Matthew P. Bucchino

Terahertz Spectroscopy of 25MgH (X2Σ+) and 67ZnH (X2Σ+): Bonding in Simple Metal Hydrides

Pure rotational spectra of (25)MgH (X(2)Σ(+)) and (67)ZnH (X(2)Σ(+)) were recorded using direct absorption techniques. These free radicals were synthesized by the reaction of metal vapor, generated in a Broida-type oven, with H2 in a dc discharge. The N = 0 → 1 and N = 1 → 2 transitions were recorded for both species in the frequency range 342-789 GHz. Spin-rotation and metal and proton hyperfine interactions were resolved in the spectra. From these data, rotational, fine structure, and hyperfine constants were determined, including the Fermi contact, dipolar, and electric quadrupole parameters of the (25)Mg and (67)Zn nuclei. Comparison of the metal and proton hyperfine terms suggests that the unpaired electron resides in a σ molecular orbital that has significant s contributions from both the metal and the hydrogen atoms. The dipolar terms for both metals are relatively large, in contrast to those of the proton, and indicate spσ and possibly sdσ (zinc only) orbital hybridization. The quadrupole constants arise principally from the p/d orbital character of the unpaired electron, although there is a non-negligible polarization contribution. These results suggest significant covalent character in both MgH and ZnH, in contrast to their fluoride analogs.

Structural Determination and Gas-Phase Synthesis of Monomeric, Unsolvated IZnCH3 (X̃1A1): A Model Organozinc Halide

The first experimental structure of a monomeric organozinc halide, IZnCH3, has been measured using millimeter-wave direct absorption spectroscopy in the frequency range 256-293 GHz. IZnCH3 is a model compound for organozinc halides, widely used in cross-coupling reactions. The species was produced in the gas phase by reaction of zinc vapor with iodomethane in the presence of a dc discharge. IZnCH3 was identified on the basis of its pure rotational spectrum as well as those of the isotopically substituted species I(66)ZnCH3, I(64)Zn(13)CH3, and I(64)ZnCD3. IZnCH3 is unmistakably a symmetric top molecule (X̃(1)A1) belonging to the C3v point group, in agreement with DFT calculations, with the following experimentally determined structural parameters: rIZn = 2.4076(2) Å, rZnC = 1.9201(2) Å, rCH = 1.105(9) Å, and ∠H-C-H = 108.7(5)°. The basic methyl group geometry is not significantly altered in this molecule. Experimental observations suggest that IZnCH3 is synthesized in the gas phase by direct insertion of activated atomic zinc into the carbon-iodine bond of iodomethane.

Rotational spectroscopy of CLZNCH3 (~X1A1): characterization of a monomeric grignard-type reagent

K. M. KILCHENSTEIN, Department of Chemistry and Biochemistry; Department of Astronomy, Arizona Radio Observatory, University of Arizona, Tuscon, AZ, USA; JIE MIN, Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA; MATTHEW BUCCHINO, Department of Chemistry and Astronomy, University of Arizona, Tucson, AZ, USA; LUCY M. ZIURYS, Department of Chemistry and Biochemistry; Department of Astronomy, Arizona Radio Observatory, University of Arizona, Tuscon, AZ, USA.

LABORATORY DETECTION OF ClZnCH3 (X1A1): FURTHER EVIDENCE FOR ZINC INSERTION

MATTHEW P. BUCCHINO, Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721; JUSTIN P. YOUNG, Department of Chemistry, Canisius College, Buffalo, New York 14208; PHIL M. SHERIDAN, Department of Chemistry, Canisius College, Buffalo, New York 14208; and LUCY M. ZIURYS, Department of Chemistry and Biochemistry, Department of Astronomy, and Steward Observatory, University of Arizona, Tucson, Arizona 85721.