Three-membered rings with dative bonds

12 Three-membered rings with dative bonds  

Molecular structures observed in the crystal of (a) the dimeric p3SiCH2NMe2 and (b) the monomeric 

Molecular structures present in crystals of (a) F3SiN(SiMe3)NMe2 and (b) p3SiNONMe2. 

Radial distribution curve of ClH2SiONMe2 as obtained from a gas-phase electron diffraction experiment. The experimental curve is drawn as solid line, and the fitted contributions of anti and gauche conformers are shown as dotted representations. 

If such a transfer of electron density takes place, we should be able to see this in the region between the Si and N atoms as a local valence charge accumulation. The electron density topologies (Section 10.10) of 

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Hydride abstraction from alkylamines forms the corresponding imi-nium ions, whose coordination to transition metals gives either a ir-complex or cr-bonded three-membered ring (Scheme 15) (26). Ligation of the cationic dehydro amines to Rh is aided by substantial electron donation from the metal to the electron-deficient carbon atom to produce the Rh(IH) complex with a covalent C—Rh bond and an N—Rh dative bond, consistent with the long C—N bond (1.467 A) and the small H— C( 1)-—N—C(2) dihedral angle (124.6°) as well as the noncoplanarity of the CH2—CH bond and a possible CH—NH2 plane seen in the allylam-ine oxidative addition product (24). 

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