with CH2Cl2 (3 × 20 ml), dried on Na2SO4 and evaporated in
vacuo to yield a brown oil (4.5 g, 83%). δH (CDCl3): 2.07 (3 H, s,
NCH3), 2.46 (2 H, m, NCH2CHЈ2N), 2.59 (2 H, m, NCH2-
CHЈ2N), 3.48 and 3.72 (2 H, s, and 2 H, s, 2 × NCH2C5H4N),
6.96–7.46 (6 H, m, 2 × C4H, C5H and C6H py) 8.35 (2 H, m,
2 × C3H py). δC (CDCl3): 42.63 (NCH3), 46.80 (CH2NHCH2-
C5H4N), 55.31 (NHCH2C5H4N), 57.29 (C5H4NCH2(CH3)-
NCH2), 64.13 (C5H4NCH2NCH3), 121.89, 121.98, 122.25,
123.11 (2 × C3 py, 2 × C5 py), 136.43, 136.46 (2 × C4 py), 149.04,
149.31 (2 × C6 py), 159.56, 160.07 (2 × C2 py).
136.24 (2 × C4 py), 138.98 (C1 phen), 148.64, 149.06 (2 × C6 py),
159.77, 159.88, (2 × C2 py).
NЈ-Benzyl-N-carboxymethyl-N,NЈ-bis(2-pyridylmethyl)-1,2-
ethanediamine (bzgbpenH). Bromoacetic acid (0.425 g, 3.05
mmol) and triethylamine (0.309 g 3.05 mmol) were added to a
solution of N-benzyl-N,NЈ-bis(2-pyridylmethyl)-1,2-ethane-
diamine (1.014 g, 3.05 mmol) in dry ethanol (2.5 ml). The solu-
tion was refluxed overnight under N2, put on ice to precipitate
Et3NHBr, which was removed. The solution was evaporated
under vacuum and redissolved in water and adjusted to pH 8
with NaOH. The aqueous phase was washed three times with
methylene chloride (3 × 15 ml) and adjusted to ca. pH 4 with
aq. HCl. The solution was evaporated to an oil which was then
redissolved in 15 ml absolute EtOH. Undissolved NaCl was
removed and the solvent removed under vacuum to give a
red–brown oil (0.799 g, 67%). δH (DMSO-d6): 2.62–2.82 (4H,
m, NCH2CH2N), 3.16 (2H, s, NCH2COOϪ), 3.4–3.8 (6H, m,
2 × NCH2C5H4N and NCH2C6H5), 7.10–7.32 (7 H, m, C6H5
and 2 × C5H py), 7.41 (2H, m, 2 × C3H py), 7.67 (2H, m, 2 ×
C4H py), 8.49 (2H, m, 2 × C6H py). δC (DMSO-d6): 51.3, 51.6
(NCH2CH2N), 57.7 (NCH2C6H5), 59.3, 59.4 (NCH2C5H4N),
60.1 (NCH2COOϪ), 121.5, 121.9, 122.4, 122.8 (2 × C3 py, 2 ×
C5 py), 126.7 (C4 Ph), 128.1, 128.5 (C2, C6, C3, C5 Ph), 136.0,
136.4, (2 × C4 Py), 138.9 (C1 Ph), 148.5, 148.6 (2 × C6 Py),
159.5, 160.6 (2 × C2 Py), 173.4 (COOH).
N-Methyl-NЈ-glycine-N,NЈ-bis(2-pyridylmethyl)-1,2-ethane-
diamine (mgbpenH). Bromoacetic acid (2.45 g, 17.6 mmol) and
triethylamine (1.79 g, 17.7 mmol) were added to a solution
of
N-methyl-N,NЈ-bis(2-pyridylmethyl)-1,2-ethanediamine
(4.50 g, 17.6 mmol) in dry ethanol (2 ml). The solution was
refluxed under N2 for 24 h and then evaporated under vacuum.
The oily residue was dissolved in water (10 ml) and pH was
adjusted to 10 with conc. aqueous NaOH. The dark solution
was extracted with CH2Cl2 (3 × 10 ml) and the aqueous phase
was evaporated in vacuo to yield a brown oil (5.48 g, 93%).
δC (CDCl3): 40.80 (NCH3), 49.52 (CH2N(CH2C5H4N)(CH2-
COOϪ)), 53.81 ((CH3)(CH2C5H4N)NCH2), 58.22 ((CH2COOϪ)-
N(CH2C5H4N)), 59.72 (C5H4NCH2NCH3), 60.00 (NCH2-
COOϪ), 123.41, 124.28, 124.84, 125.58 (2 × C3 py, 2 × C5 py),
138.51, 138.66 (2 × C4 py), 148.26, 149.50 (2 × C6 py), 156.55
(C2 py).
Mn(II) complexes
2-Phenyl-1,3-bis(2-pyridylmethyl)imidazolidine. N,NЈ-Bis(2-
pyridylmethyl)-1,2-ethanediamine (2.1 g, 10 mmol) and benz-
aldehyde (1.1 g, 10 mmol) were dissolved in 40 ml dry diethyl
ether. The reaction was stirred with 4 Å molecular sieves
overnight with CaCl2 protection. The product was isolated as a
white powder which was washed with dry ether (1.76 g, 57%).
mp. 142–146 ЊC. δH (CDCl3): 2.685, 3.305 (2 × 2H, m, NCH2-
CH2N (AAЈBBЈ), 3.517 and 3.900 (2 H, d, J 14.12 and 2 H, d,
J 13.88, 2 × NCHABC5H4N, A or B), 4.021 (1 H, s, NCH-
(C6H5)N), 7.081 (2 H, m, 2 × C5H py), 7.2–7.45 (5 H, m, C6H5),
7.5–7.7 (4 H, m, C3H py, C4H py), 8.463 (2 H, d, C6H py).
