Eleven months ago, E. I. du Pont de Nemours & Co. sued the present Iranian government for $93.4 million to compensate for the loss of its share of a huge new synthetic textile plant that had been built under an agreement with the shah's regime.

Included in de Pont's claim were the dividends it figured to receive, the gain on its original investment and the pay owed its employes working on the project.

Today the du Point suit is just one part of the tangled web of legal claims, frozen Iranian assets and hidden wealth of the late shah that has become a main stumbling block in the conditions to free the 52 American hostages.

More than 3,000 U.S. companies, banks and individuals have filed claims against Iran with the Treasury Department and more than 300 of them have pursued those same claims in court actions.

Almost all the claims in litigation, totaling nearly $6 billion, were brought only after President Carter, on Nov. 14 of last year, ordered the freezing of Iranian government assets maintained in U.S. banks and their branches abroad. His action was described at the time by a high Treasury official as a response to the taking of U.S. hostages in Tehran and a move to head off the threatened withdrawal of more than $8 billion Iran maintained in U.S. institutions.

The frozen Iranian money provided the American claimants with a ready pool of funds into which they could dip should U.S. courts award them compensation.

The list of claimants includes some of the biggest U.S. banks and corporations: Chase Manhattan ($366 million); Morgan Guaranty Trust ($66 million); Citibank ($118 million); American Express International ($50 million); Lockheed ($11 million); Reading & Bates, an oil drilling company ($34 million), and Xerox Corp. ($85 million).

Removal of the freeze, lawyers both inside and outside government agree, will bring legal and technical problems for the claimants and the Iranian and U.S. governments that seem impossible to resolve without prolonged negotiations and perhaps arbitration.

One problem is the doctrine of sovereign immunity, which states that assets of a government or central bank cannot be subjected to claims by private companies or individuals.

A second problem is that during the time the funds have been frozen, claimants have sought legal orders, called attachments, which would prevent the Iranian assets from being moved until a judgment is made on the specific claim, which could take years.

The question today is what happens if the president lifts his freeze. Would the doctrine of sovereign immunity require the funds automatically to go back to the Tehran government? Or would the court attachments now pending take effect and keep the money in the United States, frozen by judicial rather than presidential order?

U.S. bankers and other claimants worry that once Iran got back control of its assets, the funds would be quickly transferred beyond their reach -- and make worthless any future award they might receive.

The unofficial language of the conditions for hostage release dealing with assets have left U.S. government officials, lawyers for claimants and private businessmen confused as to just what is meant.

One top State Department official said yesterday there are "internal contradictions" affecting the Iranian conditions, one calling for a return to the pre-freeze status quo and another calling upon the U.S. government to set up a unique arrangement that would prohibit anyone from filing any type of claim against Iran. Under U.S. law, there is no authority for the government to prevent the filing of any lawsuit.

He suggested that the conditions represent only a first step into what both countries realize will be prolonged negotiations over the assets issue.

A U.S. Treasury official involved in the discussions said yesterday that "there is no way to sort through this thing now."

While government officials are trying to work out a general agreement to solve both countries' political needs -- and free the hostages -- American businessmen and bankers worry that their interests may be lost in the shuffle.

Yesterday a spokesman for SEDCO, a Dallas-based oil drilling firm that seeks $175 million in damages from the National Iranian Oil Co., asserted that the company would not "roll over and play dead."

SEDCO, which was founded by William P. Clements, now the governor of Texas, did a major share of its overseas business with Iran. Its subsidiary, Sediran, was a joint venture with the Pahlavi Foundation, the late shah's charitable and personal investment institution. At the time that American companies were thrown out of Iran, Sediran had 10 major billing rigs operating there.

"A lot of businessmen are worried about being painted as destroying the hostage agreement," said a Washington lawyer who represents a major corporate claimant. A London-based banker said, however, that if one claimant or group of claimants decided to press for their money "the rest would have to follow suit."

A leading New York banker viewed the situation this way: "By executive order, the president might just release all the assets. If we were called to the White House and told 'we hope you are not going to put your money ahead of the lives of American hostages,' you would have to agonize a lot about your obligations to your shareholders and your patriotism."

While high-ranking Iranian officials have maintained over the past week that they would meet their obligations to U.S. banks and companies should they regain control of their assets, the deteriorating state of the Iranian economy is adding to the jitters of American businessmen. Several said yesterday they believe the push to regain the assets is tied to a shortage of funds to buy food, military equipment and now fuel, since Iranian oil fields have been all but shut down by the war with Iraq.

Even if Iran was forced to cover every cent of claims now filed against it in U.S. courts, it would still leave the Tehran government several billion dollars in funds that are currently frozen by Carter's order. Iran, itself, puts the frozen assets figure at $14 billion. Knowledgeable U.S. Treasury officials would say only that it was "more than $8 billion" and probably close to $11 billion. The higher figure includes more than $1 billion worth of oil payments to cover shipments that were on the high seas when the freeze order went into effect.

Emergence of the assets issue has created his own political backlash. Former secretary of state Henry A. Kissinger, who works as a consultant to Chase Manhattan Bank, one of the major claimants, told a television interviewer Sunday that "the question with respect to the frozen assets is whether they are simply going to be unfrozen and therefore available to American creditors, or whether the United States is going to take the side of the Iranians in defending claims against these assets."

Yesterday, however, Kissinger said he "hadn't studied the legal ramifications of the issue" and that his main concern with regard to lifting of the freeze was not the claims issue but rather sending military equipment to Iran. He added that this was "the worst time to get a rational consideration" of the conditions proposed for the hostage release. He called for the establishment of a "bipartisan group" after the election to develop a "consensus" on the conditions and on which "I would be willing to serve," he said.