Juan F. Villa

Spin—Spin Coupling in Magnetically Condensed Complexes. XII. The Ground State of Tetrakis (N, N′‐dimethylglyoximato) dicopper (II)

The ground state of tetrakis (N, N′‐dimethylglyoximato) dicopper (II) is shown to be of triplet multiplicity with the first excited state being a singlet, at 29.8 cm−1 higher in energy. EPR measurements confirm the existence of spin—spin interactions, and a value of D=0.0340 cm−1 was obtained from the half‐field line, Hmin. The other g values obtained from the triplet state spectra were g∥ = 2.155, g⊥ = 2.122 and (g) = 2.134. Cryomagnetic measurements in the low‐temperature range (4.2–55°K) in conjunction with a best fitting procedure yielded the following values for the magnetic parameters: 〈 g 〉 = 2.157, 2J = + 29.8 cm−1 and θ = −1.45°K. A superexchange mechanism via the σ orbitals of the –N–O– bridge is proposed to account for the experimental findings. This mechanism includes both intra‐atomic direct exchange and interatomic electron transfer.

Effects of metal-ligand charge transfer on the mass spectra of bis(N,N-diethyldithiocarbamato) complexes. An application of the shannon-swan rule

Abstract The mass spectra fragmentation patterns of bis(N,N,-diethyldithiocarbamato) copper(II) and zinc(II) follow the Shannon-Swan rule, apparently because of the ability of copper(II). It is also observed that the short out-of-plane bonds between the two halves of the zinc dimer are strong enough for ions containing two zinc atoms to be observed under the severe experimental conditions employed, while the out-of-plane bonds in the copper dimer are too weak for species containing two copper atoms to be observed.

The Half Field Line of Tetrakis(Dimethtlglyoximato)Dicopper(II) in Glasses

Abstract We have reported recently the finding1 of triplet state EPR spectra in glasses of tetrakis(dimethylglyoximato)dicopper(II) in ethyl alcohol (a.) at 77°K. Now we wish to report the resolution of the half field band (HMIN) and the observation of metal and ligand nuclear hyperfine structure on this band. In previous studies of half field lines, the metal nuclear hyperfine has been sufficiently2,3,4 clear to interpret only in a few cases and the ligand nuclear hyperfine has never been observed before.

Electronic studies of copper complexes of nucleic acid components. Part 10. The copper (II)–guanosine 5′-dihydrogenphosphate system

The polymeric complex [{Cu3(guop)3(OH2)8·5H2O}n](guop = guanosine monophosphate) has been studied by i.r., e.s.r., and electronic spectroscopy and by magnetic-susceptibility measurements. The PO4 bonding to CuII in this complex does not differ much from that of other oxygen donors, and there are two sets of magnetically coupled copper(II) ions with –2J values of 130 and 15 cm–1, respectively. Corresponding coupling paths are proposed. A value of the zero-field splitting, |D|= 0.15 cm–1, has been obtained for the strongly coupled species.

Mass spectrometric evidence for out-of-plane bonding in bis-(NN-diethyldithiocarbamato)zinc(II) dimers

The first evidence for out-of-plane interactions in the gas phase is reported from the mass spectrum of the dimer [Zn(edtc)2]2.

Positive exchange coupling constant in the dimer bis-(NN-diethyldithiocarbamato)copper(II)

Based on magnetic susceptibility data from 4.2 to 56 K it is shown that the sulphur-bridged dimer [Cu(edtc)2]2 has triplet ground state and a weak lattice antiferromagnetism noticeable below 15 K.