δC (CDCl3): 51.20 (NCH2CH2N), 58.82 (2 × NCH2C5H4N),
89.00 (NCH(C6H5)N), 121.9, 122.9 (2 × C5 py, 2 × C3 py), 128.3
(C3, C5 Ph), 128.7 (C4 Ph), 129.5 (C2, C6 Ph), 136.4 (2 × C4 py),
140.1 (C1 Ph), 148.8 (2 × C6 py), 159.5 (2 × C2 py).
[Mn2(mgbpen)2(H2O)2](ClO4)2 (1). Mn(ClO4)2ؒ6H2O (1.27 g,
3.5 mmol) in methanol (10 ml) was added to a solution of
mgbpen (1.11 g, 3.3 mmol) in a 1 : 1 mixture of water–methanol
(10 ml). After 3 days, the beige crystals were isolated by fil-
tration. Yield 0.366 g (23%). ESI-MS (MeOH): m/z 368 (100%,
[(Mn(mgbpen))2]2ϩ). Anal. Calc. for C34H46Cl2Mn2N8O14:
C, 42.03; H, 4.77; N, 11.53. Found: C, 41.64; H, 4.66; N,
11.25%. The synthesis of [Mn2(bzgbpen)2(H2O)2](ClO4)2 (2) is
analogous. ESI-MS (MeCN): m/z 444.4 [(Mn(bzgbpen))2]2ϩ
,
987.4 [{(Mn(bzgbpen))2}(ClO4)]ϩ. Anal. Calc. for C46H54-
Cl2Mn2N8O14: C, 49.24; H, 4.85; N, 9.99. Found: C, 49.14; H,
4.38; N, 9.84%.
Magnetism. The magnetic susceptibility of compound
[Mn2(mgbpen)2(H2O)2](ClO4)2 was measured over the tem-
perature range 5–300 K at 0.5 and 5 T. The sample (25.6 mg)
was contained in a kel F bucket which had been independently
calibrated. The data were corrected from diamagnetism
using Pascal’s constants.16 The data have been simulated using
the van Vleck equation derived from the Heisenberg exchange
hamiltonian (H = Ϫ2JS1ؒS2) for spins S1 = S2 = 5/2 (eqn. (1)):
with k = J/0.695T and t is the temperature independent para-
magnetism. The g value was fixed to 2 in the calculations. The
goodness of fit R2 amounted to 0.9996.
N-Benzyl-N,NЈ-bis(2-pyridylmethyl)-1,2-ethanediamine. 2-
Phenyl-1,3-bis(2-pyridylmethyl)imidazolidine (1.5 g, 4.5 mmol)
was dissolved in dry methanol (45 ml). The solution was filtered
to remove molecular sieves from the previous step. NaBH3CN
(0.28 g, 4.5 mmol) in 3 ml dry MeOH was added, and then
CF3COOH (1.0 g, 9.0 mmol) was added carefully. The reaction
mixture was stirred for 24 h with CaCl2 protection. 45 ml 15%
aqueous NaOH was added and the reaction was allowed to
stir for 6 h. This mixture was extracted with methylene chloride
(20 ml) three times, the organic phase was dried on Na2SO4 and
evaporated leaving a yellow oil (1.87 g, over 100% yield due to
water and possible formation of sodium salt, however purity
was sufficient for complex formation). δH (CDCl3): 2.69 (1 H,
br s, NH), 2.732 (4 H, m, NCH2CH2N), 3.637 (2 H, s,
NCH2C6H5), 3.751 (2 H, s, NCH2C5H4N), 3.805 (2 H, s,
NCH2C5H4N), 7.0–7.2 (2 H, m, 2 × C5H py), 7.2–7.45 (5 H,
m, C6H5), 7.50–7.7 (4 H, m, 2 × C3H py, 2 × C4H py), 8.506
(2 H, m, 2 × C6H py). δC (CDCl3): 46.53, 53.60 (NCH2CH2N),
54.79 (C6H5CH2N), 58.79, 60.21 (2 × NCH2C5H4N), 121.65,
121.73, 121.95, 122.80 (2 × C3 py, 2 × C5 py), 126.82 (C4 phen),
128.08 (C3, C5 phen), 128.78 (C2, C6, C3, C5 phen), 136.15,
Electrochemistry. Electrochemical measurements were per-
formed using an EG&G PAR model 173 potentiostat/galvano-
stat equipped with a PAR model universal programmer and
a PAR model 179 digital coulometer. The standard three-
electrode electrochemical cell was used. In CH3CN medium, the
electrolyte was 0.1 M Bu4NClO4 and potentials were referred to
an Ag/10 mM AgNO3 reference electrode in CH3CN, 0.1 M
Bu4NClO4 electrolyte. Potentials referenced to that system
can be converted to the SCE by adding 300 mV. The working
electrode was a platinum disk (5 mm in diameter) polished with
2 µm diamond paste (Mecaprex Presi) for cyclic voltammetry
(CV) (Epa, anodic peak potential; Epc, cathodic peak potential;
(1)
D a l t o n T r a n s . , 2 0 0 3 , 1 7 6 5 – 1 7 7 2
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