Synthesis and structure of penta-platinum σ-bonded derivatives of corannulene

The synthesis of a new class of Pt(II) complexes with corannulene by way of either oxidative addition or reductive coupling is reported and their crystal structures are investigated. The crystal structure for {trans-Pt(PEt3)2Cl}4{cis-Pt(PEt3)2Cl}C20H5 (1) consists of two enantiomers in a unit cell and shows cis- and trans-configuration around Pt(II) due to bulky PEt3 ligands. The pentanuclear Pt(II) complex, 1, readily reacts with 1-ethynyl-4-nitrobenzene to afford the penta-alkynyl substituted Pt(II) complex (2). Although there are still bulky PEt3 ligands around the Pt atoms in 2, all five Pt(II) have trans-configurations. The bowl of corannulene in 2 is shallower than that of 1. Therefore, the bowl depth of corannulene plays a key role in the determination of molecular geometry of σ-bonded pentanuclear complexes bearing corannulene.