Structural Investigations of Vapochromic Behavior. X-ray Single-Crystal and Powder Diffraction Studies of [Pt(CN-iso-C3H7)4][M(CN)4] for M = Pt or Pd

We have synthesized [Pt(CN-iso-C3H7)4][M(CN)4] (M = Pt, Pd) and studied their reversible hydration and sorption properties with UV−vis, FT-IR spectroscopy, and X-ray diffraction. Powder diffraction studies show that anhydrous [Pt(CN-iso-C3H7)4][Pt(CN)4] and [Pt(CN-iso-C3H7)4][Pd(CN)4] crystallize in a tetragonal space group with nearly identical lattice constants. Gravimetric studies reveal that variable guest−host stoichiometries occur when solid [Pt(CN-iso-C3H7)4][Pt(CN)4] sorbs the guest at room temperature from the gas phase [water, 12.1(1) molecules per formula unit, chloroform 6.0(1), methanol 8.0(1), and trifluoroethanol 4.1(1)]; these sorption processes are reversible. The unit cell distances in the tetragonal ab-plane expand dramatically when the solvent guests are sorbed, but changes along the c-axis (the M−M direction) are minimal. Crystallization of [Pt(CN-iso-C3H7)4][Pt(CN)4] from water gives monoclinic crystals of a hexadecahydrate [Pt(CN-iso-C3H7)4][Pt(CN)4]·16H2O. This salt consists of alt...