Selective oxidation and reduction of trinuclear titanium(II) hexaazatrinaphthylene complexes-synthesis, structure, and electrochemical investigations.

Titanocene complexes with chelating N-heterocyclic ligand bridges react with ferrocenium salts as selective oxidants to afford air-stable cationic complexes and allow the preparation of exceptional mixed valence hexaazatrinaphthylene complexes [(Cp2Ti)3(mu3-HATNMe6)]n+ (1n+) (n=1, 2, 3, 4). Cyclic voltammograms (CV) and differential pulse voltammograms (DPV) show that nine oxidation states of 1 are generated without decomposition. Comproportionation constants Kc have been calculated in order to determine the extent of electronic communication between the titanium centers.

Dehydroaromatization of quinoxalines: one-step syntheses of trinuclear 1,6,7,12,13,18-hexaazatrinaphthylene titanium complexes.

We report the spontaneous coupling of N-heterocycles, initiated by C-H bond activation reactions. The reaction of quinoxalines and the titanocene acetylene complex Cp2Ti{eta2-C2(SiMe3)2}, as an excellent titanocene source, results in the formation of trinuclear 1,6,7,12,13,18-hexaazatrinaphthylene (HATN) titanium complexes. These HATN titanium complexes are thermally stable but sensitive to air and moisture.

Generation of spirotricyclic site-differentiated cyclotriphosphazenes: a solvent-free approach to multidentate N/O donor ligand systems.

Cyclotriphosphazene-based ligand systems are valuable materials to model the metal-binding event on the structurally and electronically related functionalized high molecular weight polyphosphazenes. We here report the facile synthesis of novel spirotricyclic cyclotriphosphazenes N(3)P(3)(MeNC(2)H(4)NMe)(2)L(2), N(3)P(3)(iPrNC(2)H(4)NiPr)(2)L(2), and N(3)P(3)(o-O(2)C(12)H(8))(2)L(2) that enables different substituents to be incorporated into the ligand system. This synthetic approach allows for control over the solubility and steric requirements of the exocyclic bidentate substituents, as well as the donor type and denticity of the coordination sites.