cis-Bis(isopropyl isocyanide)dicyanoplatinum(II), Pt II(CN-i- C 3H 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 3H 7) 2(CN) 2forms 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 3H 7) 2(CN) 2to 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 3H 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 PtII(Pt II(CN-i-C 3H 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 3H 7) 2(CN) 2would make a useful benzene sensor.