The effects of orbital angular momentum on the details of the spin and rotational fine structure of the[Xtilde]2B1andÃ2A1states of NH2and H2O+are considered. It is found that the erratic spin-orbit splittings and asymmetry parameters of theÃ2A1states can be reproduced with good accuracy by calculations that also account for the regular spin and rotational structures of the ground states; the only input parameters are the shapes of the Born-Oppenheimer potential curves, the bond lengths and the spin-orbit coupling constants. The same calculations give an almost quantitative explanation of various perturbations in theÃ2A1state of NH2. These perturbations are caused by the ground state and result from the presence of orbital angular momentum. Three types have been documented; one is direct spin-orbit interaction between theÃand[Xtilde]states, and the others involve rotational asymmetry, which is found to be an important mechanism for causing perturbations between electronic states.