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Complex formation between vanadate and various ethanolamine derivatives (ethanolamine, diethanolamine, methyldiethanolamine, triethanolamine and ECTEOLA–Cellulose) has been examined in detail by using 51V NMR spectroscopy. Vanadate binds with ethanolamine to form 1:1 (O)-monodentate and (N,O)-bidentate complexes which are protonated and deprotonated forms, respectively. Ethanolamine undergoes a comparatively weak interaction with vanadate relative to the other ligands. 51V NMR spectra clearly show that vanadate reacts with the functional group of ECTEOLA–Cellulose, as well as diethanolamine, methyldiethanolamine and triethanolamine, which are analogues of the functional groups of ECTEOLA–Cellulose, to form the −1 charged 1:1 (N,O,O)-tridentate complex. In addition to anion exchange interaction of monovanadate and isopolyvanadate anions with the protonated functional group, in the alkaline region the adsorbability of vanadium(V) onto ECTEOLA–Cellulose is a consequence of the complexation of vanadate with the functional group. The formation constant of the (N,O,O) complex with ECTEOLA–Cellulose was estimated to be log β ¯ ( N , O , O ) = 3 . 6 , which was almost the same as those with the analogues of the functional group.

The complexation of borate with linear dextrans consisting of pyranoside residues and their monomer derivatives (α-methyl- d -glucopyranoside and α-methyl- d -mannopyranoside) was investigated in detail by using 11 B NMR spectroscopy. For the monomer systems five kinds of borate complexes with α,β-diols and α,γ-diols of the pyranosides were present: that is, (α,β)-monochelate, (α,γ)-monochelate, (α,β)(α,β)-bischelate, (α,γ)(α,γ)-bischelate and (α,β)(α,γ)-bischelate complexes. Borate reacts with dextran to form inter-chain (α,β)(α,β)- and (α,β)(α,γ)-bischelate complexes in the 1:2-complexation in addition to the (α,β)- and (α,γ)-monochelate complexes. The formation of intra-chain bischelate complexes can be negligible for a rather stiff polymer as dextran. Formation constants of the (α,γ)-monochelate complex are almost constant among dextrans with different chain lengths except Dextran 3000 which is the shortest polymer examined. On the other hand, the stability of (α,β)-monochelate complexes decreases with an increase in the chain length. The complexation behavior for polysaccharides with various chain lengths was discussed in correlation with hydrodynamic and steric hindrance of the polymer ligands.

The complex formation of aluminum(III) with phosphinate and phosphite ions in acidic solutions (pH 1–3) has been investigated by 27 Al NMR spectroscopy. The formation of a 2:2 complex was established in addition to ordinary stepwise complexes in both Al 3+ -PH 2 O 2 − and –PHO 3 2− systems. Formation constants of these complexes formed in both systems, and thermodynamic quantities for the complexation in the Al 3+ -PH 2 O 2 − system were determined at an ionic strength of 1.0 mol dm −3 NaClO 4 . The stepwise complexation up to 1:3 becomes more exothermic and less entropy-productive in a regular manner. Both Δ H ° and Δ S ° values for the 2:2 complexation are quite large and positive due to the dimerization.