Lineare Oligophosphaalkane, XX [1]: Alkalimetall-und Trimethylsilylderivate PH-funktioneller Methylenbisphosphane / Linear Oligophosphaalkanes, XX [1]: Alkali Metal and Trimethylsilyl Derivatives of PH-Functional Methylenebisphosphanes

Abstract

The synthesis of the trimethylsilyl derivatives of the PH-functional methylenebisphosphanes, R_2-n(Me₃ Si)_nP-CH₂ -PR(SiMe₃) (R = Me, iPr, tBu, Ph, 2.4.6-Me₃C₆H₂ ; n = 0.1) is reported. In the Li-phosphides R_2-nLi_nP - CH₂ - PLiR used as reactive intermediates, a monomer-oligomer association equilibrium causes a rapid Li-exchange as indicated by the solvent and temperature dependent ³¹P{¹H} and ⁷Li NMR spectrum of (iPr)₂ P-CH₂ -P(iPr)Li in various solvents (Et₂O, THF and MTHF) in the temperature range from 30 to -110 °C. For the syntheses of the Me-and Ph-substituted PH-functional methylenebisphosphanes R₂P-CH₂ -PRH and RHP-CH₂ -PRH (R = Me, Ph) the chlorophosphane CKP -CH₂ -PCl₂ is used as a starting material. Bifunctional substituents (Ph -N̍-N̍ -Ph and Me -N̍-CO-N̍-Me) are employed for the first time as protecting groups to block one or two PCl-functions in Cl₂P-CH₂-PCI₂,. Cleavage of the PN-bonds in the five membered ring systems (R = Me, Ph) with HCl affords the P-substituted methylenebis-chlorophosphanes RClP-CH₂ - PClR in satisfactory yields. The compounds have been characterized by ¹H, ¹³ C{¹H} and ³¹P{¹H} NMR spectroscopy. With-in homologous substitution series of methylenebisphosphanes, e.g. R₂P-CH₂-PR_2-nH_nthe coupling constants ²J(PP) seem to reflect conformational changes at the PCP-skeleton.