荧光光度法同时测定稀土氧化物中铈钆铽

在０．６ｍｏｌ．Ｌ＾－１的 到介质中,分别用２５２、２７３、２２０ｎｍ作为Ｃｅ＾３＋、Ｇｄ＾３＋、Ｔｂ＾３＋的激发波和燕生相应最佳发波长为３５０、３１０和５４４ｎｍ。用盐酸体系测定混合样比用硫酸体系测定时,Ｇｄ＾３＋的检出限提高一倍,Ｇｄ＾３＋抗Ｃｅ＾３＋的干扰能力提高１０倍。同时测定三种离子的回收率在９５．３％～１０８．１％之间。     

氢化物发生原子荧光光谱法测定临床样品微量砷和硒

研究了氢化物原子荧光法测定临床床样品全血，血清，胎盘，头发，指甲和尿液中微量Ａｓ和Ｓｅ的方法。线性范围为Ａｓ１．３＊１０＾－９－２．５＊１０＾－７ｇ／ｍＬ，Ｓｅ２．８＊１０＾１０－７．５＊１０＾－８ｇ／ｍＬ；相对标准偏差（ｎ＝１３）Ａｓ２．６－３．６％，Ｓｅ２．８－４．２％；Ａｓ、Ｓｅ的标准加入回收率为９６．７－１０４．２％，用于６种临床样品中Ａｓ、Ｓｅ测定，获得满意的结果。     

铁的单点络合滴定法研究

本研究了Ｆｅ＾３＋的单点络合滴定法，导出了定量关系式，比较了以铂电极为指示电极和以ＰＶＣ膜四氯络铁（Ⅲ）阴离子电极为指示电极时电位测量的稳定性及所得的分析结果。在Ｆｅ＾３＋浓度为１．０００×１０＾－３ｍｏｌ／Ｌ时，１８次实验的平均值为１．０２×１０＾－４ｍｏｌ／Ｌ，相对偏差小于１．７％；Ｆｅ＾３＋在５．０×１０＾３ｍｏｌ／Ｌ以上时，相对偏差小于０．１％；其浓度小于１０＾－３ｍｏｌ／Ｌ而大于５×１     

催化动力学光度法测定痕量苯酚

研究了在硫酸介质中苯酚对Ｉ＾－１催化Ｃｅ＾４＋－Ａｓ（Ⅲ）反应的抑制作用及其动力学条件。建立了用催化动力这光度法测定痕量苯酚的新方法，结果表明，在０．００１ｍｏｌ／ＬＣｅ（ＳＯ４）２，０．００１２５ｍｏｌ／Ｌ，Ａｓ２Ｏ３，０．０１ｍｇ／Ｌ，ＫＩ，０．０１２５ｍｏｌ／Ｌ，Ｈ２ＳＯ４和０．１３％（ｗ／ｖ）ＮａＣｌ溶液中测定苯酚，其表面摩尔吸光系数为２．１×１０＾５Ｌ．ｍｏｌ＾－１．ｃｍ＾－１，线性范围     

裉色光度法测定SO^2—3的研究

本文研究了ＳＯ＾２－３褪色碱蓝６Ｂ的反应，在ｐＨ５．２Ａｃ－ＮａＡｃ缓冲介质中，ＳＯ＾２－３浓度在０．３９－１２ｍｇ／Ｌ范围内符合比尔定律，仅Ｆｅ＾３＋，Ｎｉ＾２＋，Ｃｒ＾３＋干扰测定，用于食品中ＳＯ＾２－３的测定，结果令人满意。     

缩合显色反应分光光度测定δ—氨基乙酰丙酸

本文报道一种新的测定δ－氨基乙酰丙烯（δ－ＡＬＡ）的分光光度法，方法基于δ－ＡＬＡ被缩合成吡咯衍生物后，在酸性条件与Ｆｅ＾３＋生成橙红色配合物，其λｍａｘ为４８０ｎｍ，ε为６．６×１０＾３Ｌ．ｍｏｌ＾－１．ｃｍ＾－１，线性范围１０～４００μｇ／２５ｍＬ，回收率９４～１０４％。     

