Synthesis and catalytic activity of novel Zn-N and Cu-N complexes

Article abstract of DOI:10.1016/j.inoche.2010.05.017

A series of zinc and copper complexes supported by 1, 3-diaminobenzene, 1, 2-aminobenzylamine, 1, 3-aminobenzylamine and m-xylylenediamine was synthesized and characterized. Reaction of 1, 3-diaminobenzene, 1, 2-aminobenzylamine, 1, 3-aminobenzylamine and m-xylylenediamine with Zn(OAc)₂?2H ₂O and Cu(OAc)₂?H₂O in alcohol, methanol or tetrahydrofuran resulted in the production of five novel zinc and copper complexes: 2, 4, 6, 8 and 9. Moreover, the structure of each of complex was determined by X-ray diffraction analysis. Every complex was also characterized by elemental analysis, ¹H NMR and IR. The complexes were then used to catalyze the Henry reaction and good catalytic results (65-99%) were achieved. The catalytic activity of the complexes was determined by ¹H NMR.

Full text of DOI:10.1016/j.inoche.2010.05.017

Inorganic Chemistry Communications 13 (2010) 1009–1013
Contents lists available at ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
Synthesis and catalytic activity of novel Zn–N and Cu–N complexes
Luo Mei a, , Jiang Li a,1, Liu Shuang Tai a,1, Lei Shang Song a, Li Qian Rong b, Zhou Shi Ming b
⁎
a
Hefei University of Technology, Department of Chemical Engineering, Hefei, 230009, China
University of Science and Technology, Department of Chemistry, Hefei, 230009, China
b
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of zinc and copper complexes supported by 1, 3-diaminobenzene, 1, 2-aminobenzylamine, 1, 3-
aminobenzylamine and m-xylylenediamine was synthesized and characterized. Reaction of 1, 3-
diaminobenzene, 1, 2-aminobenzylamine, 1, 3-aminobenzylamine and m-xylylenediamine with Zn
(OAc)2·2H2O and Cu(OAc)2·H2O in alcohol, methanol or tetrahydrofuran resulted in the production of
five novel zinc and copper complexes: 2, 4, 6, 8 and 9. Moreover, the structure of each of complex was
determined by X-ray diffraction analysis. Every complex was also characterized by elemental analysis, 1H
NMR and IR. The complexes were then used to catalyze the Henry reaction and good catalytic results (65–
99%) were achieved. The catalytic activity of the complexes was determined by 1H NMR.
© 2010 Elsevier B.V. All rights reserved.
Received 7 April 2010
Accepted 21 May 2010
Available online 4 June 2010
Keywords:
1, 3-Diaminobenzene
1, 2-Aminobenzylamine
1, 3-Aminobenzylamine and m-xylylenedia-
mine
Zn(Ac)2·2H2O
Cu(Ac)2·H2O
The Henry reaction
Many novel zinc complexes and copper complexes have been
reported recently [1–12]. Metal complexes are the subject of intensive
research not only owing to their rich coordination chemistry but also
to a number of established and potential application areas. Metal-
complexes occupy an important position in catalytic processes, as the
catalysts and they have shown high activities in organic reactions and
polymerization. Recently, organometallic complexes including Zn, Cu
(Zn, Li), Fe, Ru and other less-frequently used ions have been
developed. These complexes have been used in selective 1,2- or 1,4-
additions, transfer hydrogenations, aldol reactions and Diels–Alder
reactions [13]. For example, N, O-chelated aluminum and zinc
complexes are active catalysts in the ring-opening polymerization of
ε-caprolactone [14]. Chiral Phosphoramide–Zn (II) complexes are
highly active catalysts for enantioselective organozinc addition to
ketones [15]. Cu(II)-containing MOFs based on N-heterocyclic ligands
are widely used in the oxidative coupling of 2,6-dimethylphenol [15].
