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

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 Mel, 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 Mel, 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 / Mel, 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.