Synthesis, Spectroscopic, Molecular Structure, and Antibacterial Studies of Dibutyltin(IV) Schiff Base Complexes Derived from Phenylalanine, Isoleucine, and Glycine

Table 3

¹H NMR spectral data^a of the ligands and their corresponding organotin(IV) complexes.

Compounds	Chemical Shift (, ppm)
L^1H	11.50 (s, 1H, COOH), 4.25 (t, 1H, N–CH–CH2–), 3.08 (d, 2H, –CH2–Ph), 8.01 (s, 1H, NH), 7.20–7.80 (m, 9H, aromatic).
Bu2Sn(L^1)2	4.21 (s, 1H, N–CH–CH2), 3.10 (d, 2H, –CH–CH2–Ph), 8.03 (s, 1H, NH), 7.10–7.75 (m, 9H, aromatic); 1.60–1.15 (br m. 6H, –CH2–CH2–CH2–); 0.82 (br t, 3H, CH3 of butyl groups).
L^2H	11.39 (s, 1H, COOH), 3.96 (d, 1H, N–CH–CH–), 2.10–2.16 (m, 1H, CH3–CH–CH2–), 1.50–1.60 (m, 2H, –CH–CH2–CH3), 8.05 (s, 1H, NH), 0.85 (d, 3H, –CH–CH3), 0.95 (t, 3H, –CH2–CH3), 7.25–7.82 (m, 4H, aromatic).
Bu2Sn(L^2)2	3.98 (d, 1H, N–CH–CH), 2.08–2.16 (m, 1H, CH2–CH–CH3), 0.80 (d, 3H, –CH–CH3), 1.48–157 (m, 2H, CH–CH2–CH3), 0.99 (t, 3H, –CH2–CH3); 8.10 (s, 1H, NH), 7.22–7.80 (m, 4H, aromatic); 1.65–1.21 (br m. 6H, –CH2–CH2–CH2–); 0.80 (br t, 3H, CH3 of butyl groups).
L^3H	11.28 (s, 1H, COOH), 4.30 (s, 2H, N–CH2–), 8.02 (s, 1H, NH), 7.28–7.80 (m, 4H, aromatic).
Bu2Sn(L^3)2	4.38 (s, 2H, N–CH2–), 8.05 (s, 1H, NH), 7.25–7.78 (m, 4H, aromatic); 1.62–1.18 (br m. 6H, –CH2–CH2–CH2–); 0.84 (br t, 3H, CH3 of butyl groups).
L^4H	11.42 (s, 1H, COOH), 3.97 (d, 1H, N–CH–CH2–), 3.15 (d, 2H, –CH2–Ph), 8.08 (s, 1H, NH), 7.20–7.85 (m, 8H, aromatic);
Bu2Sn(L^4)2	4.02 (t, 1H, N–CH–CH2), 3.08 (d, 2H, –CH2–Ph), 8.10 (s, 1H, –NH–), 7.20–7.75 (m, 8H, aromatic); 1.60–1.15 (br m. 6H, –CH2–CH2–CH2–); 0.80 (br t, 3H, CH3 of butyl groups).
L^5H	11.42 (s, 1H, COOH), 3.99 (d, 1H, N–CH–CH), 2.08–2.14 (m, 1H, CH3–CH–CH2), 1.42–1.58 (m, 2H, CH–CH2–CH3), 8.10 (s, 1H, NH), 0.82 (d, 3H, –CH–CH3), 0.98 (t, 3H, –CH2–CH3), 7.20–7.80 (m, 3H, aromatic).
Bu2Sn(L^5)2	4.01 (d, 1H, N–CH–CH), 2.10–2.20 (m, 1H, CH3–CH–CH2), 0.80 (d, 3H, –CH–CH3), 1.45–1.58 (m, 2H, –CH–CH2–CH3), 1.02 (t, 3H, CH2–CH3), 8.05 (s, 1H, NH), 7.20–7.82 (m, 3H, aromatic); 1.64–1.18 (br m. 6H, –CH2–CH2–CH2–); 0.82 (br t, 3H, CH3 of butyl groups).
L^6H	11.35 (s, 1H, COOH), 4.32 (s, 2H, –CH2–), 8.12 (s, 1H, NH), 7.20–7.76 (m, 3H, aromatic).
Bu2Sn(L^6)2	4.40 (s, 2H, N–CH2–), 8.10 (s, 1, NH), 7.28–7.76 (m, 3H, aromatic); 1.65–1.21 (br m. 6H, –CH2–CH2–CH2–); 0.85 (br t, 3H, CH3 of butyl groups).

Chemical shift () in ppm: Multiplicity is given as: s = singlet, d = doublet, t = triplet, q = quartet, m = complex pattern, br = broad.