PHYSICAL AND STRUCTURAL PROPERTIES OF TWO CONDUCTING ONE‐DIMENSIONAL MATERIALS: GUANIDINIUM (GCP) TETRACYANOPLATINATE BROMIDE HYDRATE AND BARIUM VANADIUM TRISULFIDE *

One of the most important and, a t the same time, difficult questions to resolve in the study of quasi-one-dimensional materials is the specific nature of the 3-d interactions that are responsible for the coherent phasing of physical properties associated with individual I-d stacks or chains. In the partially oxidized tetra~yanoplat inates , ' -~ hydrogen bonding and the acid-base interactions between the cation and the cyanide nitrogen atom lone-pair electrons define the structure in a three-dimensional sense and are apparently responsible for the type of periodicity obtained in the insulating state.5 ' The most studied of the partially oxidized tetracyanoplatinates, in terms of both structural and physical properties, is K2[ Pt(CN),]Br,,, 3H20(KCP(Br)). This compound undergoes a very gradual transition from metallic to insulating behavior' and displays evidence of an infrared active Frijhlich mode"' a t low temperatures. Theorizing, in accordance with the well-known theorem of Landaulo that the phase transition in KCP(Br) might be sharper if there were more cross linking between the platinum chains to enhance the three-dimensional nature of the system, we have substituted the large