On the contrary, there were laws broken. And, in addition, you can be impeached without a law being broken.
The laws that were broken were
18 U.S. Code 872: Extortion by officers or employees of the United States.
2 U.S. Code 192, Refusal of witness to testify or produce papers,
18 U.S. Code 610, which covers that crime rather clearly under the title: Coercion of political activity.
r 18 U.S. Code 607, Place of solicitation, and 52 U.S. Code 30121, Contributions and donations by foreign nationals.