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Pseudotetrahedral Organocobalt(III) Compounds Containing Specific Coordination Sites for Brønsted Acids
Author(s) -
Meneghetti Mario Roberto,
Grellier Mary,
Pfeffer Michel,
Cian André De,
Fischer Jean
Publication year - 2000
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200007)2000:7<1539::aid-ejic1539>3.0.co;2-1
Subject(s) - chemistry , transmetalation , deprotonation , medicinal chemistry , protonation , ligand (biochemistry) , aryl , cobalt , intramolecular force , stereochemistry , alkyl , catalysis , inorganic chemistry , organic chemistry , ion , biochemistry , receptor
Transmetallation of the lithiated derivative 2,6‐bis[dimethyl(amino)methyl]phenyllithium with the cobalt(III) centre of the dimer bis[(η 5 ‐cyclopentadienyl)cobalt(iodo)(μ‐iodo)] has been found to afford the organocobalt compound [CoI{2‐(Me 2 NCH 2 )‐6‐(Me 2 NH + CH 2 )C 6 H 3 }(η 5 ‐C 5 H 5 )]I, 3 , in which the potentially terdentate (pincer) ligand is bound to Co through the formerly lithiated aryl carbon atom and one NMe 2 unit only, whilst the second NMe 2 group is protonated by HI. In the presence of aqueous KPF 6 , 3 has been found to undergo both substitution of the iodide bound to Co by a water molecule and deprotonation of the Me 2 NH group to afford [CoI{2,6‐(Me 2 NCH 2 ) 2 C 6 H 3 }(η 5 ‐C 5 H 5 )(H 2 O)]PF 6 , 4a . It was found that the water ligand in 4a could be substituted by neutral ligands such as PMe 2 Ph as well as by Brønsted acids such as HCl, HI, HF, or HOAc to afford the compounds [CoX{2‐(Me 2 NCH 2 )‐6‐(Me 2 NH + CH 2 )C 6 H 3 }(η 5 ‐C 5 H 5 )]PF 6 , 5a−d , where X = Cl, I, F, or OAc, respectively. Crystal structure analyses of some representative examples of these compounds, including 4a , have shown unambiguously that an intramolecular hydrogen bond is present between X and the proton of the Me 2 NH + unit. 1 H‐NMR evidence that this interaction persists in solution has been found for compounds 4a , 5a , 5c , and 5d .