Mono-C,O-chelated bromo- and triflatosilanes with an amino acid moiety: salts or covalently bonded complexes?
- Russian Academy of Sciences, A. N. Nesmeyanov Institute of Organoelement Compounds (Russian Federation)
- N. I. Pirogov Russian National Research Medical University (Russian Federation)
Derivatives of the amino acids sarcosine and proline – triflates TsN(Me)CH{sub 2}C(O)N(Me)-CH{sub 2}SiMe{sub 2}OTf and Ns–Pro–N(Me)CH2SiMe2OTf (Ns is 4-NO{sub 2}C{sub 6}H{sub 4}SO{sub 2}) – were synthesized by the reaction of trimethylsilyl triflate with halosilanes prepared previously. Bromide NsNHCH(Me)C(O)N(Me)CH2SiMe2Br was synthesized by the cleavage of the Si–O–Si moiety of the appropriate disiloxane with excess acetyl bromide. The X-ray diffraction study of these compounds and of the previously characterized bromide TsN(Ac)CH{sub 2}C(O)N(Me) CH{sub 2}SiMe{sub 2}Br showed that the Si–O coordination bond lengths in the triflates are 1.7692(14)– 1.8623(14) Å. The interatomic distances between the bromine and silicon atoms are 2.7095(8) and 2.9704(7) Å, which indicates that these bonds are weak. To elucidate the nature of Si…X bonding (X = OTf, Br), the topological analysis of electron density was performed and {sup 29}Si NMR chemical shifts were calculated. The interatomic Si…X interaction in triflate TsN(Me)CH{sub 2}C(O)- N(Me)CH{sub 2}SiMe{sub 2}OTf and bromide TsN(Ac)CH{sub 2}C(O)N(Me)CH{sub 2}SiMe{sub 2}Br is weak. In triflate Ns–Pro–N(Me)CH{sub 2}SiMe{sub 2}OTf and bromide NsNHCH(Me)C(O)N(Me) CH{sub 2} SiMe{sub 2}Br, the Si…X interaction is significantly stronger and corresponds to a weak coordination bond. Hence, the tosylates can be considered as salts, whereas the para-nitrobenzenesulfonyl derivatives are monochelated five-coordinate silicon complexes.
- OSTI ID:
- 22943301
- Journal Information:
- Russian Chemical Bulletin, Journal Name: Russian Chemical Bulletin Journal Issue: 1 Vol. 68; ISSN RCBUEY; ISSN 1066-5285
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BROMIDES
BROMINE
CHELATES
CHEMICAL SHIFT
CLEAVAGE
ELECTRON DENSITY
INTERATOMIC DISTANCES
NUCLEAR MAGNETIC RESONANCE
ORGANIC FLUORINE COMPOUNDS
PROLINE
SARCOSINE
SILICON 29
SILICON COMPLEXES
SILICON COMPOUNDS
SULFONATES
TOPOLOGY
X-RAY DIFFRACTION