Molecular and electronic structure of δ-valerothiolactone.
The crystal structure of the six-member heterocyclic δ-valerothiolactone (1-thiocycloalkan-2-one) compound has been determined by X-ray diffraction at low temperature, revealing that its skeleton adopts a half-chair conformation. The conformation around the thioester group is almost planar with an anti orientation of the C=O double bond with respect the S-C single bond [C(2)-S(1)-C(6)-O(1) = 176.26(8)°]. The skeletal parameters, especially valence angles [∠C5-C6-S = 121.19(6)°, ∠O=C6-C5 = 122.25(8)°, ∠C6-S-C2 = 106.80(4)°], differ from those typically found in acyclic thioester compounds, symptomatic of the presence of strain effects. The conventional ring strain energy was determined to be 7.5 kcal/mol at the MP2/6-311++G(d,p) level of calculation within the hyperhomodesmotic model approximation. Moreover, the valence electronic structure was investigated by HeI photoelectron spectroscopy assisted by quantum chemical calculations at the OVGF/6-311++G(d,p) level of theory. The first three bands at 9.35, 9.50, and 11.53 eV denote ionizations related with the n(S), n(O), and π(C=O) orbitals, respectively, demonstrating the importance of the -SC(O)- group in the outermost electronic properties.
CEQUINOR (UNLP-CONICET, CCT La Plata), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 962 (1900), La Plata, República Argentina.
Nahir Y
NY
Dugarte
Mauricio F
MF
Erben
Roland
R
Boese
Mao-Fa
MF
Ge
Li
L
Yao
Carlos O
CO
Della Védova
D002244:Carbon / Q000737:chemistry; D003198:Computer Simulation; D018360:Crystallography, X-Ray / Q000379:methods; D004583:Electrons; D007783:Lactones / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry; D011753:Pyrones / Q000737:chemistry*; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared / Q000379:methods; D013696:Temperature; D014961:X-Ray Diffraction
D007783:Lactones; D011753:Pyrones; C052207:delta-valerolactone; D002244:Carbon; D010100:Oxygen