THE REACTIONS OF N3P3CL6 WITH POLYFUNCTIONAL REAGENTS

Abstract

The reactions of N₃P₃Cl₆ with polyfunctional reagents, such as glycerol, are reported. NMR spectroscopic and X-ray crystallographic studies will be presented.     

Unusual Phosphorus Ligands

Abstract

A variety of novel coordination complexes with cyclo-P₃, cyclo-P₄, cyclo-P₅, P₄ ^2-, P₄ ^4- and P₄ ^6- as ligands will be described.     

Synthesis and Coordination Properties of Multifunctional Carbamoylmethyl Phosphonates

Abstract

Bifunctional carbamoylmethylphosphonates are useful extractants for lanthanide and actinide ions and the structural mechanics involved in extraction processes have been under study in our laboratory. We have recently prepared several new multifunctional ligands of the general types (RO)₂P(O)CH[C(O)NR₂][CH₂C(O)NR₂], [(RO)₂P(O)]₂CHCH₂C(O)NR₂ and [(RO)₂P(O)CHC(O)NEt₂]₂CH_2. The syntheses and characterization data for the new extractants will be described. The coordination chemistry of these ligands with lanthanide and actinide ions has been studied and crystal structure determinations for selected complexes will be shown. Lastly, liquid-liquid extraction distribution measurements for several ligands with lanthanide ions will be presented.     

Two W/Mo complexes containing 2,3-dihydroxynaphthalene: synthesis and structure analysis

Two W/Mo complexes, [Et₃NH]₂[WO₂(C₁₀H₆O₂)₂] (1) and [Et₃NH]₂[MoO₂(C₁₀H₆O₂)₂] (2), were synthesized by the reaction of Na₂WO₄?·?2H₂O and (NH₄)₂Mo₂O₇?·?4H₂O with 2,3-DHN (DHN?=?dihydroxynaphthalene) and triethylamine, and characterized by X-ray diffraction and IR. The two complexes exhibit chiral octahedral geometry at central metals, although the overall structure is racemic. Single crystals of 1 are more difficult to obtain than for 2. The molybdenum complex can be easily isolated at room temperature (around 25°C), while the tungsten one needs to be isolated under 15°C, otherwise, the quality of crystal will be poor, leading to disorder. The structures of these two complexes are chiral and enantiomorphous to each other.     

Electronic Correlation Functions in Liquid Metals

Abstract

To determine experimentally the three pair correlation functions g_ii(r), g_ie(r) and g_ee(r) in a pure liquid metal, i denoting ions and e electrons, requires three independent diffraction measurements. A brief review will be given in this difficult area, but progress is quite slow. One can make headway by confronting available experimental diffraction data with the results of computer experiments, and in particular on g_ie(r). This will be illustrated with specific reference to recent computer simulations on liquid Mg and liquid Bi. for Mg, analytic modelling is also possible and this will be discussed.

Quite independently, computer experiments have recently appeared which describe the effects of isochoric heating on dense fluid hydrogen over a wide temperature range. This prompts again reference to analytic models, both caged atomic and molecular hydrogen being considered. Finally, though the electrical conductivity of the H plasma above has not yet been studied, a brief discussion of a possible mechanism of electronic transport in strongly coupled plasma will be presented.     

Synthesis and spectral properties of novel iminophosphoranes

Three new iminophosphoranes coded as FPZ1 (Ph–C≡C–C₆H₄–N = PPh₃), FPZ2 (Ph–N = P(C₆H₄–C≡C–Ph)₃) and FPZ3 (Ph–C≡C–C₆H₄–N = P(C₆H₄–C≡C–Ph)₃) were designed and synthesized by introducing different numbers of phenylene acetylene units to FPZ0 (Ph–N = PPh₃). The effect of structural modification was studied in detail analyzing the absorption spectra, the emission spectra, and the distributions of the electron density. The absorption spectra of the new iminophosphoranes are shown to be a linear combination of the spectra of each part by the artificial combinatorial absorption spectrum, which coincides with the real one. Most probably the individual parts can’t conjugate due to the tetrahedral structure. The probably formed excimer of FPZ0 and FPZ1 causes in their solid emission spectra an obvious bathochromic shift as compared to that of FPZ2 and FPZ3. The melting point data also showed that long branches of FPZ2 and FPZ3 will attenuate the interactions between the molecules. The results of quantum chemical calculations show that the electronic density in the HOMO of FPZ1, FPZ2, and FPZ3 is delocalized over the iminoaryl moieties. The electron density in the LUMO is delocalized over the triaryl phosphine moieties, but only concentrated on two branches, which directly determines the main direction of intramolecular charge transfer.     

