These two words look similar and may even sound alike depending on where in the US you live; however, their meanings are quite different:
IMMINENT means about to happen: To date, seismologists cannot tell us when an earthquake is imminent.
EMINENT, when used about a person, means great fame or importance within a particular field: Yo Yo Ma is perhaps the eminent cellist of our time. Some may argue that other cellists are better. PREEMINENT is used when there is no doubt about a person’s manner of standing out (either in a positive or negative way): Vladimir Putin is the preeminent politician in Russia today.
When EMINENT is used about an object, it describes a particular positive quality: When introduced many decades ago, seat belts immediately became the eminent safety feature in vehicles until that time.