Synthesis and study of binuclear vanadyl complexes with acyldihydrazones of salicylaldehyde and dicarboxylic acids

The binuclear vanadyl(ii) complexes [(VO)₂·2Py·2EtOH]·mH₂O with acyldihydrazones of salicylaldehyde (H₄L) and dicarboxylic acids were synthesized and studied. In these complexes, two chelate vanadyl(ii) complexes with the tridentate bicyclic ligands are linked to each other by the polymethylene bridges —(CH₂) _n — of different lengths varying from one to four units. The ESR spectra of solutions of these complexes, unlike those of analogous copper(ii) complexes, have an isotropic signal with an eight-line hyperfine structure (g = 1.972, a _V = 93·10^–4 cm^–1) typical of monomeric vanadyl complexes, which indicates that no exchange interactions occur between the paramagnetic centers through the polymethylene chain.     

Synthesis,characterization and charge-transfer photochemistry of trans-aquo azido-N,N′-trimethylenebis(naphthylideneiminato)chromium(III)

A new Cr^III complex, viz. trans-[Cr(naphprn)(H₂O)₂]ClO₄·2H₂O, (1) {naphprn=N,N-trimethylenebis(naphthylideneimine)} has been synthesized and characterized. Aquo ligand substitution of ( 1 ) by the azide ligand gave rise to trans-[Cr(naphprn)(N₃)(H₂O)], ( 2 ). Irradiation of ( 2) in DMF gave nitrido(naphprn)chromium(V) ( 3 ). Solutions of ( 3 ) showed e.p.r. spectra at room temperature (g _iso=1.9865). The i.r. spectra showed disappearance of a band at 2067cm^–1 showing the breakdown of NN and appearance of a new band at 1074cm^–1which is assigned to the Cr¹⁴N, stretching frequency indicating the formation of a nitrido chromium(V) complex, ( 3). The u.v.–vis. spectrum of complex ( 3 ) exhibited a d–d band maximum at 553nm (=120M^–1cm^–1). The rate of formation of ( 2 ) was found to be 5.0×10^–3M^–1s^–1 in an aqueous acidic medium at [Cr^III]=0.5×10^–3M; [N₃ ^–]=0.01–0.15M; [H⁺]=0.001M and I=0.2M (LiClO₄). The rate of photo-decomposition of ( 2 ) to give rise to ( 3 ) was found to be 0.15×10^–3s^–1 in DMF.     

ESR study of weak exchange interactions in binuclear copper(ii) complexes with acyldihydrazones of fluorinated β-diketones

A series of binuclear copper(ii) complexes with acyldihydrazones of aliphatic dicarboxylic acids (from malonic to adipic) and fluorinated -diketones (trifluoro- and hexafluoroacetylacetone) of composition Cu₂L·2Py (H₄L is acyldihydrazone) were studied by ESR spectroscopy. The ESR spectra of solutions of complexes with trifluoroacetylacetone acyldihydrazones have an isotropic signal with a seven-line hyperfine structure from two equivalent copper nuclei (g = 2.112, a _Cu = (39—40)·10^–4 cm^–1), which is indicative of weak exchange interactions between the paramagnetic centers due to spin density delocalization through a chain of the -bonds of the polymethylene bridge. On going to hexafluoroacetylacetone derivatives, the coupling is suppressed and the ESR spectra of solutions of such complexes show a signal with a four-line hyperfine structure (g = 2.121—2.131, a _Cu = (55—63)·10^–4 cm^–1) typical of mononuclear copper complexes.     

Raman Combinations and Stretching Overtones from Water, Heavy Water, and NaCl in Water at Shifts to ca. 7000 cm−1

Photographic Raman spectra were obtained at shifts to ca. 7000 cm^–1 for pure water and for a saturated aqueous solution of NaCl using argon ion laser excitation. Raman spectra were also obtained photoelectrically for H₂O and D₂O between ca. 2500 and ca. 7000 cm^–1 using 248-nm excimer laser excitation and boxcar detection. Overtone and combination assignments are presented for H₂O and D₂O. The first IR OH-stretching overtone from water occurs 215 cm^–1 above the first Raman OH-stretching overtone because the IR overtones are dominated by asymmetric stretching. The second OH-stretching Raman overtone from water is estimated to occur near 10,020 ± 20 cm^–1, with 9950 cm^–1 as a lower limit.     

