Alcohol adducts of zinc dichloride: Molecular structure of [ZnCl2(THF){1-HOC(C6H11)2-2- NMe2C6H4}]

Article abstract of DOI:10.1016/j.poly.2009.07.049

The aminoalcohols 1-HOCR₂-2-NMe₂C₆H₄ [R = Ph (1), R = C₆H₁₁ (2)] and 1-HOCPh₂CH₂-2-NMe₂C₆ H₄ (3) react with ZnCl₂ in tetrah

Full text of DOI:10.1016/j.poly.2009.07.049

Polyhedron 28 (2009) 3515–3518
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Polyhedron
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Alcohol adducts of zinc dichloride: Molecular structure
of [ZnCl2(THF){1-HOC(C6H11)2-2-NMe2C6H4}]
Harbi Tomah Al-Masri b, Jens Baldamus a, Evamarie Hey-Hawkins a,
*
a Institut für Anorganische Chemie der Universität Leipzig, Johannisallee 29, D-04103 Leipzig, Germany
b Faculty of Applied Sciences, Department of Applied Chemistry, Taibah University, Madinah 1343, Saudi Arabia
a r t i c l e i n f o
a b s t r a c t
Article history:
The aminoalcohols 1-HOCR2-2-NMe2C6H4 [R = Ph (1), R = C6H11 (2)] and 1-HOCPh2CH2-2-NMe2C6H4 (3)
react with ZnCl2 in tetrahydrofuran to give the alcohol adducts [ZnCl2(THF){1-HOCR2-2-NMe2C6H4}]
[R = Ph (4), R = C6H11 (5)] and [ZnCl2(THF){1-HOCPh2CH2-2-NMe2C6H4}] (6). The complexes 4–6 were
characterized by 1H and 13C NMR spectroscopy, and 5 was also structurally characterized by X-ray
crystallography.
Received 5 June 2009
Accepted 28 July 2009
Available online 3 August 2009
Keywords:
Zinc
Ó 2009 Elsevier Ltd. All rights reserved.
Aminoalcohols
Adducts
Molecular structure
1. Introduction
[11,12], 2 [12] or 3 [12,13] in tetrahydrofuran at room temperature
(Scheme 1). In the 1H NMR spectra, the most noticeable signal is
The importance of zinc in bioinorganic chemistry [1] has
prompted us to extend our studies on the synthesis and solid-state
structures of chelated N,O and N,N complexes [2] to zinc deriva-
tives. Zinc is a constituent and activator of over 150 different en-
zymes of metabolic pathways; e.g., it is present in the active site
in hydrolytic enzymes, where it is coordinated by hard donor
atoms (N or O) [3,4], and it is a constituent of the hormone insulin
[5]. There is a considerable number of zinc complexes with N,O
chelate ligands containing the O donor as an alkoxide function
[6]. N,O chelation modes including both N and O as donor atoms
have been reported as well [7], also for macrocyclic Schiff base zinc
complexes [8]. O,O0 Bidentate chelation was observed in heterobi-
and heterotrimetallic complexes containing zinc, copper and cobalt
[9]. However, there are only a few examples of zinc complexes con-
taining neutral alcohols as ligands [10]. We now report the high-
yield synthesis and spectroscopic properties of zinc complexes
which contain neutral O-coordinating non-chelating dimethyl-
amino alcohol ligands [ZnCl2(THF){1-HOCR2-2-NMe2C6H4}]
[R = Ph (4), R = C6H11 (5)] and [ZnCl2(THF){1-HOCPh2CH2-2-
NMe2C6H4}] (6) and the crystal structure of complex 5.
that due to the N(CH3)2 and OH protons, which give rise to singlets
at about 3.44 ppm and 9.75 ppm (4), 3.38 ppm and 10.31 ppm (5),
and 2.49 ppm and 7.14 ppm (6), respectively. The signals of the
methylene protons in 6 are observed at 3.73 ppm. The 13C{1H}
NMR spectra show singlets for the N(CH3)2 and CO carbon atoms
at 45.1 ppm and 82.3 ppm (4), 46.4 ppm and 83.2 ppm (5), and
45.0 ppm and 77.0 ppm (6). The signal of the methylene carbon
atom in 6 is observed at 44.7 ppm. The signals corresponding to
the cyclohexyl and the aromatic carbons show the characteristic
resonances in their expected chemical shift regions similar to that
observed for the organic ligands 1–3 [12]. The EI mass spectra only
showed the ion peaks for the organic ligands 1–3.
2.1. Molecular structure of [ZnCl2(THF){1-HOCCy2-2-NMe2C6H4}] (5)
Colorless crystals of 5 were obtained from tetrahydrofuran at
ꢀ
20 °C. Compound 5 crystallizes in the triclinic space group P1.
The molecular structure of 5 shows a distorted tetrahedral envi-
ronment of zinc by two chloro ligands and two neutral O-donor
molecules (Fig. 1) with bond angles far from the value of 109.47°
typical for an ideal tetrahedron. The Cl(1)–Zn–Cl(2) [122.62(4)°]
and O(1)–Zn–Cl(1) [123.44(4)°] angles are large, while the four
other angles are small [98.91(4)–104.1(4)°] (Table 1).
2. Synthesis and spectroscopic properties
The colorless zinc complexes 4–6 can be readily prepared by
addition of ZnCl2 to equimolar amounts of the organic ligands 1
The dative Zn–O bond [14] of the Zn–O(THF) group [av.
2.058(2) Å] is in the same range of those in [ZnCl3(THF)]ꢀ
[2.025(3)–2.121(8) Å] [15] and in [Zn(2,4,6-tBu3C6H2)2(THF)2] [av.
2.077 Å] [16]. The Zn–O(alcohol) bond length of 1.973(1) Å is
slightly smaller and comparable to those in [Zn(SC6F6)2(3-
* Corresponding author.
E-mail address: hey@rz.uni-leipzig.de (E. Hey-Hawkins).
0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.07.049

