A polarized, twisted, ethylene: structure of methyl 2-(1,3-dimethyl-2-imidazolidinylidene)-3-oxobutyrate dihydrate, C<SUB>10</SUB>H<SUB>16</SUB>N<SUB>2</SUB>O<SUB>3</SUB>.2H<SUB>2</SUB>O

Mr=248, monoclinic, P21/n, a=12.028 (2), b=7.168( 2), c=15.187 (5) Å , β=91.88(2)°, Z=4, V=1308.6 Å3, Dm=1.26, Dx= 1.263 Mg m-3, λ (Cu Kα)=1.5418 Å, μ=0.86 mm-1, F(000)=536, T=293 K. Final R = 5.6% for 2120 observed reflexions. Owing to the push-pull effect, the C=C bond distance is as long as 1.464 (2) Å with the twist angle about the bond 62.6°

Polarized ethylenes: structure of 2-benzoyl-3-dimethylamino-3-methylthio-2-propenenitrile

C13H14N2OS, Mr=246, is monoclinic, P21/c, with a=7.214(1), b=8.935(5), c=20.243 (6) Å, β=99.42 (2)°, V=1304.83 Å3, Z=4, Dm = 1.23, Dx =1.25 Mg m-3, μ(Mo Kα, λ=0.7107 Å)=0.232 mm-1, F(000)=520. The structure was solved by direct methods and refined to an R value of 0.042 using 1127 intensity measurements. The C=C and C-N bond distances differ considerably from their normal values. An appreciable rotation [38.3(4°] about the C=C bond is observed, the bond length being 1.414(5) Å. This is due to the combination of push-pull and steric effects

Polarized Ethylenes: Structures of [Dimethylamino(methylthio)methylene]malononitrile(I), C7H9N3SC_7H_9N_3S, and [Bis(dimethylamino)methylene]malononitrile (II), C8H12N4C_8H_{12}N_4

(I): $M_r$= 167, orthorhombic, $Pna2_1$ , Z = 4, a=7.899(3), b=8.670(2), c=12.956(6) \AA, V= 887.2 $\AA^3$, $D_m$= 1.25, $D_ x$= 1.250 $Mg m^{ -3}$, $\mu$(Mo $K_\alpha$, $\lambda$ = 0-7107 \AA) = 0.299 $mm^{ -1}$, F(000) = 352, T= 293 K. (II): $M_r$= 164, orthorhombic, Pcab, Z= 8, a = 7.876 (2), b = 14.430 (4), c= 16.312 (5) \AA, V= 1853.9 ,$\AA^3$, $D_m$ = 1.18,$D_ x$ = 1.175 Mg $m^{-3}$, $\mu$(Mo $K_\alpha$, $\lambda$ = 0.7107 \AA) = 0.083 $mm^{-1}$, F(000) = 704, T= 293 K. Both structures were solved by direct methods and refined to R = 4.1% (542 significant reflections) for (I) and R = 4.9% (709 significant reflections) for (II). The C=C bond lengths are 1.397 (8)\AA in (I) and 1.407 (4)\AA in (II). The molecules are twisted about the C=C bond by $21.7^o$ in (I) and $29.3^o$ in (II)

Polarized ethylenes: structures of (1,3-dimethyl-2-imidazolidinylidene)malononitrile and (1,3-dimethyl-2-perhydropyrimidinylidene)malononitrile

Crystal structures of the title compounds, (I) and (II), have been determined by three-dimensional diffraction methods. Crystals of CsHIoN 4 (I) are monoclinic, space group P21/a with Z = 4, Mr= 162, a = 7.965 (1), b = 16.232 (2), c = 7.343 (1) A, fl = 113.54 (1) °, V = 890.7 A 3, D,n = 1.218, D x = 1.208 gcm -3, g(Cu Ka, 2 = 1.5418/~) = 6.47 em -1, F(000) = 344. The crystals of C9H12N4 (II) are orthorhombic, space group P21en, with Z = 4, Mr = 176, a = 7.983 (3), b = 8.075 (2), c = 14.652 (3) ./k, V = 944.43/~3, Dm= 1.219, D x = 1.237 g cm -3, #(Mo Ka, ). = 0.7107 ,/k) = 0.868 cm -1, F(000) = 376. Both structures were solved by direct methods and refined to R = 5.8% for (I) and 5.3 % for (II). The C-C double-bond distances are 1.407 (3) in (I) and 1.429 (6)/~ in (II), appreciably longer than normal. The steric and push-pull effects result in rotation about the C=C bond, the rotation angles being 20.2 (3) in (I) and 31.5 (6) o in (II)

