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

The sodium tetraphosphenediides Na2[tBu2RSiP–PP–PSiRtBu2] (R = tBu, Ph) were formed when P4 was treated with two equivalents of the silanides Na[SiRtBu2] in thf. Whereas treatment of P4 with three equivalents of Na[SiPhtBu2] in thf gave the tetraphosphide Na3[P(PSiPhtBu2)3] as main product (along with, e.g., Na2[PSiPhtBu2], Na2[tBu2PhSiP–PP–PSiPhtBu2], and Na2[P5(SiPhtBu2)3]). However, no tetraphosphide Na3[P(PSitBu3)3] was formed by the reaction of P4 with three equivalents of Na[SitBu3] in thf. The triphosphide Na[tBu2PhSiP–PPSiPhtBu2] could be obtained together with Na[PHSiPhtBu2] by protolysis of Na3[P(PSiPhtBu2)3]. When a mixture of a 3:1 reaction of Na[SiPhtBu2] and P4 was heated to 100 °C in vacuo, {Na[P(SiPhtBu2)2]}2 was generated along with Na2[PSiPhtBu2] and P4. Single crystals of Na[P(SiPhtBu2)2] were grown from a heptane solution at room temperature (monoclinic space group C2/c).

The sodium tetraphosphenediides Na2[tBu2RSiP–PP–PSiRtBu2] (R = tBu, Ph) were formed when P4 was treated with two equivalents of the silanides Na[SiRtBu2] in thf. However, when a mixture of a 3:1 reaction of Na[SiPhtBu2] and P4 was heated to 100 °C in vacuo, the monophosphanide {Na[P(SiPhtBu2)2]}2 was generated together with Na2[PSiPhtBu2] and P4. Whereas treatment of P4 with three equivalents of Na[SiPhtBu2] in thf gave the tetraphosphide Na3[P(PSiPhtBu2)3] as main product.Figure optionsDownload as PowerPoint slideHighlights
► The 3:1 reaction of Na[SitBu3] with P4 produces Na[tBu3SiP–PPSitBu3].
► Treatment of P4 with three equivalents of Na[SiPhtBu2] gives Na[P(SiPhtBu2)2].
► In the thermolysis of M[tBu3SiN–NNSiRtBu2] M[tBu3SiNSiRtBu2] (R = Me, tBu) are formed.