A Donor‐Stabilized Silanethione or a Si‐Substituted N‐Heterocyclic Platinum Carbene?

Abstract

Silanethione§Platinum: The oxidative addition of a silicon‐bound mercaptoimidazole to Pt0 provided access to a compound that can be regarded as both a donor‐stabilized silanethione and a zwitterionic N‐silylated N‐heterocyclic carbene complex of PtII (see figure).

Silicon Analogues of Carboxylic Acids: Synthesis of Isolable Silanoic Acids by Donor–Acceptor Stabilization

“…However, in the last decades, milestones have been achieved for the synthesis and isolation of silanechalcogenones (heavier silaketones) by taking advantage of thermodynamic and kinetic stabilization. Among the early examples, isolable silaketone‐like systems featuring donor‐stabilized SiS and SiSe bonds with four‐coordinate silicon atoms have been reported by Corriu and co‐workers1a and more recently by the research groups of Wagler,1b West,1c and Roesky 1d. Moreover, even silanechalcogenones with three‐coordinate silicon atoms have been synthesized and structurally characterized by the research groups of Okazaki, Tokitoh, Iwamoto, Törring, and Kira 2–5.…”

Anion‐Exchange‐Triggered 1,3‐Shift of an NH Proton to Iridium in Protic N‐Heterocyclic Carbenes: Hydrogen‐Bonding and Ion‐Pairing Effects

“…NHCs bearing N‐alkyl or ‐aryl wingtips are predominant, and there are only limited, although increasing, literature reports on NHC systems with hydrogen wingtips ligated on transition metals such as iridium,2 rhodium,3 osmium,4 ruthenium,4a–c, 5 rhenium,6 manganese,7 chromium,8 and platinum (Figure 1). 9 In general, these NH‐protic NHC complexes can be synthesized by 1) protonation of 2‐ or 4‐pyridyl or 2‐imidazolyl complexes;6, 10 2) cleavage of NC2c, 5a or NSi9 bonds within NHC units; 3) intramolecular attack of a ligated isonitrile by a pendent NH 2 or OH group generated in situ;5c, 8 and 4) metal‐mediated tautomerization of N‐heterocycles, a process involving CH activation 2–4. 5a,b, 11 Among these methods, metal‐mediated tautomerization is most intriguing in that N‐heterocycle to NHC tautomerization is important not only in biological process12 but also in CC bond formation, where rhodium3 and ruthenium5b protic NHC complexes are established as active catalysts.…”

Metallasilatranes: Palladium(II) and Platinum(II) as Lone‐Pair Donors to Silicon(IV)

“…Methimazolylsilanes, bearing the 2-mercapto-1-methylimidazolide ligand as a buttress capable of bridging hard and soft metal sites, were already considered as an entry into metallasilatrane chemistry in our recent studies. [9] Whereas in an initial attempt, Pt 0 underwent oxidative addition into the methimazole C=S bond under formation of a carbene complex, the present report shows that Pd II and Pt II indeed react with methimazolylsilanes under formation of metallasilatranes.…”