Preparation and mössbauer studies of tetraaquabis[maleato(1-)]-iron(II)

Summary Tetraaquabis[maleato(1-)]iron(II), Fe(C₄H₃O₄)₂ · 4H₂O has been synthesised. The compound is monomeric and is isomorphous with the manganese(II) analogue. The temperature dependence of quadrupole splitting and optical spectral data giveca. 10000 cm^–1,ca. 650 cm^–1,ca. 190 cm^–1 andca. 1400 cm^–1 for the 10 Dq, tetragonal field, rhombic field and the splitting of the E_g level, respectively. The quadrupole splitting data indicate that distortion from cubic symmetry increases in the order oxalate < malonate < maleate. DTA, TGA and Mössbauer studies indicate elimination of one molecule of maleic acid at 235 °C. The resulting product shows a less distorted structure and this is attributed to the formation of maleato(2-)iron(II).     

Untersuchungen an Kristallhydraten anorganischer Salze, 8. Mitt. Interpretation der Schwingungsspektren vonM(BF4)2·6H2O fürM=Fe2+, Co2+, Ni2+

The infrared and Raman spectra were recorded in the range 4000–160 cm^–1 forM(BF₄)₂·6 H₂O whereM=Fe²⁺, Co²⁺, Ni²⁺. The spectroscopic data support the X-ray structural data in showing that in the crystal hydrates studied two kinds of hydrogen bonds are present: H₂O...H₂O and OH₂... F₄B^–. The energies and molecular force constants (f _OH and fH₂O) andr _OH for OH₂...F₄B^– were calculated for the three crystal hydrates. It was found that the bond OH₂... F₄B^– is comparatively weak, with mean energy 3.7–3.3 kcal/mol. Two types of water molecule with different structures are existing as the first are participating in H₂O...H–O–H...F₄B^– and the second in BF₄ ^–...H–O–H...F₄B^–.     

Synthesis,Spectral Properties,and Crystal Structure of {Methoxo[4-phenylbutane-2,4-dione(p-nitrobenzoyl) hydrazonato(2-)]oxovanadium(V)}

The hydrazino complex {methoxo[4-phenylbutane-2,4-dione(p-nitrobenzoyl)hydrazonato(2-)]oxovanadium(V)}, VO(p-NO₂bhbzac)OCH₃, (1), has been prepared by the direct reaction of bis(benzoylacetonato) oxovanadium(IV), VO(bza)₂, with p-NO₂-C₆H₄C(O)NHNH₂, p-NO₂bh, in CH₃OH. The resulting compound contains benzoylacetone-(p-NO₂)benzoyl hydrazone as tridentate Schiff base-type ligand and OCH₃ group as Lewis base, both ligated to vanadium. The crystals are orthorhombic, with Z = 8, space group Pbca, a = 11.699(5) Å, b = 14.035(5) Å, c = 22.564(5) Å, R1 = 0.0756 and wR2 = 0.1302. The crystal structure demonstrated the square-pyramidal geometry of the VO_oxo(ONO)O coordination sphere with the oxo ligand at the apical position. The electronic absorption spectra revealed a ligand-to-metal charge-transfer (LMCT) band in the near UV region at _max = 23,700 cm^–1 (B = 5640 dm³ mol^–1 cm^–1) in CH₃CN, _max = 23,420 cm^–1 (B = 5550 dm³ mol^–1 cm^–1) in DMSO, and _max near 26,950 (sh) cm^–1 (B = 10,550 dm³ mol^–1 cm^–1) in CH₂Cl₂. The FT-IR spectra of (1) show the characteristic strong (V = O) stretching vibration at 993 cm^–1 and support the view that the oxovanadium complex is pentacoordinated and monomeric.     

