Spectroscopic and thermodynamic studies on solvatochromic nickel(II) complexes

Summary The solvatochromic and thermochromic behaviour of a series of mixed Ni(II) complexes with unsubstituted and substituted mg src="/content/w75k872m356u15h5/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-diketones and diamines in the solvents 1,2-dichloroethane (DCE), acetonitrile (An), acetone (AC),n-butanol (n-BuOH), formamide (FA), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO) and pyridine (PY) has been studied and characterized on the basis of electronic spectra. Spectrophotometric methods have been used to evaluate equilibrium constants and their enthalpic and entropic terms for the formation of Ni(mg src="/content/w75k872m356u15h5/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-dik)(diam)L ⁺ and Ni(mg src="/content/w75k872m356u15h5/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-dik)(diam)L ₂ ⁺ . Increasing donor strength of the donor-solvents (L) and (or) increasing electronwithdrawing parameters of the substituents at the mg src="/content/w75k872m356u15h5/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-diketone and the diamine ligands lead to increasing formation constants, paralleled by relative increase in the stability of the five-coordinated species Ni(mg src="/content/w75k872m356u15h5/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-dik)(diam)L ⁺. The results are discussed in terms of the extended donor-acceptor concept.On leave of absence from the Faculty of Education, Ain Schams University, Roxy, Cairo, Egypt     

A review ofL=λW and extensions

A fundamental principle of queueing theory isL=mg src="/content/xux070072tu26m4t/xxlarge955.gif" alt="lambda" align="BASELINE" BORDER="0">W (Little's law), which states that the time-average or expected time-stationary number of customers in a system is equal to the product of the arrival rate and the customer-average or expected customer-stationary time each customer spends in the system. This principle is now well known and frequently applied. However, in recent years there have been extensions, such as H=mg src="/content/xux070072tu26m4t/xxlarge955.gif" alt="lambda" align="BASELINE" BORDER="0">G and the continuous, distributional, ordinal and central-limit-theorem versions, which show that theL=mg src="/content/xux070072tu26m4t/xxlarge955.gif" alt="lambda" align="BASELINE" BORDER="0">W relation, when viewed properly, has much more power than was previously realized. Moreover, connections have been established between H=mg src="/content/xux070072tu26m4t/xxlarge955.gif" alt="lambda" align="BASELINE" BORDER="0">G and other fundamental relations, such as the rate conservation law and PASTA (Poisson arrivals see time averages), which show that there is a much greater unity in the overall theory than was previously realized. This paper provides a review.This paper is dedicated to the memory of our colleague Professor Peter Franken (1937–1989), who contributed greatly to the subject of this paper and to queueing theory more generally.     

