Patrice De Meester

Synthesis and reactivity of sulfur and silyl substituted α-alkylidene-β-lactams

Abstract Synthetically valuable α-alkylidene-β-lactams are produced from the addition of chlorosulfonyl isocyanate to allenyl sulfides.

Metallophosphoranes: Carbonyl substitution reactions and the X-ray crystal structure of cis-Cat2PMn(CO)4P(OPh)3 (Cat = benzodioxyl)

Abstract Cat 2 PMn(CO) 5 (1, cat = ) is found to undergo carbonyl substitution reactions with phosphorus donors to give the isolable products cat 2 PMn(CO) 4 L, where L = cis -PPh 3 ( 2 ); trans -PPh 3 ( 3 ); cis -P(OMe) 3 ( 4 ); and cis -P(OPh) 3 ( 5 ). No evidence for CO insertion into the pentacoordinate PMn bond is observed. The X-ray crystal structure of 5 shows that the crystals are monoclinic, space group P 2 1 / n . The unit cell parameters are: a 10.523(2), b 25.765(5), c 13.344(2) A, β 99.11(2)°, and Z = 4. Full matrix least squares refinement reached R = 0.054 for 3099 observed reflections. The pentacoordinate phosphorus adopts a distorted trigonal bipyramid geometry with the Mn in an equatorial position. Noteworthy is the small equatorial OPO angle of 110.1(2)°.

Terdentate co-ordination by a cysteine derivative: crystal and molecular structure of bis(S-methyl-L-cysteinato)cobalt(III) perchlorate monohydrate

The crystal and molecular structure of the title complex has been determined from three-dimensional X-ray diffractometer data by Patterson and Fourler methods. The compound crystallizes in the orthorhombic space group P212121, with Z= 4 in a cell of dimensions a= 16.196(3), b= 8.393(2), and c= 11.944(2)A. Full-matrix least-squares refinement using 1 436 independent reflections has reached R 0.043.The structure contains one independent [(S-methyl-L-cysteinato)2cobalt(III)]+ cation, a perchlorate anion, and a molecule of water of solvation. The metal, which is slightly distorted octahedral, makes two Co–S, two Co–O, and two Co–N bonds with the lignds [mean distances 2.271(2), 1.906(5), 1.946(6)A]; bond angles at Co 83.8(3)–98.9(3)°. The two carboxy-oxygen and the amino nitrogen atoms are mutually cis while the two sulphur atoms are trans.

Reductive and non-reductive insertions of silicon atoms into carbaborane cages: synthesis and structure of a carbaborane analogue of bis(cyclopentadienyl)silicon

The silacarbaboranes [(Me3Si)2C2B4H4]SiII(1) and [(Me3Si)2C2B4H4]2SiIV(2) have been prepared and the structure of (2) has been determined by X-ray crystallography.

Synthesis and X-ray structure of L-histidinyl-D-penicillaminatocobalt(III) and L-histidinyl-D-penicillaminatochromium(III)

Reaction of [M(L-his)2](MCo,Cr;hishistidyl) with D- or DL-penicillamine (pen) gives the octahedral complexes [M(L-his)(D-pen)], while reaction of [Co(L-his)-(D-his)] with DL-penicillamine gives [Co(L-his)(D-pen)] and [Co(D-his)(L-pen)]; but under mild conditions [M(L-his)(L-pen)] and [M(D-his)(D-pen)] are not obtained.

Synthesis and structural characterization of L-histidinato-D-penicillaminatochromium(III) monohydrate

The novel chromium(III) amino-acid complex L-histidinato-D-penicillaminatochromium(III) monohydrate, [Cr(L-his)(D-pen)]·H2O (his = histidine, pen = penicillamine), has been prepared by the reaction of D-penicillamine with an aqueous solution containing chromium(III) chloride (or nitrate) and L-histidine. The crystal structure of the complex has been determined from three-dimensional X-ray counter data. The complex crystallizes in the monoclinic space group P21, Z= 2, in a cell of dimensions a= 7.235(4), b= 12.150(8), c= 8.929(6)A, β= 6.00(3)°. Full-matrix least-squares refinement of the structure. using 1 635 intensities, yielded a final R of 0.035. The complex is monomeric, the distorted octahedral geometry at the chromium giving rise to cis bond angles in the range 79.8(2)–102.2(2)°. The tridentate D-penlcillamine moiety co-ordinates as the dianion, being deprotonated at S and O, with Cr–S, Cr–N, and Cr–O bond lengths of 2.332(2), 2.094(5), and 1.989(4)A, respectively. The histidine monoanion is also tridentate, co-ordlnating through N(amino), N(imidazole), and O, with associated chromium–ligand bond lengths of 2.063(4), 2.057(5), and 2.013(4)A, respectively. The geometry of this complex is, therefore, quite similar to that found for the corresponding cobalt(III) complex: in both cases, the isomer isolated has S trans to O(his) and N(pen)trans to N(imidazole).