Ab Initio Investigation on a New Class of Binuclear Superalkali Cations M\\r sub/2sub\\r Li\\r sub/\\r 2\\r k\\r +1\\r subsup+sup\\r (F\\r sub/2sub\\r Li\\r sub/3subsup+sup\\r , O\\r sub/2sub\\r Li\\r sub/5subsup+sup\\r , N\\r sub/2sub\\r Li\\r sub/7subsup+sup\\r , and C\\r sub/2sub\\r Li\\r sub/9subsup+sup\\r )