My wife has 45 days of regular menstrual cycle, trying for pregnancy, what the perfect dates to have sex? Is 45 days cycle normal or what?

Oligomenorrhea. Menstrual cycles that last longer than 35 days are abnormal and constitute a diagnosis of oligomenorrhea (infrequent periods). Infrequent periods mean infrequent ovulations and infrequent ovulations mean reduced fertility, which at your wife's age should be addressed by a fertility specialist if you're serious about attempting pregnancy. Good luck!