5523-19-3Relevant articles and documents
Diethyl(di-tert-butylphosphino)borane and related compounds: The first stable monomeric tetraalkyl phosphinoborane
Groshens, Thomas J.,Higa, Kelvin T.,Nissan, Robin,Butcher, Raymond J.,Freyer, Alan J.
, p. 2904 - 2910 (2008/10/08)
Four new phosphinoborane compounds were prepared and characterized by 1H, 13C, 31P, and 11B NMR spectroscopy and elemental analysis. Monomeric Et2BP(t-Bu)2 was isolated as a volatile yellow liquid and [Me2BP(t-Bu)2]2 as a colorless solid using salt elimination reactions. The colorless dimeric solids [Me2BP(SiMe3)2]2 and [Et2BP(SiMe3)2]2 were prepared via trimethylsilyl halide elimination reactions. The dimeric compounds dissociate in benzene or toluene at ambient temperature, and an equilibrium with the monomeric species is established. Variable-temperature 1H NMR spectroscopy showed that ΔH = -93 kJ/mol and ΔS = -285 J/(mol·K) for the dimerization of Me2BP(t-Bu)2 and ΔH = -55 ± 12 kJ/mol and ΔS = -166 ± 42 J/(mol·K) for the dimerization of Me2BP(SiMe3)2. Inverse 2D 1H/13C correlation studies were applied to monomer-dimer solutions and were vital to assignment of 13C resonances. Solid-state 31P NMR confirmed that [Me2BP(t-Bu)2]2 and [Me2BP(SiMe3)2]2 are dimeric solids. The structure of [Me2BP(t-Bu)2]2 was determined by single-crystal X-ray diffraction. Crystal data: triclinic, space group P1, a = 8.366(3) A?, b = 8.0808(2) A?, c = 9.311(2) A?, α = 74.98(2)°, β = 78.87(2)°, γ = 64.32(2)°, Z = 1, and R = 0.0628.
