The Capitals had a 3-on-2 rush, resulting in Brooks Laich's shot that goalie Steve Mason couldn't handle. The rebound went to Chimera and he tapped the puck in to give Washington its 12th victory in March.
The Capitals reached 101 points, crossing the 100-point plateau for the third straight season, to move within a point of Philadelphia for the Eastern Conference lead.
Scottie Upshaw forced overtime for Columbus, fighting off two Washington defenders to score his 22nd goal of the season with 5:37 remaining in the third period.
Antropov scored his 15th goal midway through the third period.
Mason was outstanding in the final minute. He made a kick save off his left leg and Jeff Carter's quick rebound knocked off the post with 4.7 seconds left.
The Flyers have lost five straight at home.
TAMPA, Fla. (AP) - Martin St. Louis scored his 30th goal of the season, helping Tampa Bay clinch its first playoff berth since 2007 with a victory over Pittsburgh.
Steve Downie also scored for the Lightning, who have won three in a row following a four-game losing skid.
Pittsburgh, which had won its previous four road games, got a goal from Michael Rupp.
Penguins center Sidney Crosby, sidelined for nearly three months with a concussion, resumed skating with his teammates in the game-day practice. The Pittsburgh captain, out since Jan. 6, isn't ready yet to participate in full practices. A return to game action for the postseason hasn't been completely ruled out.
UNIONDALE, N.Y. (AP) - Radek Martinek and P.A. Parenteau both had a goal and assist during the Islanders' four-goal second period, and the Islanders put the rival Rangers back into postseason peril.
After Blake Comeau got the Islanders even 1 at 3:24, Martinek put them in front 33 seconds later.
Things settled down for a bit, but the Islanders struck for two more goals 1:16 apart - the first by Jesse Joensuu at 13:28 and the second by Parenteau to turn it into a rout. Matt Moulson scored his 31st goal of the season against backup Chad Johnson with 11:22 left, and Trevor Gillies made it 6-1 at 14:00.
The Rangers were seemingly cruising for a playoff spot on the strength of an 8-1-1 spurt, but have dipped to eighth in the Eastern Conference and lead Carolina by three points with four games remaining. Carolina has five games to play in the final 10 days.
Vinny Prospal and Brandon Prust scored for the Rangers.
BOSTON (AP) - Nazem Kadri scored the only shootout goal to help Toronto beat Boston.
With the point for reaching overtime, the Bruins clinched a tie for the Northeast Division title. The next Boston win or loss by Montreal will give the Bruins the division title.
Toronto is 10th in the Eastern Conference, five points behind seventh-place Buffalo and the New York Rangers for one of the eight playoff spots.
Bruins goalie Tim Thomas, who made 28 saves, made a right-pad save on Mikhail Grabovski's penalty shot 43 seconds into overtime, but Kadri beat him with a backhand shot over the left shoulder in the shootout.
SUNRISE, Fla. (AP) - Rookie Colin Greening scored twice in the second period for Ottawa, and Craig Anderson made 37 saves to improve to 9-4-1 since being acquired in a trade with Colorado in February.
Nick Foligno and Filip Kuba also scored for Ottawa. The Senators swept the season series and have won six in a row against Florida dating to last season.
Michal Repik scored for Florida. The Panthers have lost seven straight.