[Mitch]

Since, the ligand coordinates with the Oxygen, I lean towards sayings its a hard ligand. But, bonding occurs not through just a single atom but through the delocolization of charge that also involves the Carbons as well. So, basically I'm not sure.

[AWK]

The problem is more complicated

http://chimge.unil.ch/En/complexes/1cpx27.htm
http://chimge.unil.ch/En/complexes/1cpx29.htm

[GCT]

Since, the ligand coordinates with the Oxygen, I lean towards sayings its a hard ligand. But, bonding occurs not through just a single atom but through the delocolization of charge that also involves the Carbons as well. So, basically I'm not sure.

I would probably say that it's a hard ligand also due to the oxygen factor.  I think that you could also have some type of chelate type of interaction, depending on what it's coordinated to. It's probably somewhere intermediate, really depending on what it's interacting with, whether the bond is more covalent in nature (the atomic orbitals with the proper symmetry for bonding are somewhat on an equivalent energy level) or ionic (these orbitals are farther apart).