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Structures of AX,AX2 and ABX3 type compounds

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The simple structures come from the arrangement of the anions (though sometimes the cations) in the positions of the spheres in the fcc or hcp lattices, and the cations go into some or all of the octahedral and tetrahedral holes within the lattices. Structures based on face centered cubic lattices The Rock Salt structure This the structure adopted by  Sodium Chloride , NaCl. It is based on the fcc array of the large chloride anions, and the sodium cations occupy all the octahedral holes in the fcc  lattice . However, it could also be seen as an fcc array of sodium ions, with the anions in all the octahedral holes. Each ion is octahedrally coordinated by six counterions, and so this structure has so-called  (6,6)-coordination , where the first number refers to the coordination of the  cation  and the second to the  anion . The structure beyond the first coordination sphere can also be visualized. The Rock Salt, or NaCl, structure The sodium c...
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Metal - Olefin complexes

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Metal - Olefin complexes:- Synopsis:- Definition,structure and bonding in alkene complexes,Different type of alkene complexes,catalysis,synthesis of alkene complexes ,reaction of alkene complexes,Rotational barrier, Definition :-Alkene or olefin ligands are common in organotransition metal chemistry. In fact, the first organotransition metal complex, Zeise's salt (K[PtCl3(C2H4]·H2O) was an alkene complex . While reacting K2PtCl4 with EtOH in 1827, the Danish chemist Zeise synthesized the famous Zeise’s salt K[PtCl3(C2H4)]•H2O containing a Pt bound ethylene moiety and which incidentally represented the first metal−olefin complex . Structure and bonding in olefin complexes:- The metal−olefin bonding interaction is best explained by the Dewar−Chatt model, that takes into account two mutually opposing electron donation involving σ−donation of the olefinic C=C π−electrons to an empty dπ metal orbital followed by π−back donation from a filled metal dπ orbital into the un...
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Miller planes

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Planes in a crystal are described by notations called Miller indices  Miller indices of a plane, indicated by h k l, are given by the reciprocal of the intercepts of the plane on the three axes.  The plane, which intersects X axis at 1 (one lattice parameter) and is parallel to Y and Z axes, has Miller indices h = 1/1 = 1, k = 1/ = 0, l = 1/ = 0. It is written as (hkl) = (100).  Crystal Planes To find the Miller Indices of a plane, follow these steps:  Determine the intercepts of the plane along the crystal axes  Take the reciprocals  Clear fractions  Reduce to lowest terms and enclose in brackets () Ex: Intercepts on a, b, c : ¾, ½, ¼ (h k l) = (4/3, 2, 4) = (2 3 6) Planes can also have negative intercept e.g. 1, -1/2, 1 h k l = 1 -2 1. This is denoted as ( ) 121  Family of planes {hkl}  Planes having similar indices are equivalent, e.g. faces of the cube (100), (010) and (001). This is termed as a family of planes and...
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