Novel Five-Coordinated Bis-Dioxolene Cobalt Complexes with Methoxy-Substituted Triarylphosphine.

Three novel five-coordinated bis-dioxolene cobalt complexes were synthesized and characterized by single crystal X-ray diffractometry and magnetochemistry. Structural study indicates square-pyramidal coordination geometry around cobalt ion. Structural parameters of coordinated dioxolenes together with magnetic measurements and DFT calculation data characterize compounds as mixed valence catecholato-semiquinonate derivatives of low spin cobalt(III). Magnetic moment of complex based on methoxy-substituted dioxolene grows at the temperatures above 260 K that can be interpreted as valence tautomeric/spin-crossover transition. This transition is not completed at the temperature 350 K. [ABSTRACT FROM AUTHOR]