Magnetic feature and near-infrared absorption of a [Pt(mnt)2]--based H-bond supramolecular crystal

A new salt [H2DABCO][Pt(mnt)2]2 (1) (mnt2-=maleonitriledithiolate and H2DABCO2+ is diprotonated 1,4-diazabicyclo[2.2.2]octane) has been synthesized; its crystal structure, magnetic and near-IR absorption properties have been investigated. Two different [Pt(mnt)2]- anions form the strong π-dimers, labeled as Pt(1)-dimer and Pt(2)-dimer, with quite shorter Pt…Pt and S…S distances and molecular plane-to-plane distance (<3.5Å) within a dimer. The [Pt(mnt)2]22- π-dimers are connected through the cations in the strong H-bond manner to form three-dimensional H-bond supramolecular crystal. The salt shows weak paramagnetism in 1.99–300K and this is due to the existence of strong antiferromagnetic coupling within a π-dimer. In addition, a small thermal hysteresis loop is observed at ca. 120K, indicating that a phase transition probably occurs that is further confirmed by variable-temperature IR spectra. Another fascinating functionality of 1 is the intense near-IR absorption in the region of 750–2500nm, and this near-IR absorption feature makes it to be a promising optical material.