Noise and correlation functions of hot carriers in semiconductors

We present a unifying theory of electronic noise appropriate to semiconductor materials in the presence of electric fields of arbitrary strength. In addition to thermal noise, a classification scheme for excess noise indicating different microscopic sources of fluctuations responsible for number and mobility fluctuations is provided. On the basis of simple two-level models, numerical calculations using a Monte Carlo technique are performed for the case of p-type Si at 77 K. The primary quantity which is evaluated by the theory is the auto-correlation function of current fluctuations which, subsequently, is analyzed in terms of correlation functions of the relevant physical variables. Accordingly, the corresponding current spectral-densities are determined and then compared with direct experimental results and/or analytical expressions. Important subjects which have been investigated are: (i) the effect of field assisted ionization on generation-recombination noise from shallow impurity levels; (ii) the contribution to the total noise spectrum of cross-correlation terms coupling fluctuations in velocity with those in energy and number; (iii) the current random telegraph signal and the corresponding spectral density associated with a mobility fluctuator. In all cases the numerical calculations are found to be in satisfactory agreement with experiments and/or analytical expressions thus fully supporting the physical reliability of the theoretical approach here proposed.List of the Symbols Used e Absolute value of the electron charge - f Frequency - f Distribution function - g ₁ Scattering strength with the scatter in state 1 - g ₂ Scattering strength with the scatter in state 2 - mg src="/content/v1h6u8656gk66514/xxlarge295.gif" alt="hstrok" align="BASELINE" BORDER="0"> Reduced Planck constant - j Total current density - j _c Conduction current density - j _d Displacement current density - j _x Component along the x direction of the total current density - k Carrier wavevector - m Carrier effective mass - m ₀ Free electron mass - r Position vector - s Average sound velocity - t Time - u Fraction of ionized carriers - u _i Random telegraph signal related to carrier state - u _m Random telegraph signal related to scatterer state - v _d Ensemble average of the free carrier drift-velocity - v _i Carrier group velocity - v _t Ensemble average of the carrier velocity in the direction transverse to the applied field - v _ix Component along the x direction of the carrier group velocity - v _d ^r Ensemble average of the reduced drift-velocity - v ^r _i Reduced velocity component in the field direction of the i-th particle - v _ix ^j Reduced velocity component along the x axis of the i-th particle in band j - v ^r _ix Reduced velocity component along the x axis of the i-th particle - x _d Ensemble average of the carrier displacement along the x direction from the initial position - x _i Displacement along the x direction of the i-th carrier from the initial position - y _i i-th stochastic parameter - A Cross-sectional area of a homogeneous sample - C _I Auto-correlation function of the total current fluctuations - mg src="/content/v1h6u8656gk66514/339_2004_Article_BF00324165_TeX2GIFIE1.gif" alt="
$$C_{{\text{I}}_{\text{m}} } $$
" align="middle" border="0"> Auto-correlation function of the total current fluctuations due to mobility fluctuations - D Diffusion coefficient - D _t K Optical deformation potential - E Electrical field strength - E Electric field - E _x Component of the electric field along the x direction - E ₁ ⁰ Acoustic deformation potential - G Conductance - I Total current - I ₀ Total current in the voltage noise operation - I _m Total current associated with mobility fluctuations - I ^V Total current in the current noise operation - K _B Boltzmann constant - L Length of a homogeneous sample - N Number of free carriers which are instantaneously present in the device - N _A Acceptor concentration - N _I Total number of carriers inside the device participating in the transport (here assumed to be constant in time) - N _T Total number of carriers which are instantaneously present in the device - S _I Spectral density of current fluctuations - S _V Spectral density of voltage fluctuations - mg src="/content/v1h6u8656gk66514/339_2004_Article_BF00324165_TeX2GIFIE2.gif" alt="
$$S_{{\text{I}}_{\text{m}} } $$
" align="middle" border="0"> Spectral density of current fluctuations associated with the mobility fluctuations - mg src="/content/v1h6u8656gk66514/339_2004_Article_BF00324165_TeX2GIFIE3.gif" alt="
$$S_{{\text{I}}_{{\text{cr}}} } $$
" align="middle" border="0"> Spectral density of current fluctuations due to correlations between fluctuations in number and velocity - mg src="/content/v1h6u8656gk66514/339_2004_Article_BF00324165_TeX2GIFIE4.gif" alt="