N-(2-氧乙酸-3-甲氧基)苄叉二胺合锌(Ⅱ)配合物的合成、晶体结构及光学性质研究

本文通过修饰邻香草醛芳环上羟基的方法,得到两种Schiff碱配体:N,N′-二(2-氧乙酸-3-甲氧基)苄叉乙二胺(H2L1)和N,N′-二(2-氧乙酸-3-甲氧基)苄叉1,3-丙二胺(H2L2),利用水热合成方法以新合成的配体为基点设计合成了2个新的六配位Schiff碱锌(Ⅱ)配合物[Zn(L1)]·7H2O(1)和[Zn(L2)]·7H2O(2),通过元素分析、红外光谱和核磁共振光谱等测试手段对配合物进行了表征,并用X射线单晶衍射测得Zn(Ⅱ)配合物的晶体结构。X射线晶体学研究表明两种配合物晶体结构中都包含多个溶剂水分子,配合物1是以Zn(Ⅱ)为中心扭曲的三方棱柱构型,配合物2是以Zn(Ⅱ)为中心扭曲的八面体构型。初步研究了两种配合物的固体发光性,结果表明这两种配合物具有良好的光致发光的性能,有望在光学材料方面得到应用。     

N-(2-氧乙酸-3-甲氧基)苄叉二胺合锌(Ⅱ)配合物的合成、晶体结构及光学性质研究

本文通过修饰邻香草醛芳环上羟基的方法,得到两种Schiff碱配体:N,N'-二(2-氧乙酸-3-甲氧基)苄叉乙二胺(H₂L¹)和N,N′-二(2-氧乙酸-3-甲氧基)苄叉1,3-丙二胺(H₂L₂),利用水热合成方法以新合成的配体为基点设计合成了2个新的六配位Schiff碱锌(Ⅱ)配合物[Zn(L¹)]·7H₂O(1)和[Zn(L²)]·7H₂O(2),通过元素分析、红外光谱和核磁共振光谱等测试手段对配合物进行了表征,并用X射线单晶衍射测得Zn(Ⅱ)配合物的晶体结构。X射线晶体学研究表明两种配合物晶体结构中都包含多个溶剂水分子,配合物1是以Zn(Ⅱ)为中心扭曲的三方棱柱构型,配合物2构型是以Zn(Ⅱ)为中心扭曲的八面体构型。初步研究了两种配合物的固体发光性,结果表明这两种配合物具有良好的光致发光的性能,有望在光学材料方面得到应用。     

Bioorganic Chemistry of Hypothiocyanite

Abstract

Hypothiocyanite (OSCN^?) plays an important role in the human host defense system as a nonimmunological antimicrobial agent. Although many conjugate reactions of proteins have been attributed to OSCN^?, there is little precedence for such reactions in small-molecule chemistry. We will discuss the derivative species that are in equilibrium with OSCN^?, including hypothiocyanous acid (HOSCN), thiocyanogen [(SCN) ₂ ], and trithiocyanate [(SCN) ₃ ^?], the first organic derivatives of this mixture to be fully characterized, and we will describe a new method of synthesizing hypothiocyanite.     

Towards Syntheses and Structures of Heterometallic Clusters Containing Tantalum-tetrachalcogenato Building Blocks

An approach to tackle the synthesis of mixed-transition metal tantalum chalcogenide clusters is described. The synthesis of 1/_∞[Li₃(TaSe₄)(MeCN)₄]_∞ (1) will in future allow the construction of Ta–Se-transition metal clusters. The potential of this route was demonstrated by the synthesis of the mixed-metal Ta–S–Fe and Ta–S–Cu complexes (Et₄N)₃[Fe₂(SPh)₄(TaS₄)] (2) and [Cu₃(TaS₄)(PPh₃)₄] (3). Dedicated to Professor Günter Schmid on the occasion of his 70th birthday.     

Effect of Microwave Irradiation on Reaction of Arylaldehyde Derivatives with Some Active Methylene Compounds in Aqueous Media

Abstract

The effect of microwave irradiation on the condensation reactions of arylaldehydes 1 and active methylene compounds 2 in aqueous media was studied and compared with “classical” conditions. The results show that the condensation was carried out only under microwave irradiation in the presence of ammonium chloride as a catalyst, followed by dehydration, to afford (E)‐olefins 3. The protocol was used to synthesize coumarins by a condensation reaction of salicylaldehyde or its derivatives with various derivatives of ethylacetate 5 (e.g., R³CH₂CO₂Et; R³: CO₂Et, CO₂Me, COMe, CN) in high yields. These investigations will contribute to the development of environmentally friendly and inexpensive processes in organic synthesis.     

