New phosphine-based bidentate ligands, 2-Me-8-Ph2P(X)C9H8NH (3, X = O; 4, X = S) and N-R-2-Ph2P(X)C6H4NH (5, R = Et, X = O; 6, R = Me, X = S; 7, R = Et, X = S) were prepared via ortho-lithiation of 1,2,3,4-tetrahydroquinaldine (2-Me-C9H9NH) and aniline derivatives (N-R-C6H5NH). Reaction of the ortho-lithiated compounds with 0.5 equiv of PhP(OPh)2 afforded the bis(amido)-phosphine ligands (2-Me-C9H8NH-8-yl)2PPh 8 and (N-R-C6H4NH-2-yl)2PPh (9, R = Me; 10, R = Et). Using these ligands, [amido-phosphine oxide]Hf(CH2Ph)3, [amido-phosphine sulfide]Hf(CH2Ph)3, [bis(amido)-phosphine]MX2 (M = Hf, Zr; X = CH2Ph, Cl, Me), and [amido-phosphine-amine]MCl3 complexes were prepared. The molecular structures of [amido-phosphine sulfide]Hf(CH2Ph)3 13 (prepared using 6), [bis(amido)-phosphine]ZrMe2 22 (prepared using 8), and [amido-phosphine-amine]MCl3 (23, M = Hf; 24, M = Zr; prepared using 9) were confirmed by X-ray crystallography. Most of the prepared complexes exhibited negligible or low activity for ethylene/1-octene copolymerization. The [amido-phosphine sulfide]Hf(CH2Ph)3 complex 13 exhibited relatively high copolymerization activity (19 106 g/mol-Hf•h); however, this activity was unsatisfactory compared to that of the related [amido-phosphine]Hf(CH2Ph)3 complexes (up to 48 106 g/mol-Hf•h).