Is it permissible to establish a company and contribute to it if the main partner insists that the company's accounts be held in a usurious bank?

It is not permissible to agree to place company accounts in an interest-based bank when an alternative is available. This is because merely opening an account in an interest-based bank is a form of assistance in sin, and Allah Almighty says: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." Furthermore, whoever deals with interest-based banks is either a devourer of usury, or an agent for it, or an helper of the usurer. And the Messenger of Allah, peace and blessings be upon him, cursed the devourer of usury, its agent, its scribe, and its two witnesses.