Effect of solvent on the exchange of ethylene for propylene on cis-PtCl2(C3H6)(TPPTS), TPPTS = P(m-C6H4SO3Na)3

To further understand the effect of water as a solvent in organometallic reactions, the lability of η²-alkenes coordinated to platinum(II) phosphine complexes has been studied in water and chloroform as a comparison of solvent effects on the exchange kinetics and alkene complex stability. ¹H NMR techniques with both deuterated chloroform and a deuterium oxide/deuterated methanol mixture as solvent systems were used at temperatures as low as ?50°C. Reaction of cis-PtCl₂L(η²-C₃H₆) [L?=?PPh₃ (triphenylphosphine) (1a), TPPTS (tris(m-sulfonatophenyl)phosphine) 1b] with ethylene to form cis-PtCl₂L(η²-C₂H₄) (2?a, b) was observed with dependence on the rate by starting platinum complex and ethylene. The role of water on this reaction, as well as its effect on the equilibrium, will be discussed. The equilibrium constant shows preference for coordination of ethylene and the temperature dependence indicates the reaction is entropy controlled.     

The Preparation of Butyrylated NAD+ Type of Biological Molecules

Abstract

Butyrylated NAD⁺ and its fluorescent analog, 1,N ⁶-etheno NAD⁺ are prepared in good yields by employing two-phase system, i.e., water and CH₂Cl₂ containing dimethyaminopyridine and excess butyric anhydride. The reaction condition for this reaction is so specific that several other acylating conditions attempted were totally failed, and this developed methodology will be conveniently utilized for the further study of cyclic ADP-ribose (cADPR).     

SPECULATIVE NOVEL PHOSPHORUS (V) COMPOUNDS AND MODES OF REARRANGEMENT IN RPF5-IONS

Abstract

A series of novel and somewhat speculative compounds of hypervalent phosphorus and other main group elements is presented. These include cyclic systems, oxides, ylides, acetylacetonates and π-cyclo-pentadienyl compounds. Modes of rearrangement in the ionic compounds RPF^? ₅ are developed along with the observable processes. It is hoped that suitable temperature dependent nmr studies of some appropriate such system will eventually be undertaken.     

Exchange energy density and exchange potential via a hartree–fock plus mp2 study of the electron liquid in the ground-state conformer of glycine

Very recent criticisms of existing exchange-correlation functionals by Wanko et al. applied to systems of biological interest have led us to reopen the question of the ground-state conformer of glycine: the simplest amino acid. We immediately show that the global minimum of the Hartree–Fock (HF) ground-state leads to a planar structure of the five non-hydrogenic nuclei, in the non-ionized form NH₂–CH₂–COOH. This is shown to lie lower in energy than the zwitterion structure NHB₃ ⁺–CH₂–COO^?, as required by experiment. Refinement of the nuclear geometry using second-order Møller–Plesset perturbation theory (MP2) is also carried out, and bond lengths are found to accord satisfactorily with experimentally determined values. The ground-state electron density for the MP2 geometry is then redetermined by HF theory and equidensity contours are displayed. The HF first-order density matrix γ( r , r ′) is then used to obtain similar exchange-energy density (ε _x ( r )) contours for the lowest conformer of glycine. At first sight, their shape looks almost the same as for the density ρ( r ), which seems to vindicate the LDA proportional to ρ( r )^3/4. However, by way of an analytically soluble model for an atomic ion, it is shown that this has to be corrected to obtain an accurate HF exchange energy E_x as the volume integral of ε _x ( r ). Finally, recognizing that for larger amino acids, the use of HF plus MP2 perturbation corrections will become prohibitive, we have used the HF information for ε _x ( r ) and ρ( r ) to plot the truly non-local exchange potential proposed by Slater, from the density matrix γ( r , r ′). This latter calculation should be practicable for large amino acids, but there adopting Becke's one-parameter form of ε _x ( r ) correcting LDA exchange. Some future directions are suggested.     

Analysis of Polycyclic Aromatics

Abstract

Polycyclic aromatic hydrocarbons (PAH), among them carcinogenic compounds, have been found to be widely distributed in the human environment. The formation of PAH in processes relevant to environmental pollution will be described (pyrolysis or incomplete combustion of aliphatic and aromatic material, formation in higher plants). The application of the following methods to the analysis of PAH mixtures will be discussed: gas chromatography (capillary columns, use. of liquid crystals and inorganic salts such as LiCl or Cacl₂, as stationary phases in packed columns, selective detectors); luminescence spectroscopy (use of phosphorescence in paper and thin-layer chromatography, Shpol'skii spectra, quenchofluorimetry; mass spectroscopy.     

