When BP Amoco bought 10 percent of oil giant Sidanko for $571 million, it expected to acquire assets, not liabilities. But Sidanko has fallen behind on its debts and has no prospect of making its creditors whole without a restructuring of its finances and new infusions of capital. Last week Moscow’s arbitration court denied BP Amoco’s request to name a bankruptcy manager, leaving Sidanko in limbo at least until the next court proceeding on May 18. Sidanko’s majority holder Interros, controlled by former Finance Minister Vladimir Potanin, had opposed BP Amoco’s request. BP Amoco has already written off $200 million of its investment and may have to write off more.