Deprotonation/protonation-driven change of the sigma-donor ability of a sulfur atom in iron(II) complexes with a thioamide SNS pincer type ligand

作者：Suzuki Tatsuya; Kajita Yuji; Masuda Hideki^*

来源：Dalton Transactions, 2014, 43(25): 9732-9739.

DOI：10.1039/c4dt00524d

A new iron complex with a thioamide SNS pincer type ligand, [FeBr2(kappa(3)-H2LDPM)] (kappa(3)-H2LDPM = 2,6-bis(N-2,6- bis(diphenylmethyl)-4-isopropylphenylthioamide) pyridine), was synthesized. This complex reacts with NaH in THF to yield a unique Fe(II) complex with two THF molecules, [Fe(THF)(2)(kappa(3)-L-DPM)] (kappa(3)-L-DPM = 2,6-bis( N-2,6-bis(diphenylmethyl)-4-isopropylphenyliminothiolate) pyridine). The THF molecules of [Fe-( THF)(2)(kappa(3)-L-DPM)] can be substituted with CO and CN-xylyl to give [Fe(CO)(3)(kappa(3)-L-DPM)] and [Fe(CN-xylyl)(3)(kappa(3)-L-DPM)], respectively. The complex [Fe(CN-xylyl)(3)(kappa(3)-L-DPM)] reacts with HBF4 to produce [Fe(CN-xylyl)(3)(kappa(3)-H2LDPM)](2+) with protonated thioamide units. The differences of the IR spectra before and after protonation indicate that the major binding mode of CN-xylyl to iron(II) changes from pi-back donation from metal to isocyanide to sigma-donation from isocyanide to iron(II). This indicates that the sigma-donor ability of the thioamide sulfur atom is tuned by deprotonation/protonation of thioamide.

• 出版日期2014