = 0.06 for 3178 observed reflections with I > 2σ (I).     

Structure of bis(4-Methyl Pyridine) Cadmium Tetracyanonickelate

Abstract

The structure, C₁₆H₁₄CdN₆Ni, consist of corrugated polymeric networks made up of tetracyanonickelate ions coordinated to Cd. The 4-methyl pyridine molecules bound to Cd in trans positions are located on both sides of the network. The bonding in the networks occurs because of a departure of the Ni-C-N-Cd sequence of atoms from linearity at the C and N positions. The crystal structure of the title compound was determined as monoclinic by single crystal X-Ray diffraction technique. The crystal parameters of this compound are as follows: monoclinic C2/m, a=18.156(2) Å, b=7.581(2) Å. c= 6.983(2) Å, β = 110.09(2)°, V = 902.6(5) ų Z=2, Dx = 1.698 g/cm³, F(000) - 456, λ (MoKα) = 0.71070 Å, μ = 2.121 mm^?1. The structure was solved by SHELXS-86 and refined by SHELXL-93. R = 0.02 for 1074 observed reflections with I > 2[sgrave] (I).     

Kinetic study on effect of novel cationic dimeric surfactants for the cleavage of carboxylate ester

Kinetic study has been performed to understand the reactivity of novel cationic gemini surfactants viz. alkanediyl‐α,ω‐bis(hydroxyethylmethylhexadecylammonium bromide) C₁₆‐s‐C₁₆ MEA, 2Br^? (where s = 4, 6) in the cleavage of p‐nitrophenyl benzoate (PNPB). Novel cationic gemini C₁₆‐s‐C₁₆ MEA, 2Br^? surfactants are efficient in promoting PNPB cleavage in presence of butane 2,3‐dione monoximate and N‐phenylbenzohydroxamate ions. Model calculation revealed that the higher catalytic effect of ethanol moiety of gemini surfactants (C₁₆H₃₃N⁺ C₂H₄OH CH₃ (CH₂)_S N⁺ C₂H₄OH CH₃C₁₆H₃₃, 2Br^?, s = 4, 6) is due to their higher binding capacity toward substrate. This is in line with finding that binding constants for novel series of cationic gemini surfactants are higher than conventional cationic gemini (C₁₆H₃₃N⁺(CH₃)₂(CH₂)_SN⁺(CH₃)₂C₁₆H₃₃, 2Br^?, s = 10, 12), cetyldimethylethanolammonium bromide and zwitterionic surfactants, i.e. C_nH_2n+1N⁺Me₂ (CH₂)₃ SO₃^? (n = 10; SB3‐10). The fitting of kinetic data was analyzed by the pseudophase model. Copyright © 2013 John Wiley & Sons, Ltd.     

NQR, NMR and Crystal Structure Studies of [C(NH2)3]2HgX4 (X = Br, I)

The crystal structure of [C(NH₂)₃]₂HgBr₄ has been determined at room temperature: monoclinic, space group C2/c, with a = 10.035(2), b = 11.164(2), c = 13.358(3) Å, β = 111.67(3)°, and Z = 4. The crystal consists of planar [C(NH₂)₃]⁺ and distorted tetrahedral [HgBr₄]^2? ions. The Hg atom is located on a two-fold axis such that two sets of inequivalent Br atoms exist in an [HgBr₄]^2? ion. In accordance with the crystal structure, two ⁸¹Br NQR lines widely separated in frequency were observed between 77 and ca. 380 K. [C(NH₂)₃]₂HgI₄ yielded four ¹²⁷I NQR lines ascribable to m = ±1/2 ? ±3/2 transitions, indicating that its crystal structure is different from the bromide complex. The ¹H NMR T ₁ measurements showed a single minimum for the bromide but two minima for the iodide. The analyses based on the C₃ reorientations of the planar [C(NH₂)₃]⁺ ions gave the activation energies of 29.8 kJ mol^?1 for the bromide, and 30.2 and 40.0 kJ mol^?1 for the iodide.     

