关注：

1） 一些非典型的多中心少电子键合分子；

2） 一些典型的常见分子的结构及成键方式；

3） 从典型中发现非典型情形

1.square planar molecular geometry

  The square planar molecular geometry in chemistry describes the stereochemistry (spatial arrangement of atoms) that is adopted by certain chemical compounds.

     As the name suggests, molecules of this geometry have their atoms positioned at the corners of a square on the same plane about a central atom.

Idealized structure of a compound with square planar coordination geometry.

XeF₄, with asquare planargeometry, which can gain two fluorine atoms to form...

XeF₂, with alineargeometry, which can gain two fluorine atoms to form...

XeF₆, with anoctahedralgeometry.

http://en.wikipedia.org/wiki/Square_planar_molecular_geometry

 

Molecular geometry
Main group	Normal-valent Linear   Bent   Trigonal planar   Trigonal pyramidal   Tetrahedral Hypervalent Trigonal bipyramidal   Seesaw   T-shaped   Linear Octahedral   Square pyramidal   Square planar Pentagonal bipyramidal   Pentagonal pyramidal   Pentagonal planar Square antiprismatic
Transition metal	Normal-valent Bent   Trigonal pyramidal   Tetrahedral   Square pyramidal   Trigonal prismatic Hypervalent Linear   Trigonal planar   Square planar   Trigonal bipyramidal   Octahedral   Pentagonal bipyramidal   Square antiprismatic   Tricapped trigonal prismatic
Other shapes	Distorted octahedral   Capped square antiprismatic