In this paper, we first describe the synthesis of novel complexes with a
simple, one-pot method. On the complex 9, in 2001 and 2002,
Hamerton, Ian research group reported the preparation, character-
ization, and storage behavior of transition metal–diamine complexes
as the curing agents for epoxy resins [16,17], but we first report herein
the definite crystal structure of complex 9. In recent years, it has been
reported in the literature that chiral nitrogen and zinc as well as
copper and nitrogen complexes have showed high activity in the
Henry reaction [16–22]. Inspired by their work, our complexes were
used to catalyze the Henry reaction.
The synthetic routes of the title five complexes can be summarized
as follows (Schemes 1–4, Figs. 1–5).
The syntheses of the complexes 2, 4 and 6 were all carried out
under anhydrous ethanol, using a ratio of 1.1:1 of the ligand to the
zinc acetate. After refluxing for 24 h, complex 2 was recrystallized
with dichloromethane and n-hexane (V/V: 1/1), and brown crystals
were obtained. Complex 4 was recrystallized with ethanol, and
colorless crystals were obtained. By adding 10 mL dichloromethane
and 10 mL n-hexane (v/v:1/1), complex 6 was evaporated slowly in
the air, and colorless crystals appeared.
The synthesis of complex 8 was carried out under anhydrous
methanol, first refluxed 8 h at a 1:1 ratio, then a second volume of
ligand, equal to the first, was added, and the reaction was refluxed for
an additional 8 h. Next, the product mixture was evaporated in
ethanol, and blue crystals were obtained.
The synthesis of complexes 8 and 9 was carried out under THF
using a ratio of 2:1 of the ligand to the zinc acetate or copper acetate.
Both reactions were refluxed for 24 h. Complex 9 was obtained after
slow evaporation in the ethanol.
The crystal structures of complexes 8 and 9 are distinctive.
Complex 8 also contains an acetic acid molecule with a freed root,
which is similar to the structure of complex 9.
The five complexes were all easily dissolved in dichloromethane,
chloroform, ethanol and methanol, and were difficult to dissolve in n-
hexane, petroleum ether and ether.
The coordination number was 4 for complexes 2, 4, 6, 3 for
complex 8 and 5 for complex 9. Complex 2 was a [Zn (C6H8N2) (OAc)2]
⁎
Corresponding author. Tel.: +86 551 2903073.
E-mail address: lmhh5523385@yahoo.cn (L. Mei).
Liu Shuang Tai and Jiang Li contributed equally to this work.
1
1387-7003/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2010.05.017

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L. Mei et al. / Inorganic Chemistry Communications 13 (2010) 1009–1013
Scheme 1. The synthetic route for complex 2a. aReagents and conditions: (i) ethanol, 70–80 °C, 24 h; (ii) ethanol, 70–80 °C, 24 h.
aminobenzylamine nitrogen atoms N2 and N4, thus forming a four-
coordinate complex.
Complex 8 was a Cu–N complex that consisted of a Cu (OAc)2
molecule and two m-xylylenediamine molecules. A Cu ion was
complexed with a carboxylate oxygen atom (O1) and the two m-
xylylenediamine nitrogen atoms N1, N2, N3 and N4; this, the complex
was three coordinate.
Complex 9 was a Cu–N complex that consisted of a Cu(OAc)2
molecule and two 1,2-aminobenzylamine molecules. A Cu ion was
complexed with a carboxylate oxygen atom (O1) and the aminoben-
zylamine nitrogen atoms N1, N2, N3 and N4, thus making the complex
five coordinate, The Cu1–O1 bond length [1.9939 (15) Å] and the Cu1–
N2 and Cu1–N3 bond lengths were slightly longer than the Cu1–N1
and Cu1–N4 bond lengths.
Catalyze the Henry reaction was achieved using 15 mol% of the six
complexes without any additives. The catalytic activity of the five
novel complexes in the Henry reaction was shown in Table 1.
From Table 1, we can see that the conversion efficiency for each of
these complexes was more than 60%, they are all good catalysts to the
Henry reaction. Among them, complex 6 showed the best catalytic
activity. The mechanism can be proposed that the complexes could
greatly activate the C O bond, followed by nucleophilic addition
reaction of CH2NO−2 onto the carbonyl group.