Mössbauer effect studies on alkali tris (malonato) ferrates(III)

Mössbauer spectra of alkali tris(malonato) ferrates(III) i.e. M₃[Fe(C₃H₂O₄)₃].4H₂O(M=Li, Na, K, NH₄) at 298±2K display a single broad absorption band due to spin lattice relaxation effect. The isomer shift values indicate these complexes to be high spin with octahedral symmetry. The isomer shift shows a decreasing trend with the increase in electronegativity/polarizing power of the substituent cation (Li⁺, Na⁺, K⁺, NH₄ ⁺). A linear correlation between isomer shift values and the (Fe-O) stretching freguencies has also been observed.     

Structure of Quinoline-4-Carboxaldehyde-2,4-Dinitrophenyl-N Methylhydrazone

Abstract

The crystal structure of the title compound, C₁₇H₁₃N₅O₄, has been determined by single crystal x-ray diffraction at room temperature. The molecule is not planar, with dihedral angles of 7.2(1)° between the quinoline ring and N-methylhydrazone group, and 17.45(2)° between the N-methylhydrazone group and the phenyl ring. The crystal parameters of this compound are as follows: monoclinic P 21/n, a=9.525(2)Å, b = 15.192(2) Å, c = 11.302(2) A, β = 94.722(3)°, V = 1629.8(6) ų, Z = 4, Dx = 1.432 g/cm³, F(000) = 728, λ (MoKα) = 0.71070 Å, μ = 0.106 mm^?1, R_int = 0.017. The structure was solved by SHELXS-86 and refined by SHELXL-93. R = 0.07 for 2438 observed reflections with I > 2σ (I).     

Crystal structure and ferromagnetism of (n-C3H7)4N[CoFe(dto)3] (dto=C2O2S2)

Recently, we have discovered a new type of first order phase transition around 120 K for (n-C₃H₇)₄N[Fe^IIFe^III(dto)₃] (dto=C₂O₂S₂), where the charge transfer transition between Fe^II and Fe^III occurs reversibly. In order to elucidate the origin of this peculiar first order phase transition. Detailed information about the crystal structure is indispensable. We have synthesized the single crystal of (n-C₃H₇)₄N[Co^IIFe^III(dto)₃] whose crystal structure is isomorphous to that of (n-C₃H₇)₄N[Fe^IIFe^III(dto)₃], and determined its detailed crystal structure. Crystal data: space group P6₃, a=b=10.044(2) Å, c=15.960(6) Å, α=β=90°, γ=120°, Z=2 (C₁₈H₂₈NS₆O₆FeCo). In this complex, we found a ferromagnetic transition at T_c=3.5 K. Moreover, on the basis of the crystal data of (n-C₃H₇)₄N[Co^IIFe^III(dto)₃], we determined the crystal structure of (n-C₃H₇)₄N[Fe^IIFe^III(dto)₃] by simulation of powder X-ray diffraction results.     

The crystal structure of bis-(L-threonine) copper(II).H2O

The crystal structure of bis-(L-threonine) copper (II).H₂O, Cu (C₄H₈NO₃)₂.H₂O has been determined by heavy atom and Fourier methods and refined by least-squares using visually estimated three-dimensional x-ray data of 893 reflections. The blue crystals are monoclinic, space groupP2₁ withα=11·02,b=4·90,c=11·16Å andβ=93·5°,Z=2. The finalR is 0·10. Coordination of copper is distorted square pyramidal with ligands intrans configuration. The conformation of one of the aminoacid ligand is identical with L_s-Threonine while the other has a conformation with torsional angleχ ^{1, 2}=?74(1)°.     

Structure and magnetotransport properties of the new quasi-two-dimensional molecular metal β″-(BEDT-TTF)4H3O[Fe(C2O4)3] · C6H4Cl2

