Two pairs of independent cations and anions comprise the asymmetric unit of the title salt, C(6)H(16)NO(+)·C(9)H(8)N(3)O(2)S(2) (-). The cations are virtually superimposable and each exhibits a gauche disposition of the hy-droxy O and ammonium N atoms [the O-C-C-N torsion angles are 55.5 (3) and 57.5 (3)°]. Significant differences are seen in the mol-ecular structures of the anions as seen in t...

I consider the semiclassical approximation of the graded Chern-Simons field theories describing certain systems of topological A type branes. I show that the semiclassical partition function can be expressed in terms of a certain (differential) numerical invariant which is a version of the analytic torsion of Ray and Singer, but associated with flat graded superbundles. I also discuss a ‘twiste...

The asymmetric unit of the title salt, 2C(4)H(12)NO(+)·C(14)H(8)O(4)S(2) (2-), contains an eth-yl(2-hydr-oxy)aminium cation and half a 2,2'-disulfanediyldibenzoate anion, with the latter disposed about a twofold axis. The cation is a straight chain with the exception of the terminal hydr-oxy group [the N-C-C-O torsion angle is 66.5 (2)°]. A twisted conformation is found for the anion [the C-S-S...

In the title compound, C(24)H(29)ClO(8)·2.5H(2)O, which contains two organic mol-ecules (A and B) and five heavily disordered water mol-ecules in the asymmetric unit, the γ-lactone ring and the cyclo-hexenone ring are both trans-fused to the central cyclo-decene ring. The cyclehexenone ring features an α,β-unsaturated ketone with torsion angles between the conjugated carbonyl and alkene bonds o...

The title compound, C(13)H(14)N(2)O(2)S, crystallized with two independent mol-ecules in the asymmetric unit. They both have V-shaped conformations: the dihedral angles between their benzene rings are identical [45.86 (13)°] and their C-S-N-C torsion angles are similar [67.9 (3) and 70.2 (3)°]. In the crystal, the mol-ecules are linked by N-H⋯O and N-H⋯N hydrogen bonds, generating a three-dimen...

The title compound, C(14)H(11)NO(4), crystallizes with two mol-ecules in the asymmetric unit. The major conformational difference between these two mol-ecules is the dihedral angle between the aromatic rings, namely 36.99 (5) and 55.04 (5)°. The nitro groups are coplanar with the phenyl rings to which they are attached, the O-N-C-C torsion angles being -1.9 (3) and 1.0 (3)° in the two mol-ecules.

Applying a theorem according to Rhemtulla and Formanek, we partially solve an open problem raised by Hochman with an affirmative answer. Namely, we show that if G is a countable torsion-free locally nilpotent group that acts by homeomorphisms on X, and S ⊂ G is a subsemigroup not containing the unit of G such that f ∈ 〈1, s f : s ∈ S〉 for every f ∈ C(X), then (X, G) has zero topological entropy.

In the title compound, C(18)H(29)N(3)O, a polysubstituted guanidine, the torsion angles indicate that the guanidine unit and the carbonyl group are almost perpendicular to one another [O-C-N-C= -7.40 (18), C-N-C-N= -97.21 (15) and 86.41 (13)°]. The crystal packing is stablized by inter-molecular N-H⋯O hydrogen bonds, which link the mol-ecules into a chain.

In the crystal structure of the title salt, (C(5)H(9)N(2))(2)[CuCl(4)], the organic cations and the tetrahedral [CuCl(4)] anions are linked into a three-dimensional network by N-H⋯Cl hydrogen bonds. The two 2-ethyl imidazolium cations in the asymmetric unit differ in the orientation of the ethyl group, with N-C-C-C torsion angles of -170.0 (4) and -87.6 (5)°.

There are two mol-ecules in the asymmetric unit of the title compound, C(17)H(20)O(4)S(2). There are slight differences in the twist of the two rings relative to the S-C-S chain [dihedral angles of 48.41 (18) and 87.58 (16)° in the first mol-ecule and 45.98 (18) and 87.02 (18)° in the second] and the difference in the C-S-C-S torsion angles [176.68 (17) and -77.6 (2)° for the two independent mo...