The bonds were issued in two tranches, one with a coupon rate of 8.75% worth 250 million, and the other with a coupon rate of 8.375% worth $425 million.
Taxes reduce the net income on taxable bonds, meaning that a tax-exempt municipal bond has a higher after-tax yield than a corporate bond with the same coupon rate.
To compensate for having additional value through the option to convert the bond to stock, a convertible bond typically has a coupon rate lower than that of similar, non-convertible debt.