American Realty Capital Properties Inc. said it would buy CapLease Inc. for about $2.2 billion, including debt, as the real estate investment trust looks to expand its single-tenant commercial properties.

ARCP said it would pay $8.50 per share in cash, representing a premium of about 20 percent to CapLease's Friday closing.

CapLease preferred shareholders will have the right to receive $25 per share in cash plus an amount equal to any accrued and unpaid dividends, ARCP said.

ARCP said it would assume about $580 million of CapLease's $1.2 billion of debt and intends to repay the balance.