Synthesis and structure of thienyl Fischer carbene complexes of Pt^II for application in alkyne hydrosilylation

Abstract

Transmetallation of group 6 thienylene Fischer carbene complexes to PtII precursors yielded new examples of neutral platinum(II) bisethoxycarbene complexes with either 2-thienyl (T) or 5-thieno[2,3-b]thienylene (TT) carbene substituents. The use...

Roles played by carbene substituents during ligand transfer reactions between tungsten fischer carbene complexes and [Pt(COD)Cl2]

“…In the case of the thienyl substituents, the large shift is ascribed to π-resonance effects of the electron excessive thienyl substituents via a conjugated electronic pathway. [24] The chemical shift of the carbene carbon in 2a (238.5 ppm) is however still downfield compared to that of 191.8 ppm in the tris(dimethylaminocarbene) complex 2b, where the NMe2 substituent which is directly attached to the carbene carbon acts as the primary electron donor. This is also The results of high resolution mass spectrometry (Figures S8 -S13 of the SI) and elemental analysis (see Experimental Section and listed in Table S1 of the SI) support of the NMRderived identities of the Pt-carbene complexes.…”

“…This contrasts with the behaviour of aminosubstituted thienyl and condensed thieno-[2,3-b]thienylene carbene ligands, which also afforded bis(aminocarbene) complexes of Pt(II). [24] Even when an excess of [W{C(OEt)(C6H4-4-NMe2)}(CO)5] and prolonged reaction times were employed, no corresponding cationic tris(ethoxycarbene) complex was isolated. We ascribe the difference to a stronger trans influence of the aminocarbene ligands in the Pt(II) cis-configured bis(carbene) complexes, which aids in weakening the trans Pt-Cl bond.…”

Cyclobutadiene platinum complex as a new type of precatalyst for hydrosilylation of alkenes and alkynes

“…Similar results have been noted previously by other researchers. [ 35 ] The 3‐butynol‐1 gave only traces of 2m apparently because of the side reactions of the unprotected hydroxy group. On the other hand, the cyclobutadiene catalyst 1 was compatible with various trisubstituted silanes bearing alkyl, aryl, and alkoxy groups ( 2g – 2i ).…”