Co(i) complexes with a tetradentate phenanthroline-based PNNP ligand as a potent new metal–ligand cooperation platform. Issue 41 (14th October 2020)

• Record Type: Journal Article
• Authors: Jheng, Nai-Yuan; Ishizaka, Yusuke; Naganawa, Yuki; Sekiguchi, Akira; Nakajima, Yumiko
• Is Part Of: Dalton transactions. Volume 49:Issue 41(2020)
• Page Start: 14592
• Page End: 14597
• Publication Date: 2020-10-14
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d0dt02549f
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : A cobalt(i ) alkyl complex bearing a tetradentate phenanthroline-based PNNP ligand undergoes dearomatization of the ligand backbone skeleton upon heating and furthermore achieves H–H bond cleavage. Abstract : A series of low spin cobalt(i ) complexes bearing a tetradentate phenanthroline-based PNNP ligand (2, 9-bis((diphenylphosphanyl)methyl)-1, 10-phenanthroline), [CoCl(PNNP)] (1 ), [CoMe(PNNP)] (2 ) and [Co(CH2 SiMe3 )(PNNP)] (3 ), were synthesized and structurally identified. Complex 3 underwent a structural rearrangement of the PNNP skeleton upon heating to form [Co(PNNP′)] (4 ), which is supported by an asymmetrical PNNP′ ligand with a dearomatized phenanthroline backbone. Mechanistic studies supported that the transformation from 3 to 4 was initiated by the homolysis of either a Co–CH2 SiMe3 bond or a benzylic C–H bond. Complex 4 achieved H–H bond cleavage of H2 (1 atm) at ambient temperature, to form [Co(PNNP′′)] (6 ), in which two H atoms were incorporated into the endocyclic double bond of the PNNP′′ ligand backbone.