The addition of PPh 2 H, PPhMeH, PPhH 2 , P(para-Tol)H 2 , PMesH 2 and PH 3 to the two-coordinate Ni 0 Nheterocyclic carbene species [Ni(NHC) 2 ] (NHC = IiPr 2 , IMe 4 , IEt 2 Me 2 ) affords a series of mononuclear, terminal phosphido nickel complexes. Structural characterisation of nine of these compounds shows that they have unusual trans [HÀ NiÀ PR 2 ] or novel trans [R 2 PÀ NiÀ PR 2 ] geometries. The bis-phosphido complexes are more accessible when smaller NHCs (IMe 4 > IEt 2 Me 2 > IiPr 2 ) and phosphines are employed. PÀ P activation of the diphosphines R 2 PÀ PR 2 (R 2 = Ph 2 , PhMe) provides an alternative route to some of the [Ni(NHC) 2 (PR 2 ) 2 ] complexes.DFT calculations capture these trends with PÀ H bond activation proceeding from unconventional phosphine adducts in which the H substituent bridges the NiÀ P bond. PÀ P bond activation from [Ni(NHC) 2 (Ph 2 PÀ PPh 2 )] adducts proceeds with computed barriers below 10 kcal mol À 1 . The ability of the [Ni(NHC) 2 ] moiety to afford isolable terminal phosphido products reflects the stability of the NiÀ NHC bond that prevents ligand dissociation and onward reaction.