|MadSci Network: Chemistry|
Garima, This is a fairly complicated question to answer in a few brief paragraphs. Basically, it has to do with the available bonding orbitals in the ligands (i.e. the things attached to the central metal atoms). Carbon has room in it's p-orbitals to overlap with the metal atoms, so it forms pi-type bonds. Chlorine uses s- orbitals to form sigma-type bonds to the central metal. Ligands with room in their d-orbitals will form still different kinds of bonds. I recommend taking a look at a college freshman chemistry book (e.g. Zumdahl, "General Chemistry"). Also, look at high-spin vs. low-spin complexes. Regards, Marc
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