Molecular structure and properties of bis(O-diiminobenzosemiquinonato) metal(II) complexes monocation in salts and charge transfer complexes

For the first time, we have determined the crystal structure of CT complexes between M(isq)2 and CHL (isq = diiminobenzosemiquinonato; CHL = p-chloranil; M=Ni, Pt). M(isq)2 and CHL formed segregated stacking and 1 -D uniformly spaced chain with face to face separations of 3.30–3.35 Å for M(isq)2 and 3.15 Å for CHL The M-M distances were 3.61 Å for Ni and 3.60 Å for Pt, and no M…M interaction was found. The geometries, IR, and UV spectra indicated ionic ground states of the CT complexes. The CT complexes exhibited semiconducting character with similar activation energy of ca 0.2 eV at 200–300 K. The reaction of Ni(isq)2 with 2,5-dichlorobenzoquinone gave not an expected CT complex but a salt with composition of [Ni(isq)2]3Cl2. X-ray structure analysis revealed separated monomer and dimer of Ni(isq)2. The weak Ni…Ni interaction of 2.804 Å was found in the dimer. The geometries suggested that monomeric Ni(isq)2 was nearly neutral and that the Ni(isq)2 in the dimer was ionic with the charge of +1. The salt also showed a semiconductive behavior with activation energy of 0.27 eV at 200–300 K.