TNREF III High Ridge LLC, a joint venture between Darien-based Baywater Properties and an investment fund managed by True North Management Group LLC of White Plains, has bought 225 High Ridge Road in Stamford for $22.5 million.

The property is an 81 percent leased, 244,104-square-foot Class A office building on the northern border of the Stamford central business district. Its tenants include Synapse (66,530 square feet), Bank of America (26,319 square feet) and Mass Mutual (11,469 square feet). There is nearly 47,000 square feet in vacancy.

Jeffrey Dunne, Steven Bardsley and Travis Langer of CBRE’s Institutional Properties represented the seller, RA 225 High Ridge LLC, an entity controlled by RNY Property Trust.