Cubane‐Like Bismuth‐Iron Cluster: Synthesis, X‐ray Crystal Structure and Theoretical Characterization of the [Bi₄Fe₈(CO)₂₈]^4– Anion

Abstract

The reaction of cyclo‐Bi4[Si(SiMe3)3]4 (1) with Na2[Fe(CO)4] in the presence of nBu4NCl leads to the formation of the cage compound [nBu4N]4[Bi4Fe8(CO)28] (2). According to X‐ray single‐crystal structure analysis, the faces of the tetrahedral Bi4 core are capped by Fe(CO)3 moieties in a μ3 fashion to give a cubanoid Bi4Fe4 framework. The four Fe(CO)4 fragments are μ1‐coordinated to bismuth, each. With 12 skeletal electron pairs the [Bi4Fe8(CO)28]4– anion (2a) is a Bi4Fe4 cubane. The negative charge is localized within cluster 2a according to the NBO analysis of its derivatives. The strength of metal–ligand interactions Bi–μ3‐Fe(CO)3 is responsible for the size of the cluster's cubic core. NICS computations at the cage centers of considered molecules show that 2a has paratropic character, whereas removal of four μ1‐Fe(CO)4 fragments from latter causes spherical aromaticity of the modified clusters [Bi4Fe4(CO)12]4– (2aa) and [Bi4Fe4(CO)12]2+ (2ab), mediated by a Bi4 cluster π orbital.

Novel carbonyl iron–bismuth clusters – synthesis, structure, CO2 insertion and potential as molecular precursors for BiFeO3

“…The NPA charges at the bismuth atoms are in the range from þ1.265 to þ1.356 which is in accordance with the NPA charge of the bismuth atoms in the cluster [Bi 4 Fe 8 (CO)28 ] 4À (Q NPA þ 1.285)[15].Also the Wiberg bond indices for the BieBi bonds in both compounds are comparable (3: WBI BieBi 0.108e0.118; [Bi 4 Fe 8 (CO) 28 ] 4À : WBI BieBi 0.112). Due to the difference in the overall charge of both clusters the NPA charge on the m 3 -coordinated Fe atoms differ significantly as do the Wiberg bond indices for the Biem 3 Fe bonds (3: Q NPA (Fe) þ 0.090, WBI Biem3Fe 0.500e0.545; [Bi 4 Fe 8 (CO) 28 ] 4À : Q NPA (Fe) À2.244, WBI Biem3Fe 0.615).…”

“…However, bismutheiron carbonyl clusters are well known and a variety of complexes such as Bi 2 Fe 3 (CO) 9 , [Bi{Fe(CO) 4 } 4 ] 3À , [BiFe 3 (CO) 10 ] À , [BiFe 3 (CO) 9 (COMe)], [Bi 2 Fe 4 (CO) 13 ] 2À , [Bi 4 Fe 4 (CO) 13 ] 2À and [Bi 2 Fe 3 (CO) 9 ] 2À have been reported previously [8e14]. Recently, an even larger anionic cluster composed of twelve metal atoms, [Bi 4 Fe 8 (CO) 28 ] 4À [15], and formerly, compounds such as [{Fe 3 (CO) 9 {BiFe(CO) 2 Cp 00 }] (Cp 00 ¼ h 5 -C 5 H 3 t Bu 2 ) were also investigated [16]. Quite a large number of compounds with transition metalebismuth bonds is known to date [17] and the first attempt to prepare the organobismutheiron complex (CO) 4 FeBiPh 3 by the reaction of Ph 3 Bi with Fe(CO) 5 was reported already in 1941.…”

Transition metal complexes of the naked pnictide elements

“…Normally, silyl reagents would be treated with metal halide or alkoxide complexes to remove the silyl groups, but in the formation of [(n-Bu)4N]4[Fe4(CO)12Bi4{Fe(CO)4}4], loss of silyl groups from Bi4[Si(SiMe3)3]4 is initiated by (nBu)4NCl followed by condensation with Na2[Fe(CO)4]. 62 The yield is low and presumably more complex redox processes are involved.…”

Nitrogen, phosphorus, arsenic, antimony and bismuth

“…122 ] which has a tetrahedral Bi 4 core with each face bridged by a Fe(CO) 3 group and an additional Fe(CO) 4 Z 1 -coordinated to each Bi. 123 The reaction of [Os 3 (CO) 11 (NCMe)] with BiPh 3 has been shown to give a number of products including [Os 2 (CO) 8 (m-BiPh)] which contains two Os-Bi bonds. 124 The synthesis of the bismuth azides Bi(N 3 ) 3 , [Bi(N 3 ) 4 ] À and [Bi(N 3 ) 6 ] 3À has been reported.…”