Platinum complexes with pyrimidine-functionalized N-heterocyclic carbene ligands – Synthesis and solid state structures

The ligands of the two most successful systems described in the literature for the activation and functionalization of methane have been merged and a series of novel pyrimidine functionalized platinum(II)(NHC) complexes with aryl and alkyl substituents [1-(2-Pyrimidyl)-3-(aryl or alkyl)imidazoline-2-ylidene platinum(II) chlorides] was synthesized by transmetalation via the corresponding silver complexes. All compounds have been fully characterized by 1H and 13C-NMR spectroscopy, elemental analysis, and with five X-ray single crystal structures. As for the related palladium(II)complexes in most cases we observed structures of the type [Pt(L)Cl2], while for the sterically less demanding methyl substituent a complex is formed, where two ligands are coordinated to one metal center [Pt(L)2Cl]+.

Graphical abstractA series of pyrimidine functionalized platinum(II)(NHC) complexes with aryl- and alkyl substituents is reported, which could be shown to form different complexes depending on the substituent R. While for R = Me a complex of the type [Pt(pym^NHC–R)2Cl]+ is observed, R = DIPP, Mes, Cy lead to a [Pt(pym^NHC–R)Cl2] structure.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Pyrimidine functionalized Pt(II)(NHC) complexes with aryl- and alkyl substituents. ► Fusion of the two most successful catalytic systems for the methane activation. ► All complexes had to be synthesized via “the silver route”. ► Five solid state structures are reported.