单柱离子色谱法测定痕量草酸根离子

本文采用单柱离子色谱系统测定了Ｃ２Ｏ＾２－４，以１．３ｍｍｏｌ／Ｌ葡萄糖酸钠／１．３ｍｍｏｌ／Ｌ硼砂为淋洗液测定Ｃ２Ｏ＾２－４，８常见阴离子Ｃｌ＾－，ＮＯ＾－３，ＨＰＯ＾２－４，ＳＯ＾２－４不干扰测定，Ｃ２Ｏ＾２－４的检出限为０．５７ｍｇ／Ｌ，相对标准偏差为１．０７％，工作曲线的线性范围为０．５７－５００ｍｇ／Ｌ，应用本方法测定了加Ｃ２Ｏ＾２－４的自来水样，Ｃ２Ｏ＾２－４的回收率为９９．５２％。     

单柱离子色谱法测定过热器管垢和锅炉垢中铁、镁和钙的含量

首先用碱熔融法分解试样,然后加抗坏血酸将试液中的Ｆｅ３＋还原为Ｆｅ２＋,再用离子色谱法测定试液中的Ｆｅ２＋,Ｍｇ２＋和Ｃａ２＋。采用Ｓｈｉｍ－ｐａｃｋＩＣ－Ｃｌ阳离子交换柱分离样品离子,以０．２５ｍｍｏｌ／Ｌ乙二胺－０．５０ｍｍｏｌ／Ｌ柠檬酸（ｐＨ４．５０）为流动相,以ＣＤＤ－６Ａ电导检测器检测,使被测组分得到满意的分离和检测。Ｆｅ,Ｍｇ和Ｃａ的加标回收率均在９０％以上。测定结果与原子吸收光谱法测定结果相近。     

PTFE—乙醚柱反相萃取层析连续分离和测定镓（Ⅲ）铟（Ⅲ）的研究

研究了在抗坏血酸存在下的６ｍｏｌ／Ｌ ＨＢｒ介质作流动相，以ＰＴＦＥ（聚四氟乙烯）负载的乙醚作固定相，反相萃取层析使微量Ｇａ（Ⅲ），Ｉｎ（Ⅲ）与Ｆｅ＾３＋、Ｔｌ＾３＋、Ｍｏ＾６＋、Ａｕ＾３＋、Ｔｉ＾４＋、Ｂｉ＾３＋、Ａｌ＾３＋、Ｍｇ＾２＋、Ｃａ＾２＋、Ｎｉ＾２＋、Ｃｏ＾２＋、Ｃｄ＾２＋、Ｚｎ＾２＋、Ｐｂ＾２＋、Ｃｕ＾２＋等多种离子分离。留于柱上的铟、镓分别用ＨＣｌ（４ｍｏｌ／Ｌ）－Ｈ２Ｏ２（３％）     

KBrO3—KBr紫外分光光度法测定痕量水杨酸

研究了ＨＣｌ溶液中ＫＢｒＯ３－ＫＢｒ紫外分光光度法测定水杨酸的条件,建立了测定痕量水杨酸的新方法。结果表明,在０．６ｍｏｌ／ＬＨＣｌ,３＊１０＾－５ｍｏｌ／ＬＫＢｒＯ３,５＊１０＾－４ｍｏｌ／ＬＫＢｒ,６＊１０＾－４ｍｏｌ／ｌＫＩ溶中测定水杨酸,其线性范围为０．２－４．０ｍｇ／Ｌ,表观摩尔吸光系数为１．９＊１０＾－４Ｌ．ｍｏｌ＾－１．ｃｍ＾－１,Ｓａｎｄｅｌｌ为７．３μｇ／ｃｍ＾２。ｓｇ ｉｆ ｅ     

Selenoether macrocyclic chemistry--syntheses and properties of new potentially tridentate and hexadentate Se/O-donor macrocycles

