(PHOSPHINOALKYL)SILANES .4. HYDROZIRCONATION AS A NONPHOTOCHEMICAL ROUTE TO (PHOSPHINOPROPYL)SILANES - FACILE ASSEMBLY OF THE BIS(3-(DIPHENYLPHOSPHINO)PROPYL)SILYL (BIPSI) LIGAND FRAMEWORK - ACCESS TO THE RELATED POLY(3-(DIMETHYLSILYL)PROPYL)PHOSPHINES RNP(CH2CH2CH2SIME2H)(3-N) (N=1, R=PH N=0)

Treatment of SiEt3(CH=CH2) with ZrCp2HCl (Schwartz's reagent) followed by reaction with PPh2Cl provides a high-yield (75%) route to Ph2PCH2C H2SiEt3, and accordingly hydrozirconation of CH2=CHCH2SiHMe2 affords t he intermediate ZrCp2(CH2CH2CH2SiHMe2)CI (2). The latter, which is ver y sensitive to hydrolysis and reacts with HCl forming SiHMe2Prn and wi th NBS or I-2 affording SiHMe2CH2CH2CH2X (X = Br (3), I (4)), behaves similarly with PPh2Cl, PPhCl2, or PBr3 undergoing cleavage to the know n Ph2PCH2CH2CH2SiMe2H (i.e. chelH, A) and the novel bis- and tris(sily lpropyl)phosphines PhP(CH2CH2CH2SiMe2H)(2) (5) and P(CH2CH2CH2SiMe2H)( 3) (6), respectively, with concomitant formation of ZrCp2Cl2. Correspo nding hydroboration of allylsilanes is facile, but subsequent phosphin e halide cleavage yields (phosphinoalkyl)silanes only as constituents of intractable mixtures. Hydrozirconation followed by phosphination wi th PPh2Cl also converts SiHMe(CH2CH=CH2)2 to SiHMe(CH2-CH2CH2PPh2)(2) (i.e. biPSiH, B) together with a propyl analogue Ph2PCH2CH2CH2SiMe(Pr- n)H (7) of A (ca. 2:1 ratio), as well as SiH(CH2CH=CH2)(3) to a mixtur e (ca. 5:2:1 ratio) of SiH(CH2CH2CH2PPh2)(3) (i.e. triPSiH, C), a new analogue SiH(Pr-n)(CH2CH2CH2PPh2)(2) (8) Of B, and a further analogue Ph2PCH2CH2CH2SiHPr2n (9) of A. A further analogue SiH2(CH2CH2CH2PPh2)2 (10) of biPSiH (B) is obtained similarly starting from SiH2(CH2CH=CH2 )(2). Steric control of silylalkyl cleavage from 2 is indicated by the fact that, like PPh2Cl (which forms B), two further biPSiH analogues SiH(Me)[CH2CH2CH2P(n-hex)(2)](2) (11) and SiH(Me)(CH(2)CH(2)CH(2)PPhBz )(2) (12) were obtained using P(n-hex)(2)Cl tie. n-hex = CH3(CH2)(4)CH 2-) or PPhBzCl (i.e. Bz = -CH2C6H5), respectively, whereas neither (PP r2Cl)-Cl-i nor (PBu2Cl)-Cl-t led to (phosphinoalkyl)silane formation. The surface-substrate linking reagent Ph2PCH2CH2CH2Si(OEt)(3) (D) is f ormed efficiently by similar means from Si(OEt)(3)(CH2CH=CH2). NMR dat a (H-1, C-13, Si-29, P-31) for 2-12 have been measured and are discuss ed.