Edwin A. C. Lucken

The diphenylphosphino radical, (C6H5)2˙P

The diphenylphosphino radical, (C6H5)2P, has been observed at room temperature in X-irradiated single crystals of triphenylphosphine oxide and diphenylphosphine sulphide and in ultra-violet irradiated polycrystalline diphenylphosphine at 77 K. The isotropic 31P coupling constant is deduced to be +252 MHz and the anisotropic components are approximately 504, -252, -252 MHz. The largest value of the g tensor lies perpendicularly to the direction of the largest hyperfine coupling constant, the values in diphenylphosphine sulphide being 2·0094, 2·0035 and 2·0021. X-irradiated triphenylphosphine oxide also contains the (C6H5)2PO radical.

The microwave spectrum of cyclobutadiene iron tricarbonyl

Abstract The microwave spectrum of cyclobutadiene iron tricarbonyl has been observed from 8.0 to 12.4 GHz and from 26.5 to 40.0 GHz. The spectrum is essentially that of a symmetric top and the value of Bo(962.41 MHz) is close to that calculated from the results of recent electron diffraction studies.

Nuclear quadrupole resonance studies of chelated antimony complexes. Part 6. Tricyclic molecules

Abstract The 35 Cl Nuclear Quadrupole Resonance spectra of three tricyclic molecules of known structure containing SbCl 3 fragments have been measured. Several other analogous compounds have been shown, by a combination of 35 Cl, 121 Sb and 123 Sb NQR spectroscopy, to have similar structures. The relationship between bond length and 35 Cl resonance frequency for these compounds containing SbCl 3 fragments was investigated; the resonance frequency is less sensitive to bond length than related complexes containing the SbCl 4 group.

Phosphoranyl radicals: An esr study of Ph3PBr Trapped in a single crystal

Abstract X-irradiation of a single crystal of triphenyliminophosphonim bromide yields an oriented free radical which is identified via its ESR spectrum as the triphenylbromophosphoranyl radical, Ph 3 PBr . The g tensor, the magnetic hyperfine tensors of the 31 P and 81 Br nuclei and the quadrupole coupling tensor of the 81 Br nucleus are reported. the directions of the maximum value of the 31 P magnetic hyperfine tensor and of the 81 Br magnetic hyperfine tensor are inclined at an angle of 35° thus indicating a structure intermediate between the C 2v structure of PF 4 and the C 3v structure of Ph 3 PCI.

63Cu NQR spectra of dicoordinated Cu(I) cations with imidazole and pyrazole ligands

Abstract The 63 Cu NQR spectra of five dicoordinated complex cations of Cu(I) with substituted imidazoles as ligands and six analogous complexes with substituted pyrazoles as ligands are reported. The structures of four of these complexes have been previously determined and the relationship of their 63 Cu resonance frequency to the average CuN bond length is compared to that of the analogous lutidine or collidine complexes. It is concluded that there are probably significant differences between the electronic structures of the pyridine complexes and those of the pyrazole or imidazole series.

The EPR spectrum of the triphenylchloroarsanyl radical, Ph3ÅsCl, trapped in a single crystal of triphenylmethylarsonium chloride

Abstract X-irradiation of single crystals of triphenylmethylarsonium chloride at room temperature produces a radical which is identified as Ph 3 AsCl. The EPR parameters indicate that it has a structure intermediate between that of the analogous ṖF 4 and Ph 3 ṖCl.

Étude du complexe d'addition moléculaire du pentachlorure d'antimoine avec le chlorure de cyanogène par résonance quadripolaire nucléaire

Abstract The nuclear quadrupole resonance spectrum of the addition complex of antimony pentachloride and cyanogen chloride was recorded in the region of 121 Sb, 123 Sb, 35 Cl and 37 Cl transitions. The results are compared with those already given in the literature for similar complexes CH 3 CN-SbCl 5 and Cl 3 PO-SbCl 5 and are discussed in the approximation of Townes and Dailey.

Nuclear quadrupole resonance of 63Cu and 65Cu in complexes of Cu(I) halides with alkyl pyridines

Abstract Nuclear quadrupole resonance spectra are reported for the 63,65 Cu nuclei in complexes of known crystal structure of monovalent copper halides with alkylpyridine ligands. The results confirm trends previously observed for analogous complexes with triphenylphosphine ligands. The trends are briefly discussed in terms of the electronic environment of the copper nucleus in these complexes.

Zeeman nuclear quadrupole resonance study of a germanium tetrachloride single crystal

Abstract Zeeman studies of a single crystal of GeCl4 have been carried out on a previously described pulsed FT NQR spectrometer. The technique for growing single crystals from liquid samples is described. The Zeeman-split spectrum for each of the resonances at μ1 = 25.4493, μ2 = 25.7133, μ3 = 25.7354, and μ4 = 25.7457 MHz reveals four quadruplets. The asymmetry parameters found lie in two groups of average values η = 0.035 and η = 0.078, much lower than the previously reported value of η = 0.35 obtained from a polycrystalline sample. The crystal of GeCl4 is found to be orthorhombic with mmm or D2h symmetry. From the directions of the field gradient axes the interbond angles have been calculated and show that the GeCl4 molecule is a slightly distorted tetrahedron.

Order-disorder effects of small guests in clathrates studied by nuclear quadrupole resonance and crystallography. Part I. Carbon tetrachloride and related molecules in Ni(SCN)2(3-methylpyridine)4

AbstractNQR spectroscopy and X-ray crystallography have been jointly applied to the study of the small guest molecules CH2Cl2, CHCl3, CCl4, CBr2Cl2, C(CH3)2Cl2 etc. in the Werner host complex Ni(SCN)2(3-methylpyridine)4. Specific host-guest dipole-dipole interactions play an important role in order-disorder effects for guest molecules in the cavities of orthorhombic system,Fddd. Thus a weakly polar molecule such as CBr2Cl2 exhibits a disordered alternation, both the bromine and the chlorine atoms occupying the two possible sites in theC2 cavity, whereas for the polar molecule C(CH3)2Cl2, an ordered structure is observed. In addition, two new types of crystal structures,C2/c andP