Zur Kenntnis neuer 1,3,2,4‐Diphosphadisiletan‐ und Diorganodi(phosphino)silan‐Derivate

Reaction of the bulkily substituted dichlorodiorganosilanes R 1 R 2 SiCl 2 (R 1 = Mesityl, R 2 = Mesityl, t Bu, O t Bu, Xylyl, iBu) with LiPH 2 . dme in a 1 : 2 molar ratio in THF at ‐30°C leads to the new organo‐substituted 1,3,2,4‐diphosphadisiletanes 1a—e. Compounds 1c—e are isolated as mixtures of diastereomers. The crowded dichlorosilane Is( t Bu)SiCl 2 (Is = 2,4,6‐ triisopropylphenyl) reacts with LiPH 2 . dme above 10°C to yield the disubstituted products Is( t Bu)Si(PH 2 ) 2 (2f) in 87% yield and only minor amounts of the corresponding four‐membered ring [Is( t Bu)SiPH] 2 (1f), detected by 31 P‐ and 29 Si‐NMR spectroscopy. Treatment of 2f with 2 equivalents of n BuLi in Et 2 O gives Is( t Bu)Si(PHLi) 2 (3f), which with Is( t Bu)SiCl 2 forms 1f. The reaction of difluorodiisitylsilane with LiPH 2 .dme in THF leads to different products, depending on the reaction temperature. At — 30°C Is 2 Si(PHLi)F (7g) is obtained as sole product, whereas at 28°C the air‐stable diphosphino‐substituted Is 2 Si(PH 2 ) 2 (2g) is formed. Elimination of LiF from 7g affords the tetraisityl‐substituted P 2 Si 2 ‐cyclobutane 1g, and treatment with H 2 O and Me 3 SiCl leads to Is 2 Si(PH 2 )F (8g) and Is 2 Si(PHSiMe 3 )F (9g). The temperature‐dependent 1 H‐NMR spectra of 1a — g exhibit two dynamic processes: hindered rotation of the aryl groups at silicon and inversion at phosphorus. — The solid state structures of 1a, 1b, 1g, and 2g are established by X‐ray crystallography. Reaction of 1a with 2 equivalents of M(CO) 5 .thf (M = Cr, W) yields the P,P ′‐bis(pentacarbonylmetal) complexes 10a (M = Cr) and 11a (M = W). A single‐crystal X‐ray diffraction analysis of 10a is performed. Concerning New 1,3,2,4‐Diphosphadisiletanes and Diorganodi(phosphino)silane Derivatives