Synthesis and structural features of new sterically hindered azaphosphatrane systems:: ZP(RNCH2CH2)3N

The synthesis of [ZP(RNCH2CH2)(3)N]CF3SO3 wherein Z = H+ and R = SiMe3 (1f), SiEt3 (1g), SiPh3 (1h), SiPh2Me (1i) and Li (Ij), are reported along with that of 2f wherein Z = 1p and R = SiMe3. Also described are the transformations of 1j to 1f-i, 2f to OP(Me3SiNCH2CH2)(3)N (3b), 5 to 3b, and 2f to SP(Me3SiNCH2CH2)(3),N (3a). The structures of 2f and 3a determined by X-ray means are also presented. Compound 2f displays a bridgehead-bridgehead distance of 3.360(7) Angstrom while that in 3a is 3.152(7) Angstrom. The smaller distance in the latter by ca. 0.1 Angstrom is attributed to the wider NPN bond angle by ca. 5 degrees in 3a. VT P-31-NMR studies revealed no evidence for transannulation or tautomerism in 3b. (C) 1999 Elsevier Science S.A. All rights reserved.