The β″-(BEDT-TTF)₄A^I[M^III(C₂O₄)₃] · G(A^I=NH ₄ ⁺ , H₃O⁺, K⁺, Rb⁺; M^III=Fe, Cr; G = “guest” solvent molecule) family of layered molecular conductors with magnetic metal oxalate anions exhibits a pronounced dependence of the conducting properties on the type of neutral solvent molecules introduced into the complex anion layer. A new organic dichlorobenzene (C₆H₄Cl₂)-containing conductor of this family, namely, β″-(BEDT-TTF)₄H₃O[Fe(C₂O₄)₃] · C₆H₄Cl₂, is synthesized. The structure of the synthesized single crystals studied by X-ray diffraction is characterized by the following parameters: a = 10.421(1) Å, b= 19.991(2) Å, c= 35.441(3) Å, β = 92.87(1)°, V= 7374(1) ų, space groupC2/c, and Z = 4. In the temperature range 0.5&;2-300 K, the conductivity of the crystals is metallic without changing into a superconducting state. The magnetotransport properties of the crystals are examined in magnetic fields up to 17 T at T = 0.5 K. In fields higher than 10 T, Shubnikov-de Haas oscillations are detected, and the Fourier spectrum of these oscillations contains two frequencies with maximum amplitudes of about 80 and 375 T. The experimental results are compared with the related data obtained for other phases of this family. The possible structural mechanisms of the effect of a guest solvent molecule on the transport properties of the β″-(BEDT-TTF)₄A^I[M^III(C₂O₄)₃] · G crystals are analyzed.     

Fluorescence of 5-hydroxy-6-methyl-(1-thietanyl-3)-pyrimidine-2,4(1 H,3 H)-dione at the transition with the second singlet-excited S 2 level to the ground level in acetonitrile solutions

The influence of the excitation wavelength on the fluorescence spectra of 5-hydroxy-6-methyl-(1-thietanyl-3)pyrimidine-2,4(1H,3H)-dione (TOMU) in acetonitrile solutions has been studied. It is found that, upon excitation of the singlet S ₂ state of TOMU luminescence, occurs from not only the first excited S ₁ level (??_max. = 350 nm, quantum yield ??(S ₁ ?? S ₀) = (4.5 ± 0.5) × 10^?3), but also at the transition from the second S ₂ level to the ground level (??_max = 305 nm, ??(S ₂ ?? S ₀) = (1.0 ± 0.1) × 10^?3).     

Analysis of newly synthesized disulfides of aryldithiocarbonates and vanadium(V) and niobium(V) complexes of aryldithiocarbonates based on spectroscopic,thermogravimetric, SEM and DFT studies

ABSTRACT

Oxidation of the sodium salt of 2-methyl, 3-methyl, 4-methyl and 4-chloro-3-methylphenyldithiocarbonic acid by I₂ affords the disulfides of respective dithiocarbonates [(ArOCS₂)₂] (Ar?=?2-CH₃C₆H₄, 3-CH₃C₆H₄, 4-CH₃C₆H₄ and 4-Cl-3-CH₃C₆H₃. Vanadium(V) and Niobium(V) complexes of 2-methyl, 3-methyl, 4-methyl and 4-chloro-3-methylphenyldithiocarbonates have also been synthesised by one-step synthetic route. The metal salt (VOCl₃ and NbCl₅) were reacted with 2-CH₃C₆H₄, 3-CH₃C₆H₄, 4-CH₃C₆H₄ and 4-Cl-3-CH₃C₆H₃OCS₂Na in 1:2 stoichiometric molar ratio yielding the complexes corresponding to the molecular formula [(ArOCS₂)₂VO(Cl)] and [(ArOCS₂)₂NbCl₃] [Ar?=?2-CH₃C₆H₄, 3-CH₃C₆H₄, 4-CH₃C₆H₄ and 4-Cl-3-CH₃C₆H₃OCS₂)]. The compounds were characterised by elemental analyses, infrared, mass and heteronuclear NMR (¹H and ¹³C) spectroscopic studies. Thermogravimetric analysis and scanning electron microscopic analyses were also carried out for deeper investigation of the structural features. Comprehensive theoretical investigation was performed by applying density functional theory (DFT) calculations on vanadium and niobium complexes by the DFT/B3LYP/LANL2DZ method to obtain the optimised molecular geometry, vibrational frequencies, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), thermodynamic properties and various other quantum-mechanical parameters.     

