New 1,1′- or 1,2- or 1,3-bis(diphenylphosphino)ferrocenes

Investigation of novel and reinvestigation of known cyclopentadienylphosphanes: News on [1,5] sigmatropic rearrangements

“…The results of these studies suggested a reinvestigation of the mixture of isomers of the parent compound Ph 2 PCp tBu (4). Deviations from an earlier report [33] with respect to the molecular structures of two of the four the isomers of 4 were found.…”

“…These findings are in full congruency with our results on Me 2 PCp tBu (3). However, they deviate in some points from the conclusions drawn in an earlier publication [33], in which the same number of isomers and similar molar percentages of the single isomers were reported, but different molecular structures were proposed for the isomers 4b and 4c.…”

“…The detailed analysis of the NMR data is presented in the electronic supplement. The molecular structures established for 3 differ in some points from those which were reported for the parent compound 4 [33]. In the course of our studies we also synthesised 4 for further derivatisation reactions.…”

“…This also proved to be the case when the novel cyclopentadienylphosphane Me 2 PCp tBu (3) was synthesised in analogy to the protocol which was established for the parent compound Ph 2 PCp tBu (4) [33]. All isomers of 3 exhibit the typical substitution pattern, in which the two bulky substituents are separated by a C1-bridge, which is attributed to steric repulsion.…”

“…Moreover we would like to report the synthesis of two novel cyclopentadienylphosphanes, (Me 2 N) 2 PCp # (2) and Me 2 PCp tBu (3) (Cp tBu ¼ C 5 H 4 tBu), and the detailed NMR spectroscopic analysis of the isomers present in thermodynamic equilibrium. The results obtained on 3 prompted us to reinvestigate the mixture of tautomers of the parent compound Ph 2 PCp tBu (4) [33] with respect to the molecular structures of the single isomers.…”