The [Cp*Ir(t75-2,5-Me2T)](BF4)2 complex (Id), where Cp* is 7?5-C5Me5 and 2,5-Me2T is 2,5-dimethylthiophene (other thiophenes react similarly), undergoes a two-electron reduction using Na[H2Al(OCH2CH2OMe)2] to give Cp*Ir- (r;4-2,5-Me2T) (2d). Basic Al203 catalyzes the isomerization of 2d to the more stable and novel 3d. X-ray and NMR studies 1d 2d 3dsupport a structure for 3d in which the -system of the six-membered ring is delocalized and may best be described as an iridathiabenzene. Oxidation of both 2d and 3d (surprisingly) yield Id. In addition to 2d and small amounts of 3d, the BH3 adduct Cp*Ir(ji4-2,5-Me2T-BH3) (4d) in which the BH3 is coordinated to the sulfur of 2d was isolated in trace amounts from the reduction of Id; the structure of 4d was established by an X-ray diffraction investigation.

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The manuscript describes positive and negative Doppler shifts at optical frequencies in an acousto-optic superlattic modulator using a fibre Bragg grating. Associated amendments have been made to the text, a citation to this work has been added and the references have been renumbered accordingly. This revision has been made to the HTML and PDF versions of the Letter.

By using the method of modal expansions of the independent transverse fields, a formula of vector plane wave spectrum (VPWS) of an arbitrary polarized electromagnetic wave in a homogenous medium is derived. In this formula VPWS is composed of TM- and TE-mode plane wave spectrum, where the amplitude and unit polarized direction of every plane wave are separable, which has more obviously physical meaning and is more convenient to apply in some cases compared to previous formula of VPWS. As an example, the formula of VPWS is applied to the well-known radially and azimuthally polarized beam. In addition, vector Fourier-Bessel transform pairs of an arbitrary polarized electromagnetic wave with circular symmetry are also derived.

Observation of the inverse Doppler effect in negative-index materials at optical frequencies.