Structural aspects of [2.2]heterophanes. Part II. Molecular structure of [2.2](2,5)thiophenophane and [2.2](2,5)furanophane
- 1 January 1978
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 1,p. 42-45
- https://doi.org/10.1039/p29780000042
Abstract
The crystal and molecular structure of the title compounds has been determined from the three-dimensional X-ray data by conventional Patterson and Fourier methods for (I) and by direct methods for (II). Crystals of (I) are monoclinic, space group P21/c, with a= 6.052(6), b= 12.63(1), c= 7.111(7)Å, β= 101.34(9)°, Z= 2. Crystals of (II) are orthorhombic, space group Pbca, with a= 13.60(1), b= 7.507(7), c= 9.725(7)Å, Z= 4. The structures were refined by least squares techniques to R 0.030 (I) and 0.041 (II) on the basis of 1215 and 421 independent reflections. The molecules of both compounds are centrosymmetric and well approximate to C2h symmetry. The heteroatoms are displaced (S 0.196, O 0.082 Å) from the planes of the aromatic rings which are parallel and separated by 2.63 (I) and 2.34 Å(II). The CH2–CH2 bond lengths are significantly stretched [1.592(2)(I), and 1.569(6)Å(II)]. The differently stepped structures are related to the different steric hindrance of oxygen and sulphur which determines the considerably different conformational mobility of such phanes.Keywords
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