Question

The geometry about the titanium hehe in TiCl2(acac)2 is\napproximately octahedral. Draw the three possible stereoisomers of\nTiCl2(acac)2 and note which two form an enantiomeric pair. In your\nstructural diagrams be sure to clearly show the delocalised bonding\nthat is present in the acetylacetonate ligands.<\/p>\n

How many d electrons occur in TiCl2(acac)2? Suggest a reason why\nthe compound is so highly coloured.<\/p>\n

Answer 1

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Answer 2

The complex is:-

Titanium bis(acetylacetonate)dichloride, or

The central metal atom/ ion is titanium which is linked to 2 acetylacetonate ligands via two ligand sites each and 2 chloride ligands.

Also, the acetylacetonate ligand is a resonance stabilized ligand which has two oxygen atoms and can serve as a bidentate ligand. The resonance structures are shown below as:-

The stereoisomers of the given complex are:-

The cis isomers shown in the image are enantiomers as they are mirror images of themselves.

The trans isomer is optically inactive.

Calculation of the oxidation state of the Ti in the complex as:-

Charge on the acetylacetonate ligand = -1

Charge on the chloride ligand = -1

Let the oxidation state of the metal Ti in the complex be x.

So,

x = 4

Thus it exists as in the complex.

The electronic configuration of the titanium is:-

The electronic configuration of the is:-

Thus, has electrons.

The complex has color due to charge-transfer complex. The transitions occur from the transfer of the electrons from the molecular orbitals of the ligand to the empty orbitals of the metal atom/ ion. Thus, it is known as LMCT (ligand to metal charge transfer).