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Updated: Nov 24, 2025

Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of PhosphorusI
Published on: November 22, 2016
Phosphido-bis(borane) complexes of the alkaline earth metals
Keith Izod1, James M Watson1, Ross W Harrington1
1Main Group Chemistry Laboratories, School of Chemistry, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK. keith.izod@ncl.ac.uk.
Abstract:
The reaction between two equivalents of {(Me3Si)2CH}(Ph)PH(BH3) (1) and Bu2Mg, followed by two equivalents of BH3·SMe2, gives the corresponding phosphido-bis(borane) complex, which may be crystallised as two distinct chemical species: the complex [{(Me3Si)2CH}(Ph)P(BH3)2]2Mg(THF)4·THF (2a), and two different THF solvates (1 : 1 and 1 : 2) of the solvent-separated ion triples [{(Me3Si)2CH}(Ph)P(BH3)2]2[Mg(THF)6]·THF (2b) and [{(Me3Si)2CH}(Ph)P(BH3)2]2[Mg(THF)6]·2THF (2c). Similar reactions between two equivalents of 1 and either (4-tBuC6H4CH2)2Ca(THF)4 or [(Me3Si)2CH]2Sr(THF)2, followed by two equivalents of BH3·SMe2, give the heavier alkali metal complexes [{(Me3Si)2CH}(Ph)P(BH3)2]2M(THF)4 [M = Ca (3), Sr (4)]. Surprisingly, compounds 2a, 3 and 4 adopt almost identical structures in the solid state, which differ only in the geometrical arrangement of the phosphido-bis(borane) ligands and the hapticity of the borane groups.
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