The open-chain triphosphanes RMe2SiCH2P(PR'2)2 (R = Me, Ph; R' = SiMe3, Cy, Ph).

The triphosphanes RMe(2)SiCH(2)P(PR'(2))(2) (R = Me, Ph; R' = SiMe(3), Cy) are synthesised in good yield via metathesis of organodichlorophosphanes and LiPR'(2), while for R' = Ph a propensity to form (Ph(2)P)(2) precludes isolation of the in situ characterised triphosphanes. Where R = Me and R' = SiMe(3) the triphosphane has also been characterised by single crystal X-ray diffraction and exhibits a single geometric conformer in the solid state, though solution-phase NMR spectra are indicative of facile conformational exchange across a wide temperature range. All of the described triphosphanes exhibit comparable behaviour, with their respective (31)P{(1)H} NMR spectra manifesting anomalous 'second-order' characteristics, which are considered using full spin-Hamiltonian simulation. Preliminary studies of coordination chemistry and ancillary reactivity of the triphosphanes are described.