Preparation and structural characterization of the isomorphous compounds: [Bu4N][Mo3(μ3-O)(μ-X)3(μ-OAc)3 X 3]·(CH3)2CO,X=Cl,Br

The reaction of MoCl₃(H₂O)₃ with a mixture of acetic acid and acetic anhydride in the presence of [N(C₄H₉)₄][BF₄] followed by crystallization from acetone/hexane gives a 77% yield of dark purple [NBu₄][Mo₃OCl₆(OAc)₃]·Me₂CO (1). A similar reaction employing MoBr₃(H₂O)₃ gives purple [NBu₄][Mo₃OBr₆(OAc)₃]·Me₂CO (2) in 50% yield. Also produced in this reaction in low (10–20%) yields are [NBu₄]₂[Mo₄OBr₁₂] · 0.5Me₂CO and [NBu₄]₂[Mo₃OBr₆(OAc)₃] · Me₂CO which will be discussed elsewhere Compounds (1) and (2) are isomorphous, space groupP2₁/n,Z=4 with the following unit cell dimensions, where the values for (1) and (2) are given in that order for each one:a=13.406(4), 13.726(5) Å;b=15.701(4), 15.839(5) Å;c=19.250(5), 19.831(6) Å; =101.61(2), 102.92(3)°. Both (1) and (2) are eight-electron species in which the mean Mo-Mo distances are 2.578(1) Å and 2.597(1) Å, respectively.     

Anion radicals of [60]fullerenes. An EPR study

Photochemically induced electron transfer in homogeneous systems (using triethylamine donor) and heterogeneous systems (using photoexcited TiO₂ suspension) was applied in in situ reduction of [60]fullerene. The anion radicals generated were characterized by means of EPR and VIS/near-IR spectroscopy. Narrow EPR lines were found. Radical A with g_A=2.0000 and peak-to-peak width, pp_A=0.09mT was observed as the primary product; followed by its consecutive product B with g_B=2.0006, pp_B=0.04mT, and in some cases product C with g_C=2.0009 and pp_c<0.1 mT. Radical A was assigned to [60]fullerene mono-anion, also characterized by a near-IR band at 1077 nm. B is presumably di-anion or a dimeric form of mono-anion. Identical results were also obtained using cathodic in situ reduction. Applying these generation techniques to [60]fullerene derivatives produced narrow EPR lines analogous to those described for pristine [60]fullerene. This was the case not only in organic solvents, but also in aqueous solutions. The results obtained present a contrast with the original ex situ EPR investigations describing [60]fullerene mono-anion with wide lines. According to the results presented here, the narrow and wide EPR lines do not represent contradictory phenomena, but are an integral part of the relatively complicated manifestations of various fullerene states and both will have to be seriously considered in the future.     

Theoretical calculations of the chemical shifts of cyclo[n]phosphazenes for n = 2, 3, 4 and 5 (X2PN)n with X = CH3, F,Cl and Br: the effect of relativistic corrections

Abstract

Di, tri, tetra and pentacyclophosphazenes substituted on the phosphorus atoms by CH₃, F, Cl and Br atoms corresponding to (X₂PN)_n structures have been studied theoretically at the B3LYP/6-311++G(d,p) level. After a brief discussion of their geometries comparing them to those of the conjugated carbocycles, (CH)_n, of the same size, the absolute shieldings calculated with the GIAO and ZORA approximations will be reported. For the Cl and mainly for the Br substituted cyclo[n]-phosphazenes, relativistic corrections are absolutely necessary for ³¹P and useful for ¹⁵N chemical shifts.     

Radical–molecule reaction CH<Subscript>2</Subscript>Cl + NO<Subscript>2</Subscript>: a mechanistic study

The radical–molecule reaction mechanism of CH₂Cl with NO₂ has been explored theoretically at the B3LYP/6–311G(d,p) and MC–QCISD (single-point) levels of theory. Our results indicate that the title reaction proceeds mostly through singlet pathways, less go through triplet pathways. The initial association between CH₂Cl and NO₂ is found to be the carbon-to-nitrogen attack forming the adduct a H₂ClCNO₂ with no barrier, followed by isomerization to b ₁ H₂ClCONO-trans which can easily convert to b ₂ H₂ClCONO-cis. Subsequently, the most feasible pathway is the C–Cl and O–N bonds cleavage along with the N–Cl bond formation of b (b ₁ , b ₂ ) leading to product P ₁ CH₂O + ClNO, which can further dissociate to give P ₅ CH₂O + Cl + NO. The second competitive pathway is the 1,3-H-shift associated with O–N bond rupture of b ₁ to form P ₂ CHClO + HNO. Because the intermediates and transition states involved in the above two favorable channels all lie below the reactants, the CH₂Cl+NO₂ reaction is expected to be rapid, as is confirmed by experiment. The present results can lead us to understand deeply the mechanism of the title reaction and may be helpful for further experimental investigation of the reaction.