Extended X‐ray absorption fine structure and multiple‐scattering simulation of nickel dithiolene complexes Ni[S 2 C 2 (CF 3 ) 2 ] 2 n ( n = −2, −1, 0) and an olefin adduct Ni[S 2 C 2 (CF 3 ) 2 ] 2 (1‐hexene)

A series of Ni dithiolene complexes Ni[S 2 C 2 (CF 3 )] 2 n ( n = −2, −1, 0) ( 1 , 2 , 3 ) and a 1‐hexene adduct Ni[S 2 C 2 (CF 3 ) 2 ] 2 (C 6 H 12 ) ( 4 ) have been examined by Ni K ‐edge X‐ray absorption near‐edge structure (XANES) and extended X‐ray absorption fine‐structure (EXAFS) spectroscopies. Ni XANES for 1 – 3 reveals clear pre‐edge features and approximately +0.7 eV shift in the Ni K ‐edge position for `one‐electron' oxidation. EXAFS simulation shows that the Ni—S bond distances for 1 , 2 and 3 (2.11–2.16 Å) are within the typical values for square planar complexes and decrease by ∼0.022 Å for each `one‐electron' oxidation. The changes in Ni K ‐edge energy positions and Ni—S distances are consistent with the `non‐innocent' character of the dithiolene ligand. The Ni—C interactions at ∼3.0 Å are analyzed and the multiple‐scattering parameters are also determined, leading to a better simulation for the overall EXAFS spectra. The 1‐hexene adduct 4 presents no pre‐edge feature, and its Ni K ‐edge position shifts by −0.8 eV in comparison with its starting dithiolene complex 3 . Consistently, EXAFS also showed that the Ni—S distances in 4 elongate by ∼0.046 Å in comparison with 3 . The evidence confirms that the neutral complex is `reduced' upon addition of olefin, presumably by olefin donating the π‐electron density to the LUMO of 3 as suggested by UV/visible spectroscopy in the literature.