2,2′:6′,2"-Terpyridine Trimethylplatinum(IV) Iodide Complexes as Bifunctional Halogen Bond Acceptors

Three new organometallic trimethylplatinum(IV) iodide complexes of 2,2':6',2 ''-terpyridines have been synthesized and characterized by H-1 NMR spectroscopy, mass spectrometry, elemental analysis, and single crystal X-ray diffraction analysis. The X-ray crystal structures of PtMe3I(L) complexes 1-3 {L for 1 = 4'-chloro-2,2':6',2 ''-terpyridine, 2 = 4'-(4-cyanophenyl)-2,2':6',2 ''-terpyridine, and 3 = 4'-(4-tolyl)-2,2':6',2 ''-terpyridine} reveal distorted octahedral coordination geometry of the platinum(IV) metal centers with bidentate coordination of the terpyridine ligands. Complexation of 1-3 with iodopentafluorobenzene (IPFB) afforded single-crystal structures of halogen bond (XB) complexes 1a-3a, in which the Pt-complexes act as bifunctional XB bond acceptor wherein the pendant pyridine nitrogen atom and the platinum bound iodine atom act as XB acceptors toward the polarized iodine of IPFB. In addition, complexation of 1 with 1,4-dliodotetrafluobenzene (DITFB) afforded single-crystal structure of dimeric XB complex (1b), in which the halogen bonding occurs via the pyridine nitrogen atoms of two 1 and DITFB, whereas the iodine on each Pt-complex forms weak hydrogen bond with solvent molecule (chloroform).