Cyclometallated Platinum(II) Complexes with Small Crown Ether Rings: Appropriate Choice of the Bridging Diphosphane to Coordinate Potassium Cations.

This account reports the synthesis and structural characterization of the first cyclometallated platinum(II) complex that coordinates a potassium cation in a sandwich arrangement via two 15-crown-5 ether rings within the same molecule. The cooperation of the two small crown ether moieties allows the entrapment of the non-ideal potassium ion. The reaction of the parent thiosemicarbazone ligand 3,4-(CHO)CHC(Me)=NN-(H)C(=S)NHMe, , containing the crown ether ring, with K[PtCl], or alternatively with PtCl(DMSO), and subsequent treatment with the diphosphanes PhPCHPPh (dppm) and PhPC(=CH)PPh (vdpp) produced the double nuclear platinacycles , , and , probably via formation of the and intermediates.

A Highly Effective Strategy for Encapsulating Potassium Cations in Small Crown Ether Rings on a Dinuclear Palladium Complex.

The potential of 15-crown-5 ethers to link large cations, such as potassium, is limited by the quasi-parallel arrangement of two oxygen donor moieties upon appropriate orientation of the corresponding ether-ring-containing molecules. Substrates bearing the two crown ethers that are capable of achieving such coordination are hitherto unknown. The synthesis and isolation of a tailor-made dinuclear palladacycle bearing 15-crown-5 ether rings on the metallated phenyls offers such a possibility, providing the adequate environment for the formation of the sandwiched [K(metallacycle-15-crown-5) ] moiety.