General manager Paul Holmgren, who is gambling that MacDonald signs with the Flyers, called the newest addition a "solid two-way defenseman who brings us depth and experience."
There is a chance MacDonald is paired with Mark Streit, his former defensive partner with the Islanders for about three seasons, although they were not together too often last season.
Streit called MacDonald "a great puck mover and a great skater." MacDonald was not available for comment.
To make room for MacDonald, the Flyers loaned waiver-exempt Michael Raffl to the Phantoms to get their roster down to 23 players, the league maximum. Raffl will be recalled Wednesday, when rosters are allowed to expand.
Mangene is a 24-year-old Long Island native who had three goals and three assists in 51 games with the Phantoms this season.
The deal gives the Flyers nine defensemen, and another move figures to be made before Wednesday's 3 p.m. trade deadline. It would not be surprising if the Flyers dealt Andrej Meszaros and recouped a draft pick (or two) that was lost in the MacDonald deal.
"Whatever happens, happens," Meszaros said after the Flyers practiced Tuesday in Voorhees, before the MacDonald trade. "It's out of your hands; it's a business thing. We'll see. It'll be interesting."
Meszaros, 28, a potential unrestricted free agent in July, has been drawing interest from around the league, especially from Boston.
A nine-year veteran, Meszaros said he used to find deadline day unsettling.
"When I was a little bit younger, I used to get nervous because I didn't want to leave," Meszaros said. "But once you get older, you understand the business, and you know how it works. You're not thinking about it. You just go day by day."
For the most part, Meszaros has played well despite being yanked in and out of the lineup. He has 17 points in 38 games and is plus-1.
Asked if he would rather be dealt somewhere if he could be a regular, Meszaros said: "I prefer to play, and I prefer obviously to stay here and play here. . . . Everybody wants to play all the time. It was tough for me this year, but I still like it here. I really enjoy being here with the guys."
Blossoming center Brayden Schenn, who has 16 goals, shrugged off rumors about being sent to Vancouver for center Ryan Kesler. The Flyers do not want to deal Schenn - and they appear to be trying to push up Kesler's price because division rival Pittsburgh is interested in him.
"I'm not going to sit there and try to read into things," Schenn said. "It doesn't really affect me. . . . It's just a whole lot of rumors."
Schenn said he had no ill effects from being boarded Sunday by Washington defenseman Dmitry Orlov, who received a two-game suspension. The teams meet again Wednesday at the Wells Fargo Center.
The Flyers overcame a 4-2 third-period deficit Sunday and jolted the host Capitals in overtime, 5-4, to register their sixth win in their last seven games.
The Caps on Tuesday acquired veteran left winger Dustin Penner from Anaheim for a fourth-round draft pick. Penner (13 goals, 32 points) is expected to play on the Caps' top line with Nicklas Backstrom and Alex Ovechkin.
On Monday, Holmgren said backup goalie Ray Emery had recovered from an apparent groin injury and was ready to play. But the Flyers recalled Cal Heeter on an emergency basis Tuesday night from the Phantoms, signifying Emery is not ready.