866613-65-2Relevant articles and documents
Ni, Pd, and Pt complexes of a tetradentate dianionic thiosemicarbazone-based O^N^N^S ligand
Haseloer, Alexander,Denkler, Luca Mareen,Jordan, Rose,Reimer, Max,Olthof, Selina,Schmidt, Ines,Meerholz, Klaus,H?rner, Gerald,Klein, Axel
, p. 4311 - 4322 (2021)
New tetradentate phenolate O^N^N^S thiosemicarbazone (TSC) ligands and their Ni(ii), Pd(ii) and Pt(ii) complexes were studied. The diamagnetic and square planar configured orange or red complexes show reversible reductive electrochemistry and in part reversible oxidative electrochemistry at very moderate potentials. DFT calculations show essentially pyridyl-imine centred lowest unoccupied molecular orbitals (LUMO) while the highest occupied molecular orbitals (HOMO) receive contributions from the phenolate moiety, the metal d orbitals and the TSC thiolate atom in keeping with UV-vis spectroelectrochemistry. DFT calculations in conjunction with IR spectra showed details of the molecular structures, the UV-vis absorptions were modelled through TD-DFT calculation with very high accuracy. UPS is fully consistent with UV-vis absorption and TD-DFT calculated data and shows decreasing HOMO-LUMO gaps along the series Pd > Pt > Ni.
Use of Suzuki cross-coupling as a route to 2-phenoxy-6-iminopyridines and chiral 2-phenoxy-6-(methanamino)pyridines
Davies, Christopher J.,Gregory, Andrew,Griffith, Phillip,Perkins, Tom,Singh, Kuldip,Solan, Gregory A.
, p. 9857 - 9864 (2008/12/23)
The anisyl boronic acids, 2-OMe-3-R2-5-R1-C6H2B(OH)2 (R1=R2=H (a); R1=H, R2=Ph (b); R1=Me, R2=H (c); R1=Cl, R2=H (d); R1=t-Bu, R2=H (e)), have been employed in Suzuki cross-coupling reactions with either 2-bromo-6-formylpyridine (I) or 2-bromo-6-acetylpyridine (II) generating, following a facile deprotection step, the 2-phenoxy-6-carbonylpyridines, 2-(2′-OH-3′-R2-5′-R1-C6H2)-6-(CH{double bond, long}O)C5H3N (R1=R2=H (1a); R1=Me, R2=H (1c); R1=Cl, R2=H (1d); R1=t-Bu, R2=H (1e)) and 2-(2′-OH-3′-R2-5′-R1-C6H2)-6-(CMe{double bond, long}O)C5H3N (R1=R2=H (2a); R1=H, R2=Ph (2b)). Condensation reactions of 1 and 2 with 2,6-diisopropylaniline proceed smoothly to give the 2-phenoxy-6-iminopyridines, 2-(2′-OH-3′-R2-5′-R1-C6H2)-6-{CH{double bond, long}N(2,6-i-Pr2C6H3)}C5H3N (R1=R2=H (3a); R1=Me, R2=H (3c); R1=Cl, R2=H (3d); R1=t-Bu, R2=H (3e)) and 2-(2′-OH-3′-R2-5′-R2-C6H2)-6-{CMe{double bond, long}N(2,6-i-Pr2C6H3)}C5H3N (R1=H, R2=Ph (4a), R1=H, R2=Ph (4b)). Reduction of the imino unit (and concomitant C-C bond formation) in 3 can be achieved by?treatment with trimethylaluminium or methyllithium which, following hydrolysis, furnishes the racemic chiral 2-phenoxy-6-(methanamino)pyridines, 2-(2′-OH-3′-R2-5′-R1-C6H2)-6-{CHMe-NH(2,6-i-Pr2C6H3)}C5H3N (R1=R2=H (5a); R1=Me, R2=H (5c); R1=Cl, R2=H (5d); R1=t-Bu, R2=H (5e)). This work represents a straightforward and rapid synthetic route to libraries of sterically and electronically variable phenoxy-substituted imino- and methanamino-pyridines, which are expected to act as useful ligands or proligands for late and early transition metal-mediated alkene polymerisation catalysis.