In conclusion, five novel complexes were synthesized with a
simple, one-pot method, and their crystal structures were deter-
mined. Further research on the use of these complexes in other
organic reactions such as the cyanosilylation reaction and allylation is
ongoing.
Scheme 2. The synthetic route for complexes 4 and 6a. aReagents and conditions:
(i) ethanol, 70–80 °C, 24 h; (ii) ethanol, 70–80 °C, 24 h.
unit consisting of polymer complexes [Zn (C6H8N2) (OAc)2]n, which
was an unlimited extension of its chain structure. The carboxylate
oxygen atoms (O1 and O3) and the nitrogen atoms N1, N2 of
phenylenediamine constitute the four atoms coordinated to Zn.
Complex 4 consisted of a Zn (OAc)2 molecule and two 1, 2-
aminobenzylamine molecules. The Zn ion was coordinated with the
carboxylate oxygen atoms O1 and O1i and the 1, 2-aminobenzylamine
nitrogen atoms N1 and N1i forming a four-coordinated complex.
Similarly, Complex 6 single also consisted of a Zn (OAc)2 molecules
and two 1, 2-aminobenzylamine molecules. The Zn ion was
coordinated with carboxylate oxygen atoms O1 and O3 and with
Acknowledgment
This work was supported by Hefei University of Technology.
Appendix A. Supplementary data
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.inoche.2010.05.017.
Scheme 3. The synthetic route for complex 8a. aReagents and conditions: (i) methanol, 60–70 °C, 16 h.

L. Mei et al. / Inorganic Chemistry Communications 13 (2010) 1009–1013
1011
Scheme 4. The synthetic route for complex 9a. aReagents and conditions: THF, 60–70 °C, 24 h.
[13] H.J. Zhu, J.X. Jiang, J. Ren, Y.M. Yan, C.U. Pittman Jr., Current Organic Synthesis 2
(2005) 547–587.
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Fig. 1. ORTEP diagram of complex 2 (30% probability thermal ellipsoids). Selected bond
lengths (Ǻ) and angles (deg): Zn(1)–O(1) 2.006(3), Zn(1)–O(3) 2.001(3), Zn(1) –N(1)
2.038(4), Zn(1)–N(2) 2.032(4), O(1)–C(8) 1.281(5), O(2)–C(8) 1.222(5), O(3)–C(9)
1.275(5), O(4)–C(9) 1.235(5), N(1)–C(4) 1.4385, N(2)–C(2) 1.436(5), O(1)–Zn(1)–O
(3) 92.28(12), O(1)–Zn(1)–N(1) 107.72(13), O(1)–Zn(1)–N(2) 109.76(13), O(3)–Zn
(1)–N(2) 110.77(14), O(3)–Zn(1)–N(1) 107.89(14), N(2)–Zn(1)–N(1) 123.83(14), C
(8)–O(1)–Zn(1) 109.9(3), C(9)–O(3)–Zn(1) 108.8(3), C(4)–N(1)–Zn(1) 120.9(3), C
(2)–N(2)–Zn(1),117.5(3). Elemental analysis: Anal. Calc. for Zn[C10H14N2O4]: C, 41.19;
H, 4.839; N, 9.607%; Found: C, 41.50; H, 4.976; N, 9.799%. 1H NMR (300 MHz,CDCl3,
27 °C): δ(ppm)=6.93 (t, 1H), 6.11–6.12 (d, J=6.5 Hz, 2H), 6.04(s, 1H), 3.82(s,4H),
2.11(s, 6H), IR (KBr, pellet):3434, 3219,3143, 3013, 2975, 2923, 2365, 1632, 1615, 1587,
1505, 1483, 1424, 1387, 1335, 1320, 1206, 1192, 1149, 1125, 1052, 1038, 1019, 950,
930, 859, 773, 675, 619, 585, 553, 540, 442.
