Pressure-induced spin-state isomerizations in weakly tetragonal Nickel(II) complexes with diethylthiourea

Abstract

The ability of high pressure to influence spin-state equilibria in (Ni(detu){sub 4}X{sub 2}) (detu = N,N{prime}-diethylthiourea; X = Cl, Br, I) is demonstrated. The complexes are six-coordinate and weakly tetragonal. An equilibrium between singlet and triplet isomers is present. High-pressure shifts the equilibrium toward the triplet isomer in each complex. The equilibria are monitored spectroscopically. The results represent the first examples of low-spin to high-spin conversion via pressure-induced changes in molecular geometry.