Clayton expected the pair to become the seventh and eighth experienced players to become Suns by the 2pm deadline to sign uncontracted players, with the Magpies to be compensated according to AFL rules.
Brennan's deal will involve the exchange of NAB AFL Draft picks, given his Lions teammate Michael Rischitelli has already been listed by the club as an uncontracted player.
Clayton said the duo would be the last of the uncontracted and experienced players recruited by the league's 17th club.
They have already secured Rischitelli, Adelaide's Nathan Bock, Port Adelaide's Nathan Krakouer, Hawthorn's Campbell Brown, the Western Bulldogs' Jarrod Harbrow and their main man, Geelong's Gary Ablett.
"[Fraser and Brennan] should happen today prior to 2pm. We're confident to both of those things occurring," Clayton told afl.com.au's Trade Week Radio.
"We've always rolled out we'll probably take eight uncontracted players and that will be it, I'd say.
"We have tried to get a good mix of position and age and all those things, and we've ended up where we are today."
Clayton also confirmed the Suns would pre-list former Richmond player Andrew Krakouer and then trade him with young ruckman John Ceglar to Collingwood in exchanged for the Magpies' No.25 pick.
While selections will be exchanged for Brennan, Clayton said the priority for the Suns was to maintain their nine picks in the top 15 of the draft order.
Meanwhile, Richmond remains intent on trading for Carlton's Shaun Grigg and Essendon's Bachar Houli but football manager Craig Cameron said there was still some way to go before any deals were completed.
Both players have agreed to come to the Tigers but Cameron said the Blues and Bombers were yet to name their respective prices.
"When two young players want to leave their clubs and the clubs want to hold on to them, it makes those deals drag on a little bit longer," he said.
"Naturally those clubs will want to talk to those players about remaining and clearly they're their players so the club is within its right to do that.
"We'll continue to talk to those clubs over the next few days."
Cameron also said defender Will Thursfield had requested a trade and had spoken to a few clubs, including Fremantle.
He also said Thursfield would be required at Richmond next year if a trade could not be completed.
Follow our complete coverage of the 2010 AFL exchange period from October 5-11. No trades are official until paperwork has been accepted by the AFL and formally recognised after 2pm on Monday, October 11.
Join the AFL trade conversation on Twitter: use #tradeweek in your tweets.