$$S_{{\text{I}}_{{\text{gr}}} } $$
" align="middle" border="0"> Spectral density of current fluctuations due to generation-recombination processes - mg src="/content/v1h6u8656gk66514/339_2004_Article_BF00324165_TeX2GIFIE5.gif" alt="
$$S_{{\text{I}}_{\mathop {\text{v}}\nolimits_{\text{d}} } } $$
" align="middle" border="0"> Spectral density of current fluctuations due to free carrier drift-velocity fluctuations - S _I ^l Longitudinal component with respect to the applied field of the current spectral-density - S _I ^t Transverse component with respect to the applied field of the current spectral-density - T Absolute temperature - T _e Electron temperature - V Electrical potential - V ^I Electrical potential in the voltage noise operation - W Collision rate - Zmg src="/content/v1h6u8656gk66514/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0"> Small signal impedance - mg src="/content/v1h6u8656gk66514/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"> Poole-Frenkel factor - mg src="/content/v1h6u8656gk66514/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0"> Equilibrium generation rate - mg src="/content/v1h6u8656gk66514/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0"> _E Field dependent generation rate - mg src="/content/v1h6u8656gk66514/xxlarge948.gif" alt="delta" align="BASELINE" BORDER="0"> Typical energy for thermally escaping from the impurity level - mg src="/content/v1h6u8656gk66514/xxlarge948.gif" alt="delta" align="BASELINE" BORDER="0">v _d ⁽⁰⁾ Fluctuation of the ensemble average of the driftvelocity associated with Brownian-like motion - mg src="/content/v1h6u8656gk66514/xxlarge948.gif" alt="delta" align="BASELINE" BORDER="0">v _d ^r(0) Fluctuation of the ensemble average of the reduced drift-velocity associated with Brownian-like motion - mg src="/content/v1h6u8656gk66514/xxlarge603.gif" alt="epsiv" align="BASELINE" BORDER="0"> Carrier energy - mg src="/content/v1h6u8656gk66514/xxlarge603.gif" alt="epsiv" align="BASELINE" BORDER="0">₀ Vacuum permittivity - mg src="/content/v1h6u8656gk66514/xxlarge603.gif" alt="epsiv" align="BASELINE" BORDER="0">_a Energy of the acceptor level - mg src="/content/v1h6u8656gk66514/xxlarge603.gif" alt="epsiv" align="BASELINE" BORDER="0">_r Relative static dielectric constant - mg src="/content/v1h6u8656gk66514/xxlarge952.gif" alt="theta" align="BASELINE" BORDER="0"> Angle between initial and final k states - mg src="/content/v1h6u8656gk66514/xxlarge952.gif" alt="theta" align="BASELINE" BORDER="0">_op Optical phonon equivalent temperature - mg src="/content/v1h6u8656gk66514/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0"> Mobility - mg src="/content/v1h6u8656gk66514/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">₀ Chemical potential - mg src="/content/v1h6u8656gk66514/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">₁ Mobility with the fluctuating scatterer in state 1 - mg src="/content/v1h6u8656gk66514/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">₂ Mobility with the fluctuating scatterer in state 2 - mg src="/content/v1h6u8656gk66514/xxlarge1009.gif" alt="rhov" align="MIDDLE" BORDER="0">₀ Crystal density - mg src="/content/v1h6u8656gk66514/xxlarge1009.gif" alt="rhov" align="MIDDLE" BORDER="0">_E Field dependent volume recombination rate - mg src="/content/v1h6u8656gk66514/xxlarge1009.gif" alt="rhov" align="MIDDLE" BORDER="0">_eq Equilibrium volume recombination rate - mg src="/content/v1h6u8656gk66514/xxlarge963.gif" alt="sgr" align="BASELINE" BORDER="0"> Conductivity - mg src="/content/v1h6u8656gk66514/xxlarge963.gif" alt="sgr" align="BASELINE" BORDER="0">_g Cross-section for impact ionization - mg src="/content/v1h6u8656gk66514/xxlarge964.gif" alt="tau" align="BASELINE" BORDER="0">_c Average scattering time - mg src="/content/v1h6u8656gk66514/xxlarge964.gif" alt="tau" align="BASELINE" BORDER="0">_g Generation time - mg src="/content/v1h6u8656gk66514/xxlarge964.gif" alt="tau" align="BASELINE" BORDER="0">_l Carrier lifetime - mg src="/content/v1h6u8656gk66514/xxlarge964.gif" alt="tau" align="BASELINE" BORDER="0"> _m Scatterer lifetime - mg src="/content/v1h6u8656gk66514/xxlarge964.gif" alt="tau" align="BASELINE" BORDER="0"> _m1 Mean value of the time spent by the fluctuating scatterer in state 1 - mg src="/content/v1h6u8656gk66514/xxlarge964.gif" alt="tau" align="BASELINE" BORDER="0"> _m2 Mean value of the time spent by the fluctuating scatterer in state 2 - mg src="/content/v1h6u8656gk66514/xxlarge964.gif" alt="tau" align="BASELINE" BORDER="0">_r Average recombination time - mg src="/content/v1h6u8656gk66514/xxlarge964.gif" alt="tau" align="BASELINE" BORDER="0">_T Transit time - mg src="/content/v1h6u8656gk66514/xxlarge915.gif" alt="Gamma" align="BASELINE" BORDER="0"> Scattering rate - mg src="/content/v1h6u8656gk66514/xxlarge934.gif" alt="PHgr" align="BASELINE" BORDER="0"> _AB Correlation function of the two variables A and B     

