Abstract
Trigonal bipyramidal {Fe(NO)} 7 complex [(NO)Fe(SC 9 H 6 N) 2 ] (2) with NO ligand occupying equatorial position, obtained from nitrosylation of complex [(Cl)Fe(SC 9 H 6 N) 2 ] - (1) accompanied by elimination of [Cl] - , was characterized by IR, UV-Vis, EPR, SQUID and single-crystal X-ray diffraction. Compared to the S = 3/2 ground state displayed by the trigonal bipyramidal complex [Et 4 N][(ON)Fe(N- (CH 2 CH 2 S) 3 )], the chelating ligands ([SC 9 H 6 N] - ) play a key role in modulating the position of exogenous NO ligand and controlling the spin state of complex 2 (S = 1/2). In contrast to nitrosylation of [Fe(NO)(SPh) 3 ] - MNIC yielding [Fe(NO) 2 (SPh) 2 ] - DNIC, the inertness of complex 2 toward NO (g) was observed. Reaction of [NO][BF 4 ] and complex 2 in a 1:1 stoichiometry led to the formation of homodinuclear {Fe(NO)} 7 -{Fe(NO)} 9 complex [(ON)Fe(-SC 9 H 6 N) 2 Fe(NO) 2 ][BF 4 ] (3) characterized by IR, UV-vis, 1 H NMRand single-crystal X-ray diffraction. Antiferromagnetic coupling between the S = 1/2 {Fe(NO)} 7 [S 2 Fe(NO) 2 ] core and the S = 1/2 {Fe(NO)} 7 [(NO)FeS 2 N 2 ] core may account for the diamagnetism and the EPR silence of complex 3. This study provides the evidence that the geometric and electronic structures of {Fe(NO)} 7 MNICs modulated by the coordination environment of iron center determines the nitrosylation products.