Assembly and X-ray crystal structures of heterometallic multiporphyrins with complementary coordination between ruthenium(II) and tin(IV) porphyrins

Abstract

Two new heterometallic multiporphyrins Sn-Ru4 and Sn-Ru6 have been synthesized by adopting two simple approaches based on metal ion recognition by a ditopic ligand and mutually non-interfering coordination properties of the Ru(II)-N and Sn(IV)-O interactions. We have synthesized the pentameric Sn-Ru4 and the heptameric Sn-Ru6 using trans-dihydroxo[5,10,15,20-tetrakis(4-pyridyl)porphyrinato]tin(IV) and trans-diisonicotinato[5,10,15,20-tetrakis(4-pyridyl)porphyrinato]tin(IV), respectively, from the reaction with [5,10,15,20-tetrakis(4-tert-butylphenyl)porphyrinato]ruthenium(II)carbonyl [(TtBPP)Ru(CO)]. The reaction of Sn-Ru4 with 2 equivalents of isonicotinic acid followed by 2 equivalents of [(TtBPP)Ru(CO)] in refluxing CHCl3 also leads the formation of Sn-Ru6. The formation of newly hybrid multiporphyrin arrays were confirmed by 1H NMR spectroscopic studies and single crystal X-ray diffraction techniques. 1H NMR measurements on Sn-Ru4 and Sn-Ru6 indicate that the protons on the core template are extremely shielded as a result of the anisotropy of the peripheral porphyrin units. X-ray crystallographic analysis reveals an open-box shaped pentaporphyrin array for Sn-Ru4 and the full encapsulation of a Sn(IV) porphyrin moiety surrounded by six Ru(II) porphyrin units in Sn-Ru6. So far no example of well-defined X-ray crystallographic structure for Sn(IV) porphyrins with high nuclearity is reported.