Crystal Structure and Properties of Rb4H2I2O10 · 4H2O

Single crystals of the Rb₄H₂I₂O₁₀· 4H₂O were synthesized for the first time and studied by X-ray diffraction analysis. The crystals are monoclinic, a = 7.321(6) Å, b = 12.599(8) Å, c = 8.198(8) Å, = 96.30(7)°, Z = 2, space group P2₁/c. The H₂I₂O₁₀ ^4– anion is formed by the edge-sharing IO₆ octahedra. The anions are united by hydrogen bonds into a chain running along the x axis. The chains are combined by water molecules into a three-dimensional structure through hydrogen bonds. The compound is a proton conductor. The conductivity values measured at 20–60°C vary within 10^–6 to 10^–4 ohm^–1 cm^–1.     

Heat of fusion and specific volume of poly(ethylene terephthalate) and poly(butylene terephthalate

Summary Concerning the relation between the experimental heat of fusion H* and the specific volumev of PETP a considerable uncertainty exists in literature. For PBTP obviously no data have been reported. The present paper reports H* andv measurements for undrawn PETP and PBTP samples which have been crystallized from the glassy state or from the melt at different temperatures for different periods of time.For PETP a linear relation is obtained: H* = 1411–1886v (Jg^–1). Published values for the specific volumev _c of the PETP crystal range from 0.660 to 0.687 cm³g^–1. Ifv _c = 0.660 cm³g^–1 is accepted, a heat of fusion M _m = 166 Jg^–1 is obtained for the PETP crystal.For PBTP also a linear relation is found: H* = 1296–1628v (Jg^–1). Withv _c = 0.71 cm³g^–1 one obtains H _M = 140 Jg^–1 as the heat of fusion of the PBTP crystal. The specific volumev _a of amorphous PBTP (H* = 0) is 0.796 cm³g^–1 which is much higher than the hitherto used values of 0.781–0.782 cm³g^–1. The reason for this difference is thatv _a cannot directly be measured, because the low quasi-static glass temperature of 15 °C enables quenched PBTP to undergo cold crystallization at 20 °C.

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Zusammenfassung Hinsichtlich des Zusammenhangs zwischen experimenteller Schmelzwärme H* und spezifischem Volumenv von PETP bestehen in der Literatur beträchtliche Diskrepanzen. Für PBTP wurden bislang offensichtlich keine Ergebnisse veröffentlicht. In der vorliegenden Arbeit werden Messungen von H* undv für unverstreckte PETP- und PBTP-Proben mitgeteilt, die unterschiedlich lange bei ver-schiedenen Temperaturen aus dem Glaszustand oder aus der Schmelze kristallisiert wurden.Für PETP ergibt sich die lineare Beziehung: H* = 1411–1886v (Jg^–1). Literaturwerte für das spezifische Volumenv _c des PETP-Kristalls schwanken zwischen 0.660 und 0.687 cm³g^–1. Nimmt manv _c = 0.660 cm³g^–1 als richtig an, so erhält man als Schmelzwärme des PETP-Kristalls H _M = 166 Jg^–1 = 32 kJ mole^–1.Auch für PBTP erhält man eine lineare Abhängigkeit: H* = 1296–1628v. Mitv _c = 0.71 cm³g^–1 ergibt sich als Schmelzwärme des PBTP-Kristalls H _M = 140 Jg^–1 = 31 kJ mole^–1. Das spezifische Volumen des amorphen PBTP beträgt _a = 0.796 cm³g^–1 und ist erheblich größer als der bisher angenommene Wert von 0.781 cm³g^–1. Die Ursache fÜr diese Diskrepanz liegt darin begündet, daßv _a nicht direkt gemessen werden kann, weil wegen der niedrigen quasi-statischen Glastemperatur von 15°C bei abgeschrecktem PBTP die Kaltkristallisation bei 20°C bereits einsetzt.

