Heat broiler to high with the rack 6 inches from the flame.
Combine the orange, clementines, mushrooms, onion, ¼ cup of the oil, and 1 teaspoon each salt and pepper and toss to coat. Spread in an even layer on a baking sheet. Combine the remaining oil, the coriander, and ½ teaspoon each salt and pepper and spread all over the chicken. Nestle the chicken in the vegetables and broil, turning the chicken every 5 minutes, until the vegetables are crisp-tender and the chicken is golden and a thermometer inserted into the thickest part of a leg registers 165° F, 15 to 18 minutes.
Meanwhile, toss together the arugula and pine nuts. Season with a pinch each of salt and pepper.
Remove the chicken. Use a spatula to toss the vegetables in the chicken juices and oil to coat. Serve the vegetables with the chicken, sprinkled with the arugula and pine nuts.