C. D. Garner

Core electron ionization energies and electronic structure of Ti(NO3)4 and Cu(NO3)2

Abstract Gas phase X-ray photoelectron spectra of Ti(NO 3 ) 4 and Cu(NO 3 ) 2 are reported and discussed in terms of the molecular charge distributions. No measurable splitting is observed between the 1 s ionization energies of the chemically distinct oxygen atoms in either molecule. Ab initio calculations for Cu(NO 3 ) 2 suggest that this is due in large measure to differential orbital relaxation occurring upon core electron ionization.

Bis(tetraethylammonium) di-μ-sulphido-bis[oxo(disulphido)molybdenum]

[N(C2Hs)412[Mo202S2(S2)2], 2CsH20N+.Mo2 O2S~-, M r = 676.6, monoclinic, P2;/c, a = 13.485 (3), b = 1 4 . 3 5 4 ( 3 ) , c = 14. 749 (3) A, f l = 97.50 (2) °, U = 2830.2.3, 3, Z = 4, D x = 1.588 Mg m-3; final R = 0.0358 for 4025 reflexions. The anion contains two Mo v atoms, each with a terminal 0 2and an edge-on (

EXAFS Studies of Zinc and Copper in Chemical and Biochemical Systems

2) 2ligand, bridged by two S 2ligands, and has approximate C2~ (mm) symmetry. Introduct ion . The compound was obtained from a reaction between MoCI 3 and NaSPh (1:5 molar ratio) in methanol, followed by treatment with NEt4C1, and was recrystallized from a methyl cyanide-diethyl ether mixture. Intensities were collected from a crystal of average dimension 0.28 mm by a profile-fitting procedure (Clegg, 1981) with graphite-monochromated Mo Ka radiation (2 = 0.71069/k) and a Stoe-Siemens AED four-circle diffractometer. 4025 unique reflexions with 7 _< 20 < 60 ° and I >_ 20(I) were measured and corrected for absorption by an empirical method based on measurements of sets of 0567-7408/80/112784-03501.00 reflexions at different azimuthal angles (g = 1.31 mm-~; transmission factors range from 0.588 to 0.654). Cell dimensions were obtained from the diffractometer angles for 50 centred reflexions with 20 _< 20<_ 25°. The structure was solved by Patterson and Fourier methods, and refined to a minimum value of ~. wA 2 [A = l E o 1 IFcl; w -1 = o2(Fo)]. Anisotropic thermal parameters were refined for all non-H atoms. H atoms were assigned isotropic thermal parameters fixed at 1.3 times the equivalent isotropic value for the corresponding C atom. C--H lengths and H--C--H angles were constrained to 0.96 A and 109.5 °. The final R is 0.0358, with R w = (~ wA2/Y WF2o) ~/2 = 0.0291. Coordinates and derived bond lengths and angles are given in Tables 1 and 2.* * Lists of structure factors, H atom coordinates and anisotropic thermal parameters have been deposited with the British Library Lending Division as Supplementary Publication No. SUP 35466 (27 pp.). Copies may be obtained through The Executive Secretary, International Union of Crystallography, 5 Abbey Square, Chester CH 1 2HU, England.

Reaction of Some Heterocyclic Formamidines with Trimethylsilylethynyllithium

Recent X-ray absorption spectroscopic studies we have undertaken at the Daresbury Laboratory using the dedicated Synchrotron Radiation Source have included investigations of the copper and zinc sites of mammalian liver metallothioneins and bovine erythrocyte superoxide dismutase. Corresponding studies have been accomplished for several copper and zinc compounds, the structure of each having been established by X-ray crystallography and shown to have some relevance to that of the metals in one or other of the above proteins.

Mixed-halide complex trans-tetrahalobis-(triphenylphosphine oxide)rhenium(IV)

The reaction of a 2-[(dimethylamino)methyleneamino]pteridine, two 2-[(dimethylamino)methyleneamino]pyrimidines, and a 2-[(dimethylamino)methyleneamino]pyrido[2,3-d]pyrimidine with trimethylsilylethynylithium in the presence of benzyl chloroformate leads to the corresponding 2-[bis(trimethylsilylethynyl)methylamino]-substituted heterocycles. A series of such substrates was prepared and some of the factors which permit this transformation were delineated. An X-ray crystal structure was determined of one of the products - 2-[bis(trimethylsilylethynyl)methylamino]-5,6,7,8-tetrahydro-3-(2,2-dimethylpropanoyloxymethyl)quinazolin-4-one.

N-3-Allylation of 2-(N,N-Dimethylaminomethyleneamino)-6-formylpteridin-4-one

The molecule of the red title compound, trans-tetra-(chloro/bromo) bis( triphenylphosphine oxide - O) rhenium(IV), [ReBr 2.5 Cl 1.5 {OP(C6H5) 3 } 2 ], lies on a crystallographic centre of symmetry. Coordination of rhenium by the four halides is square planar, capped by two mutually-trans triphenylphosphine oxide groups.

Fluorescence EXAFS of biological systems at SRS

The reaction of 2-(N,N- dimethylaminomethylene-amino)-6-formylpteridin-4-one with allyl bromide in the presence of diazabicycloundecane as base leads to allylation on N3 and the production of the title compound, 3-allyl-2-(N, N-dimethylaminomethylene-amino)-6-formylpteridin-4-one, C 13 H 14 N 6 O 2 .

Structures of four complexes of copper with N-methylimidazole and chloro ligands

Abstract A fluorescence detection system consisting of five scintillation detectors has been commissioned recently on an EXAFS station at the worlds first dedicated X-ray synchrotron radiation source (SRS). This facility has been established to measure the X-ray fluorescence excitation spectrum of specimens containing small amounts of metal atoms with absorption edges between 1 A and 3.1 A. Results recently obtained on copper containing enzymes are presented.