grade and used without further purification. (2-Pyridyl-
methyl)iminodiacetic acid (H2pmida)15 and [VO(pmida)-
(H2O)]ؒH2O 13 were prepared as described previously. Methanol
was dried over Na and distilled. Microanalyses were performed
by Desert Analytics, Tucson, AR.
with cold water (10 cm3) and twice with acetone (30 cm3)
(Found: C, 45.4; H, 5.0; N, 11.3. C14H15N3O6ؒ2H2O requires C,
47.05; H, 5.3; N, 11.8%). NMR (D2O, pD 8.5): 1H (300 MHz), δ
3.31 (s, 4 H, NCH2CO2H), 4.04 (s, 2 H, CCH2N), 5.11 (s, 2 H,
aryl NCH2CO2H), 7.37 (m, 2 H, aryl CH) and 7.71 (m, 2 H,
aryl CH); 13C-{1H} (75 MHz), δ 50.2, 60.4, 66.2, 68.0, 113.7,
119.7, 127.5, 127.8, 137.2, 139.6, 157.8, 175.5, 181.0 and 182.9.
Synthesis of ligands
N-(2-Pyridylmethyl)iminodiethanol (H2pmide). Diethanol-
amine (31.21 g, 296.8 mmol) was dissolved in PriOH (100 cm3),
followed by addition of 2-(chloromethyl)pyridine (16.55 g,
100.9 mmol); this solution was refluxed overnight. The red solu-
tion was evaporated until dryness and the oily residue extracted
with hot acetonitrile (2 × 200 cm3). The acetonitrile was evap-
orated and the residue distilled under vacuum (12 mbar, 185–
220 ЊC). The yellow oil (6.0 g, 30%) was redistilled and now
passed at 195–210 ЊC (Found: C, 61.3; H, 8.1; N, 14.2.
C10H16N2O2 requires C, 61.2; H, 8.2; N, 14.3%). NMR (D2O):
1H (300 MHz), δ 2.74 (t, 4 H, CH2OH), 3.67 (t, 4 H, NCH2CH2),
4.82 (s, 2 H, NCH2N), 7.37, 7.50, 7.85, 8.45 (t, d, t, d, 4 H, pyri-
dine H); 13C-{1H} (75 MHz), δ 58.3, 61.5, 62.3, 125.9, 127.4,
140.8, 159.9 and 160.1.
N-(Benzimidazol-2-ylmethyl)iminodiethanol
(H2bmide).
Bicine [N,N-bis(2-hydroxyethyl)glycine] (9.00 g, 55.2 mmol)
and 1,2-phenylenediamine (5.50 g, 50.9 mmol) were dissolved in
7 mol dmϪ3 HCl (60 cm3). The brown solution was refluxed for
2 d. The resulting green solution was cooled to room tem-
perature and the pH adjusted to 11.0 by addition of 10 mol
dmϪ3 NaOH. The brown solution was concentrated in vacuo
until a white precipitate began to form. The mixture was main-
tained at Ϫ10 ЊC overnight allowing more of the compound to
precipitate. The precipitate (13 g, 93%) was filtered off and
washed with cold water (10 cm3) and twice with cold acetone
(10 cm3). The compound was recrystallized from hot acetone,
initially forming an oil. After removal of the acetone the oil
solidified upon standing. Owing to its hygroscopic nature the
hydrochloride salt was prepared by addition of concentrated
HCl to a concentrated ethanolic solution of the free ligand, and
subsequent recrystallization from methanol (Found: C, 46.15;
H, 6.0; N, 13.45. C12H17N3O2ؒ2HCl requires C, 46.75; H, 6.2; N,
13.6%). NMR (D2O): 1H (300 MHz), δ 2.92 (t, 4 H, CH2OH),
3.73 (t, 4 H, NCH2CH2), 4.17 (s, 2 H, NCH2N) and 7.43 (m,
4 H, aryl CH). 13C-{1H} (75 MHz), δ 53.6, 58.5, 60.7, 117.4,
126.7, 138.4 and 152.3.
2-(Aminomethyl)benzimidazole dihydrochloride. Glycine
(10.00 g, 133.2 mmol) and 1,2-phenylenediamine (10.80 g,
99.87 mmol) were dissolved in 4 mol dmϪ3 HCl (150 cm3). The
brown solution was refluxed for 4 d. The resulting blue solution
was concentrated to 50 cm3 and kept at Ϫ20 ЊC overnight at
which time bluish crystals had formed. The crystals (16 g, 74%)
were filtered off and washed twice with acetone (50 cm3)
(Found: C, 40.3; H, 5.5; N, 17.4. C8H11Cl2N3ؒH2O requires C,
40.3; H, 5.5; N, 17.65%). NMR (D2O): 1H (300 MHz), δ 4.85 (s,
2 H, CCH2NH2) and 7.80 (m, 4 H, aryl CH); 13C-{1H} (75
MHz), δ 36.9, 117.1, 129.9, 133.6 and 146.1. These data corre-
spond to those reported previously.16
Synthesis of vanadium complexes
Na[VO2(pmida)] 1. Sodium trioxovanadate NaVO3 (0.400 g,
3.28 mmol) was dissolved in water (10 cm3). Solid H2pmida
(0.800 g, 3.57 mmol) was added and the mixture stirred until
dissolution was complete. The pH was adjusted to 7.5 by add-
ition of 5 mol dmϪ3 NaOH after which point acetone (35 cm3)
was added. The resulting yellow solution was kept at Ϫ15 ЊC for
5 d after which time a yellow crystalline material had formed.
