29949-75-5Relevant articles and documents
Synthesis, Structure, and Solution Studies of Lithiated Allylic Phosphines and Phosphine Oxides
Eren, Nimrod M.,Orr, Samantha A.,Thompson, Christopher D.,Border, Emily C.,Stevens, Michael A.,Blair, Victoria L.
supporting information, p. 2080 - 2090 (2020/06/05)
This study reports a new series of 12 α-lithiated allylic phosphines and phosphine oxides. By incorporating Lewis base donors including diethyl ether (Et2O), tetrahydrofuran (THF), N,N,N′,N′,-tetramethylethylenediamine (TMEDA), and N,N,N′,N′,N″,-pentamethyldiethylenetriamine (PMDETA), nine complexes were structurally characterized by single-crystal X-ray crystallography. This includes novel dilithiated allylic phosphine 4 [PhP{CHCHCH2Li(TMEDA)}2] and a rare hemisolvated lithiated phosphine oxide 6 [{Ph2P(O)CHC(Me)CH2Li}2(TMEDA)]. Interestingly, in the solid state, P(III) complexes take advantage of Li-πinteractions to the newly formed delocalized system, in comparison to P(V) complexes where the oxophillic nature of the lithium atom dominates. All 12 complexes were fully characterized in the solution state by multinuclear NMR spectroscopy. DFT calculations on isomers of monomeric lithiated complex 3 [Ph2PCHC(Me)CH2Li(PMDETA)] described the low energy barrier between transition steps of the subtle delocalization of the allylic chain.
Intramolecular Lewis pairs with two acid sites-reactivity differences between P- and N-based systems
K?rte, Leif A.,Blomeyer, Sebastian,Heidemeyer, Shari,Nissen, Jan Hendrick,Mix, Andreas,Neumann, Beate,Stammler, Hans-Georg,Mitzel, Norbert W.
, p. 17319 - 17328 (2016/11/13)
The doubly acid-functionalised aniline PhN[(CH2)3B(C6F5)2]2 shows rapidly exchanging boron acid groups at the central base function and is an active frustrated Lewis pair due to cooperative hydride binding by both Lewis acids. Here we report investigations on the effect of different substituents at the central nitrogen atom and on the effect of exchanging nitrogen by phosphorus. Treatment of diallyl-tert-butylaniline with one equivalent of HB(C6F5)2 led to formation of a seven-membered iminium hydridoborate ring; after mono-hydroboration the intermediately formed frustrated Lewis pair reacts with the second allylamine function under ring closure. Phosphorus based Lewis pairs with two acid sites were prepared by hydroboration of diallylphenylphosphane and diallyl-tert-butylphosphane. Unlike the aniline PhN[(CH2)3B(C6F5)2]2 the doubly hydroborated species (tBu/Ph)P[(CH2)3B(C6F5)2]2 show no dynamic exchange of the boron Lewis acid functions in solution and are not catalytically active in terms of H/D-scrambling as well as hydrogenation reactions. Quantum-chemical investigations revealed the B-P bond dissociation Gibbs free energy to be much larger than those of the nitrogen analogue. The absence of an active open form in solution prevents an activity in heterolytic hydrogen splitting.
