Asymmetric Synthesis and Metal Complexes of a C 3-Symmetric P-Stereogenic Triphosphine, (R)-MeSi(CH2PMe(t-Bu))3 (MT-Siliphos)

Asymmetric deprotonation of PMe2(t-Bu)­(BH3) with s-BuLi/(−)-sparteine, followed by treatment with MeSiCl3, gave a 2.6:1 mixture of the C 3- and C 1-symmetric triphosphine–boranes MeSi­(CH2PMe­(t-Bu)­(BH3))3 (3). Recrystallization gave highly diastereomerically and enantiomerically enriched C 3-3. After deprotection with morpholine, the triphosphine (R)-MeSi­(CH2PMe­(t-Bu))3 (4; (Me, t-Bu)-Siliphos or MT-Siliphos) was used to prepare the metal complexes [Rh­(MT-Siliphos)­(norbornadiene)]­[OTf] (5), Ru­(MT-Siliphos)­(DMSO)­Cl2 (6), [Ru­(MT-Siliphos)­(NCMe)3]­[OTf]2 (7), M­(MT-Siliphos)­(PPh3) (M = Pd (8), Pt (9)), Cu­(MT-Siliphos)­(Cl) (10), and polymeric [Cu2Cl2(μ-(κ2,κ1)-MT-Siliphos)]∞ (11). The crystal structures of C 3-3 and of complexes 5, 7, and 11 were determined, and dynamic processes in 6 and 8 were characterized by variable-temperature NMR spectroscopy.