Push-pull ethylenes: the structures of 3-(2-imidazolidinylidene)-2,4-pentanedione (I), C<SUB>8</SUB>H<SUB>12</SUB>N<SUB>2</SUB>O<SUB>2</SUB>, and 3-(1,3-dimethyl-2-imidazolidinylidene)-2,4-pentanedione trihydrate (II), C<SUB>10</SUB>H<SUB>16</SUB>N<SUB>2</SUB>O<SUB>2</SUB>.3H<SUB>2</SUB>O

(I): Mr=168, triclinic, P1, Z=2, a=5.596 (2), b=6.938 (3), c=10.852 (4) Å, α=75.64 (3), β=93.44 (3), γ=95.47 (3)°, V = 406.0 Å3, Dm=1.35 (by flotation using carbon tetrachloride and n-hexane), Dx=1.374 Mg m-3, μ (Mo Kα, λ=0.7107 Å) =1.08 cm-l, F(000)=180, T=293 K. (II): Mr= 250, triclinic, P1, Z=2, α=7.731(2), b=8.580(2), c=11.033 (3) Å , α = 97.66 (2), β = 98.86 (2), γ=101.78 (2)°, V=697.5 Å3, Dm=1.18 (by flotation using KI solution), Dx=1.190Mg m-3, μ (Mo Kα, β=0.7107 Å)=1.02 cm-1, F(000)=272, T=293 K. Both structures were solved by direct methods and refined to R=4.4\% for 901 reflexions for (I) and 5.7% for 2001 reflexions for (II). The C=C bond distances are 1.451 (3) Å in (I) and 1.468 (3) Å in (II), quite significantly longer than the C=C bond in ethylene [1.336 (2) Å]. The twist angle about the C=C bond in (II) is 72.9(5)° but molecule (I) is essentially planar, the twist angle being only 4.9 (5)°

Push–Pull Ethylenes: The Structures of 3-(2- Imidazolidinylidene)-2,4-pentanedione (I), C8H12N2O2C_8H_{12}N_2O_2, and 3-(1,3-Dimethyl-2- imidazolidinylidene)-2,4-pentanedione Trihydrate (II), C10H16N2O2.3H2OC_{10}H_{16}N_2O_2.3H_2O

(I): $M_r$= 168, triclinic, $P^-_1$, Z=2, a=5.596 (2), b = 6.938 (3), c = 10.852 (4)\AA, \alpha= 75.64 (3), \beta= 93.44 (3), \gamma= 95.47 $(3)^o$, V=406.0 $\AA^3$, $D_m$= 1.35 (by flotation using carbon tetrachloride and n-hexane), $D_x$= 1.374 $Mg m^{-3}$, \mu(Mo K\alpha, \lambda = 0.7107 \AA) = 1.08 $cm^{-l}$, F(000) = 180, T= 293 K. (II): $M_r$= 250, triclinic, $P^-_1$, Z= 2, a = 7.731(2), b=8.580(2), c=11.033(3)\AA, \alpha= 97.66 (2), \beta= 98.86 (2), \gamma= 101.78 $(2)^o$, V= 697.5 $\AA^3$, $D_m$ = 1.18 (by flotation using KI solution), $D_x$= 1.190Mg $m^{-3}$, \mu(Mo K\alpha, \gamma=0.7107 \AA)= 1.02 $cm^{-1}$, F(000) = 272, T= 293 K. Both structures were solved by direct methods and refined to R = 4.4\% for 901 reflexions for (I) and 5.7\% for 2001 reflexions for (II). The C=C bond distances are 1.451 (3) \AA in (I) and 1.468 (3)\AA in (II), quite significantly longer than the C=C bond in ethylene [1.336 (2)\AA; Bartell, Roth, Hollowell, Kuchitsu & Young (1965). J. Chem. Phys. 42, 2683-2686]. The twist angle about the C=C bond in (II) is 72.9 $(5)^o$ but molecule (I) is essentially planar, the twist angle being only 4.9 $(5)^o$

Polarized ethylenes: structures of (1,3-dimethyl-2-imidazolidinylidene)malononitrile and (1,3-dimethyl-2-perhydropyrimidinylidene)malononitrile

Crystal structures of the title compounds, (I) and (II), have been determined by three-dimensional diffraction methods. Crystals of C<SUB>8</SUB>H<SUB>10</SUB>N<SUB>4</SUB> (I) are monoclinic, space group P2<SUB>1</SUB>/a with Z=4, M<SUB>r</SUB>=162, a=7.965 (1), b=16.232 (2), c=7.343 (1) Å , β=113.54 (1)° , V=890.7 Å<SUP>3</SUP>, D,<SUB>n</SUB>=1.218, D<SUB>x</SUB> = 1.208 gcm<SUP>-3</SUP>, μ (Cu Kα, λ=1.5418 Å)=6.47 cm<SUP>-1</SUP>, F(000) = 344. The crystals of C<SUB>9</SUB>H<SUB>12</SUB>N<SUB>4</SUB> (II) are orthorhombic, space group P2<SUB>1</SUB>cn, with Z=4, M<SUB>r</SUB>=176, a = 7.983 (3), b=8.075 (2), c=14.652 (3) Å, V = 944.43 Å<SUP>3</SUP>, D<SUB>m</SUB>=1.219, D<SUB>x</SUB>=1.237 g cm<SUP>-3</SUP>, μ(Mo Kα, λ=0.7107 Å)=0.868 cm<SUP>-1</SUP>, F(000)=376. Both structures were solved by direct methods and refined to R=5.8% for (I) and 5.3 % for (II). The C-C double-bond distances are 1.407 (3) in (I) and 1.429 (6) Å in (II), appreciably longer than normal. The steric and push-pull effects result in rotation about the C=C bond, the rotation angles being 20.2 (3) in (I) and 31.5 (6) o in (II)