Treatment of O(CH2CH2SeCN)2 with Na in NH3(l), followed by dropwise addition of a thf solution of o-C6H4(CH2Br)2 at -40 degrees C leads to formation of three mixed Se/O-donor macrocycles which are separable by column chromatography, the [1 + 1] species L1, the [2 + 2] ring L2 and the [3 + 3] ring L3, of which L2 is by far the major species. Using the same starting materials, but in a high dilution cyclisation at room temperature with NaBH4 in thf/EtOH gives exclusively the [1 + 1] ring, L1. The saturated ring Se/O-donor macrocycles, L4 and L5 are obtained by simultaneous dropwise addition of solutions of O(CH2CH2SeCN)2 and Br(CH2)3Br to NaBH4 suspended in thf/EtOH. The small tridentate Se2O-donor ring, L4, is again the dominant product under these conditions (71%), although the more flexible precursors in this reaction also give rise to the larger Se4O2-donor ring, L5, as a by-product in 8% yield. These compounds are readily separated and purified by column chromatography (ethyl acetate:hexane, 1:19). The new macrocycles have been characterised by 1H, (13)C{1H} and (77)Se{1H} NMR spectroscopy and mass spectrometry, together with crystal structures of L1 and L2. Complexes of L1 and L2 with late transition metals (Pd(II), Pt(II), Cu(I) and Ag(I)) are also described.     

Structures and physical properties of new semiconducting polyselenides Ba2CudeltaAg4-deltaSe5 with unprecedented linear Se(3)4- units

The title compounds were prepared from the elements in evacuated silica tubes at 650 degrees C, followed by slow cooling. Ba2Ag4Se5 forms a new structure type, space group C2/m, with a=16.189(2) A, b=4.5528(6) A, c=9.2500(1) A, beta=124.572(3) degrees, and V=561.4(1) A3 (Z=2). A maximum of 44% of the Ag atoms may be replaced with Cu atoms without changing the structure type. The crystal structure is composed of Ag4Se(5)4- layers, interconnected via the Ba2+ cations. The Ag atoms show irregular [3+1] coordination by the Se atoms, and the Ba atoms are located in capped square antiprisms formed by Se atoms. Most intriguing is the unprecedented occurrence of linear Se(3)4- units. According to the formulation (Ba2+)2(Ag+)4Se(3)4-(Se2-)2, this selenide is electron-precise with eight positive charges equalizing the eight negative charges. Electronic structure calculations indicated the presence of a band gap, as was experimentally confirmed: the electrical conductivity measurement revealed a gap of 0.6 eV for Ba2CuAg3Se5.     

六氰合铁酸铜钴薄膜修饰铂电极的电化学、XRD及XPS研究

采用循环伏安法在铂电极上电聚合了六氰合铁酸铜钴薄膜,并用电化学、XRD 和XPS对该薄膜进行了表征。研究表明此薄膜属于取代型的多核六氰合铁酸盐,由 Cu~(2+),Co~(2+)和Fe~(2+)共同占据晶格格点。通过改变Cu~(2+),Co~(2+)和 Fe~(3+)在沉积液中的比例可以改变聚合膜的性质。随沉积液中Cu~(2+)含量的增加 ,聚合膜中铜的含量相应增加而晶格常数则逐渐减小,但保持着面心立方的晶格对 称性。当沉积液中Cu~(2+):Co~(2+):Fe~(3+) = 1:1:2时,得到的聚合膜具有比较 典型的性质,该薄膜修饰的铂电极在pH 4～10之间均能保持着稳定的电化学响应。 其对一价阳离子的选择性顺序为K~+ > Li~+ > Na~+ > NH_4~+,与单组分的六氰铁 酸酮和六氰合铁酸钴都存在着较大的差别。XPS实验表明氧化态薄膜中铁元素以Fe (III)存在,并且在X射线的照射下很快转化为Fe(II)。     

Bonding, structure, and energetics of gaseous E8(2+) and of solid E8(AsF6)2 (E = S, Se)

