The difference regarding the reactivity of the silanides Na[SitBu3] and Na[SiPhtBu2] towards white phosphorus

The sodium tetraphosphenediides Na-2[tBu(2)RSiP-P=P-PSiRtBu(2)] (R = tBu, Ph) were formed when P-4 was treated with two equivalents of the silanides Na[SiRtBu(2)] in thf. Whereas treatment of P-4 with three equivalents of Na[SiPhtBu(2)] in thf gave the tetraphosphide Na-3[P(PSiPhtBu(2))(3)] as main product (along with, e.g., Na-2[PSiPhtBu(2)], Na-2[tBu(2)PhSiP-P=P-PSiPhtBu(2)], and Na-2[P-5(SiPhtBu(2))(3)]). However, no tetraphosphide Na-3[P(PSitBu(3))(3)] was formed by the reaction of P-4 with three equivalents of Na[SitBu(3)] in thf. The triphosphide Na[tBu(2)PhSiP-P=PSiPhtBu(2)] could be obtained together with Na[PHSiPhtBu(2)] by protolysis of Na-3[P(PSiPhtBu(2))(3)]. When a mixture of a 3:1 reaction of Na[SiPhtBu(2)] and P-4 was heated to 100 degrees C in vacuo, {Na[P(SiPhtBu(2))(2)]}(2) was generated along with Na-2[PSiPhtBu(2)] and P-4. Single crystals of Na[P(SiPhtBu(2))(2)] were grown from a heptane solution at room temperature (monoclinic space group C2/c). (C) 2011 Elsevier B.V. All rights reserved.