The research on the synthesis and structure of some new ferrocene derivatives

The reaction of C₅H₄RLi with FeCl₂ gave nine new compounds of Fe(C₅H₄R)₂ [R=C(CH₃)₂C₆H₄CH₃-p(-m,-o), C₆H₁₀C₆H₅, C(Me)₂C₆C₄OCH_3-o, C₆H₁₀C₆H₄CH₃-p(,-m,-o), C₆H₁₀C₆H₄OCH₃-p]. The compositions of compounds were determined through elementary analysis. The structural determination was made by IR and H²NMR. Mossbauer spectia were taken at room temperature. The IS and QS values are 0.41–0.45mm/s and 2.3–2.5mm/s., respectively. The solid state structure of the complex has been determined by a single crystal x-ray diffraction study, crystal data for Fe[C₅H₄C(CH₃)₂C₆H₅]₂: a=17.988(2)A, b=17. 411(2)A, c=7.496(1)A, α=β=90°, r=112.23°, Z=4, monoclinic form, space group C2/c. Our conclusions are: in π-acceptor ligand, the nucleophilic substituents decrease and the electrophilic substituts increase the metal to ligand electron cloud shift, which results in a decrease or an increase in the strength of the coordinate bonds and in the stabilization of the complexes by their steric effect.     

Vibrational spectra of ethylene and acetylene on metal surfaces - an electron energy loss study of ethylene adsorbed on Ni(110) and its carbided surface,and the use of metal-cluster analogies

An analysis has been made of on- and off-specular electron energy loss spectra (EELS) from C₂H₄ and C₂D₄ adsorbed on a clean Ni(110) and also a carbided Ni(110) surface. The carbided surface was prepared by heating the clean Ni surface in ethylene to 573 K or above. EELS spectra were obtained using a Leybold-Heraeus spectrometer at a beam energy of 3.0 eV and with a resolution of ca. 6.5 meV (ca. 50 cm^?1).The loss spectrum from ethylene at low temperatures (110 K) showed principal features at 3000 (w), 1468 (w), 1162 (s), 879 (w) and 403 cm^?1 (s) (C₂D₄ adsorption) and 2186 (w), 1258 (ms), 944 (ms), 645 (w) and 400 cm^?1 (s) (C₂D₄ adsorption). The overall pattern of wavenumbers and intensifies of the C₂H₄/C₂D₄ loss peaks is very similar in form (although systematically different in positions) to those previously observed on Ni(111) (ref.1) and Pt(111) (ref.2) surfaces at low temperatures. Like these earlier spectra,the EELS results for C₂H₄/C₂D₄ adsorbed on clean Ni(110) can be well interpreted in terms of a MCH₂CH₂M/MCD₂CD₂M species (M = metal) with the CC bond parallel to the surface.After adsorption on the carbided Ni(110) surfaces at 125 K,the main loss features occur at 3065 (m), 2992 (m), 1524 (ms), 1250 (s), 895 (s), and 314 cm^?1 (vs) (C₂H₄ adsorption) and 2339 (m), 2242 (m), 1395 (s), 968 (s), 661 (m) and 314 cm^?1 (vs). With the exceptions of reduced intensities of the bands at 895 cm^?1 (C₂H₄) and 661 cm^?1 (C₂D₄) this pattern of losses - particularly the 1550-1200 cm^?1 features which can be assigned to coupled νCC and δCH₂/δCD₂ modes - is well related to similar results on Cu(100) (ref.3) and Pd(111) (ref.4) which have been interpreted convincingly in terms of the presence of π-bonded species, (C₂H₄)M or (C₂D₄)M on the surface. This structural assignment is supported by comparison with the vibrational spectra of Zeise's salt, K[PtCl₃(C₂H₄)].H₂O (refs.5&6).Spectral changes occur on warming C₂H₄ on the clean Ni(110) surface with a growth of a feature near 895 cm^?1 at 200 K. At 300 K a rather poorly-defined spectrum occurs, which differs substantially from those found on (111) surfaces of Pt (ref.2), Rh (ref.7) or Pd (ref.8) at room temperature. These latter have been attributed to the ethylidyne, CH₃.CM₃, surface species (ref.9). For adsorption on Ni(110) there is clearly a mixture of species at room temperature.The analysis of the vibrational spectra of selected metal-cluster compounds of known structure with selected hydrocarbon ligands has helped substantially to assign the spectra of surface species in terms of bonding structures of the adsorbed species, as in the cases of the identification of (C₂H₄)M π-adsorbed (refs.5&6) and the ethylidyne CH₃.CM₃ species (ref.9). We have recently analysed the infrared and Raman spectra of the cluster compound (C₂H₂)Os₃(CO)₁₀ and its deuterium-containing analogue. The infrared frequency and intensity pattern for the A′ modes (C_S symmetry) of the two isotopomers bears a remarkable resemblance to EELS spectra previously obtained at low temperature for C₂H₂/C₂D₂ adsorbed on Pt(111) (ref.2) and (after taking into account systematic frequency shifts) for Pd(111) (ref.4). There is good evidence for believing that the structure of the hydrocarbon ligand interacting with the osmium complex takes the form

