Synthesis, structure and optical limiting effect of two new nickel complexes containing strongly bound geometrically fixed multisulfur 1,2-dithiolene ligands showing remarkable near-IR absorption

Abstract

Two new nickel complexes containing strongly bound multi-sulfur'1,2-dithiolene ligands, [NBu4][Ni(bddt)2] 1 and [Ni(bddt)2] 2 (bddt=4a,5,6,7,8,8a-hexahydro-l,4-benzodithiin-2,3-dithioIate), have been synthesized and characterized by electrochemical measurements, IR and UV-VIS-NIR spectroscopies. The optical limiting properties of these nickel complexes have been determined with 32 ps laser pulses of 532 nm wavelength. The limiting thresholds of 1 and 2 are ca. 0.6 and 0.7 J cm-2, respectively, which are comparable to that observed in C60. Such results show that the nickel dithiolene complexes may be new candidates for optical limiting applications. In addition, the neutral complex [Ni(bddt)2] 2, which shows remarkable absorption in the near-IR region (ε = 63000dm3mol-1 cm-1 at 1035 nm) and is an excellent candidate as a near-IR dye for Q-switching neodymium lasers, has been additionally characterized by X-ray diffraction.