The attempt to prepare hitherto unknown homopolyatomic cations of sulfur by the reaction of elemental sulfur with blue S8(AsF6)2 in liquid SO2/SO2ClF, led to red (in transmitted light) crystals identified crystallographically as S8(AsF6)2. The X-ray structure of this salt was redetermined with improved resolution and corrected for librational motion: monoclinic, space group P2(1)/c (No. 14), Z = 8, a = 14.986(2) A, b = 13.396(2) A, c = 16.351(2) A, beta = 108.12(1) degrees. The gas phase structures of E8(2+) and neutral E8 (E = S, Se) were examined by ab initio methods (B3PW91, MPW1PW91) leading to delta fH theta[S8(2+), g] = 2151 kJ/mol and delta fH theta[Se8(2+), g] = 2071 kJ/mol. The observed solid state structures of S8(2+) and Se8(2+) with the unusually long transannular bonds of 2.8-2.9 A were reproduced computationally for the first time, and the E8(2+) dications were shown to be unstable toward all stoichiometrically possible dissociation products En+ and/or E4(2+) [n = 2-7, exothermic by 21-207 kJ/mol (E = S), 6-151 kJ/mol (E = Se)]. Lattice potential energies of the hexafluoroarsenate salts of the latter cations were estimated showing that S8(AsF6)2 [Se8(AsF6)2] is lattice stabilized in the solid state relative to the corresponding AsF6- salts of the stoichiometrically possible dissociation products by at least 116 [204] kJ/mol. The fluoride ion affinity of AsF5(g) was calculated to be 430.5 +/- 5.5 kJ/mol [average B3PW91 and MPW1PW91 with the 6-311 + G(3df) basis set]. The experimental and calculated FT-Raman spectra of E8(AsF6)2 are in good agreement and show the presence of a cross ring vibration with an experimental (calculated, scaled) stretching frequency of 282 (292) cm-1 for S8(2+) and 130 (133) cm-1 for Se8(2+). An atoms in molecules analysis (AIM) of E8(2+) (E = S, Se) gave eight bond critical points between ring atoms and a ninth transannular (E3-E7) bond critical point, as well as three ring and one cage critical points. The cage bonding was supported by a natural bond orbital (NBO) analysis which showed, in addition to the E8 sigma-bonded framework, weak pi bonding around the ring as well as numerous other weak interactions, the strongest of which is the weak transannular E3-E7 [2.86 A (S8(2+), 2.91 A (Se8(2+)] bond. The positive charge is delocalized over all atoms, decreasing the Coulombic repulsion between positively charged atoms relative to that in the less stable S8-like exo-exo E8(2+) isomer. The overall geometry was accounted for by the Wade-Mingos rules, further supporting the case for cage bonding. The bonding in Te8(2+) is similar, but with a stronger transannular E3-E7 (E = Te) bonding. The bonding in E8(2+) (E = S, Se, Te) can also be understood in terms of a sigma-bonded E8 framework with additional bonding and charge delocalization occurring by a combination of transannular n pi *-n pi * (n = 3, 4, 5), and np2-->n sigma * bonding. The classically bonded S8(2+) (Se8(2+) dication containing a short transannular S(+)-S+ (Se(+)-Se+) bond of 2.20 (2.57) A is 29 (6) kJ/mol higher in energy than the observed structure in which the positive charge is delocalized over all eight chalcogen atoms.     

Preparation of a family of hexanuclear rhenium cluster complexes containing 5-(phenyl)tetrazol-2-yl ligands and alkylation of 5-substituted tetrazolate ligands

The preparation of two new families of hexanuclear rhenium cluster complexes containing benzonitrile and phenyl-substituted tetrazolate ligands is described. Specifically, we report the preparation of a series of cluster complexes with the formula [Re(6)Se(8)(PEt(3))(5)L](2+) where L = benzonitrile, p-aminobenzonitrile, p-methoxybenzonitrile, p-acetylbenzonitrile, or p-nitrobenzonitrile. All of these complexes undergo a [2 + 3] cycloaddition with N(3)(-) to generate the corresponding [Re(6)Se(8)(PEt(3))(5)(5-(p-X-phenyl)tetrazol-2-yl)](+) (or [Re(6)Se(8)(PEt(3))(5)(2,5-p-X-phenyltetrazolate)](+)) cluster complexes, where X = NH(2), OMe, H, COCH(3), or NO(2). Crystal structure data are reported for three compounds: [Re(6)Se(8)(PEt(3))(5)(p-acetylbenzonitrile)](BF(4))(2)?MeCN, [Re(6)Se(8)(PEt(3))(5)(2,5-phenyltetrazolate)](BF(4))?CH(2)Cl(2), and [Re(6)Se(8)(PEt(3))(5)(2,5-p-aminophenyltetrazolate)](BF(4)). Treatment of [Re(6)Se(8)(PEt(3))(5)(2,5-phenyltetrazolate)](BF(4)) with HBF(4) in CD(3)CN at 100 °C leads to protonation of the tetrazolate ring and formation of [Re(6)Se(8)(PEt(3))(5)(CD(3)CN)](2+). Surprisingly, alkylation of the phenyl and methyl tetrazolate complexes ([Re(6)Se(8)(PEt(3))(5)(2,5-N(4)CPh)](BF(4)) and [Re(6)Se(8)(PEt(3))(5)(1,5-N(4)CMe)](BF(4))) with methyl iodide and benzyl bromide, leads to the formation of mixtures of 1,5- and 2,5-disubstituted tetrazoles.     

