ChemSiddiqui Posted November 2, 2009 Share Posted November 2, 2009 (edited) Hey everyone, I was just wondering in the VO(acac)2 which is a Vandium (IV) complex the V=O bond length is significantly shorter than V-O bond length so the discription that it has a square-pyramidal geometry is somewhat misleading. what do you guys thing? I know that in books and at various places it is stated to be square-pyramidal. I am also suspecting some distortion because of the Jahn-teller effect? your opinion on that is welcome. PS. I just realised I said Jahn-teller distortion which is obviuosly not possible for this complex. Edited November 2, 2009 by ChemSiddiqui Link to comment Share on other sites More sharing options...
aeontide Posted November 2, 2009 Share Posted November 2, 2009 (edited) acac is shorthand for a 2,4-Pentanedione ligand--common name ACetylACetone. This ligand is bidentate and has two donor atoms--the two oxygens. This suggests two points of attachment and you have placed two acac groups on the V central atom--accounting for all four of the equatorial bonds. I'm fairly certain both acac ligands take on an aromatic character when bonding to the metal as well--I have the proton NMR's for a Co(acac)3 which has a singlet integrating to 1, shifted down to just shy of 6. The lone oxygen will occupy an axial position and it leaves room for a sixth ligand to come in from the bottom... square pyramidal is actually quite a common geometry for this type of molecule. Wikipedia has a pretty decent picture of it where you can more clearly see the square-pyramidal structure: http://en.wikipedia.org/wiki/Vanadyl_acetylacetonate Edited November 2, 2009 by aeontide Link to comment Share on other sites More sharing options...
ChemSiddiqui Posted November 3, 2009 Author Share Posted November 3, 2009 Thanks aeontde for that but that is what I already know. I merely wanted opinion on the geometry, because in this complex vanadium can adopt the 5 or 6 coordination. but anyway, you are right acac- do have the aromatic character. I got the bond length data and similar bond lengths suggest delocalisiation. thanks again. Link to comment Share on other sites More sharing options...
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