Alfredo Ricci

Group IVB 1.3-Dithiolanes and corresponding open-chain compounds: UV pes and theoretical study of the electronic and conformational properties

Abstract The results of a UPS and theoretical study on two classes of compounds containing the S-X(CH 3 ) 2 -S group (X  C, Si and Sn), i.e. dithiolanes and the related open-chain species, are reported. The first few bands of the spectra are assigned to the corresponding MOs. It is found that the preferred conformations of the (Ch 3 ) 2 X(SCH 3 ) 2 species contain in all cases a planar X mo/iety. Furthermore it is found that d -orbital participation is significant only when X  Si, and the inductive effect operates in a detectable way only when X  Sn.

Bonding between sulfur and the elements of group IV studied by uv photoelectron spectroscopy

Abstract The photoelectron spectra of the S[X(CH3)3]2 and CH3SX(CH3)3 series (X = C, Si, Ge, Sn and Pb) are reported, and assigned on the basis of the semilocalized orbitals approximation and a consideration of symmetry and substituent effects. The electronic interactions between the X(CH3)3 substituents and the sulfur nπ orbital are discussed in terms of the relative importance of hyperconjugation (nσ mixing), (pd)π bonding and electrostatic interactions.

A C-13 NMR and theoretical study of the electronic structure of acylsilanes

Abstract The results of a C-13 NMR study on a series of acylsilanes and carbon analogs are reported. The results are rationalized in terms of a theoretical analysis based on the σ and π charge components of XH 3 and HCzO moieties.

Transformation of α-assisted carbanions into the corresponding trimethylsiloxy derivatives using bis(trimethylsilyl)peroxide

Abstract The reaction of bis(trimethylsilyl)peroxide with tlithium derivatives of sulphides and nitriles is reported to give the corresponding O-trimethylsilyl hemithioacetals and cyanohydrins. From these products the carbonyl function can be exposed in acidic media or in the presence of fluoride ions. This methodology provides an attractive route to transform a CH 2 -X group (X = PhS, MeS or CN) into the corresponding CHO, allowing the preparation of aldehydes that can be considered difficult to prepare such as, for example, formyltrimethylsilane which was generated and trapped in situ using a Wittig reaction.

Photoelectron spectra of substituted dialkylphenylthioboranes

Abstract The photoelectron He(I) spectra of some thioboranes XC 6 H 4 SB(n-C 3 H 7 ) 2 (X = p -Cl, m -Cl, p -Br, H, p -CH 3 , m -CH 3 and p -OCH 3 ) have been recorded and assigned respective to those of related simple molecules and by a perturbational molecular orbital analysis and CNDO/2 calculations on the simpler thioborane C 6 H 5 SBH 2 . The interaction between the phenyl ring and the SBR 2 group is briefly discussed.