Stephanie is correct. I only wish to add to her answers. The +2 charge on platinum is indicated by the oxidation number in "Platinum (II) Acetate." The roman numeral II (2) indicates the oxidation state of the platinum. There are other oxidation states possible, such as +4 and -2.
The structure of an acetate is hard to draw here. You can think of it like this: CH3-COO-, where one carbon has bonds to 3 hydrogens and to the other carbon. The second carbon is bonded to two oxygens. Usually this is represented as one double bond to an oxygen and one single bond to the other oxygen with a negative charge on the single bonded oxygen. The negative charge is actually stabilized by resonance of the bonds so it is also appropriate to represent each oxygen as having a 1.5 fold bond to the carbon, with the negative charge delocalized between them. In any case, it is the oxygen containing end of the 2 carbon acetate chains which point toward the platinum ion. These can be thought of as ionic attractions but since platinum is a transition metal, it is better to call them coordination bonds since it will most likely be d orbitals from the platinum that are bonding.
VSEPR theory predicts that the 4 lone pairs and the 2 coordination bonds of the platinum (II) acetate complex would have octahedral geometry, with the two acetates occupying opposite poles, giving the overall complex a linear shape:
Ac- ···········+Pt+··········· -Ac
Dick B.
VSEPR is actually not a good model to use for transition metals. Ligand field theory is a much better predictor. While a tetrahedral structure is certainly possible, a square planar structure seems more likely, assuming a monomeric structure (which is a big assumption).
02/11/13