Why Bond angle of NF3(102 degree) is lesser than in NH3 (107) ? explaine.

Bond angle of NF₃(102 degree) is lesser than in NH3 (107) as per VSEPR theory which suggests that in case of less electronegative terminal atoms like H, Bond pairs would be closer to more electronegative central atom, N and hence bonds open up due to repulsion between  bond pairs electron density in vicinity. But bond angle of PF₃(100) is greater than PH₃, its due to possibility of back bonding in PF₃ between lone pair of fluorine and vacant d-orbital of phosphorous (2pπ-3dπ) hence forth P-F bond acquires partial double character and we know well that multiple bonds causes more repulsion so bond angle is greater.