Issue 1, 2018

Synthesis, spectroscopic characterisation and transmetalation of lithium and potassium diaminophosphanide-boranes

Abstract

A secondary diaminophosphane-borane (Et2N)2PH(BH3) was prepared from a chlorophosphane precursor and LiBH4 and metalated by reaction with anion bases (n-BuLi, KN(SiMe3)2) to yield the corresponding metal diaminophosphanide-boranes [(Et2N)2P(BH3)]M (M = Li, K). Multinuclear NMR studies permitted the first spectroscopic characterisation of the metalation products and revealed the presence of monomeric (for M = Li) contact ion pairs in solution. NMR spectroscopic evidence that the ions in each pair interact via Li⋯P- rather than Li⋯H3B-interactions as had been inferred for a Ph-substituted analogue was confirmed by DFT studies, which revealed also that the borane coordination plays a decisive role in boosting the PH-acidity of the original secondary diaminophosphane precursor. Transmetalation of the potassium and lithium diaminophosphanide-boranes with Cu(I) and Zn(II) chlorides afforded the first functional transition metal complexes of a P-heteroatom-functionalised phosphanide-borane ligand. Both products were fully characterised. Thermolysis of the Cu-complex induced a reaction which involved transfer of an NHC ligand from the metal to the phosphorus atom and yielded a phosphaalkene NHC[double bond, length as m-dash]PH (NHC = N-heterocyclic carbene) as the major phosphorus-containing product.

Graphical abstract: Synthesis, spectroscopic characterisation and transmetalation of lithium and potassium diaminophosphanide-boranes

Supplementary files

Article information

Article type
Paper
Submitted
31 Okt. 2017
Accepted
27 Nov. 2017
First published
27 Nov. 2017

Dalton Trans., 2018,47, 112-119

Synthesis, spectroscopic characterisation and transmetalation of lithium and potassium diaminophosphanide-boranes

M. Blum, J. Kappler, S. H. Schlindwein, M. Nieger and D. Gudat, Dalton Trans., 2018, 47, 112 DOI: 10.1039/C7DT04110A

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