We've talked about this before. It is hardly unheard of for an incoming administration to make contacts with other countries before taking office. It's not right, you could argue, but it happens. The Reagan admin talked to the Iranians about the hostages. Easily the worst case was the Nixon admin, which told North Vietnam to hold off on making peace until they got there.
If all he did was talk about sanctions, that is not bad.
The question, then, becomes why he lied about it. At the very least, it raises suspicions that there is more to this.
As to the unprecedented nature of the sanctions, that is overblown. Presidents act during their lame-duck time...Pres Bush 41 sent US troops into Somalia in December 1992 and then handed it over to Clinton (which was the right thing to do, by the way). So there was nothing especially crazy about the sanctions and ejection of Russian spies.