New Oxypyridinate Paddlewheel Ligands for Alkane-Soluble, Sterically-Protected Ru 2 (II,III) and Ru 2 (II,II) Complexes

• Published in: Inorganic chemistry 2018-08, Vol.57 (16), p.10331-10340
• Main Authors: Brown, Tristan R, Lange, Josephine P, Mortimer, Michael J, Berry, John F
• Format: Article
• Language: English
• Subjects: Chemistry
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.8b01553

The paddlewheel complex Ru (chp) Cl (1-Cl, chp = 6-chloro-2-oxypyridinate), upon reduction with Zn, has been previously shown to dimerize to [Ru (chp) ] (2), blocking further chemistry at the Ru (II,II) axial site [ Inorg. Chem. 2015 , 54 , 8571 - 8589 ]. Functionalization of the chp ligand at the 3 and 5 positions with either bromine (dbchpH = 3,5-dibromo-6-chloro-2-pyridone) or trimethylsilyl (TMS) groups (dsichpH = 6-chloro-3,5-bis(trimethylsilyl)-2-pyridone) allows for the preparation of the Ru (II,II) paddlewheel complexes Ru (dbchp) (3) and Ru (dsichp) (6), respectively, neither of which shows evidence of dimerization. Though the utilization of 3 is limited due to insolubility, complex 6 is soluble even in typically non-coordinating solvents, forming a stable κ -axial adduct in CH Cl (6-CH Cl ) and showing evidence of an axial interaction with n-decane. The first example of an axially free Ru (II,II) complex with a A ground state is observed upon crystallization of 6 from benzene (6-C D ). Complex 6 is accessed via Zn reduction of Ru (dsichp) Cl (4-Cl), which along with Ru (dsichp) N (4-N ), show similar structural and electronic properties to their non-TMS-substituted analogues, 1-Cl and 1-N . Photolysis of 4-N in frozen solution generates Ru (dsichp) N (5); no N atom transfer to PPh is observed upon room temperature photolysis in fluid solution.