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Cyclic Diynes with Silicon in the Bridges: Structural and Photoelectron Spectroscopic Investigations
Author(s) -
Stahr Helmut,
Gleiter Rolf,
Haberhauer Gebhard,
Irngartinger Hermann,
Oeser Thomas
Publication year - 1997
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19971301216
Subject(s) - chemistry , crystallography , silicon , spectral line , solid state , x ray photoelectron spectroscopy , atomic orbital , stereochemistry , nuclear magnetic resonance , physics , organic chemistry , quantum mechanics , astronomy , electron
The structures of 6‐isopropylidene‐1,1‐dimethyl‐1‐silacyclodeca‐3,8‐diyne ( 2 ), 1,6‐dimethyl‐1,6‐disilabicyclo[4.4.4]tetradeca‐3,8,12‐tryine ( 4 ), and 1,1,2,2,3,3‐hexamethyl‐1,2,3‐trisilacyclodeca‐4,9‐diyne ( 6 ) have been investigated by means of X‐ray crystallography. In 2 and 6 a chair conformation is adopted in the solid solid state. In 4 the three butyne groups are twisted around the SiSi axis against one another. The torsion along the triple bond axis (Si‐CH 2 ‐CH 2,/ Si) amounts to 29.0(1). The He(I) photoelectron (PE) spectra of 2 and 6 together with those of 1,1‐dimethyl‐1‐silacyclodeca‐3,8‐diyne ( 1 ), 1,1,6,6‐tetramethyl‐1,6‐disilacyclodeca‐3,8‐diyne ( 3 ),1,12,2,3,3‐hexamethyl‐1,2,3‐trisilacycloundeca‐4,10‐diyne ( 7 ) have also been recorded. The PE spectra were interpreted on the basis of results from SCF MO calculations (3–21G*). They reveal a smaller splitting of the π‐bands in 1–3 as compared to cyclodeca‐1,6‐diyne. In the PE spectra of 5–7 we encountered a strong interaction between the silicon chain and the in‐plane π‐orbitals.