What is the minimum denticity of a ligand in a Metal Organic Framework(MOF)?
Is this number fixed for all MOFs?
To Abdolazim Hasseli:
I'm not an expert in MOFs, but the minimum denticity of any ligands is 1. Just consider water molecules in MOFs which are coordinated only through the O atom. For more information, please see the attached recent article entitled "Metal-Organic Frameworks and Metal-Organic Cages – A Perspective". Of course you can also find numerous papers on MOF's right here on RG. Just search the platform for "metal-organic frameworks" and you will find hundreds (if not thousands) of publication on this topic, many of them available as public full texts.
Dear Frank T. Edelmann ,
Thank you for your reply but my concern is about the minimum denticity of ligands in MOF.
Ligand with denticity of one can have just one bond with one metal ion in MOF while in MOF, one ligand seems to have bond with at least two metal ions.
My answer to my question is 2 but I want to make sure.
Abdolazim - Perhaps I did not understand your question correctly. Do you really mean the "minimum denticity of a ligand" or do you mean the coordination number of the metals? The minimum coordination number of a metal in a MOF is indeed 2. Ligands can have various denticities ranging from monodentate to e.g. octadentate or even more. If you consider e.g. ammonia (NH3) as ligand, it can only act as a monodentate ligand. Typical linkers used in MOF's such as the terephthalate dianion, –O2C-C6H4-CO2–, are e.g. tetradentate ligands.
See this article
Metal‐Organic Frameworks and Metal‐Organic Cages – A Perspective
Dear Frank T. Edelmann ,
Actually my question is about the ligands. For example can we use a monodentate ligand like NH3 to construct a MOF? What about bidentate ligands?
Abdolazim - As I mentioned earlier, I'm not a real expert when it comes to MOF's. According the the respective Wikipedia entry MOF's "are a subclass of coordination polymers, with the special feature that they are often porous. The organic ligands included are sometimes referred to as "struts" or "linkers", one example being 1,4-benzenedicarboxylic acid (BDC)." You cannot construct MOF's just with a monodentate ligand like NH3. Ammonia will coordinate to a metal under formation of a mononuclear complex, but not a coordination polymer. Even bidentate ligands alone will normally not result in MOF formation. You always need the linkers to create the voids. In typical MOF's you don't have just one sort of ligand, but the linkers plus other (e.g. bidentate) ligands.
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