Low-temperature redetermination of 4-chloro-2-[tris­(hydroxy­meth­yl)methyl­imino­meth­yl]phenol as zwitterionic 4-chloro-2-[tris­(hydroxy­meth­yl)methyl­iminiometh­yl]phenolate

The title Schiff base, C(11)H(14)ClNO(4), originally refined as a neutral mol­ecule [Chumakov, Antosyak, Mazus, Tsapkov & Samus (2000), Crystallogr. Rep. 45, 945–950], is inter­preted as a zwitterionic compound. There are two independent zwitterions in the asymmetric unit. Five of the six hydr­oxy groups of the –CH(2)OH fragments are disordered. In one zwitterion, two are disordered over three sites [0.53 (1):0.33 (1):0.14 (1) and 0.65 (1):0.18 (1):0.17 (1)] and the third over two sites [0.66 (1):0.34 (1)]. In the second zwitterion, two are disordered over two sites [0.84 (1):0.16 (1) and 0.83 (1):0.17 (1)] and the third hydr­oxy group is ordered.