In large bowl, whisk together all marinade ingredients (brown sugar through black pepper)
Reserve ½ cup marinade in separate container (for basting)
Place chicken in remaining marinade, coat evenly, and refrigerate 4+ hours (overnight best)
Preheat grill to medium-high (400°F) and oil grates
Grill chicken 6 minutes undisturbed on first side
Flip, baste with reserved marinade, cook 5 minutes
Continue flipping and basting every 2 minutes until internal temp reaches 165°F (~15 min total)
Grill pineapple rings 2 minutes per side while chicken rests
Garnish with green onions and serve immediately