Andreas H. Maulitz

Selective reduction of sulfuric chloride: the structure of the chlorosulfite ion

The stable salt 2 is obtained from the reaction of SO2Cl2 with the imidazol-2-ylidene 1; the pyramidal structure of the chlorosulfite anion is confirmed both by X-ray structure and MO calculation.

Hyperconjugation as a driving force for the different conformation of symmetric triethyl derivatives of boroxin, borazine, benzene and triazine

Abstract The molecular structure of the symmetric triethyl derivatives of boroxin ( 1 ), borazine ( 2 ), s-triazine ( 3 ), and benzene ( 4 ) have been studied by a combination of X-ray structure determinations and ab initio methods. A single crystal structure determination of ( 2 ) and ( 4 ) has been carried out. The molecular symmetry of 1,3,5-triethylbenzene ( C s ) has been experimentally determined to be different in comparison to triethylboroxin and B,B′,B″-triethylborazine ( C 3h ). Ab initio optimizations imposing both symmetries have been carried out at the HF /6–31G(d) level of theory. Natural bond orbital analyses were utilized to establish hyperconjugation to be responsible for the arrangement of the ethyl groups with respect to the plane of the six-membered rings. Various conformers for triethylboroxin have been taken into account. MP 2/6–31G(d) calculations were performed to estimate the relative stability of the different conformers.

Ab initio studies on halosulfite ions

Abstract High level ab initio studies were performed to investigate the stability of halosulfite ions. The basis set 6-31+G(3df) was used for the fluorosulfite and chlorosulfite ions. Pseudopotential functions were used for describing the core electrons of the heavier halogen atoms. Hartree-Fock and MP2 optimizations were carried out and various levels of theory up to QCISD(T) were used for the energy calculations. Additional calculations were performed to investigate the stability of the ions in polar environments. The calculated stability trend with respect to halosulfite ion formation from SO2 and the halide ion (SO2F−(≈ 50 kcal mol−1) > SO2Cl−1 (≈ 20 kcal mol−1) > SO2Br−1 (≈ 18 kcal mol−1) > SO2I−1 (≈ 13 kcal mol−1)) is in agreement with the experimentally observed trend. From these calculations, only the fluorosulfite ion appears to be stable in polar solvents, while all the other anions may dissociate.

Diarylmethylenecyclopropabenzenes in cycloaddition

Diarylmethylenecyclopropabenzenes react in [2+4] cycloaddition at the ‘cyclopropene’ bridge bond rather than at the exocyclic olefin. The results are in accord with computational data.

X-Ray crystal and ab initio structure of 3-ethynylcyclopropene: a curiously short carbon–carbon double bond

The X-ray crystal structure of 3-ethynylcyclopropene shows that the carbon–carbon double bond of the molecule is unusually short [1.255(2) A], whereas theoretical calculations suggest a relative insensitivity of the bond length to adjacent orbital interactions.