Effects of lanthanide metal size and amino ligand denticity on the solvothermal systems Ln/Sn/Se/en and Ln/Sn/Se/dien (Ln = lanthanide)

Two systems, Ln/Sn/Se/en and Ln/Sn/Se/dien, were investigated under solvothermal conditions, and novel lanthanide selenidostannates [{Ce(en)(4)}(2)(μ-Se(2))]Sn(2)Se(6) (1a), [{Ln(en)(3)}(2)(μ-OH)(2)]Sn(2)Se(6) (Ln = Pr(1b), Nd(1c), Gd(1d); en = ethylenediamine), [{Ln(dien)(2)}(4)(μ(4)-Sn(2)Se(9))(μ-Sn(2)Se(6))](∞) (Ln = Ce(2a), Nd(2b)), and [Hdien][Gd(dien)(2)(μ-SnSe(4))] (2c) (dien = diethylenetriamine) were prepared and characterized. Two structural types of lanthanide selenidostannates were obtained across the lanthanide series in both systems. In the Ln/Sn/Se/en system, two types of binuclear lanthanide complex cations [Ce(2)(en)(8)(μ-Se(2))](4+) and [{Ln(en)(3)}(2)(μ-OH)(2)](4+) (Ln = Pr, Nd, Gd) were formed depending on the Ln(3+) ions. The complex cations are compensated by the [Sn(2)Se(6)](4-) anions. In the Ln/Sn/Se/dien system, coordination polymer [{Ln(dien)(2)}(4)(μ(4)-Sn(2)Se(9))(μ-Sn(2)Se(6))](∞) and ionic complex [Hdien][Gd(dien)(2)(μ-SnSe(4))] are obtained along the lanthanide series, among which the μ(4)-Sn(2)Se(9), μ-Sn(2)Se(6) and μ-SnSe(4) ligands to the Ln(3+) ions were observed. The formation of title complexes shows the effects of lanthanide metal size and amino ligand denticity on the lanthanide selenidostannates. Complexes 1a-2c exhibit semiconducting properties with band gaps between 2.08 and 2.48 eV.     

Synthesis and Single Crystal Structure of RbEr_2Cu_3Se_5

1 INTRODUCTION Halide fluxes are excellent media for growing single crystals of chalcogenides[1~3]. It is well known that during the single crystal growth via flux methods, occasional inclusion of the flux elements in the structure leads to the formation of new phases[4~9]. Several rare earth chalcogenides have been prepared through such reactive halid flux methods[4~9]. Thus we used RbCl as reactive flux to explore a new quaternary selenide by the reaction of ErCuSe precursor with Rb…     

First examples of thallium chalcogenide cages. Syntheses, 77Se, 203Tl, and 205Tl NMR study of the Tl4Se5(4-) and Tl4Se6(4-) anions, the X-ray crystal structure of (2,2,2-crypt-K+)3Tl5Se5(3-), and theoretical studies

