1,16‐Di‐tert‐butyl‐1,16‐diphospha[5.5]ferrocenophane: Synthesis, Reactions and Mössbauer Spectroscopy

Abstract

1,16‐Di‐tert‐butyl‐1,16‐diphospha[5.5]ferrocenophane was prepared in 76% yield by deprotonation of 1,1’‐di(2‐tert‐butylphosphanylethyl)ferrocene followed by treatment with 1,1’‐di(2‐bromoethyl)ferrocene. The ferrocenophane exists as a mixture of syn and anti diastereomers, which were separated by repeated precipitation of one of them. Reaction with borane afforded the respective borane adducts in 47% yield. Methylation with iodomethane gave the respective diphosphonium salt in quantitative yield. Oxidation with 1.0 or 5.0 equivalents of silver hexafloroantimonate gave a green and a blue material, respectively, presumably the mono and the diferrcenium salts. 1,16‐Di‐tert‐butyl‐1,16‐diphospha[5.5]ferrocenophane and its oxidation products were subjected to a temperature‐dependent Mössbauer effect (ME) study to elucidate their dynamical and paramagnetic relaxation characteristics. The ME data are consistent with the absence of spin averaging for the two distinct Fe sites in the monooxidation product over the temperature range 91<T<236 K. The metal atom vibrational amplitudes as a function of temperature have been determined for 1,16‐di‐tert‐butyl‐1,16‐diphospha[5.5]ferrocenophane as well as for the diamagnetic site in the monooxidation product.

Ferrocenophanium Stability and Catalysis

“…Ferrocenophanes or ansa -ferrocenes are a well-known compound class [ 74 ]. The bridges can be all-carbon [ 74 , 75 ] or contain heteroatoms [ 76 , 77 ], and several synthetic methods for their access have been described [ 78 ]. Either the two ring systems are connected by a series of organic transformations, or a preformed, bidentate dicyclopentadienyl ligand is coordinated to an iron center (“flytrap method”) [ 79 ].…”

The First Anionic Thia‐Fries Rearrangement at the Cobaltocenium Cation

“…We have investigated the chemistry of ferrocene under a variety of aspects for a longer period of time [11–25] . Among these, the first anionic thia‐Fries rearrangements at ferrocene were reported, which start from ferrocenyl triflate ( 1 ) or from 1,1’‐ferrocenediyl ditriflate ( 3 ) and gave rearranged products 2 or 4 , respectively in high yields under very mild reaction conditions (Scheme 1).…”

“…[9,10] We have investigated the chemistry of ferrocene under a variety of aspects for a longer period of time. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] Among these, the first anionic thia-Fries rearrangements at ferrocene were reported, which start from ferrocenyl triflate (1) or from 1,1'ferrocenediyl ditriflate (3) and gave rearranged products 2 or 4, respectively in high yields under very mild reaction conditions (Scheme 1). [24] Remarkably, 4 was exclusively formed as the meso diastereomer, an unprecedented interannular stereoinduction, which was recently investigated by theoretical calculations.…”