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  2. Coordination geometry - Wikipedia

    en.wikipedia.org/wiki/Coordination_geometry

    The number of coordination bonds (coordination number) can vary from two in K[Ag(CN) 2] as high as 20 in Th(η 5-C 5 H 5) 4. [2] One of the most common coordination geometries is octahedral, where six ligands are coordinated to the metal in a symmetrical distribution, leading to the formation of an octahedron if lines

  3. Geometry index - Wikipedia

    en.wikipedia.org/wiki/Geometry_index

    where: β > α are the two greatest valence angles of coordination center; θ = cos −1 (− 1 ⁄ 3) ≈ 109.5° is a tetrahedral angle. Extreme values of τ 4 and τ 4 ′ denote exactly the same geometries, however τ 4 ′ is always less or equal to τ 4 so the deviation from ideal tetrahedral geometry is more visible.

  4. Pauling's rules - Wikipedia

    en.wikipedia.org/wiki/Pauling's_rules

    The radius ratio rules are a first approximation which have some success in predicting coordination numbers, but many exceptions do exist. [3] In a set of over 5000 oxides, only 66% of coordination environments agree with Pauling's first rule. Oxides formed with alkali or alkali-earth metal cations that contain multiple cation coordinations are ...

  5. VSEPR theory - Wikipedia

    en.wikipedia.org/wiki/VSEPR_theory

    The steric number of a central atom in a molecule is the number of atoms bonded to that central atom, called its coordination number, plus the number of lone pairs of valence electrons on the central atom. [11] In the molecule SF 4, for example, the central sulfur atom has four ligands; the coordination number of sulfur is four. In addition to ...

  6. Coordination number - Wikipedia

    en.wikipedia.org/wiki/Coordination_number

    The most common coordination number for d-block transition metal complexes is 6. The coordination number does not distinguish the geometry of such complexes, i.e. octahedral vs trigonal prismatic. For transition metal complexes, coordination numbers range from 2 (e.g., Au I in Ph 3 PAuCl) to 9 (e.g., Re VII in [ReH 9] 2−).

  7. Cation-anion radius ratio - Wikipedia

    en.wikipedia.org/wiki/Cation-anion_radius_ratio

    This diagram is for octahedral interstices (coordination number six): 4 anions in the plane shown, 1 above the plane and 1 below. The stability limit is at r C /r A = 0.414. The radius ratio rule defines a critical radius ratio for different crystal structures, based on their coordination geometry. [1]

  8. Trigonal planar molecular geometry - Wikipedia

    en.wikipedia.org/wiki/Trigonal_planar_molecular...

    Structure of boron trifluoride, an example of a molecule with trigonal planar geometry.. In chemistry, trigonal planar is a molecular geometry model with one atom at the center and three atoms at the corners of an equilateral triangle, called peripheral atoms, all in one plane. [1]

  9. Trigonal bipyramidal molecular geometry - Wikipedia

    en.wikipedia.org/wiki/Trigonal_bipyramidal...

    In chemistry, a trigonal bipyramid formation is a molecular geometry with one atom at the center and 5 more atoms at the corners of a triangular bipyramid. [1] This is one geometry for which the bond angles surrounding the central atom are not identical (see also pentagonal bipyramid), because there is no geometrical arrangement with five terminal atoms in equivalent positions.