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With 7 figures and 3 tables

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Dedicated to Professor Dr. Matthias Seefelder on the occasion of his 60th birthday     

Mutual diffusion coefficients of aqueous ZnSO4 at 25°C

Diffusion coefficients of the system ZnSO₄–H₂O at 25°C have been measured using Rayleigh optics from 0.004 to 3.33m. The results appear to extrapolate with reasonable agreement to the data of Harned and Hudson at very low concentration. The diffusion coefficients decrease from 0.8486×10^–5 at 0m to 0.2813×10^–5 cm²-sec^–1 at 3.33m. Densities were measured over the concentration range 0.10 to 3.60m and combined with the data of Geffcken and of Gibson to obtain an analytical expression for density over the concentration range 0m3.6.     

Study of the equilibrium of formation of arsenic(iii) lacunar heteropolytungstates by Raman spectroscopy

The formation of lacunar heteropolyanions (HPA): [AsW₉O₃₃]^9–, [As₂W₁₉O₆₇(H₂O)]^14–, and [As₂W₂₀O₆₈(H₂O)]^10– in aqueous solutions was investigated by Raman spectroscopy at [Na₂HAsO₃]₀ = 0.1, [Na₂WO₄]₀ = 0.9 mol L^–1 and pH 9.4–1.6. The [AsW₉O₃₃]^9– HPA is characterized by the most intense band ns (W=O) at 948 cm^–1 retaining its position in the pH range from 8.9 to 7.5. Under these conditions, the equilibrium constant of [AsW₉O₃₃]^9– formation from H₂AsO₃ ^– and WO₄ ^2– ions was estimated (logK = 87.0±1.0). The asymmetrical band at 952 cm^–1 corresponding to H_x[As₂W₁₉O₆₇(H₂O)]^(14–x)– shifts to 960 cm^–1 as the pH decreases from 6.5 to 5.5, which is due to the change in HPA protonation. The [As₂W₂₀O₆₈(H₂O)]^10– HPA is formed at pH 3.1—1.6; it is characterized by a band at 972 cm^–1.     

The structure of binuclear molybdenum(VI) oxocomplexes with dianionic tridentate Schiff bases

Summary The new Mo^VI complex [Mo(O) (-O) (SAE)]₂ was prepared and characterized by means of spectroscopic (i.r.,¹Hn.m.r.) and crystallographic measurements. Crystals of the [Mo(C₉H₈NO₂)(H₂O)]₂, M=582.3, orthorhombic, space group Pbca,a=13.108(4),b=8.982(2),c=16.842(4) Å, v=1982.9 ų, z=4, D_m=1.93(2), D_c=1.95 g cm^–3, MoK =0.71069 Å, =1.3 mm^–1, F(000)=1152, T=295K, R=0.035 for 2413 reflections.The crystal structure consists of [Mo(O)(-O)(L)]₂, in dimeric units. The coordination geometry around each molybdenum atom is distorted octahedral with Mo–O (terminal) and Mo–O (bridge) distances of 1.694(3) and 1.760(3) Å, respectively, and with the angle O(1)–Mo–O(2) of 105.6(1)^o, typical for manycis-dioxocomplexes of Mo^VI. The asymmetric bridge is characterized by the following parameters: Mo–O(2)ⁱ and Mo–Moⁱ distances equal 2.408(3) and 3.319(3) Å, respectively, and the Mo–O(2)–Moⁱ and O(2)–Mo–O(2)ⁱ angles equal 104.5(1)^o and 75.5(1)^o, respectively.The i. r. and Raman spectra of molybdenum complexes with an asymmetric double oxygen bridge display a strong absorption the 800–850 cm^–1 range.     

