Simulation · Chemistry · Class 12
Build coordination isomers and turn them in 3D
From the lesson Geometrical and optical isomerism in Coordination Compounds. Change the values and watch what happens.
Build coordination isomers and turn them in 3DChemistry · Class 12
The idea behind it
NCERT §5.4.1; §5.4.2
- Isomers share a formula but differ in how the atoms are arranged. Stereoisomers have the same bonds in different spatial arrangements; structural isomers have different bonds.
- Geometrical isomerism appears in heteroleptic complexes of CN 4 and 6. In square planar [MX₂L₂], the two X ligands sit side by side (cis) or across from each other (trans), as in cis- and trans-[Pt(NH₃)₂Cl₂].
- Square planar [MABXL] with four different unidentate ligands has three geometrical isomers: two cis and one trans.
- Tetrahedral complexes never show geometrical isomerism: every position is adjacent to every other, so the ligands' relative positions are all alike.
- Octahedral [MX₂L₄] ([Co(NH₃)₄Cl₂]⁺) and [MX₂(L–L)₂] ([CoCl₂(en)₂]⁺) also form cis and trans isomers.
- Octahedral [Ma₃b₃], such as [Co(NH₃)₃(NO₂)₃], gives fac and mer isomers: three identical donors on the corners of one face (facial), or along a meridian of the octahedron (meridional).
- Optical isomers (enantiomers) are non-superimposable mirror images, and such molecules or ions are chiral. The dextro (d) form rotates plane-polarised light to the right and the laevo (l) form to the left in a polarimeter.
- Optical isomerism is common in octahedral complexes with didentate ligands, e.g. [Co(en)₃]³⁺. For [PtCl₂(en)₂]²⁺ only the cis isomer is optically active; the trans form has a mirror plane.
- Of cis- and trans-[CrCl₂(ox)₂]³⁻, only the cis form is chiral.