五配位铁硫化合物(Et4N)4〔Fe2(S,X-C6H4-o)4〕的合成与晶体结构

利用无水FeCl与双齿配体Na_2BDT或Na_2MP(Na_2S,X-C,H_4-o_2:X=S,BDT;X=O,MP)在乙醇溶液中反应,然后加入沉淀剂Et_4NBr,可以得到双核铁硫化合物(Et_4N)_2[Fe_(S,X-CH_4-o)_4](1,X=S;2,X=0)。它们分别具有以双硫或双氧桥联起来的五配位扭曲三角双锥构型的铁原子。分子为心对称,核心Fe_2X_2~(2+)为平面。每个铁原子上的二个苯环平面A和B相互近于平行(1,二面角10.1°)或近于垂直(2,二面角100.2°);但铁原子与XSCC平面非共面。Fe原子离平面0.05～0.5A。2是第一个以双齿配位的双氧桥铁硫化合物,它既含有桥基氧原子又具有端基氧原子,对研究含氧配位的铁原子周围环境,为模拟固氧酶中的“P簇”,有一定意义。

SYNTHESIS AND CRYSTAL STRUCTURES OF FIVE-COORDINATE IRON-SULFUR COMPLEXES (Et4N)[Fe2(S,X-C0H4-o)4]

By reaction of anhydrous FeCl₃ and Xa₂BDT or Na₂MP(Na₂S, X-C₆H₄-o: X = S, BDT;X = O, MP) in absolute ethanol, and on addition of Et₄NBr, black crystalline products of (Et₄N)₂[Fe₂(S ,X-C₆H₄-o)] (1,X = S; 2, X = O) were obtained in high yields . Both 1 and 2·2CH₂CX are cen-trosymmetric and have distorted trigonal bipyramidal Fe atoms bridged by disulfur or dioxygen atoms respectively forming planar Fe₂X₂²⁺ rhombs. The two apical atoms X₁ and X₂ form bond angles with Fe atom of 166.6 (1) and 17.1.8°(2). The Fe atom is above the basal plane of the pyramid by 0.0036Å and 0.177Å respectively. The two benzene rings A and B on each Fe atom are either parallel (1, dihedral angle 10.1°) or perpendicular (2, dihedral angle 100.2°) to each other. This result may be caused by the different atomic diameter and electronegativity of sulfur and oxygen atoms. Compound 2 is the first dioxobridged five-coordinate iron-sulfur compound w ith bidentate ligand, which has both terminal and bridging oxygen atoms and is important in the study of the 'P cluster' of nitro-genase.