New York will receive defenseman Max Kondratiev, center Jarkko Immonen, a 2004 first-round choice and a 2005 second-rounder.
Toronto was in the bidding for former All-Star Sergei Gonchar, even creating a page for him on the team's website last weekend. But Maple Leafs General Manager John Ferguson Jr. turned his attention to Leetch after the Washington Capitals traded Gonchar to Boston earlier Wednesday.
Leetch won the Norris Trophy in 1992 and 1997 as the NHL's top defenseman and the Conn Smythe Trophy in 1994, when the Rangers ended their 54-year Stanley Cup drought.
Toronto has gone 37 years since its last championship but is tied for first place in the Eastern Conference with Philadelphia, Ottawa and Tampa Bay.