You see the concentration of three heavy White pieces aimed at f7; the question is how to take advantage of it. Not with Rxf7: Black then has QxRf1+, which loses his queen to QxQ but then allows him RxR at the other end of the board—and he has won two rooks for his queen. The general idea was right: try to bait Black's castled rook forward. But the beauty of a queen sacrifice for the purpose is that it gives check, keeping the position under tight control. Thus 1. Qxf7+, RxQ; and now 2. Rc8+. White mates with one rook or the other (after Black tries useless interpositions with his c6 bishop and then with Rf8).