where the arrow denotes a π-bond to the third metal atom. This strongly confirms the structure for the low-temperature acetylene species on Pt(111) as proposed by Ibach and Lehwald (ref.2).Finally the room-temperature spectra for ethylene adsorbed on finely-divided silica-supported Pt and Pd catalysts have previously been interpreted in terms of the presence of MCH₂CH₂M (ref.10) and π-bonded (C₂H₄)M species (ref.11). However comparisons with the more recent EELS spectra from ethylene on Pt(111) at room temperature (ref.2) now leads to a reassignment of the 2880 cm^?1 band, on Pt, previously assigned to MCH₂CH₂M, together with a new, related,band at 1340 cm^?1 (ref.12), to the ethylidyne species CH₃CPt₃ found on the single crystal surface.More detailed analyses of the spectra reported here will be published later. Acknowledgement is given to substantial assistance for this programme of research from the Science and Engineering Research Council.     

Hartree–Fock and density functional theory study of remote substituent effects on heterolytic Fe–N bond energies of p‐G‐C6H4NHFe(CO)2(η5‐C5H5) and p‐G‐C6H4N(COMe)Fe(CO)2(η5‐C5H5)

The nature and strength of metal–ligand bonds in organotransition‐metal complexes are crucial to the understanding of organometallic reactions and catalysis. Quantum chemical calculations at different levels of theory have been used to investigate heterolytic Fe–N bond energies of para‐substituted anilinyldicarbonyl(η⁵‐cyclopentadienyl)iron [p‐G‐C₆H₄NH(η⁵‐C₅H₅)Fe(CO)₂, abbreviated as p‐G‐C₆H₄NHFp (1), where G = NO₂, CN, COMe, CO₂Me, CF₃, Br, Cl, F, H, Me, MeO, and NMe₂] and para‐substituted α‐acetylanilinyldicarbonyl(η⁵‐cyclopentadienyl)iron [p‐G‐C₆H₄N(COMe)(η⁵‐C₅H₅)Fe(CO)₂, abbreviated as p‐G‐C₆H₄N(COMe)Fp (2)] complexes. The results show that BP86 and TPSSTPSS can provide the best price/performance ratio and more accurate predictions in the study of ΔH_het(Fe–N)'s. The linear correlations [r = 0.98 (g, 1a), 0.93 (g, 2b)] between the substituent effects of heterolytic Fe–N bond energies [ΔΔH_het(Fe–N)'s] of series 1 and 2 and the differences of acidic dissociation constants (ΔpK_a) of N–H bonds of p‐G‐C₆H₄NH₂ and p‐G‐C₆H₄NH(COMe) imply that the governing structural factors for these bond scissions are similar. And the linear correlations [r = ?0.99 (g, 1c), ?0.92 (g, 2d)] between ΔΔH_het(Fe–N)'s and the substituent σ_p^? constants show that these correlations are in accordance with Hammett linear free energy relationships. The polar effects of these substituents and the basis set effects influence the accuracy of ΔH_het(Fe–N)'s. ΔΔH_het(Fe–N)'s(1, 2) follow the captodative principle. ME_{α‐COMe, para‐G}s include the influences of the whole molecules. The correlation of ME_{α‐COMe, para‐G}s with σ_p^? is excellent. ME_{α‐COMe, para‐G}s rather than ΔΔH_het(Fe–N)'s in series 2 are more suitable indexes for the overall substituent effects on ΔH_het(Fe–N)'s(2). Insight from this work may help the design of more effective catalytic processes. Copyright © 2012 John Wiley & Sons, Ltd.     