Oxidative homolysis of organochromium(III) macrocyclic complexes

Summary Organochromium complexes, [CrRL(H₂O)]²⁺] (L = 1,4,8,12-tetraazacyclopentadecane; R = 1°- or 2°-alkyl, or para-substituted benzyl), are oxidized to [CrRL(H₂O)]³⁺, which rapidly decomposes (k ₃ > 10² s^–1) by homolysis of the Cr-C bond. Rate constants of the oxidation of these complexes by [IrCl₆]^2– range from 2.20 × 10^–1 (R = Me) to 4.60 × 10⁵ (R = 4-MeC₆H₄CH₂)dm³ mol^–1 s^–1. A very negative reaction constant (–4.3) is found for the oxidation of para-substituted benzlchromium(III) complexes which, in conjunction with the results of product analysis, indicates a [Cr^III/R^.] type transition state.     

Preparation and examination of properties of lanthanide chloride salts with hexamethylenetetramine

Summary New complex salts of lanthanide chlorides with hexamethylenetramine of the general formulaLnCl₃·2HMTA·nH₂O [Ln=La, Pr, Nd, Sm, Dy, Er;HMTA-hexamethylenetetramine N₄(CH₂)₆;n=8, 10, 12] have been obtained. On the basis of IR IR spectra (4000-200cm^–1) and Raman spectra (3000-300 cm^–1), changes in the coordination sphere structure of the salts occurring in the course of thermal dehydration have been determined.

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Darstellung und Untersuchung der Eigenschaften von Komplexsalzen der Lanthanidchloride mit Hexamethylentetramin

Zusammenfassung Neue Komplexsalze der Lanthanidchloride mit Hexamethylentetramin mit der allgemeinen FormelLnCl₃·2HMTA·nH₂O [Ln=La, Pr, Nd, Sm, Dy, Er;HMTA — Hexamethylentetramin N₄(CH₂)₆;n=8, 10, 12] wurden dargestellt. Die Änderungen in der Struktur der Koordinationssphäre während der thermischen Dehydration der Salze wurden mittels Infrarot-(4 000–200 cm^–1) und Ramanspektroskopie (3 000–300 cm^–) bestimmt.

     

Spectra and structure of small ring compounds. LIX

The Raman (3200 to 10 cm^–1) and far infrared (380 to 60 cm^–1) spectra of gaseous fluorocyclobutane,c-C₄H₇F, have been recorded. A series of Q-branches observed in both of these spectra beginning at 166 cm^–1 with successive transitions falling to lower frequencies have been assigned to the ring puckering vibrations of both the low energy equatorial and high energy axial conformers. These data have been fit to an asymmetric potential function of the form:V (cm^–1)=(1.76±0.05)10³X+(4.88±0.28)10⁴X²+(2.12 ±0.16)10³ exp(–5.66±0.41)10X² with a reduced mass function ofg ₄₄= 0.00386–0.00295X+0.03485X²+0.1228X³ +0.3459X⁴, whereX is the ring puckering coordinate. Utilizing this potential, the difference between the puckering angles for the two conformers was calculated to be 4° with the equatorial conformer having the larger value of 28°. This potential function is consistent with an energy difference between the equatorial and axial forms of 447 cm^–1 (1.28 kcal/mol) and a barrier to ring inversion from the equatorial to the axial conformation of 713 cm^–1 (2.04 kcal/mol). Experimental values for the enthalpy difference between the two conformers have been determined for both the liquid (400±30 c^–1) and gas (413±43 cm^–1) from investigations of the Raman spectra at variable temperatures. The conformational stability, enthalpy difference, structural parameters, and fundamental vibrational frequencies, which have been determined experimentally, are compared to those obtained from ab initio Hartree-Fock calculations employing the 3-21G, 6-31 G^*, and 6-31 G^** basis sets.For part LVIII, seeStruct. Chem. 1991,2, 195.Taken in part from the thesis of M. J. Lee, which has been submitted to the Department of Chemistry in partial fulfillment of the Ph.D. degree, May 1991.     