Reaction of the dimethoxyaminyl radical with tertiary nitrosoalkanes as a method for the preparation of N-alkyl-N′-methoxydiazene N-oxides

The reaction of the dimethoxyaminyl radical with functionally substituted nitrosoalkanes (2) in a 2:1 ratio at 20°C gives the corresponding N-alkyl-Nmg src="/content/n8p08k8m45267484/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-methoxydiazene N-oxides (3) as a single isomer in preparative yields.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2443–2445, October, 1992.     

X-ray study of volatile Ni(II), Cu(II), and Pd(II) complexes of β-ketoimine pivalyltrifluoroacetone

Synthesis of volatile complexes based on mg src="/content/m3634247u647303k/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-ketoimine pivalyltrifluoroacetone, C(CH₃)₃C(NH)CH₂COCF₃, is described. The general formula of the complexes is M(L)₂, where M = Cu, Ni, Pd. Complexes of this kind with Ni and Pd were obtained for the first time. The Cu and Pd complexes were found to be isostructural. A comprehensive crystal-chemical study showed that all structures are molecular and built of trans-complexes. The central atom has a square plane environment. The average M-O and M-N distances are nearly equal in all compounds: 1.84 mg src="/content/m3634247u647303k/xxlarge8491.gif" alt="angst" align="MIDDLE" BORDER="0">, 1.92 mg src="/content/m3634247u647303k/xxlarge8491.gif" alt="angst" align="MIDDLE" BORDER="0">, and 1.98 mg src="/content/m3634247u647303k/xxlarge8491.gif" alt="angst" align="MIDDLE" BORDER="0"> for Ni, Cu, and Pd complexes, respectively; the mean values of the O-M-N chelate angles are 93.4°, 91.9°, and 92.7°, respectively.Original Russian Text Copyright © 2004 by I. A. Baidina, G. I. Zharkova, N. V. Pervukhina, S. A. Gromilov, and I. K. IgumenovTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 713–722, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Synthesis and X-Ray Crystal Structure Study of ]2-Methyl-4-(2-methylbenzoyl)-phenoxy] Acetic Acid Hydrazide

