Tetrakis-pentamethylcyclopentadienyl-cyclotetrastiban (PcpSb)₄ : Synthese, Molekül-und Kristallstruktur / Tetrakis-pentamethylcyclopentadienyl-cyclotetrastibane (PcpSb)₄ : Synthesis, Molecular and Crystal Structure

Abstract

<jats:title>Abstract</jats:title><jats:p>Reaction of SbCl<jats:sub>3</jats:sub> with KPcp (Pep = pentamethylcyclopentadienyl) in etheral solution at -78 °C affords dimeric pentamethylcyclopentadiene and orange-red (PcpSb)<jats:sub>4</jats:sub> in high yield. <jats:sup>1</jats:sup>H, <jats:sup>13</jats:sup> C NMR, IR, UV and mass spectra are reported. The tetrameric structure was found by a crystal structure determination carried out with X-ray diffraction data collected at -50 °C (928 independent observed reflexions. R = 0.055). Crystal data: tetragonal, space group I4<jats:sub>1</jats:sub>/amd, a = 2400.0(5), c = 781.7(5) pm, Z = 4. The (PcpSb)<jats:sub>4</jats:sub> molecules have a non-planar Sb<jats:sub>4</jats:sub> ring with Sb -Sb bond lengths of 285.6(1) pm, one η<jats:sup>1</jats:sup>-Pcp ring is attached to each Sb atom. Contrary to the solid state structure, monomeric molecules are found in benzene and hexane solutions.</jats:p>

Syntheses and chemistry of hypervalent cyclo-R4Sb4, cyclo-(RSbE)n[R = 2-(Me2NCH2)C6H4, E = O, S] and precursors

“…45 The drawings were created with the Diamond program. 46 CCDC reference numbers 241384 (1), 241385 (2), 229634 (3), 229637 (4), 229636 (5), 229635 (6), 241386 (7) and 241387 (9).…”

“…Over the last decades the investigation of organoantimony oligomers, R n Sb n , has revealed an extraordinary diversity of structural features and of the chemical behaviour of cyclic and noncyclic systems under a strong influence of the organic substituents. [1][2][3][4][5][6] Bulky groups [R = t Bu, 7 Mes, 8 Cp*, 9,10 (Me 3 Si) 2 CH 11,12 ] protect four-membered rings, cyclo-R 4 Sb 4 , and preserve the ring size on phase transition. 3 In contrast, when aromatic groups, e.g.…”

“…We report here on the synthesis and structural characterisation of the novel four-membered arylantimony ring, cyclo- (6), I ( 7); E = S, X = Cl (8), Br (9)] is also described.…”

Synthesis of polyantimony ligand complexes starting from Cp*4Sb4

“…All Sb-Sb distances are between 2.8384(3) Å and 2.8654(3) Å and are in the range of single bonds 15,17,20,21 and match the values reported for 1. 27 The Sb 4 ring is not planar and shows a folding angle of 119.761. Within the distorted ring, Sb-Sb-Sb angles from 81.438(9)1 to 81.866(9)1 are observed.…”

“…Due to the bulkier iron fragments, they are slightly smaller than the values for 1. 27 Aside from 1, cyclo-Sb 4 units are known, but only with organic 26,[28][29][30][31][32][33][34] or pnictogen 35,36 substituents. Therefore, all the compounds 7 represent novel coordination compounds containing a cyclo-Sb 4 unit.…”