Pentacoordinate hydrochlorosilanes with lactamomethyl ligand

The synthesis and reaction behavior of pentacoordinate hydrochlorosilanes LCH₂SiRHCl (L- 2-piperidonyl ligand, R = Me, Ph, Bn) are described. The intramolecular O-Si and N-Si coordination is discussed on the basis of the NMR data. The strength of the O-Si coordinate bond is nearly the same for chelates 5, 6, 8 irrespective of the equatorial substituent R at the silicon atom. However, the nature of R substituent markedly affects the stability of the complexes with the N-Si intramolecular bond.     

Intramolecular mobility of pentacoordinated tin compounds

The ¹¹⁹Sn NMR and ¹³C NMR data are reported for N-alkyl-5,5-di-t-butyldiptychoxazstannolidines. The activation parameters of an intramolecular process are estimated from the temperature dependence of the ¹H NMR spectra in different polar solvents, The NMR data support the dissociation—inversion mechanism for this process.     

Atranes

The PMR spectra of acidified solutions of metalloatrane-3,7,10-trione dihydrates containing a group-IIIB metal atom (M=Al, Ga, In, Tl) in D₂O were studied. The equivalence of the three atrane half-rings in all of the investigated molecules and of the methylene protons in each half-ring was proved. Spin-spin coupling of²⁰³Tl and²⁰⁵Tl with protons, which is apparently realized through a TlN transannular coordinate bond, is observed in the PMR spectrum of thallatrane-3,7,10-trione (M=Tl). The factors that determine the magnitudes of the chemical shifts of the methylene protons are discussed.See [1] for communication XXXII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 312–314, March, 1973.