Acta Crystallographica Section B

Structural Science

Volume 58, Part 3 Number 2 (June 2002)

Acta Cryst. (2002). B58, 530-544 [doi:10.1107/S0108768102000642]

Chiral versus racemic building blocks in supramolecular chemistry: malate salts of organic diamines

D. M. M. Farrell, G. Ferguson, A. J. Lough and C. Glidewell

Abstract: (S)-Malic acid forms a salt with N,N'-dimethylpiperazine, [MeN(CH₂CH₂)₂NMe]H₂²⁺·2C₄H₅O₅^- (1) (triclinic, P1, Z' = 1), in which the cations link pairs of hydrogen-bonded anion chains to form a molecular ladder. With 4,4'-bipyridyl, (S)-malic acid forms a 1:1 adduct which crystallizes from methanol to yield two polymorphs, (2) (triclinic, P1, Z' = 1) and (3) (monoclinic, C2, Z' = 1), while racemic malic acid with 4,4'-bipyridyl also forms a 1:1 adduct, (4) (monoclinic, P2₁/c, Z' = 1). In each of (2), (3) and (4) the components are linked by O-HN and N-HO into chains of alternating bipyridyl and malate units, which are linked into sheets by O-HO hydrogen bonds. In each of the 1:1 adducts (5) and (6), formed by, respectively, (S)-malic acid and racemic malic acid with 1,2-bis(4'-pyridyl)ethene, the diamine is disordered over two sets of sites, related by a 180° rotation about the NN vector. In (5), (C₁₂H₁₀N₂)H⁺·C₄H₅O₅^- (triclinic, P1, Z' = 1), the components are again linked by a combination of N-HO and O-HO hydrogen bonds into sheets, while in (6) (triclinic, P ${\overline 1}$ , Z' = 0.5) there is only partial transfer of the H atom from O to N and the malate component is disordered across a centre of inversion. With 1,4-diazabicyclo[2.2.2]octane, racemic malic acid forms a 1:2 salt, [(C₆H₁₂N₂)H₂]²⁺·2C₄H₅O₅^- (7) (monoclinic, P2₁/c, Z' = 2), while (S)-malic acid forms a 1:1 adduct, (8) (monoclinic, P2₁, Z' = 3). There are thus six independent molecular components in each. In (7) the ions are linked by an extensive series of N-HO and O-HO hydrogen bonds into a three-dimensional framework, but in (8) there is extensive disorder involving all six components, and no refinement proved to be feasible.

Online 29 May 2002


	Structure factor file (CIF format) (100.4 kbytes) Contains datablock 1

	Structure factor file (CIF format) (72.3 kbytes) Contains datablock 2

	Structure factor file (CIF format) (66.4 kbytes) Contains datablock 3

	Structure factor file (CIF format) (148.7 kbytes) Contains datablock 4

	Structure factor file (CIF format) (106.5 kbytes) Contains datablock 5

	Structure factor file (CIF format) (63.6 kbytes) Contains datablock 6

	Structure factor file (CIF format) (372.1 kbytes) Contains datablock 7

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