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The notion that the best hydrogen-bond donor preferentially interacts with the best hydrogen-bond acceptor has been explored in the synthesis and structural characterization of 12 salts based on asymmetric 2-aminopyrimidinium cations: 2-amino-4-methoxy-6-methylpyrimidinium 2-fluorobenzoate, 2-amino-4-methoxy-6-methylpyrimidinium 3-chlorobenzoate, 2-amino-4-methoxy-6-methylpyrimidinium 3-nitrobenzoate, 2-amino-4-methoxy-6-methylpyrimidinium benzoate, 2-amino-4-methoxy-6-methylpyrimidinium 3-N,N ‘(dimethyl)aminobenzoate, 2-amino-4-methoxy-6-methylpyrimidinium methylene-hydrogensuccinate hydrate, bis(2-amino-4-methylpyrimidinium) fumarate, 2-amino-4-methylpyrimidinium 3-fluorobenzoate, 2-amino-4-methylpyrimidinium nitrate, 2-amino-4-methylpyrimidinium 3-chlorobenzoate, 2-amino-4-methylpyrimidinium 2-methyl-hydrogenmaleate, and 2-amino-4-chloro-6-methylpyrimidinium 3,5-dinitrobenzoate toluene0.4. In each structure, the −COO- acceptor consistently seeks out the −N−H+ donor generating the most important interm...

Tetracyanocalix[4]arene has been synthesized in a cone conformation and crystallized from solution in an orthorhombic system, space group P212121, with a = 13.7999(9) A, b = 16.820(1) A, c = 21.754(1) A, Dc = 1.218 g/cm3, Z = 4 (C62H47N5O4). Refinement based on 11008 observed reflections yielded R1 = 0.042. Further crystallographic studies have revealed that this compound self-assembles into a one-dimensional coordination polymer in the presence of Ag+ cation. This extended structure also crystallizes in an orthorhombic system, space group Cmca, with a = 17.770(1) A, b = 31.498(2) A, c = 23.107(2) A, Dc = 1.319 g/cm3, Z = 8 (C63H52AgCl2F6N4O6P). Refinement based on 7391 observed reflections yielded R1 = 0.109.