The Tl5Se5(3-) anion has been obtained by extracting KTlSe in ethylenediamine in the presence of 2,2,2-crypt. The salt, (2,2,2-crypt-K+)3Tl5Se5(3-), crystallizes in the triclinic system, space group P1, with Z = 2 and a = 11.676(2) A, b = 16.017(3) A, c = 25.421(5) A, alpha = 82.42(3) degrees, beta = 88.47(3) degrees, gamma = 69.03(3) degrees at -123 degrees C. Two other mixed oxidation state TlI/TlIII anions; Tl4Se5(4-) and Tl4Se6(4-), have been obtained by extracting KTlSe into liquid NH3 in the presence of 2,2,2-crypt and have been characterized in solution by low-temperature 77Se, 203Tl, and 205Tl NMR spectroscopy and were shown to exist as a 1:1 equilibrium mixture at -40 degrees C. The couplings, 1J(203,205Tl-77Se) and 2J(203,205Tl-203,205Tl), have been observed for Tl4Se5(4-) and Tl4Se6(4-) and have been used to arrive at the solution structures of both anions. Structural assignments were achieved by detailed analyses and simulations of all spin multiplets that comprise the 205,203Tl NMR spectra and that arise from natural abundance 205,203Tl and 77Se or enriched 77Se isotopomer distributions. The structures of all three anions are based on a Tl4Se4 cube in which Tl and Se atoms occupy alternate corners. There are one and two exo-selenium atoms bonded to thallium in Tl4Se5(4-) and Tl4Se6(4-), respectively, so that these thalliums are four-coordinate and possess a formal oxidation state of +3 and the remaining three-coordinate thallium atoms are in the +1 oxidation state. The structure of Tl5Se5(3-) may be formally regarded as an adduct in which Tl+ is coordinated to the unique exo-selenium and to two seleniums in a cube face containing the TlIII atom. The Tl4Se5(4-), Tl4Se6(4-), and Tl5Se5(3-) anions and the presently unknown, but structurally related, Tl4Se4(4-) anion can be described as electron-precise cages. Ab initio methods at the MP2 level of theory show that Tl4Se5(4-), Tl4Se6(4-), and Tl5Se5(3-) exhibit true minima and display geometrical parameters that are in excellent agreement with their experimental cubanoid structures, and that Tl4Se4(4-) is cube-shaped (Td point symmetry). The gas-phase energetics associated with plausible routes to the formation and interconversions of these anions have been determined by ab initio methods and assessed. It is proposed that all three cubanoid anions are derived from the known Tl2Se2(2-), TlSe3(3-), Se2(2-), and polyselenide anions that have been shown to be present in the solutions they are derived from.     

Preconcentration of inorganic selenium species (Se (IV) and Se (VI)) in an alumina filled microcolumn and on-line determination by hydride generation atomic absorption spectrometry

A flow injection system has been developed consisting of on-line preconcentration of selenium species in a microcolumn filled with activated alumina, reduction of Se(VI) to Se(IV) and determination by HG-AAS. When 0.01 mol/L HNO₃ is used both as carrier and activation reagent for the alumina microcolumn, up to 150 ng of Se(IV) and Se(VI) can be preconcentrated and quantitatively eluted by 500 L of 2 mol/L NH₃. The preconcentration factor is 50 when 25 mL of sample is used. The detection limit is about 6 ng/L, the precision is 5% for low concentrations such as 150 ng/L and 3% at high concentrations such as 120 ng/mL. The proposed method is suitable for natural water samples and inorganic Se speciation can be performed by determining Se(IV) and total selenium [Se(VI) is evaluated from the difference].     

Contributions from atomic p(Se), d(Se), and f(Se) orbitals to absolute paramagnetic shielding tensors in neutral and charged SeHn and some oxides including the effect of methyl and halogen substitutions on sigmap(Se)

Contributions from atomic p(Se), d(Se), and f(Se) orbitals to sigmap(Se) are evaluated for neutral and charged Se*Hn (*=null, +, or -) and some oxides to build the image of the contributions. The effect of methyl and halogen substitutions is also examined employing RrSe*XxOo (*=null, +, or -) where R=H or Me; X=F, Cl, or Br. The p(Se) contributions are larger than 96 % for SeH- (Cinfinityv), SeH2 (C2v), SeH3 + (C3v), SeH3 + (D3h), and SeH4 (Td). Therefore, sigmap(Se) of these compounds can be analyzed based on p(Se). The p(Se) contributions are 79-75 % for SeH4 (TBP), SeH5 + (TBP), SeH5 + (SP), and SeH5 - (SP). Methyl and halogen substitutions increase the contributions by 1-2 % (per Me) and 4-7 % (per X), respectively. The contributions are 92-79 % for H2SeO (Cs), H2SeO2 (C2v), and H4SeO (C2v). The values are similarly increased by the substitutions. Consequently, sigmap(Se) of these compounds can be analyzed based on p(Se) with some corrections by d(Se). The p(Se) contribution of SeH6 (Oh) is 52 %: sigmap(Se: SeH6 (Oh)) must be analyzed based on both p(Se) and d(Se). The contributions for the Me and X derivatives of SeH(6) amount to 86-77 %. Therefore, sigmap(Se) of the derivatives can also be analyzed mainly based on p(Se) with some corrections by d(Se). Contributions from f(Se) are negligible. Contributions from 4p(Se) in vacant orbitals are also considered. A utility program derived from the Gaussian 03 (NMRANAL-NH03G) is applied to evaluate the contributions.