EPR and optical absorption studies of Cr ions in d-gluconic acid monohydrate

EPR studies are carried out on Cr³⁺ ions doped in d-gluconic acid monohydrate (C₆H₁₂O₇·H₂O) single crystals at 77 K. From the observed EPR spectra, the spin Hamiltonian parameters g, |D| and |E| are measured to be 1.9919, 349 (×10⁻⁴) cm⁻¹ and 113 (×10⁻⁴) cm⁻¹, respectively. The optical absorption of the crystal is also studied at room temperature. From the observed band positions, the cubic crystal field splitting parameter Dq (2052 cm⁻¹) and the Racah interelectronic repulsion parameter B (653 cm⁻¹) are evaluated. From the correlation of EPR and optical data the nature of bonding of Cr³⁺ ion with its ligands is discussed.     

Energy levels and crystal-field calculations of trivalent ytterbium in yttrium aluminum garnet and yttrium gallium garnet

The splitting of the two ² F states of Yb³⁺:YAlG and Yb³⁺:YGaG, have been determined from fluorescence and absorption spectra at low temperatures. The levels of the ground states of Yb³⁺: YAlG are at: 0, 388, 613, 778 cm^–1, those of Yb³⁺: YGaG at 0, 308, 567, and 672 cm^–1. Crystal field calculations yield the following values for Yb³⁺:YAlG; A ₂ ⁰ =270 cm^–1, A ₄ ⁰ =–165 cm^–1, A ₄ ⁴ =–1155 cm^–1, A ₀ ⁶ =21 cm^–1, A ₄ ⁶ =–304 cm^–1 and for Yb³⁺:YGaG: A ₀ ² =110 cm^–1, A ₀ ⁴ =–125 cm^–1, A ₄ ⁴ =–1250 cm^–1, A ₀ ⁶ =10 cm^–1 and A ₄ ⁶ =–142 ^–1 A satisfactory agreement has been found for calculated and observed splitting patterns.

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Zusammenfassung Die Aufspaltung der ² F-Zustände von Yb³⁺:YAlG(I) und Yb³⁺:YGaG (II) wurde bei tiefen Temperaturen aus Fluoreszenz- und Absorptionsspektren bestimmt. Die Niveaus des Grundzustandes von (I) liegen bei 0, 388, 613, 778 ^–1, die von (II) bei 0, 308, 567 und 672 ^–1. Die Ligandenfeldtheorie ergibt folgende Werte für die Kristallfeldparameter: für (I) A ₂ ⁰ =270 cm^–1, A ₄ ⁰ =–165 cm^–1, A ₄ ⁴ =–1155 cm^–1, A ₀ ⁶ =21 cm^–1, A ₄ ⁶ =–304 cm^–1 unf für (II) A ₀ ² =110 cm^–1, A ₀ ⁴ =–125 cm^–1, A ₄ ⁴ =–1250 cm^–1, A=10 cm^–1 and A ₄ ⁶ =–142 ^–1. Die Übereinstimmung zwischen berechneter und beobachteter Aufspaltung war befriedigend.

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Résumé La division, par le champ de ligandes, des états ² F _7/2 et ² F _5/2 dans Yb³⁺:YAlG et Yb³⁺:YGaG a été déterminée des spectres de fluorescence et d'absorption. Les sous-niveaux de l'état fordamental se situent à 0, 388, 613, 778 cm^–1 dans Yb³⁺:YAlG, à 0, 308, 567, 672 cm^–1 Yb³⁺: YGaG. Le calcul fournit les valeurs suivantes pour les paramètres: Yb³⁺: YAlG A ₂ ⁰ =270 cm^–1, A ₄ ⁰ =–165 cm^–1, A ₄ ⁴ =–1155 cm^–1, A ₀ ⁶ =21 cm^–1, A ₄ ⁶ = -304 cm^–1 Yb³⁺:YGaG: A ₀ ² =110 cm^–1, A ₀ ⁴ =–125 cm^–1, A ₄ ⁴ =–1250 cm^–1, A ₀ ⁶ =10 cm^–1 et A ₄ ⁶ =–142 ^–1. L'accord entre les spectres calculé et observé est satisfaisant.

