No diplomatic settlement is possible with Amadhinejad in
office.
One he's removed maybe there will be something to talk about.
That's assuming he actually makes the key decisions in Tehran, and I'm not so sure about that. I've heard the top Ayatollah actually has more power. But in the end, removal of the "psychopath" from office may be an informal element in a diplomatic solution.
Keep in mind that all the mullahs are getting even richer as a result of this war as the price of oil continues to increase. So they're not in any hurry yet to make a deal, and that's why this issue has gone to the UNSC to start the process of economic sanctions and making Iran pay a price for their stubborn refusal to stop uranium enrichment. As James Baker said, so far "we've offer all carrots and no sticks to Iran and the Iranians know this." Now we're about to see Iran get hit with some sticks.