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

Abstract

Two new nickel complexes containing strongly bound multi-sulfur 1,2-dithiolene ligands, [NBu 4 ][Ni(bddt) 2 ] 1 and [Ni(bddt) 2 ] 2 (bddt = 4a,5,6,7,8,8a-hexahydro-1,4-benzodithiin-2,3-dithiolate), 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 C 60 . 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 (e = 63 000 dm 3 mol –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.