Études Structurales en Relation Avec le Concept de Substitution “Capto‐Dative” II. Analyse des déformations moléculaires dans cinq déhydrodimères de formule générale: RCH2 (CN) (SR') C‐C (CN) (SR') CH2R(1, 2)

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Abstract
The crystal structures of five 1,4‐butanedinitrile derivatives have been determined using X‐Ray diffractometry in order to study the effects of captodative substitution on molecular geometry. (I) meso 2,3‐diacetonyl‐2,3‐bis (tert‐butylthio)‐1,4‐butanedinitrile, C18H28N2O2S2, is monoclinic, P21/c with a = 9.694(6), b = 10.208(4), c = 10.404(4) Å, β = 97.46(4) º, V = 1020.8(8)Å3, Z = 2. (II) meso 2,3‐bis[(acetylthio)methyl]‐2,3‐bis(tert‐butylthio)‐1,4‐butanedinitrile, C18H28N2O2S4, is triclinic, PI, with a = 12.867(4), b = 11.175(3), c = 10.430(2)Å, α = 90.43(2), β = 54.82(2), γ = 103.61(2) º, V = 1175.8(6)Å3, Z = 2. (III) meso 2,3‐bis(tert‐butylthio)‐2,3‐bis(butyrylmethyl)‐1,4‐butanedinitrile, C22H36N2O2S2 is monoclinic, C2/c, with a = 22.562(6), b = 10.932(4), c = 10.157(4)Å, β = 90.35(4) º, V = 2505.2(8)Å3, Z = 4. (IV) meso 2,3‐bis (tert‐butylthio)‐2,3‐diethyl‐l,4‐butanedinitrile, C16H28N2S2, is monoclinic, P21/n, with a = 10.004(2), b = 13.794(2), c = 6.633(1)Å, β = 95.61(2) º, V= 910.9(3)Å3 Z = 2. (V) dl 2,3‐diacetonyl‐2,3‐bis(methylthio)‐1,4‐butanedinitrile, C12H16N2O2S2, is triclinic, P1, with a = 9.347(3), b = 9.646(1), c = 8.318(2)Å, α = 99.70(2), β = 104.65(2), γ = 99.23(2) º, V = 698.8(3)Å3, Z = 2.The central carbon carbon bond lengths are very long in the five molecules. Mean C‐C distance is 1.593(2)Å. Bond angles around central carbon atom take values between 105 and 115°.