A coordinate-invariant generalization of the Lyddane-Sachs-Teller relation is presented for polar vibrations in materials with monoclinic and triclinic crystal systems. The generalization is derived from an eigendielectric displacement vector summation approach, which is equivalent to the microscopic Born-Huang description of polar lattice vibrations in the harmonic approximation. An expression...

the reaction of [pphj, nos,] with cucl and kscn (1 :3:3) in acetone produces the yell-ow crystals of [pph,], [wos,(cuncs),]. the crystals are triclinic, space group p1(2), z=2, a=12.4823(7), b=12.9224(7), c=18.6395(10)?, ?=83.907(5), ?= 73.152(4), y= 65.194(4)'. the crystal structure was determined by single crystal xray diffraction methods (mo-k ?) and refined by least-squares calculation...

The title compound, C18H18O4, is a triclinic polymorph of the previously reported monoclinic polymorph [Han & Zhen (2005 ▶). Acta Cryst. E61, o4358-o4359]. In the crystal of the triclinic polymorph, molecules are linked by two pairs of C-H⋯O hydrogen bonds, forming a two-dimensional network parallel to (102), and enclosing loops with graph set motifs of R2(2)(8) and R2(2)(6).

The crystal structures of ds-(«-Bu4N)2[ReBr4(NCS)2] (1) (triclinic, space group Pi, a = 11.475(6), b = 20.096(16), c = 22.144(11) A, a = 110.56(6), ß = 92.97(5), 7 = 99.77(7)°, Z = 4), m-(n-Bu4NMReBr4(NCSe)i] (2) (triclinic, space group PI, a = 11.527(3), b = 20.237(7), c = 22.07(2) Ä, a = 110.05(4), ß = 93.86(6), 7 = 99.49(4)°, Z = 4) and cis-{nBu4N)2[ReBr4(NCS)(NCSe)] (3) (triclinic, space gr...

THE TITLE COMPOUND (SYSTEMATIC NAME 2-mercaptoethan-aminium chloride), C(2)H(8)NS(+)·Cl(-), the hydro-chloride salt of cysteamine, in contrast to the previously reported triclinic polymorph [Kim et al. (2002 ▶). Polyhedron, 21, 225-228], crystallized in the monoclinic crystal system. In the crystal, the cysteaminium cations are linked to the chloride anions via one S-H⋯Cl and three N-H⋯Cl hydro...

The enzyme omega-transaminase catalyses the conversion of chiral omega-amines to ketones. The recombinant enzyme from Chromobacterium violaceum has been purified to homogeneity. The enzyme was crystallized from PEG 4000 using the microbatch method. Data were collected to 1.7 A resolution from a crystal belonging to the triclinic space group P1, with unit-cell parameters a = 58.9, b = 61.9, c = ...