Transition metal complexes with sulfur ligands. XXXVIII. 18 and 19 electron iron(II) nitrosyl complexes with thiolato thioether ligands including nitrogen and oxygen donators in S 5, OS 4, NS 4, S 4 and S 3 donator sets: synthesis and reactions of [Fe(NO)(‘S 5’)] n+, [Fe(NO)(‘N HS 4’)] n+ ( n=0,1) and [Fe(NO) 2(L)] and X-ray structure analysis of [Fe(NO)(‘N HS

Abstract

In order to investigate the coordination and activation of nitrogen monoxide by iron centers in a coordination sphere dominated by sulfur, a series of new iron nitrosyl complexes has been synthesized. The monomtrosyl Fe II complexes [Fe(NO)(‘S 5’)]BF 4 and [Fe(NO)(‘N HS 4’)]BF 4 with the pentadentate ligands ‘S 5’ 2−=1,5-bis-(2-mercaptophenylthio)-3- thiapentane(2−) or ‘N HS 4’ 2−=1,5-bis-(2-(2-mercaptophenylthio)ethyl)amine(2−) are obtained from NOBF 4 and [Fe(CO)(‘XS 4’)] (XS, NH). If these and related carbonyl complexes are reacted with gaseous nitrogen monoxide the dinitrosyl complexes [Fe(NO) 2(L)] are isolated with L=‘S 5’ 2−, ‘OS 4’ 2−= 1,5-bis(2-(2-mercaptophenylthio)ethyl)ether(2−), ‘S 4’ 2−=2,3,8,9-dibenzo-1,4,7,10-tetrathiadecane(2−) and ‘S 3’ 2−=1,4,7-trithiaheptane(2−). Reacting [Fe(NO)(‘XS 4’)]BF 4 with N 2H 4 or N 3 − does not lead to a nucleophilic attack at NO, but to a reduction yielding the neutral 19 electron species [Fe(NO)(‘XS 4’)] (XNH, S); the reaction between [Fe(NO)(‘S 5’)]BF 4 and hydroxylamine gives the dinitrosyl species [Fe(NO) 2(‘S 5’)] again. The formation of the different products is explained by a primary reaction resulting in the 19 electron complexes [Fe(NO)(‘XS 4’)] ·, (XS, NH); they are either isolated or react with another NO (e.g. from gaseous NO or NH 2OH) yielding the dinitrosyl species in which S or X donators are decoordinated. This is supported by the reaction of [Fe(NO)(‘S 5’)]BF 4 with sodium borohydride resulting again in [Fe(NO)(‘S 5’)]. A 19 electron intermediate forms also in the reaction between [Fe(NO)(‘XS 4’)]BF 4, XS, NH and PMe 3 leading to a substitution-reduction product [Fe(PMe 3)(‘XS 4’)] under smooth conditions. The [Fe(NO)(‘XS 4’)] species (XS, NH) are paramagnetic (μ eff=2.36 and 2.13 BM respectively); all other complexes are diamagnetic and were characterized by spectroscopic means and elemental analyses. [Fe(NO)(‘N HS 4’)] crystallizes in space group P2 1/ c with a=1262.7(6), b=744.9(7), c=1988.6(9) pm, β=106.45(4)°, Z=4 and D calc=1.60 g/cm 3 R=0.067, R w=0.058. The lion center is pseudo- octahedrally coordinated by four S atoms in a plane and two trans N atoms; the FeNO group is strongly bent (147.2(7)°). Bond distances and angles of the [FeN 2S 4] core indicate that the odd electron occupies a molecular orbital of π *(NO) as well as [FeN HS 4] character.