Fig. 2. ORTEP diagram of complex 4 (30% probability thermal ellipsoids). Selected bond
lengths (Ǻ) and angles (deg): Zn(1)–O(1) 1.953(5), Zn(1)–N(1) 2.019(5), O(1)–C(8)
1.279(7), O(2)–C(8) 1.220(8), N(1)–C(1) 1.496(7), N(2)–C(3) 1.381(9), C(8)–C(9)
1.484(9), C(1)–C(2) 1.502(7),O(1)–Zn(1)–N(1) 120.5(2), C(1)–C(2)–C(3) 120.6(5), N
(1)–Zn(1)–N(1i) 107.0(3), Zn(1)–O(1)–C(8) 118.5(5), Zn1–N(1)–C(1)115.5(4), N(1)–
C(1)–C(2) 112.4(5), N(2)–C(3)–C(2) 120.9(6), N(2)–C(3)–C(4) 120.9(5), O(1)–C(8)–
O(2) 121.5(6), O(1)–C(8)–C(9) 116.1(6), O(2)–C(8)–C(9) 122.4(6), C(1)–C(2)–C(7)
120.7(5). Elemental analysis: Anal. Calc. for Zn[C9H13N2O2]2: C, 50.53; H, 6.13; N,
13.10%. Anal. Calc. for Zn[C9H13N2O2]2:Found:C, 50.74; H, 6.208; N, 13.11%. 1H NMR
(300 MHz,CDCl3, 27 °C), δ(ppm)=7.10–7.29(m, 4H), 6.80–6.89 (m, 4H), 3.99 (s,
4H),1.96 (s, 6H),1.89(br, 8H), IR (KBr, pellet):3852, 3738, 3431, 3303, 3245, 2931,1613,
1587, 1494, 1391, 1337, 1275, 1158, 1023, 977, 937, 865, 743, 624, 580, 494.

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L. Mei et al. / Inorganic Chemistry Communications 13 (2010) 1009–1013
Fig. 3. ORTEP diagram of complex 6 (30% probability thermal ellipsoids). Selected bond lengths (Ǻ) and angles (deg): Zn(1)–O(1) 1.9618(19), Zn(1)–O(3) 1.9722(19), Zn(1)–N(4)
2.019(2), Zn(1)–N(2) 2.036(2), O(1)–C(16) 1.253(4), O(2)–C(16) 1.228(3), O(3)–C(17) 1.277(3), O(4)–C(17) 1.225(3), N(1)–C(1) 1.387(5), N(2)–C(7) 1.472(3), N(3)–C(8) 1.366
(4), N(4)–C(14) 1.439(3), C(3)–C(7) 1.506(4), C(12)–C(14) 1.513(4), O(1)–Zn1–N(2) 108.7(9), O(1)–Zn1–N(4) 102.95(9), O(1)–Zn1–O(3) 110.29(9), O(3)–Zn1–N(2) 109.76(8),
O(3)–Zn1–N(4) 114.72(10), N(2)–Zn1–N(4) 110.10(11), Zn1–O(1)–C(16) 112.81(19), Zn1–O(3)–C(17) 112.89(17), Zn1–N(2)–C(7) 113.93(15), Zn1–N(4)–C(14) 118.66(19), N
(1)–C(1)–C(6) 122.3(4), N(1)–C(1)–C(2) 119.6(4), N(3)–C(8)–C(9) 120.7(3), N(3)–C(8)–C(13) 120.7(3), N(4)–C(14)–C(12) 117.5(3). Elemental analysis: Anal. Calc. for Zn
[C9H13N2O2]2: C, 50.53; H, 6.13; N, 13.10%; Found: C, 50.31; H, 6.15; N, 13.32%. 1H NMR (300 MHz, CDCl3, 27 °C): δ(ppm)=7.11 (t, J=0.5 Hz, 2H), 6.58–6.65 (m, 6H), 3.76(s, 4H), 2.2
(s, 8H), 2.00(s, 6H), IR (KBr pellet): 3430, 3320, 3230, 2950, 2360, 2140, 1590, 1400, 1330, 1140, 1010, 781, 679, 623, 476.
