The airplane experienced a loss of engine power at 1815 Eastern time while descending for a landing. Visual conditions prevailed; the airplane received substantial damage and the Private pilot reported minor injuries. While descending through 6000 feet, the pilot heard a pop sound and the engine began to run rough with partial power. The pilot declared an emergency and requested a clearance direct to the nearest airport. After a 180-degree turn and descending through clouds, the pilot observed the airport straight ahead. The pilot descended over the airport to lose altitude and turned on final approach, but the engine quit at 300 feet. Unable to reach the airport, the pilot initiated a forced landing to an open field.