The 24-year-old nominated Adelaide as his preferred destination with the Tigers keen to secure the pick at the end of round one the Crows were given as compensation for losing Nathan Bock to Gold Coast.
"I expect that to go through today or tomorrow," Nixon told afl.com.au's Trade Week Radio.
"After dealing with a few other clubs, Richard has decided he wants to go to Adelaide; I've told Richmond that so we're [trying] to do the deal."
Should the trade be completed, the Tigers will be able to use the selection in any of the next five NAB AFL Drafts.
Nixon, who believes Tambling is best suited to a role at half back, is confident he will flourish at the Crows.
He has already met with coach Neil Craig to discuss his potential spot in the side.
"With Neil Craig, I haven't had much to do with him and I thought it was better that Richard meet with him, and he has a couple of times," he said.
"I'm sure Neil would have expressed where he sees him fitting into the team.
"Good clubs do ... [say] this is where we see our team next year, this is where we see you playing.
"I think that's always quite impressive and I know Melbourne has done that with David Hale."
Nixon said if the trade fell over, Damien Hardwick and the Tigers would be happy to retain Tambling.
"Richmond has been very good in suggesting that he may be getting a fresh start somewhere," he said.
"At the end of the day, if he's still at Richmond, he's welcome back with open arms."
Nixon also said he was still fielding interest for North Melbourne ruckman Hale, with Melbourne and Hawthorn keen suitors.
"I think he's an ideal fit for Melbourne with their current forward six with [Liam] Jurrah, [Jack] Watts, [Austin] Wonaeamirri ... [Hale] would complement them a bit," he said.
"They haven't really got that full marking option up forward."
He also said the Hawks had already looked at their structure and how Hale could fit in with tall forwards Lance Franklin and Jarryd Roughead.
"They explained to me a totally different scenario that's probably not one I can say publically," he said.
"Let's just say they showed me where they might play a couple of superstars differently and then all of a sudden they went, 'Ooh, that works all right'."
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.
