Dichroic Palladium Dithiolate Coordination Polymers

An isomorphous series of coordination polymers with thegeneralformula M(H2O)(4)[Pd(iso-maleonitriledithiolate)(2)]& BULL;2H(2)O (M = Mn, Co, Zn) was structurally characterized.They exhibit a 1-D zig-zag chain structure which further interactsvia hydrogen bonding to form a highly aligned 2-D array of 1-D chainsin the solid state. Single crystals are moderately pigmented orangein color when viewed under unpolarized visible light, but under plane-polarizedlight, they are dichroic down the 001 face, with a change in colorfrom red to yellow upon rotation by 90 & DEG;. Solid-state polarizedabsorption and, for the Zn-analogue, unpolarized emission spectraare reported and assigned as an MLCT transition and a d-d transitioninvolving an excited triplet state with the LUMO (dx (2)-y (2)) populated by one electron,respectively. These materials represent the first transition-metalcoordination polymers that incorporate the [Pd(i-mnt)(2)](2-) building block. The coordination polymers M(H2O)(4)[Pd(iso-maleonitriledithiolate)(2)]& BULL;2H(2)O (M = Mn, Co, Zn) are 1-D zig-zag chainsthat are highly alignedvia hydrogen bonding to yield strong visible dichroism under plane-polarizedlight.

Automated summary

This is a study on coordination polymers, which are found to have a 1-D zig-zag chain structure that interacts via hydrogen bonding to form a highly aligned 2-D array. These materials represent the first transition-metal coordination polymers that incorporate the [Pd(i-mnt)(2)](2-) building block.