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The rotational spectra of CoNO were measured using a Fourier-transform microwave (FTMW) spectrometer. The CoNO molecules were generated in supersonic jets using the pulse-discharge reaction of Co(CO)3NO diluted with Ar. The amount of CoNO generated under the present experimental conditions was significantly more than that of CoCO, although the CO contained in a molecule of the precursor Co(CO)3NO is three times more than NO. The quadrupole parameter of the N nucleus was determined for a transition metal mononitrosyl complex for the first time and compared with those of other nitrosyl compounds.

The rotational spectra of NiCO and PdCO in the ground and ν(2) excited vibrational states were observed by employing a source-modulated microwave spectrometer. The NiCO and PdCO molecules were generated in a free space cell by the sputtering reaction of nickel and palladium sheets, respectively, lining the inner surface of a stainless steel cathode with a dc glow plasma of CO and Ar. The molecular constants of NiCO and PdCO were determined by least-squares analysis. By force field analysis for the molecular constants of not only NiCO and PdCO but also of PtCO as previously reported, the harmonic force constants were determined for these three group 10 metal monocarbonyls. The vibrational wavenumbers derived for the lower M-C stretching vibrations were in good agreement with those obtained from the IR spectra in noble gas matrices and those predicted by several quantum chemical calculations published in the past. The bending vibrational wavenumbers derived by the force field analysis were also consistent with most quantum chemical calculations previously reported, but showed systematic discrepancies from the matrix IR values by about 40 cm(-1), even after reassignment (ν(2) band → 2ν(2) band) of the matrix IR spectra of PdCO and PtCO.

Monomeric platinum cyanide, PtCN, was detected in the gas phase by employing a source-modulated microwave spectrometer. The PtCN radical was generated in a free space cell using the sputtering reaction from a platinum sheet placed on the inner surface of a stainless steel cathode through a dc glow plasma of CH 3 CN diluted with Ar. The rotational constants obtained for several isotopomers indicated that the monomeric platinum cyanide is in a cyanide form (PtCN) and not in an isocyanide form (PtNC). Observed fine- and hyperfine-spectral patterns suggest that the PtCN radical has the 2 Δ 5 / 2 electronic ground state.

The chemistry of the group 11 metal cyanide system has been of considerable interest because of the commercial importance of some of the complexes formed in this system. These metal cyanides contain one-dimensional linear -M-CN-M-CN-M- chains in the solid state; however, they have not been observed as free monomeric species. This Article reports the first detection of monomeric AgCN and AuCN in the gas phase by using rotational spectroscopy. The sputtering reaction of silver and/or gold sheets placed on a stainless steel cathode with CH3CN diluted in Ar resulted in the production of AgCN and AuCN spectra. Spectroscopic observation of the parent and several rare isotopic species allowed the determination of r(0), r(s), r(Iepsilon), r(m)(1), and r(m)(2) structures in the case of AgCN and r(0) and r(s) structures in the case of AuCN. All data indicate that these two species have a linear MCN geometry with a low-energy bending vibration.

The rotational transitions of AuH and AuD with the hyperfine structure due to the gold nucleus (I = 3/2) were observed in the 220, 430, and 650 GHz regions with source modulation microwave spectrometers. The AuH and AuD molecules were generated by sputtering from a gold sheet lining the inner surface of a stainless-steel cathode in a dc glow discharge through hydrogen and deuterium gases, respectively, diluted with argon gas. The nuclear electric quadrupole coupling constant and the nuclear magnetic spin-rotation coupling constant were determined for each isotopomer by a least-squares analysis.

Platinum monofluoride (PtF) and platinum monochloride (PtCl) were detected in the gas phase using a source-modulated microwave spectrometer. The PtF and PtCl radicals were generated in a free space cell using the sputtering reaction from a platinum sheet placed on the inner surface of a stainless steel cathode through a dc glow discharge plasma of CF(4) and Cl(2), respectively, diluted with Ar. Rotational transitions were measured in the region between 150 and 313 GHz. Rotational, centrifugal distortion, and several fine- and hyperfine-structure constants were determined by a least-squares analysis. The observed fine-structure spectral patterns indicate that both PtF and PtCl radicals have the (2)Π(3/2) electronic ground states, while the related cyanide PtCN and hydride PtH radicals have the (2)Δ(5/2) electronic ground states.

The millimeter- and submillimeter-wave spectra of the NiI radical in the XΔ5∕22 and AΠ3∕22 states were observed by a source-modulated microwave spectrometer. The NiI radical was generated by a dc glow discharge in the mixture of CH3I vapor and Ar gas through the sputtering reaction with a Ni cathode. Observed transition frequencies for each electronic state were independently analyzed using a polynomial energy expression based on Hund’s case (c) approximation. The deperturbed rotational constants were also estimated by the perturbation analysis including interaction terms between the ground state and the lowest excited state.