Benzophenone analog 3 has been synthesized and characterized by the X-ray diffraction (XRD) method. The compound crystallizes in a monoclinic space group P2₁/c with cell parameters a = 7.701(8) Å, b = 7.151(5) Å, c= 28.323(3) Å, mg src="/content/hk1675u9m65164v2/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"> = 104.639(4)°, Z = 4. The structure exhibits intra- and intermolecular hydrogen bonding of the type N–Hmg src="/content/hk1675u9m65164v2/xxlarge8901.gif" alt="sdot" align="BASELINE" BORDER="0">mg src="/content/hk1675u9m65164v2/xxlarge8901.gif" alt="sdot" align="BASELINE" BORDER="0">mg src="/content/hk1675u9m65164v2/xxlarge8901.gif" alt="sdot" align="BASELINE" BORDER="0">O, C–Hmg src="/content/hk1675u9m65164v2/xxlarge8901.gif" alt="sdot" align="BASELINE" BORDER="0">mg src="/content/hk1675u9m65164v2/xxlarge8901.gif" alt="sdot" align="BASELINE" BORDER="0">mg src="/content/hk1675u9m65164v2/xxlarge8901.gif" alt="sdot" align="BASELINE" BORDER="0">O, and N–Hmg src="/content/hk1675u9m65164v2/xxlarge8901.gif" alt="sdot" align="BASELINE" BORDER="0">mg src="/content/hk1675u9m65164v2/xxlarge8901.gif" alt="sdot" align="BASELINE" BORDER="0">mg src="/content/hk1675u9m65164v2/xxlarge8901.gif" alt="sdot" align="BASELINE" BORDER="0">N. The molecules are interlinked through hydrogen bonds forming an infinite chain. This polymeric-like structure may play an important role in biological activity.     

X-ray spectroscopic characterization of Cu2+-phenanthroline complexes intercalated in α-zirconium phosphate

X-ray photoelectron spectroscopy provides evidence that when [Cu(phen)₂]²⁺(phen = 1,10-phenanthroline) is diffused between the layers of mg src="/content/q57m436828621065/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-zirconium phosphate, the complex species does not remain intact after intercalation, but some Cu-N bonds are broken, replaced with Cu-O bonds and the released nitrogen atoms can now interact with the PO₃-OH groups of the host. XPS also provides evidence for coordination of the Cu²⁺ ions when they are diffused by ion exchange in the phenanthroline-mg src="/content/q57m436828621065/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-zirconium phosphate intercalation compound. Although Cu²⁺ and phen are in a 1 : 1 molar ratio in the interlayer region of the host, so that a 1 : 1 coordination could be expected between the two species, the characteristic peaks of the uncoordinated phenanthroline, even though at a low intensity, are still present. The differences between the two Cu(II)-intercalation compounds are discussed.     

Terpenes in organic synthesis

A seven-step synthesis ofS-(+)-hydroprene (S-1) in mg src="/content/q7718m1w037843t2/xxlarge8764.gif" alt="sim" align="MIDDLE" BORDER="0">20 % overall yield starting fromS-(+)-3,7-dimethyl-1,6-octadiene (2) of 55+-10 % optical purity is described. The introduction of an optical enhancement step in the synthetic sequence at the stage ofS-(–)-3,7-dimethyl-1-octanol (9) raises the optical purity ofS-1 from mg src="/content/q7718m1w037843t2/xxlarge8764.gif" alt="sim" align="MIDDLE" BORDER="0">50 % to mg src="/content/q7718m1w037843t2/xxlarge8764.gif" alt="sim" align="MIDDLE" BORDER="0">80 %.For part 13, see. ref.¹ Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 342–348, February, 1993.     

An improved procedure for the synthesis of N-bromoacetyl-β-glycopyranosylamines, derivatives of mono- and disaccharides

An improved procedure for the synthesis of N-bromoacetyl-mg src="/content/m64323v43026736l/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-glycopyranosylamines from the corresponding mg src="/content/m64323v43026736l/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-glycosylamines was developed. The procedure is applicable to a wide range of derivatives of monosaccharides (hexoses, 2-acetamido-2-deoxyhexoses, hexuronamides, and 6-deoxyhexoses) and some disaccharides. For the derivatives of pentoses and 2-deoxyhexoses, the use of the corresponding mg src="/content/m64323v43026736l/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-glycosylammonium carbamates was found to be more convenient. N-Bromoacetyl-mg src="/content/m64323v43026736l/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-glycopyranosylamines derived from D-mannose, L-rhamnose, D-glucuronamide, 2-deoxy-D-arabino-hexose, 2-deoxy-D-lyxo-hexose, and melibiose were obtained for the first time.