     

Synthesis,crystal structure and properties of the dimeric copper(II) complex, [Cu2(Hboa)2(H2O)2] · (ClO4)2 (H2boa = biacetyl oxime azine)

The crystal structure of the polyhydrazone dioxime-containing dimeric copper(II) (polyhydrazone dioxime: HON=CMe[CMe=NN=CMe] _n CMe=NOH) complex, [Cu₂(Hboa)₂(H₂O)₂] · (ClO₄)₂ (1) (H₂boa = biacetyl oxime azine) has been determined. Complex (1) contains an unusual six-membered ring, which is composed of two oxime groups and two Cu^II ions. The variable temperature magnetic susceptibility of (1) in the 5–300 K range has been interpreted in terms of a Cu^II dimer. The magnetic behavior shows that the bridging six-membered ring mediates very strongly in the antiferromagnetic exchange interaction, with the fitting value J = –361(1) cm^–1 and the e.p.r. g-value of 2.193.     

Conformational stability,barriers to internal rotation,normal coordinate analysis,and vibrational assignment of chloroacetyl bromide

The infrared spectra (3200 to 30 cm^–1) of gaseous and solid chloroacetyl bromide, CH₂ClC(O)Br, and the Raman spectra (3200 to 10 cm^–1) of the gas, liquid (with depolarization data), and solid have been recorded. From the observed asymmetric torsional transitions, the potential function governing internal rotation of the CH₂Cl moiety has been determined with the following coefficients:V ₁=336±11,V ₂=73±10,V ₃=757+7,V ₄=103±3, andV ₆=5±2 cm^–1. This potential function is consistent with s-trans to gauche and gauche to gauche barriers of 963±11 and 709±12cm^–1, respectively, and enthalpy difference of 373 ± 24 cm^–1 with the dihedral angle of the gauche rotamer being 115°. The enthalpy difference has been determined experimentally from the studies of the Raman spectra at different temperatures to be 359±68 cm^–1 (1.03±0.19 kcal mol^–1) and 507±24 cm^–1 (1.45±0.07 kcal mol^–1) for the gas and liquid, respectively, with the s-trans conformer being the more stable conformer in the gas and liquid and the only one present in the annealed solid. A complete assignment of the vibrational fundamentals is proposed from spectral data obtained for the gas, liquid, and solid. The assignment is supported by a normal coordinate calculation utilizing a modified valence force field to obtain the frequencies for the normal vibrations and the potential energy distribution. The results are discussed and compared to the corresponding quantities for some similar molecules.Taken in part from the thesis of H. V. Phan, which will be submitted to the Department of Chemistry in partial fulfillment of the Ph.D. degree.     

Interlayer inclusion of tetracyanonickelate anion and water molecules: The crystal and molecular structure of [-ZN(en)2-μ-(NC)2-NI-μ -(CN)2-ZN(en) -] n 2n+ ·n[NI(CN)4]2− · 3n H2O

The crystal structure of [Zn(en)₂- (NC)₂Ni(CN)₂ Zn(en)][Ni(CN)₄]· 3 H₂O consists of infinite positively charged wave-shaped layers of composition [Zn(en)₂-(NC)₂Ni(CN)₂- Zn(en)] _n ²ⁿ⁺ with the [Ni(CN)₄]^2– anions and water molecules included between them. Both Ni atoms exhibit square-planar coordination. The chelate bonded en (=ethylenediamine) and N-bonded cyano ligands around two independent zinc atoms form a deformed tetrahedron and a deformed octahedron, respectively. Yellow needles of the complex belong to the orthorhombic space groupPbcm witha = 6.977(1),b = 25.407(4),c = 14.876(2)Å,Z = 4,D _m = 1.74(1) g cm^–3 andD _c = 1.739 g cm^–3. The structure was refined toR = 6.31 %.