Electronic coupling in diiron complexes with the butadienediyl-bridged chain.

The butadienediyl-bridged complexes [eta5-Cs Me5]Fe(CO)(PPh3)]2 (micro-CH=CH-CH=CH) have been prepared and characterized by cyclic voltammetry, NMR, and X-ray crystallography. Compound 3 diastereomers showed two reversible one-electron oxidations at -0.053 approximately -0.

Temperature-dependent coordination of phosphine to five-coordinate alkenylruthenium complexes.

The red, five-coordinate complexes Ru(CO)Cl(PPh(3))2(CH=CHPh) and [Ru(CO)Cl(PPh(3))2]2(mu-CH=CHC(6)H(4)CH=CH) undergo reversible coordination of PPh(3) at low temperature to produce the pale yellow, six-coordinate complexes Ru(CO)Cl(PPh(3))3(CH=CHPh) and [Ru(CO)Cl(PPh(3))3]2(mu-CH=CHC(6)H(4)CH=CH). X-ray crystal structures of the latter complex and of the hydride complex RuH(CO)Cl(PPh(3))3 were obtained. 1H and 31P NMR spectra between 20 and -70 degrees C exhibit large changes in both equilibrium constants and dynamic effects.

Trithiocarbonate-mediated free-radical photopolymerization: improved uniformity in hologram recording.

A holographic material based on a photopolymerizable nematic acrylate was improved by the addition of the trithiocarbonate, EtO2CCH2SC(S)SCH2CO2Et, increasing uniformity and reproducibility in the formation of electrically switchable holographic gratings. Diffraction efficiencies as high as 34%, the thin-grating theoretical maximum, were achieved at large (10-14 microm) grating spacings. Improved diffraction efficiency was seen over a range of grating spacings (0.