The synthesis of two new chiral guanidines 5 and 12 and derived guanidinium salts 6, 11, 13 -15 with one and three N-(1-phenylethyl) substituents is described. In both cases, the well-precedented, reliable route via chloro-formamidines was taken. Since direct attachment of the N-methyl-N-(1-phenethyl)-amino group failed, the two-step protocol -introduction of the primary 1-phenethylamino group first followed by N-methylation -was employed. Crystal structures and NMR data reveal, that the sterically highly congested "tris" salt -with formal C 3 symmetry, albeit unsymmetrical in the crystal -constitutes an intriguing structure with two rotamers present in solution.
C0H13.26lN2O1.13, monoclinic, C\2lm\ (no. 12), a = 11.910(2) Â, b = 8.011(2) Â, c = 10.071(2) Â, β = 91.24(2)°, V = 960.6 λ\ Ζ = 4, R gt (F) = 0.041, wRkÌF 1 ) = 0.088, T= 293 Κ. Source of materialThe title compound was isolated as a hydrolysed side-product, which was formed in an abnormal way by addition of methyl iodide to the (S)-N-( 1,3-dimethyl-imidazolidin-2-ylidene)-N-( 1 -phenylethyl)amine [1,2]. The usual reactions of guanidines with methylating agents take place at the imine nitrogen [2]. The compound was crystallized from acetonitrile and diethyl ether to give colourless crystals (m.p. 418 K), which turn amorphous at ca. Experimental detailsDisplacement ellipsoids of Ol, CI, and N1 show large elongations perpendicular to the mirror plane (figure, bottom). This is an indication of a disorder, but the resolution of the data is too weak for refinement of discrete disorder positions, with respect to the flat geometry forced by the caibonyl function. Twin refinement strategies also did not lead to better results. The disordered hydrogen positions of C2, C3, C3 A and C4 are generated by the mirror plane operator. The hydrogen atoms of the methylene functions at C2 and C3 were calculated and then fixed with respect to the disorder. The hydrogen atoms of the methyl groups were refined with fixed individual displacement parameters using a riding model with a d(C-H) distance of 0.96 Â and were allowed to rotate but not to tip. DiscussionIn the tide crystal structure, the atoms Ol, CI, Nl, C2, C4, and II lie on special positions of the mirror plane χ,Ο,ζ. The mirror plane operator χ,-y¿ completes the ammonium ion with the methyl group C5A and generates the second domain of the disordered methylene functions of C3, C3A. The five-membered ring system shows an envelope conformation, where the disordered positions of the methylene groups at C3 and C3A are situated 0.470(9) À below and above the mirror plane. We localized an electron density peak, which was identified as a fraction of an oxygen atom of a solvent water molecule. Free refinement of coordinates, anisotropic displacement parameters and of the population factor converged by a fraction of 1/8 of the occupancy factor.
Source of materialThe title compound was isolated as ah ydrolysed side-product, which was formed in an abnormal way by addition of methyl iodide to the( S )-N-(1,3-dimethyl-imidazolidin-2-ylidene)-N-(1-phenylethyl)amine [1,2]. The usual reactions of guanidines with methylating agents take place at the imine nitrogen [2]. The compound was crystallized from acetonitrile and diethyl ether to give colourless crystals (m.p. 418 K), which turn amorphous at ca. Experimental detailsDisplacement ellipsoids of O1, C1, and N1 show large elongations perpendicular to the mirror plane (figure, bottom). This is an indication of adisorder, but the resolution of the data is too weak for refinement of discrete disorder positions, with respect to the flat geometry forced by the carbonyl function. Twin refinement strategies also did not lead to better results. The disordered hydrogen positions of C2, C3, C3A and C4 are generated by the mirror plane operator. The hydrogen atoms of the methylene functions at C2 and C3 were calculated and then fixed with respect to the disorder. The hydrogen atoms of the methyl groups were refined with fixed individual displacement parameters using ar iding model with a d(C-H) distance of 0.96 .Å and were allowed to rotate but not to tip. DiscussionIn the title crystal structure, the atoms O1, C1, N1, C2, C4, and I1 lie on special positions of the mirror plane x,0,z.The mirror plane operator x,−y,z completes the ammonium ion with the methyl group C5A and generates the second domain of the disordered methylene functions of C3, C3A. The five-membered ring system shows an envelope conformation, where the disordered positions of the methylene groups at C3 and C3A are situated 0.470(9) Å below and above the mirror plane. We localized an electron density peak, which was identified as afraction of an oxygen atom of as olvent water molecule. Free refinement of coordinates, anisotropic displacement parameters and of the population factor converged by afraction of 1/8 of the occupancy factor. Hydrogen atoms of the water molecule could not be localized. O1W lies on the special position ½,y,0. The O1W···I1 contact is 3.34(3) Å, which is remarkably short.
Source of materialThe title compound was prepared by reacting (S)-l-phenylethylamine with 2-chloro-l,3-dimethyl-imidazolinium chloride [1,2], The crude product was recrystallized from acetonitrile to give colourless crystals (m.p. 480 K) [1]. The enantiomerically pure compound has = -41 (c = 1.04, CH3CN). Experimental detailsΗ atoms were located on difference fourier map, but refined with fixed individual displacement parameters using a riding model with d(C-H) ranging from 0.93 to 0.98 Â, except for H3 of the ammonium ion which is refined free because of its relevance for the intermolecular hydrogen bond. In addition, the methyl groups were allowed to rotate but not to tip. DiscussionThe absolute configuration of the tide compound, as known from the starting material (S)-1 -phenyl-ethylamine, was confirmed by the absolute structure determination by X-ray data indicated by the Flack parameter of χ = 0.01(11). The imidazolidine ring is showing a flat conformation forced by the guanidinium system C1, Ν1, N2 and N3 and is characterized by a r.m.s. ¿=0.0344 À of the best plane formed by the atoms NI, CI, N2, C2 and C3. N1 and N2 are showing a slight pyramidalization, where the methyl group C4 lies 0.43 A above and the methyl group C5 -0.34 Â below this plane. A strong intermolecular hydrogen bond between the ammonium ion N3-H3 as donor and the chlorine ion Cll as acceptor is evident. The H3-C11 distance is 2.32(3) Λ and the angle N3-H3-C11 is 174(3)°.
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