A special dividend is different from a regular dividend in that all option prices are reduced by that amount. For example I am short the feb 55 calls. On ex div date the call strike price will change to 49.5.
As an aside the ex date is always 72 working hours before the date of record. Further you do not have to own the stock on the date of record to receive the divvy. It goes ex-div tomorrow at the open you can sell on the open and you will still get the div.
Spoke with Investor Relations @ CVR Energy this morning. As long as you purchase shares by close of market on Tuesday 2/5/13 you are a "shareholder of record". However, note the following:
Sentiment: Strong Buy
When you say "purchase" do you mean the settlement date - or - the day you made the buy on your broker's website? This wikipedia article, in the "Payment Date" section, with regard to "special dividends" over 25%, which this apparently is, makes it seem like buying it (on your broker's website) on the ex-dividend date, is the first date when you WOULDN'T be eligible for the special dividend: