Zur Reaktion von PCl3 mit NaR*, KR* und ZnR*2 (R* = SitBu3) [1]: Bildung des Diphosphens R*P=PR*, Tetraphosphans P4R* 2 , Tetraphosphanids NaP4R* 3 sowie von Halogenphosphanen R* mPmClp / On the Reaction of PCl3 with NaR*, KR* and ZnR*2 (R*= SitBu3) [1]: Formation of the Diphosphene R*P=PR*, Tetraphosphane P4R*2, Tetraphosphanide NaP4R*3 as well as Halogenophosphanes R*mPnClp

Abstract

The reaction of PCl3 at r. t. with an equimolar amount of NaR* in heptane gives the colorless phosphane R*PCl2 (1), the colorless diphosphane R*ClP-PClR* (2), the light green diphosphene R*P=PR* (4), the cyclotetraphosphane R*2P4Cl2 (6) (not isolated), the light yellow bis(cyclotriphosphanyl) P6R*4 (7), the cyclotriphosphane R*2P3Cl (8) (not isolated), and the colorless bicyclophosphane P4R*2 (9).With a threefold molar amount of NaR* in tetrahydrofuran the blue violet triphosphanide NaP3R*2 (10), the dark red tetraphosphanide NaP4R*3 (11), and the orange pentaphosphanediide Na2P5R*3 (12) are formed from PCl3 besides the phosphanides NaPR*2, Na2PR* (isolated), NaP2R*3 and Na2P2R*2. With a four-fold molar amount of KR* in benzene PCl3 gives the green diphosphanediide K2P2R*2 and the red phosphanediide K2PR*, and with an equimolar amount of ZnR*2 in heptane the compounds 1, 2, 4, 7 and 8 are obtained. The compound R*P=PR* (4), the first diphosphene with two silyl substituents, is formed in high yields from the action of Na on R*PCl2 in heptane at 90 "C. It gives a [2+4] cycloadduct with 2,3-dimethylbutadiene and phosphanides (Na2P2R*2 or Na2PR*) with Na or NaR*. Bicyclotetraphosphane P4R*2 (9) (structure: two R*P3 rings with a common edge) is exclusively obtained from Na2P4R*2 (formed quantitatively from P4 and 2 NaR*) and TCNE. 9 may be reduced (Na, THF) with reformation of Na2P4R*2 and reacts in the presence of NaR* with formation of dark red NaP4R*3 (11) (structure: P3 ring with two R* substituents in trans position and one PNaR* substituent). Straightforward syntheses of halogenophosphanes include (i) reactions of ZnR*2 with PCl3 or PBr3 (mole ratio 1 : 2) in heptane to form R*PCl2 (1) or R*PBr2, and (ii) reaction of R*2 with R*PCl2 (mole ratio 1 : 2) without a solvent, or of KR* and PCl3 (mole ratio 2 : 1) in benzene to formR*ClP-PClR* (2). The halogenophosphanes R*2P3Cl (8) (structure: P3 ring with two R* substituents in trans position and one Cl substituent) as well as R*2P4Cl2 (6) (structure: P4 ring with alternating R* and Cl substituents) have not been isolated. The 31P-NMR spectra and the pathways of formation of the phosphorus compounds are discussed