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Abstract As part of our efforts to interface late transition metals with Lewis acidic main group fragments, we have decided to investigate gold complexes bearing halogermanes as Z‐type ligands. Toward this end, we have synthesized complexes of general formula [(o‐(Ph2P)C6H4)2(Ph)(X)GeAuCl] (X = F, Cl). Experimental and computational analyses indicate the presence of an Au→Ge interaction in both cases. Chloride abstraction reactions have also been investigated. In the case of X = Cl, double chloride abstraction with AgSbF6affords a putative dication that gradually abstracts fluoride from its counterion. This putative dication is also significantly more active as a catalyst than its monocationic analog in alkyne hydroamination reactions.
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Abstract With the discovery of late transition metal platforms that support clean photoreductive halogen eliminations, we now describe an indazol‐3‐ylidene gold trichloride complex ([7]+) decorated at the 4‐position by a xanthylium unit. This orange complex features a low energy band in the visible part of the spectrum, assigned to the charge transfer excitation of the indazol‐3‐ylidene/xanthylium donor/acceptor dyad. Green‐light irradiation of this complex in the presence of a chlorine trap elicits the clean photoelimination of chlorine radicals, producing the corresponding gold(I) complex. This visible‐light‐induced photoreduction is very efficient, reaching quantum yields close to 10 %. A neutral analog of [7]+featuring an anthryl group rather than a xanthylium unit proved to be perfectly photostable, supporting the importance of the xanthylium‐based photoredox unit present in [7]+.more » « less
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Evidence for the amphoteric behavior of an acridinium unit has been gathered through the investigation of two rhodium complexes in which the cationic moiety acts either as a Z- or L-type ligand, depending on the coordination environment of the metalmore » « lessFree, publicly-accessible full text available June 18, 2026
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The entrance channel of bimolecular reactions sometimes involves the formation of outer complexes as weakly bound, fleeting intermediates. Here, we characterize such an outer complex in a system that models the bimolecular, C-O bond–forming reaction of a phosphine oxide Lewis base with a carbenium Lewis acid. Crystallographic studies show that the C-O distance in the outer form exceeds that of the final or inner adduct by 1.1 angstroms. As the system samples the two forms of the complex, which correspond to minima on the corresponding potential energy surface, the C-O linkage switches from a secondary interaction in the outer complex to a dative bond in the inner complex. This phenomenon is harnessed as a functional feature to stabilize xanthylium-based photoredox catalysts.more » « less
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Aiming to study the interaction of gold with the highly Lewis acidic fluorenyl cation, we synthesised ( o -[Ph 2 P(C 6 H 4 )Flu)AuCl(tht)][BF 4 ] ([2][BF 4 ]) and ( o -Ph 2 P(C 6 H 4 )Flu)AuCl 2 (3) (Flu = 9-fluorenyl) and found that the latter could be converted into [( o -Ph 2 P(C 6 H 4 )Flu)AuCl] + ([4] + ) upon treatment with NaBArF 24 (BArF 24 = B(3,5-C 6 H 3 (CF 3 ) 2 ) 4 ). [4] + , which has been isolated as a chloride-bridged dimer, readily catalyses the cycloisomerisation of 2-allyl-2-(2-propynyl)malonate. Computational results show that [4] + possesses a strong Au → C + bond and readily activates enynes.more » « less
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We describe a novel gold chloride complex supported by an ambiphilic phosphine/xanthylium ligand in which the AuCl moiety interacts with the π + surface of the xanthylium unit as indicated by structural studies. Energy decomposition analyses carried out on a model system indicates the prevalence of non-covalent interactions in which the electrostatic and dispersion terms cumulatively dominate. The presence of these AuCl–π + interactions correlates with the high catalytic activity of this complex in the cyclisation of 2-(phenylethynyl)phenylboronic acid, N -propargyl- t -butylamide, and 2-allyl-2-(2-propynyl)malonate. Comparison with the significantly less active acridinium and the 9-oxa-10-boraanthracene analogues reinforces this conclusion.more » « less
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We report the synthesis and characterization of two phosphine gold carbinol species designed to support intramolecular Au⋯H–O hydrogen bonding. Increasing the metallobasicity of gold through chloride to phenyl ligand substitution produced an observable increase in this hydrogen bond's strength which was analyzed experimentally and computationally.more » « less
