A Platinum(II) Extended Linear Chain Material That Selectively Uptakes Benzene

cis -Bis(isopropyl isocyanide)dicyanoplatinum(II), Pt II (CN- i -C 3 H 7 ) 2 (CN) 2, has been synthesized, and its solid-state characteristics have been investigated. X-ray crystallographic data show that Pt II (CN- i -C 3 H 7 ) 2 (CN) 2 forms an extended linear chain (ELC) material in the solid state that is yellow and luminescent. Exposure of crystalline films of Pt II (CN- i -C 3 H 7 ) 2 (CN) 2 to benzene vapor leads to a solid-state luminescence color change from yellow to blue and a loss of crystallinity. Single-crystal X-ray data obtained for a benzene solvate of Pt II (CN- i -C 3 H 7 ) 2 (CN) 2 suggest that the luminescent blue form observed in the thin film results from a structural rearrangement. In the benzene solvate single crystal the lattice is changed from a staggered to an eclipsed ELC material in which the unit cell has expanded by 20% in volume and contains one benzene molecule for every two Pt II (CN- i -C 3 H 7 ) 2 (CN) 2 molecules. The selectivity, kinetics, and reversibility of this transformation have been studied to determine if crystalline films of Pt II (CN- i -C 3 H 7 ) 2 (CN) 2 would make a useful benzene sensor.