Synthetic and Structural Investigations on Double- and Single-Butterfly Fe/E (E = S, Se) Cluster Complexes Containing Diselenolate Ligands

Abstract

The first examples of diselenolate ligand-containing butterfly Fe/E (E = S, Se) complexes are now reported. When ca. 1 equiv of dilithium reagent 4-LiC 6 H 4 C 6 H 4 Li-4‘ containing n -BuBr (prepared from 1 equiv of 4,4‘-dibromobiphenyl and n -BuLi) was treated with 2 equiv of elemental selenium and Fe 3 (CO) 12 followed by treatment with excess CS 2 and MeI, both double-butterfly complex (4- μ -SeC 6 H 4 C 6 H 4 Se- μ -4‘)[( μ -S CSMe)Fe 2 (CO) 6 ] 2 ( 4 ) and single-butterfly complex (4- n -BuSeC 6 H 4 C 6 H 4 Se- μ -4‘)[( μ -S CSMe)Fe 2 (CO) 6 ] ( 4* ) were produced in 11% and 20% yields, respectively. However, when ca. 1 equiv of dilithium reagent 4-LiC 6 H 4 C 6 H 4 Li-4‘ without n -BuBr ( n -BuBr was removed by evaporation of the initially prepared dilithium reagent containing n -BuBr) reacted with 2 equiv of elemental selenium and Fe 3 (CO) 12 followed by treatment with excess CS 2 and MeI, only the double-butterfly complex 4 was obtained in a higher yield (21%) without any single-butterfly complex being isolated. Other double-butterfly complexes, such as (4- μ -SeC 6 H 4 C 6 H 4 Se- μ -4‘)[( μ -S CSR)Fe 2 (CO) 6 ] 2 ( 5, R = Et; 6, PhCH 2; 7, PhC NPh; 8, Cp(CO) 2 Fe), (4- μ -SeC 6 H 4 C 6 H 4 Se- μ -4‘)[( μ -SePh)Fe 2 (CO) 6 ] 2 ( 9 ), and (4- μ -SeC 6 H 4 C 6 H 4 Se- μ -4‘)[( μ -CH 2 SMe)Fe 2 (CO) 6 ] 2 ( 10 ), could be similarly prepared via the latter method by using electrophiles CS 2 /EtBr, CS 2 /PhCH 2 Br, CS 2 /PhC(Cl) NPh, CS 2 /Cp(CO) 2 FeI, PhSeBr, and MeSCH 2 Cl instead of CS 2 /MeI, respectively. A possible pathway for production of the double- and single-butterfly complexes 4 − 10 and 4* has been proposed, in which the versatile two- μ -CO-containing double-butterfly dianion (4- μ -SeC 6 H 4 C 6 H 4 Se- μ -4‘)[(μ-CO)Fe 2 (CO) 6 ] 2 2 - ( 3 ) and the one- μ -CO-containing single-butterfly monoanion (4- n -BuSeC 6 H 4 C 6 H 4 Se- μ -4‘)[(μ-CO)Fe 2 (CO) 6 ] - ( 3* ) are involved. All the new complexes were fully characterized by elemental analysis and spectroscopy, as well as by X-ray crystallography for 4* and 10 .