Analysis of the ESR Spectrum of a Rhodium (II) Complex

Abstract

Rh(II) complexes are rather scarce¹ and often form dimeric structures, which are diamagnetic. The ESR spectra of definite Rh(II) species have so far been claimed for Rh in ZnWO₃ ², [Rh S₄C₄(CN)₄]^{2 ?}, ^3′4 [Rh(π-C₅H₅)₂]⁵, [(π-C₅H₅)Rh(π-C₂H₄)₂]⁺⁶, and an irradiation produced [RhCπ₂(CN)₄]^{2 ?} complex.⁷ A detailed analysis has been performed on the first², the second⁴ and the last⁷ complexes. The first system shows an almost axial symmetry and the unpaired electron has been assigned to the d_xy orbital² (the x,y,z axes are defined along the octahedral metal-ligand directions). The sulfur ligand complex and the dichlorotetracyano system have their unpaired electron in the d_Z ² orbital. ^4,7 In the course of studies ^8-10 on oxygenation of a Rh(I) complex, [RhCπ(C₈H₁₄)₂]₂, we observed ¹⁰ that a well defined ESR spectrum develops during the reaction in N,N′-dimethylacetamide (DMA) - lithium chloride media. For experimental detail, reference 10 should be consulted. The data summarized in the table refer to the spectrum B in that reference and are attributed to a Rh(II) species.     

ESR investigation of some copper(II)-dioxime-dichloride compounds

The following copper(II)-dioxime-dichloride compounds: [Cu(G)Cl₂]₂, [Cu(P)Cl₂]₂, [Cu(DMG)Cl₂]₂ and [Cu(O)Cl₂]₂ (where G=C₂H₄O₂N₂, P=C₃H₆O₂N₂, DMG=C₄H₈O₂N₂, O=C₈H₁₄O₂N₂) were investigated by ESR method. Spectra of powder samples obtained in the g?2 region suggest the presence of triplet ground state (S=1) realized by a weak ferromagnetic exchange coupling. In liquid and frozen solutions the monomeric species (S=1/2) prevail. Some delicate changes in the coordination polyhedra symmetry in terms of ligand molecules and solvents nature were evidence. A 4p-admixture degree of 2% in the d_xy ground state was estimated for pseudotetrahedral (Td) species in frozen solutions.     

Analysis of the ν6(A″2) band of cyclopropane-d6 recorded under high resolution

The parallel band ν₆(A″₂) of C₃D₆ near 2336 cm^?1 has been studied with high resolution (Δν = 0.020 – 0.024 cm^?1) in the infrared. The band has been analyzed using standard techniques and the following parameters have been determined: B″ = 0.461388(20) cm^?1, D″_J = 3.83(17) × 10^?7 cm^?1, ν₀ = 2336.764(2) cm^?1, α^B = (B″ ? B′) = 8.823(12) × 10^?4 cm^?1, β^J = (D″_J ? D′_J) = 0, and α^C = (C″ ? C′) = 4.5(5) × 10^?4 cm^?1.     

Experimental determination of the potential energy curves of the I(3/2u) and I(3/2g) states of Kr+ 2

The I(3/2u) and I(3/2g) states of Kr⁺ ₂ have been investigated by pulsed-field-ionization zero-kinetic-energy (PFI-ZEKE) photoelectron spectroscopy following (2 + 1′) resonance-enhanced multiphoton excitation via the 0⁺ _g Rydberg state located below the Kr?([4p]⁵5p[1/2]₀) + Kr(¹S₀) dissociation limit of Kr₂. From the positions of a large number of vibrational bands in the spectra of the ⁸⁴Kr₂ and ⁸⁴Kr-⁸⁶Kr isotopomers, the adiabatic ionization potentials (IP(I(3/2u)) = 112672.4 ± 0.8cm^?1, IP(I(3/2g)) = 111 395.0 ± 1.4cm^?1), the dissociation energies (D ⁺ ₀(I(3/2u)) = 368.8 ± 2.0cm^?1, D ⁺ ₀(I(3/2g)) = 1646.2 ± 2.3cm^?1) and vibrational constants for both ionic states have been determined. Potential energy curves have been extracted which perfectly reproduce all experimental observations and are accurate over a wide range of energies and internuclear distances. The equilibrium internuclear distances (R ⁺ _e(I(3/2u)) = 4.11 ± 0.04 Å, R ⁺ _e(I(3/2g)) = 3.35 ± 0.10 Å) have been derived by comparing the intensity distribution in the PFI-ZEKE photoelectron spectra to calculated Franck-Condon factors. The dissociation energy of the I(3/2g) state and the equilibrium internuclear distance of the I(3/2u) state differ markedly from previously reported values.