Τίτλος:
Investigating the Structural, Spectroscopic, and Electrochemical
Properties of [Fe(EPiPr(2))(2)N(2)] (E = S, Se) and the Formation
of Iron Selenides by Chemical Vapor Deposition
Περίληψη:
The anionic L = [(EPiPr(2))(2)N](-) (E = S, Se) form of the
dichalcogenidoimidodiphosphinato-type ligands containing iPr peripheral
groups has been shown previously to afford tetrahedral [(ML2)-L-II]
complexes (E = S, M = Mn, Co, Ni, Zn; E = Se, M = Co, Ni, Zn). The
syntheses of the analogous [FeL2] complexes [E = S (1), Se (2)] were
performed in this work through metathesis reactions between FeCl2 and
the corresponding KL salts. For both 1 and 2, X-ray crystallography
revealed two distinct molecules in the asymmetric unit. Complexes 1 and
2 are isostructural and exhibit P-E and P-N bond-length differences
compared with those of the free ligands, and these differences are
translated into shifts of the corresponding IR bands. Cyclic voltammetry
studies showed that the Fe-II Fe-III oxidation in 2 occurs at a lower
potential than that of 1. The zero-field Mossbauer spectra of the two
complexes are quite similar and provide evidence of similar S = 2
electronic structures. The observation of crystallographically distinct
(FeE4)-E-II sites for both 1 and 2 is also revealed in the corresponding
Mossbauer spectra. Complex 2 was employed as a single-source precursor
in catalyst-aided chemical vapor deposition experiments, which afforded
the iron selenides FeSe and Fe3Se4.