Novel Main Group-Transition Metal Cluster Compounds Incorporating Antimony, Iron and Cobalt

Abstract

The reaction of [{Cpx(CO)2Fe}SbCl2] [1a: Cpx = η5‐C5H3tBu2‐1,3 (Cp"); 1b: Cpx = η5‐C5Me5 (Cp*)] with Na2[Fe(CO)4] or K[Co(CO)4] affords the novel antimony‐transition metal cluster compounds [{μ3‐SbFe(CO)2Cp"}3{Fe(CO)3}4] (2), [{Fe3(CO)9}{μ3‐SbFe(CO)2Cp"}2] (3) and [{μ4‐SbFe(CO)2Cp*}2{Co4(CO)10(μ‐CO)}] (4). All products were characterised by X‐ray structure analyses and other methods. Cluster 2 reveals a novel Sb3Fe4 core, which does not follow the Wade−Mingos rules. Cluster 3 forms a square‐pyramidal nido‐cluster. The Sb2Co4 cluster core of 4 derives from a pentagonal bipyramid and consists of apical Sb and equatorial Co atoms with one missing pentagonal core atom.

Transfer of polyantimony units

“…12,[34][35][36][37] A remarkable difference between the geometry of 4 and 5 is represented by the M-M distances. While, in 4, the Co-Co distances are all very similar (2.7284(6)Å to 2.7332(5)Å) and lie in the same range of elongated single bonds, 33,43 in 5, there are one short (2.4489(6)Å and 2.4895(6)Å) and two longer Fe-Fe distances (2.8076(6)Å to 2.9230(6)Å). 44 Interestingly, the nitrogen congener of 5, [(Cp 000 Fe) 3 (m 3 -N) 2 ], possesses uniform Fe-Fe distances varying from 2.4727(4)Å to 2.4734(4)Å, 45 while the phosphorus and arsenic derivatives [(Cp*Fe) 3 (m 3 -E) 2 ] (E ¼ P, As) 46 show a distortion of the Fe 3 fragment that is similar to 5, but less accentuated.…”

Extension and Fusion of Cyclic Polyantimony Units

“…Compared with the Ru–Sb bonds in the cluster [RuSb 15 ] 3– (2.5964–2.7200 Å), the Ru–Sb bond lengths in [RuSb 13 ] 3– fall into a larger range of 2.5535–2.7347 Å, thus being shorter than those of [Sb 6 (RuCp*) 2 ] 2– (2.6848–2.7903 Å) . There are only a limited number of examples for which to compare Fe–Sb bonds with literature data because only a few organometallic compounds exist, such as [{Fe 3 (CO) 9 }­{μ 3 -SbFe­(CO) 2 Cp″} 2 ] (2.5075–2.5607 Å) and [Fe 2 Sb­(CO) 5 Cp] 4 (2.6136–2.6581 Å), which are comparable to those in the cluster [FeSb 15 ] 3– (2.5251–2.6769 Å). , It is worth noting that some of the coordination modes of the metal-Sb n frameworks show similarities between the cluster [(NbCp) 2 Sb 10 ] 2– and the clusters [MSb 13 ] 3– and [MSb 15 ] 3– (M = Fe/Ru). As shown in Figures c and d, one central atom is coordinated by two Sb–Sb units and one Sb atom.…”

New Main-Group-Element-Rich nido-Octahedral Cluster System: Synthesis and Characterization of [Et4N][Fe2(CO)6(μ3-As){μ3-EFe(CO)4}2]

“…The related M 3 E 2 nido- octahedral compounds have been known for some time, − and the compounds reported here may be viewed as an isolobal replacement of Fe­(CO) 3 – by P or As. [Et 4 N]­[ II ] and [Et 4 N]­[ III ] are electron precise, and the core electron count of each is consistent with that predicted by the Wade–Mingos rules for a nido- octahedron with seven skeletal electron pairs distributed across five vertices …”