Is it illegal for Governor to trade jobs for favors?

Ethics, morality, and good judgements aside, is a Governor forbidden by law from trading appointments for favors? Are bartering, selling, or the simple act of exchanging favors for jobs, illegal?

If there are no specific instruction and guidelines fot a Governor of a State to select a Senator, or specific laws forbidding a Governor accepting favors for making assignments; why is the Illinois Governor being indicted for his action which seems to be consistent with his role of making sure Illinois is properly represented in Washington.