Fig. 5. ORTEP diagram of complex 9 (30% probability thermal ellipsoids). Selected bond
lengths (Ǻ) and angles (deg): Cu(1)–N(1) 1.9843(17), Cu(1)–O(1) 1.9939(15), Cu(1)–
Fig. 4. ORTEP diagram of complex 8 (30% probability thermal ellipsoids). Selected bond
lengths (Ǻ) and angles (deg): Cu(1)–N(1) 2.026(3), Cu(1)–N(2) 2.031(3), Cu(1)–O(1)
2.034(3), O(3)–C19 1.230(6),O(2)–C(17) 1.239(6), O(4)–C(19) 1.250(6), N(3)–C(15)
1.388(8), N(4)–C(16) 1.357(8), N(1)–Cu(1)–O(1) 86.29(13), N(2)–Cu(1)–O(1) 92.58
(13), N(1)–Cu(1)–N(3) 90.79(16), N(2)–Cu(1)–N(3) 90.90(16), O(1)–Cu(1)–N(3)
149.63(16), N(1)–Cu(1)–N(4)87.09(15), N(2)–Cu(1)–N(4)92.18(16), O(1)–Cu(1)–N
(4) 117.25(19), N(3)–Cu(1)–N(4) 92.7(2), C(17)–O(1)–Cu(1) 108.7(3), C(7)–N(1)–Cu
(1) 117.4(3), O(2)–C(17)–O(1) 122.6(4),O(2)–C(17)–C(18) 120.3(4), O(1)–C(17)–C
(18) 117.1(4). Elemental analysis: Anal. Calc. for C20H30N4O4Cu: C, 52.91; H, 6.66; N,
12.34%; Found: C, 52.54; H, 6.78; N, 13.33%. IR (KBr pellet): 3334, 3219, 2926, 2878,
1571, 1444, 1401, 1332, 1174, 1158, 1090, 1055, 993, 926, 919, 791, 755, 734,703,
651,639, 616.
N(4) 2.0153(17), Cu(1)–N(2)2.1205(17), Cu(1)–N(3)2.2846(16), O(3)–C17 1.253(3),
O(1)–C(15) 1.267(3), N(3)–C(8) 1.422(3), N(4)–C(14) 1.484(3), N(1)–C(7) 1.471(3),
O(4)–C(17) 1.225(3), N(2)–C(1) 1.433(3), O(2)–C(15)1.227(3), N(1)–Cu(1)–O(1)
86.76(7), N(1)–Cu(1)–N(4) 177.54(7), O(1)–Cu(1)–N(4) 91.42(7), N(1)–Cu(1)–N(2)
91.01(7), O(1)–Cu(1)–N(2) 157.23(6), N(4)–Cu(1)–N(2)90.02(7), N(1)–Cu(1)–N(3)
92.84(6), O(1)–Cu(1)–N(3) 103.69(6), N(4)–Cu(1)–N(3) 89.20(6), N(2)–Cu(1)–N(3)
99.06(6), C(15)–O(1)–Cu(1) 114.36(13), C(8)–N(3)–Cu(1) 113.67(12), C(14)–N(4)–
Cu(1) 116.57(13), C(7)–N(1)–Cu(1) 116.37(14),C(1)–N(2)–Cu(1) 115.04(13), Anal.
Calc. for Cu[C9H13N2O2]2: C, 50.70; H, 6.10; N, 13.15%. Found: C, 50.55; H, 6.43; N,
13.38%, IR (KBr pellet): 3451, 3342, 3230, 3183, 3113, 3067, 3028, 2950, 2886, 2349,
1576, 1496, 1468, 1454, 1418, 1394, 1334, 1279, 1223, 1159, 1121, 1087, 1041, 1020,
995, 945, 860, 846, 754, 664, 650, 623, 587, 492, 472.

L. Mei et al. / Inorganic Chemistry Communications 13 (2010) 1009–1013
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Table 1
Catalytic activity of the six complexes to the Henry reactiona.
Complex
Conversion (%)b
2
4
6
8
9
63
67
N99
69
67
a
Reactions were carried out with 1 mmol PhCHO and 0.2 mL CH3NO2 in 5 mL CH3OH
using 15 mol% of catalysts at room temperature (10–20 °C).
b
Conv.% was determined by 1H NMR.