The syntheses and characterizations of six [Cu(N^N)(POP)][PF] and [Cu(N^N)(xantphos)][PF] compounds (POP = bis(2-(diphenylphosphino)phenyl)ether, xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene), in which N^N is a bpy ligand (1-Naphbpy, 2-Naphbpy, 1-Pyrbpy) bearing a sterically hindered 1-naphthyl, 2-naphthyl or 1-pyrenyl substituent in the 6-position, are reported. Single-crystal structure determinations of five complexes confirm a distorted tetrahedral environment for copper(i) and a preference for the N^N ligand to be oriented with the sterically-demanding aryl group being remote from the (CH)O unit of POP or the xanthene 'bowl' of xantphos. The angle between the ring planes of the bpy range from 5.8 to 26.0° and this is associated with interactions between the aryl unit and the phenyl substituents of the P^P ligand. In solution at room temperature, the complexes undergo dynamic behaviour which has been investigated using variable temperature 2D NMR spectroscopy. The [Cu(N^N)(xantphos)] complexes exist as a mixture of conformers which interconvert through inversion of the xanthene bowl-shaped unit; the preference for one conformer over the other is significantly changed on going from N^N = Phbpy to 1-Pyrbpy (Phbpy = 6-phenyl-2,2'-bipyridine). The electrochemical and photophysical properties of the [Cu(N^N)(POP)][PF] and [Cu(N^N)(xantphos)][PF] compounds are presented; the compounds are orange emitters but the introduction of the 1-naphthyl, 2-naphthyl or 1-pyrenyl substituents result in poor photoluminescence quantum yields.
Chain-walking is a powerful approach toward the functionalization of C−H bonds remote to a functional group. Whereas various Pdcatalyzed migratory cross-couplings have been developed in the past years, the design of an efficient migratory version of the popular Suzuki−Miyaura cross-coupling has remained elusive. The current article reports a one-pot procedure consisting of alkene hydroboration and migratory Suzuki−Miyaura coupling of the resulting alkylboronic acid intermediate. A high regioselectivity for the benzylic position of the initial alkene was achieved by using P(t-Bu) 2 Me as the ligand and an ortho-substituted aryl electrophile. Regioconvergence from alkene positional and geometrical isomers and long-range migration were demonstrated. Mechanistic investigations indicated that the migration occurs through a partially reversible, nondissociative mechanism.
A general and highly enantioselective arylation of carbamates derived from primary alcohols was developed by combining Hoppe's sparteine-mediated asymmetric lithiation with Negishi cross-coupling. Coupled with Aggarwal's lithiation-borylation sequence, the current method provides a short and divergent access to a variety of enantioenriched secondary and tertiary benzylic alcohols.
Replacing phosphonic acid by (1-cyanovinyl)phosphonic acid anchors in heteroleptic bis(diimine)copper(i) dyes in DSCs gives a gain in JSC; a dye with a bpy-based anchor gives improved performance over one with a phen-based anchor.
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