The crystals (0.63 g, 58% with respect to NaVO3) were filtered
off and washed twice with ethanol (10 cm3) and acetone (10
cm3) (Found: C, 34.4; H, 3.5; N, 7.9. C10H10N2NaO6Vؒ1.5H2O
requires C, 33.8; H, 3.7; N, 7.9%). IR (KBr, cmϪ1): 3447s,
2365m, 2342m, 1651s, 1619s, 1398m, 1164w, 899s, 776w and
528w. NMR (D2O): 51V (79 MHz), δ Ϫ503; 13C-{1H} (75 MHz),
δ 65.5, 67.7, 68.0, 127.0, 128.6, 144.5, 154.8, 159.9, 181.3 and
183.1.
N-(Benzimidazol-2-ylmethyl)iminodiacetic acid (H2bmida).
2-(Aminomethyl)benzimidazole dihydrochloride (7.80 g, 35.5
mmol) and chloroacetic acid (6.37 g, 67.5 mmol) were dissolved
in water (10 cm3). The pH of the solution was adjusted to 8.0 by
the addition of 5 mol dmϪ3 NaOH. It was refluxed and the pH
checked at hourly intervals and adjusted as above. After
approximately 5 h the pH no longer changed. The solution was
cooled to room temperature and filtered to remove some pre-
cipitated decomposition product. The pH was adjusted to 2.5
by addition of 5 mol dmϪ3 HCl and a white precipitate began to
form. The mixture was cooled to 0 ЊC for 6 h further to precipi-
tate product. The precipitate (4.5 g, 25%) was filtered off and
washed with cold water (10 cm3) and twice with acetone (30
cm3) (Found: C, 53.5; H, 4.9; N, 15.45. C12H13N3O4ؒ0.5H2O
requires C, 52.9; H, 5.1; N, 15.4%). NMR (D2O): 1H (300
MHz), δ 3.57 (s, 4 H, NCH2CO2H), 4.34 (s, 2 H, CCH2N) and
7.46 (m, 4 H, aryl CH); 13C-{1H} (75 MHz), δ 54.0, 60.3, 117.6,
126.5, 138.9, 151.7 and 177.8. The elemental analysis corre-
sponds to those reported previously.17
[VO2(Hpmide)] 2a. Vanadium() oxide (0.15 g, 0.80 mmol)
was added to water, followed by tetraethylammonium hydrox-
ide (0.67 g, 1.6 mmol); the solution was heated. After the V2O5
had dissolved H2pmide (0.45 g, 2.3 mmol) was added, the mix-
ture stirred and the pH adjusted to 6.6 with 6 mol dmϪ3 HCl.
Acetone was added until precipitation was observed and the
sample maintained at Ϫ15 ЊC overnight. The crystalline com-
pound formed (0.37 g, 64% with respect to V2O5) was filtered
off (Found: C, 34.3; H, 6.1; N, 8.0. C10H15N2O4Vؒ4H2O requires
C, 34.3; H, 6.6; N, 8.0%). IR (KBr, cm1): 3386s, 1652m, 1606m,
1477m, 1454m, 1329w, 1292w, 1076s, 1057s, 919s, 872s, 776s,
725s, 651m and 563s.
N-(1-Carboxymethylbenzimidazol-2-ylmethyl)iminodiacetic
acid (H3bmidaa). 2-(Aminomethyl)benzimidazole dihydrochlo-
ride (6.50 g, 29.6 mmol) and chloroacetic acid (16.75 g, 177.3
mmol) were dissolved in water (10 cm3). The pH of the solution
was adjusted to 8.0 by the addition of 5 mol dmϪ3 NaOH. The
solution was refluxed and the pH adjusted as above at hourly
intervals. After approximately 4 h the pH no longer changed.
Chloroacetic acid (8.38 g, 88.7 mmol) was added and the solu-
tion refluxed overnight. The solution was cooled to room tem-
perature and filtered to remove some precipitated decom-
position product. The pH was adjusted to 2.5 by the addition of
5 mol dmϪ3 HCl and a white precipitate began to form. The
mixture was cooled to 0 ЊC for 6 h further to precipitate prod-
uct. The precipitate (6.9 g, 72%) was filtered off and washed
Na[VO2(pmide)] 2b. The compound NaVO3 (0.20 g, 1.6
mmol) was dissolved in water (10 cm3), H2pmide (0.45 g, 2.3
mmol) added and the mixture stirred until dissolution was
complete. The pH was adjusted to 6.5 by addition of 5 mol
dmϪ3 HCl. Acetone was added until the solution became
cloudy. The resulting greenish solution was kept at Ϫ15 ЊC for
4 d at which time a yellow crystalline material had precipitated.
The precipitate (0.59 g, 94% with respect to NaVO3) was filtered
2800
J. Chem. Soc., Dalton Trans., 1997, Pages 2799–2812