Recent studies on chemistry of novel μ-CO-containing butterfly Fe/E (E = S, Se, Te) cluster salts

Abstract

This article describes recent developments in chemical study on a series of butterfly-shaped μ-CO-containing Fe/E (E = S, Se, Te) cluster salts. These salts include eleven novel cluster anions, which are the single butterfly one μ-CO-containing [(μ-RE)(μ-CO)Fe 2 (CO) 6 ] − (A), the double butterfly two μ-CO-containing {[(μ-CO)Fe 2 (CO) 6 ] 2 (μ-EZE-μ)} 2− (B, E = S; C, E = Se), the triple butterfly three μ-CO- containing {[(μ-CO)Fe 2 (CO) 6 ] 3 [(μ-SCH 2 CH 2 ) 3 N]} 3− (D), {[(μ-CO)Fe 2 (CO) 6 ] 3 [1,3,5-(μ-SCH 2 ) 3 C 6 H 3 ]} 3− (E), {[(μ-CO)Fe 2 (CO) 6 ] 3 [(μ-SCH 2 ) 3 CMe]} 3− (F), the double butterfly one μ-CO-containing {[(μ-CO)Fe 2 (CO) 6 ] [Fe 2 (CO) 6 ][(μ-SCH 2 ) 3 CMe]} − (G) derived in situ from F, the quadruple butterfly four μ-CO-containing {[(μ-CO)Fe 2 (CO) 6 ] 4 [1,2,4,5-(μ-SCH 2 ) 4 C 6 H 2 ]} 4− (H), the triple butterfly two μ-CO-containing {[(μ-CO)Fe 2 (CO) 6 ] 2 [Fe 2 (CO) 6 ][1,2,4,5-(μ-SCH 2 ) 4 C 6 H 2 ]} 2− (I) derived in situ from H, the quadruple butterfly four μ-CO-containing {[(μ-CO)Fe 2 (CO) 6 ] 4 [(μ-SCH 2 ) 4 C]} 4− (J), and the triple butterfly two μ-CO-containing {[(μ-CO)Fe 2 (CO) 6 ] 2 [Fe 2 (CO) 6 ][(μ-SCH 2 ) 4 C]} 2− (K) derivedin situ from J. This article describes not only the synthetic methods for formation of such anionic cluster (A-K) salts, but also their novel reactions leading to various new types of butterfly Fe/E cluster complexes. All these findings described in this article are important both theoretically and practically.

Synthesis, Structure, and Electrocatalysis of Butterfly [Fe2SP] Cluster Complexes Relevant to [FeFe]-Hydrogenases

“…The synthetic routes for preparing the target [Fe 2 SP] model complexes 1 – 5 are primarily based on the well-known chemical reactivity of the μ-CO-containing complex salts [Et 3 NH]­[(μ-CO)­(μ - SR)­Fe 2 (CO) 6 ] , as well as the familiar functional transformation and CO substitution reactions included in organometallic and coordination chemistry. , Thus, as shown in Scheme , (i) when the μ-CO-containing complex salt [Et 3 NH]­[(μ-CO)­(μ - SCH 2 CH 2 OH)­Fe 2 (CO) 6 ] ( m 1 ) formed from Fe 3 (CO) 12 , HSCH 2 CH 2 OH, and Et 3 N was treated in situ with electrophile PCl 3 (via nucleophilic attack of the negatively charged Fe atom of intermediate m 1 at the P atom of PCl 3 ) followed by intramolecular cyclization of the resulting intermediate m 2 with the aid of Et 3 N/DBU, the all-carbonyl [Fe 2 SP] complex 1 was produced in 24% yield; (ii) functional transformation of the isolated complex 1 with PhOH in the presence of NaH in refluxing THF gave the corresponding PhO group-containing model complex 2 in 92% yield; (iii) similar to 1 , the all-carbonyl model complex 3 could be prepared in 34% yield by in situ reaction of m 1 with PPhCl 2 followed by intramolecular cyclization of the resulting m 3 with the aid of Et 3 N/DBU; and (iv) further CO substitution of the isolated 3 with PPh 3 or PPh 2 H in the presence of decarbonylating reagent Me 3 NO in MeCN at room temperature afforded the corresponding phosphine-monosubstituted model complexes 4 and 5 in 96% and 86% yields, respectively. It should be noted that the reactive intermediate m 1 has been isolated and fully characterized by elemental analysis and IR, 1 H NMR, and 13 C­{ 1 H} NMR spectroscopy (see Experimental Section).…”

Synthesis of Diiron(I) Dithiolato Carbonyl Complexes

“… − The formulas for these monothiolato diiron(0) species are sometimes more explicitly written as [Fe 2 (μ-SR)­(μ-CO)­(CO) 6 ] − , which highlights their structural similarity to Fe 2 (μ-SR) 2 (CO) 6 . The salts Et 3 NH­[Fe 2 (μ-SR)­(CO) 7 ] convert to the diiron­(I) dithiolates, usually in low yields, upon heating − and with weak oxidants and electrophiles. − These diiron(0) anions are oxidized by S 8 to give what are proposed to be diiron­(I) anions. Thus, treatment of [Fe 2 (μ-SEt)­(CO) 7 ] − with sulfur followed by methylation with MeI gave both Fe 2 (μ-SEt) 2 (CO) 6 and Fe 2 (μ-SMe)­(μ-SEt)­(CO) 6 (Scheme ).…”

Diiron Dichalcogenolato (Se and Te) Complexes: Models for the Active Site of [FeFe] Hydrogenase

“…Recently, we and others paid attention to model complexes containing the heavier chalcogens such as Se or Te instead of sulfur. [52][53][54][55][56][57][58][59][60] Herein we highlight recent work on this topic, in order to give the reader an overview of the consequences of substituting selenium or tellurium in lieu of sulfur in dichalcogenolato [FeFe] hydrogenase model compounds.…”