2.2.1. Synthesis of Complex 1a
A 100 mL three-necked flask was equipped with a three-way stopcock and a magnetic stirring bar. After the flask was flushed with nitrogen, tetrahydrofuran (40 mL) and 8-(phenylamino) naphthalene-1-sulfonic acid (1.5 g, 5.0 mmol) was added, and then vanadium (V) trichloride oxide (0.88 g, 5.1 mmol) was added at −20 °C. The reaction mixture was warmed to room temperature and stirred for 48 h. The solvent was removed in vacuo, the resulting solid was repeatedly washed with hexane and dried under vacuum to give a brown solid; yield (1.2 g, 3.0 mmol), 60%. IR (KBr, cm−1): 1618, 1602, 1483, 1251, 1141, 1037, 999, 762, 747, 681. 1H NMR (CDCl3) δ (ppm): 8.28 (s, 1H, Ar), 7.82 (s, 1H, Ar), 7.61−7.12 (m, 8H, Ar), 6.78 (s, 1H, Ar). Anal. Calcd for C16H11ClNO4SV: C, 48.08; H, 2.77; N, 3.50; S, 8.02. Found: C, 50.80; H, 2.56; N, 2.99; S, 8.50.