Pnictogen bonding at the service of gold catalysis: the case of a phosphinostiborane gold complex.

The search for alternative gold catalyst activators has led us to consider the design of platforms in which a phosphine gold chloride moiety could be activated formation of a pnictogen bond with a neighboring antimony unit. Here, we describe that such a system can be accessed from 4-(diphenylphosphino)-5-(diphenylstibino)-2,7-di--butyl-9,9-dimethylxanthene, by oxidation of the stibine with 3,5-di--butyl--benzoquinone and by coordination of an AuCl unit to the phosphine. This strategy affords a complex in which a Lewis acidic or pnictogen-bond donor catecholatostiborane unit flanks the adjacent gold chloride moiety.

Four-Electron Reduction of O Using Distibines in the Presence of -Quinones.

This study, which aims to identify atypical platforms for the reduction of dioxygen, describes the reaction of O with two distibines, namely, 4,5-bis(diphenylstibino)-2,7-di--butyl-9,9-dimethylxanthene and 4,5-bis(diphenylstibino)-2,7-di--butyl-9,9-dimethyldihydroacridine, in the presence of an -quinone such as phenanthraquinone. The reaction proceeds by oxidation of the two antimony atoms to the + V state in concert with reductive cleavage of the O molecule. As confirmed by O labeling experiments, the two resulting oxo units combine with the -quinone to form an α,α,β,β-tetraolate ligand that bridges the two antimony(V) centers.

Redox-controlled chalcogen-bonding at tellurium: impact on Lewis acidity and chloride anion transport properties.

Our interests in the chemistry of atypical main group Lewis acids have led us to devise strategies that augment the affinity of chalcogen-bond donors for anionic guests. In this study, we describe the oxidative methylation of diaryltellurides as one such strategy along with its application to the synthesis of [Mes(CF)TeMe] and [(CF)TeMe] starting from Mes(CF)Te and (CF)Te, respectively. These new telluronium cations have been evaluated for their ability to complex and transport chloride anions across phospholipid bilayers.

Anion Chelation via Double Chalcogen Bonding: The Case of a Bis-telluronium Dication and Its Application in Electrophilic Catalysis via Metal-Chloride Bond Activation.

Telluronium cations have long been known to engage their counteranions via secondary interactions. Yet, this property has rarely been exploited for anion binding. Motivated by such an application, we have now synthesized a bis-telluronium dication ([]) that was obtained as a tetrafluoroborate salt by reaction of 2,7-di--butyl-9,9-dimethylxanthene-4,5-diboronic acid with phenoxatellurine difluoride and BF·OEt.

Distiboranes based on -phenylene backbones as bidentate Lewis acids for fluoride anion chelation.

As part of our efforts in the chemistry of main group platforms that support anion sensing and transport, we are now reporting the synthesis of anitmony-based bidentate Lewis acids featuring the o-C6F4 backbone. These compounds can be easily accessed by reaction of the newly synthesized o-C6F4(SbPh2)2 (5) with o-chloranil or octafluorophenanthra-9,10-quinone, affording the corresponding distiboranes 6 and 7 of general formula o-C6F4(SbPh2(diolate))2 with diolate = tetrachlorocatecholate for 6 and octafluorophenanthrene-9,10-diolate for 7, respectively. While 6 is very poorly soluble, its octafluorophenanthrene-9,10-diolate analog 7 readily dissolves in CH2Cl2 and undergoes swift conversion into the corresponding fluoride chelate complex [7-μ2-F]- which has been isolated as a [nBu4N]+ salt.

Tautomerization of 2,6-lutidines in the presence of B(C6F5)3 using catecholborane as a precatalyst.

2,6-Lutidine and its derivatives in the presence of B(C6F5)3 undergo tautomerization to yield the corresponding enamine·B(C6F5)3 adducts when catecholborane is applied as a precatalyst. This reaction provides a straightforward way for benzylic C-H borylation of lutidines.