The red form of [Re(phen)(CO)3(H2O)]-CF3SO3.H2O.

The coordination geometry of the cations in the red form of aquatricarbonyl(1,10-phenanthroline-N,N')rhenium(I) trifluoromethanesulfonate hydrate, [Re(C12H8N2)(CO)3-(H2O)]CF3SO3.H2O, is approximately octahedral, with a facial arrangement of the linearly coordinated carbonyl ligands. The phenanthroline (phen) ligands interleave to form a columnar pi-stacked structure.

Structures of ruthenium-modified Pseudomonas aeruginosa azurin and [Ru(2,2'-bipyridine)2(imidazole)2]SO4 x 10H2O.

The crystal structure of Ru(2, 2'-bipyridine)2(imidazole)(His83)azurin (RuAz) has been determined to 2.3 A -resolution by X-ray crystallography. The spectroscopic and thermodynamic properties of both the native protein and [Ru(2, 2'-bipyridine)2(imidazole)2]2+ are maintained in the modified protein. Dark-green RuAz crystals grown from PEG 4000, LiNO3, CuCl2 and Tris buffer are monoclinic, belong to the space group C2 and have cell parameters a = 100.6, b = 35.4, c = 74.7 A and beta = 106. 5 degrees. In addition, [Ru(2,2'-bipyridine)2(imidazole)2]SO4 x 10H2O was synthesized, crystallized and structurally characterized by X-ray crystallography. Red-brown crystals of this complex are monoclinic, space group P21/n, unit-cell parameters a = 13.230 (2), b = 18.197 (4), c = 16.126 (4) A, beta = 108.65 (2) degrees. Stereochemical parameters for the refinement of Ru(2, 2'-bipyridine)2(imidazole)(His83) were taken from the atomic coordinates of [Ru(2,2'-bipyridine)2(imidazole)2]2+. The structure of RuAz confirms that His83 is the only site of chemical modification and that the native azurin structure is not perturbed significantly by the ruthenium label.

A chiral N-crotonyloxazolidinone Diels-Alder adduct.

(4S)-4-Benzyl-3-[(4S,5S)-(1-methoxy-5-methylcyclohexen-4- yl)carbonyl]-2-oxazolidinone, C19H23NO4, M(r) = 329.40, monoclinic, P2(1), a = 11.453 (3), b = 7.163 (4), c = 11.929 (2) A, beta = 111.86 (2) degree, V = 908.3 (5) A3, Z = 2, D chi = 1.20 g cm-3, lambda (Mo K alpha) = 0.71073 A, mu = 0.79 cm-1, F(000) = 352, T = 297 K, R = 0.034 for 885 reflections with Fo2 greater than 0. The molecule is extended in the crystal; there is a small twist, -13.1 (2) degree, about the amide-like C--N bond joining the oxazolidinone ring to the carbonyl group. The configurations at the two optical centers in the cyclohexene ring confirm the anticipated stereospecificity of the Diels-Alder cycloaddition synthesis.

Synthesis of organic salts with large second-order optical nonlinearities.

A series of organic salts, in which the cation has been designed to have a large molecular hyperpolarizability, has been prepared. Variation of the counterion (anion) in many cases leads to materials with large powder second harmonic generation efficiencies, the highest of which is roughly 1000 times that of a urea reference.

Structure of an oxygen-carrying cobalt complex.

Bis(3-fluorosalicylaldehyde) ethylenediimine cobalt(II), a reversible oxygen-carrying compound, has been crystallized as a tetramer with two oxygen molecules bound to the four cobalt atomns, each oxygen molecule bridging between two metal atoms. These dimers are further linked by two bonds between the oxygen atom of the salicylaldehyde and the cobalt atom. The oxygen-to-oxygen distance, 1.21 angstroms in molecular oxygen, has increased to 1.308(28) angstroms (where the number in parentheses is the estimated standard deviation) in this compound, the shortest distance yet observed in sutch a bridging arrangement.