3516
H.T. Al-Masri et al. / Polyhedron 28 (2009) 3515–3518
ZnCl2
1-HOCR2-2-NMe2C6H4
[ZnCl2(THF){1-HOCR2-2-NMe2C6H4}]
[R = Ph (4), R = C6H11 (5)]
ZnCl2
1-HOCPh2CH2-2-NMe2C6H4
[ZnCl2(THF){1-HOCPh2CH2-2-NMe2C6H4}] (6)
Scheme 1. Preparation of 4–6.
Fig. 1. Molecular structure of 5 showing the atom numbering scheme employed (ORTEP, 50% probability, SHELXTL-PLUS; XP) [18]. Hydrogen atoms (other than O–H) are omitted
for clarity.
Table 1
Selected bond lengths (Å) and bond angles (°) for 5.
NMR spectra were recorded with an AVANCE DRX 400 spectrome-
ter (Bruker). Chemical shifts for 1H and 13C NMR spectra are re-
Zn(1)–O(1)
Zn(1)–O(THF)av.
Zn(1)–Cl(1)
Zn(1)–Cl(2)
Cl(1)–Zn(1)–Cl(2)
1.973(1)
2.058(2)
2.1949(6)
2.2092(7)
122.62(4)
O(1)–Zn(1)–Cl(1)
O(THF)–Zn(1)–Cl(1)av.
O(1)–Zn(1)–Cl(2)
O(THF)–Zn(1)–Cl(2)av.
O(1)–Zn(1)–O(THF)av.
123.44(4)
102.3(3)
98.91(4)
104.1(4)
102.6(6)
ported in parts per million (ppm) at 400.13 MHz and 100.63 MHz
with tetramethylsilane as external standard. Elemental analyses
were determined with a VARIO EL (Heraeus). Melting points (Gal-
lenkamp) are uncorrected. Mass spectra were recorded with an
MAT-8230 (EI-MS, 70 eV). 1-HOCPh2-2-NMe2C6H4 (1) [11,12], 1-
HOC(C6H11)2-2-NMe2C6H4 (2) [12], and 1-HOCPh2CH2-2-
NMe2C6H4 (3) [12,13] were prepared by literature procedures.
(CH2OH)C5H4N)] [2.123(3) Å], and similar to those found in {N,N0-
bis[1-(2-hydroxy-4-methoxyphenyl)ethylidene]ethylenediamine-
j2O,O0}dichlorozinc(II) [1.975(5) Å] [7]. The Zn–Cl bond lengths
(Table 1) are in the same range and comparable to those found
in [ZnCl2(C10H12NO2)2] [2.219(2)–2.233(2) Å] [7] and [ZnCl2(8-
(diphenylphosphino)quinoline] [2.218(2) and 2.201(2) Å] [17].
The non-involvement of the NMe2 nitrogen atom in zinc coordi-
nation seems to be due to two combined factors: the better donor
quality of the THF molecule, and the strong intramolecular O(1)–
H(9)ꢁꢁꢁN(1) hydrogen bond [O–H 0.94(3) Å, HꢁꢁꢁN 1.55(3) Å, OꢁꢁꢁN
2.464(2) Å, O–H–N 160(3)°]. The intramolecular O(1)–H(9)ꢁꢁꢁN(1)
hydrogen bond of 5 is stronger than that in the free ligand 2 [O–H
0.92(2) Å, NꢁꢁꢁH 1.73(2) Å, NꢁꢁꢁO 2.591(1) Å, N–HꢁꢁꢁO 155(2)°] [12].
The bond lengths and angles of the organic fragment of 5 are similar
to those observed for the corresponding free ligand 2 [12].
3.1. Preparation of [ZnCl2(THF){1-HOCPh2-2-NMe2C6H4}] (4)
A 150 ml Schlenk flask was charged with 1-HOCPh2-2-NMe2C6H4
(1) (0.48 g, 1.6 mmol) and tetrahydrofuran (50 ml). Then ZnCl2
(0.22 g, 1.6 mmol) was added at room temperature. The solution
was stirred for about 3 h. The remaining solid was then removed
by filtration and the solution was concentrated to give the product
in 94% yield. Mp. 177–178 °C. 1H NMR (DMSO, d/ppm): 1.76 (m,
4H, CH2 (THF)), 3.44 (s, 6H, N(CH3)2), 3.60 (m, 4H, CH2O (THF)),
6.56–7.54 (m, vbr, 14H, C6H4 and C6H5), 9.75 (s, 1H, OH). 13C {1H}
NMR (DMSO, d/ppm): 21.0 (THF), 45.1 (N(CH3)2), 67.0 (THF), 82.3
(C–O), 124.3 (s, C6 in C6H4), 125.2 (s, C4 in C6H4), 126.9 (s, C3 in
C6H4), 127.8 (s, C5 in C6H4), 128.6 (s, p-C in C6H5), 129.5 (s, o-C in
C6H5), 139.0 (s, m-C in C6H5), 142.3 (s, C2 in C6H4), 147.5 (s, C1 in
C6H4), 152.0 (s, ipso-C in C6H5). MS: m/z 303.4 (M+-ZnCl2-THF).
Found: C, 58.64; H, 5.69; N, 2.72%. Calcd. for C25H29Cl2NO2Zn
(511.80): C, 58.67; H, 5.71; N, 2.74%.
3. Experimental
All experiments were carried out under purified dry nitrogen.
Solvents were dried and freshly distilled under nitrogen [19]. The

