Brassard said he was told by Senators general manager Pierre Dorion he had been traded at 2 p.m. ET on Friday, but the complicated deal didn't become official until several hours later.
"All day after [that call] I was really unsure what was going to happen," Brassard said. "Even my agent didn't know what was going to happen.
"Finally, I got a call from [Penguins GM] Jim [Rutherford] around 9:30 p.m. that everything was done."
Brassard, who needs to clear up issues related to his work visa before he can play for Pittsburgh, said he hopes to make his debut with the Penguins against the New Jersey Devils at PPG Paints Arena on Tuesday (7 p.m. ET; SN, TVAS, ATTSN-PT, MSG+, NHL.TV).
"I'm just really excited to be joining the team that won the last two Stanley Cups," Brassard said. "I think it's a great opportunity for me right now in my career to have a chance to win. I'm just really, really, really excited to be joining the team."
Pittsburgh will play it's first game without Cole on Saturday.
"[Ian] was a good player for us," Penguins coach Mike Sullivan said. "He was a good defender, he was a good penalty killer, he was a good shot blocker, he's hard in the front of the net. He brought a lot of things to our defense corps.
"The nature of these trades is difficult because you have to give up something to get something. [Ian] has been a very good player for us and we're going to have to replace what he brought by committee. Everybody is going to have to step up and bring a little bit more from a defensive standpoint. We're going to need guys to fill in on the penalty kill. I don't think it's going to be any one person. It's going to be a group of people."
Brassard, who played for the New York Rangers from 2013-14 to 2015-16 and for Ottawa the past two seasons, knows a lot about the two-time defending Stanley Cup champions.
"I faced the [Penguins] four times [in the playoffs] in the past four years, so I'm pretty familiar with the team," said Brassard, who has 420 points (159 goals, 261 assists) in 702 regular-season NHL games and 55 points (22 goals, 33 assists) in 78 Stanley Cup Playoff games. "I don't think it'll be weird. I'm just really, really excited."
He's also used to going deep in the playoffs, having played in the Eastern Conference Final three times and once in the Stanley Cup Final. Pittsburgh led the Metropolitan Division by one point over the Washington Capitals and two points over the Philadelphia Flyers entering play Saturday.
"The playoffs is another level. It's a matter of playing the passion of the game, the emotion," he said. "I felt like, especially in New York, it pushed me to push myself personally and try to be the best player I can be. It's the best time of the year. You have a chance to win the Stanley Cup. That's the ultimate prize."
