Terms of the deals weren't released.
Wright played two seasons with New Jersey before he was acquired by the Mavs on Feb. 19 as part of the deal that also brought Jason Kidd to Dallas.
New Jersey took Wright with the 15th pick in the 2005 NBA draft.
Wright last season, in 56 games, averaged a career-high 6.3 points, 2.6 rebounds and 1.4 assists.
McLeod and Singleton have played in the NBA, but most recently played in Europe.
The 6-foot-2 McLeod played 200 NBA games over four seasons with Minnesota, Utah, Golden State and Indiana. Undrafted out of Bowling Green in 2002, McLeod has career averages of 5.5 points, 2.7 assists and 1.3 rebounds.
Singleton played for the Los Angeles Clippers from 2005-07, averaging 2.6 points and 2.7 rebounds in 112 games. The 6-8 forward was undrafted in 2003.