Polarized Ethylenes: Structure of 2-Benzoyl-3-dimethylamino-3-methylthlo-2-propenenitrile

C13H14N2OS, M r = 246, is monoclinic, P21/c, with a = 7.214(1), b = 8.935(5), c = 20.243 (6) A, fl =99.42 (2) °, V = 1304.83 ,~3, Z = 4, D m = 1.23, D x =1.25 Mg m -3, p(Mo Ka, 2 = 0.7107 A) = 0.232 mm -~,F(000) = 520. The structure was solved by direct methods and refined to an R value of 0.042 using 1127 intensity measurements. The C=C and C-N bond distances differ considerably from their normal values. An appreciable rotation [38.3(4) °] about the C=C bond is observed, the bond length being 1.414(5)A.This is due to the combination of push-pull and steric effects

Polarized Ethylenes: Structures of (l,3-Dimethyl-2-imidazolidinylidene)malononitrile and (l,3-Dimethyl-2-perhydropyrimidinylidene)malononitrile

Crystal structures of the title compounds, (I) and (II), have been determined by three-dimensional diffraction methods. Crystals of CsHIoN 4 (I) are monoclinic, space group P21/a with Z = 4, Mr= 162, a = 7.965 (1), b = 16.232 (2), c = 7.343 (1) A, fl = 113.54 (1) °, V = 890.7 A 3, D,n = 1.218, D x = 1.208 gcm -3, g(Cu Ka, 2 = 1.5418/~) = 6.47 em -1, F(000) = 344. The crystals of C9H12N4 (II) are orthorhombic, space group P21en, with Z = 4, Mr = 176, a = 7.983 (3), b = 8.075 (2), c = 14.652 (3) ./k, V = 44.43/~3, Dm= 1.219, D x = 1.237 g cm -3, #(Mo Ka, ). = 0.7107 ,/k) = 0.868 cm -1, F(000) = 376. Both structures were solved by direct methods and refined to R = 5.8% for (I) and 5.3 % for (II). The C-C double-bond distances are 1.407 (3) in (I) and 1.429 (6)/~ in (II), appreciably longer than normal. The steric and push-pull effects result in rotation about the C=C bond, the rotation angles being 20.2 (3) in (I) and 31.5 (6) o in (II)

Push-pull ethylenes: the structures of 3-(2-imidazolidinylidene)-2,4-pentanedione (I), C8H12N2O2, and 3-(1,3-dimethyl-2-imidazolidinylidene)-2,4-pentanedione trihydrate (II), C10H16N2O2.3H2O

(I): Mr= 168, triclinic, P1, Z=2, a= 5.596 (2), b = 6.938 (3), c = 10.852 (4) A, ~t= 75.64 (3), fl= 93.44 (3), ),= 95.47 (3) °, V= 406.0A 3, Din= 1.35 (by flotation using carbon tetrachloride and n-hexane), D x= 1.374 Mg m -3, g(Mo Kct, 2 = 0.7107 A) = 1.08 cm -l, _F(000) = 180, T= 293 K. (II): Mr= 250, triclinic, P1, Z= 2, a = 7.731(2), b=8.580(2), c=11.033(3)A, a= 97-66 (2), fl= 98.86 (2), y= 101.78 (2) °, V= 697.5 A 3, D m = 1.18 (by flotation using KI solution), Dx= 1.190Mgm -3, g(MoKa, 2=0.7107A)= 1.02 cm -1, F(000) = 272, T= 293 K. Both structures were solved by direct methods and refined to R = 4.4% for 901 reflexions for (I) and 5.7% for 2001 reflexions for (II). The C=C bond distances are 1.451 (3) A in (I) and 1.468 (3)A in (II), quite significantly longer than the C=C bond in ethylene [1.336 (2).~; Bartell, Roth, Hollowell, Kuchitsu & Young (1965). J. Chem. Phys. 42, 2683-2686]. The twist angle about the C=C bond in (II) is 72.9 (5) ° but molecule (I) is essentially planar, the twist angle being only 4.9 (5) °