H.T. Al-Masri et al. / Polyhedron 28 (2009) 3515–3518
3517
Table 2
Crystal data and structure refinement for 5.
Formula
C25H41Cl2NO2Zn
Z
2
Formula weight
Temperature (K)
Crystal system
Space group
a (Å)
523.86
298(2)
Triclinic
Dcalcd (g cmꢀ1
F(0 0 0)
)
1.316
556
Crystal size (mm)
0.60 ꢂ 0.50 ꢂ 0.40
Absorption coefficient (mmꢀ1
)
1.152
ꢀ
P1
8.9841(7)
9.5300(7)
16.838(1)
81.206(2)
85.350(1)
68.180(1)
1322.1(2)
194 393
Number of reflections collected
Number of independent reflections
Rint
Number of parameters
R1 (I > 2
12485
6197
b (Å)
c (Å)
0.0231
459
0.0381
0.1136
0.497
a
(°)
b (°)
r(I))
c
(°)
wR2 (all data)
V (Å3)
(
(
D
D
/
/
q
q
)
)
(e Åꢀ3
)
)
min
Deposition number
(e Åꢀ3
ꢀ0.406
max
Phenylene ring numbering scheme:
fractometer. All observed reflections were used for determination
of the unit cell parameters. Empirical absorption correction was
performed with SADABS [20]. The structure was solved by direct
methods (SHELXTL-PLUS [15]). H atoms were located by difference
maps and refined isotropically, except for the hydrogen atoms
of the disordered THF ligand (O2, C22–C25 and O3, C26–C29;
these atoms were refined with 63% and 37% occupancy,
respectively).
2
NMe2
1
3
4
6
5
Appendix A. Supplementary data
CCDC 194393 contains the supplementary crystallographic data
for 5. These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: (+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
3.2. Preparation of [ZnCl2(THF){1-HOCCy2-2-NMe2C6H4}] (5)
A similar procedure to that described for 4 was used here, ex-
cept 1-HOC(C6H11)2-2-NMe2C6H4 (2) (0.51, 1.6 mmol) was em-
ployed instead of 1 and colorless crystals were obtained from
tetrahydrofuran at 20 °C in 80% yield. Mp. 170–172 °C. 1H NMR
(DMSO, d/ppm): 0.69–1.73 (vbr, 22H, C6H11), 1.77 (m, 4H, CH2
(THF)), 3.38 (s, 6H, N(CH3)2), 3.61 (m, 4H, CH2O (THF)), 10.31 (s,
1H, OH), 7.04–7.39 (m, 4H, C6H4). 13C {1H} NMR (DMSO, d/ppm):
21.0 (THF), 26.4 (s, C4 in C6H11), 29.2 (s, C3/C5 in C6H11), 30.4 (s,
C2/C6 in C6H11), 45.8 (s, C1 in C6H11), 46.4 (N(CH3)2), 67.0 (THF),
83.2 (C–O), 124.5 (s, C6 in C6H4), 125.4 (s, C4 in C6H4), 126.1 (s,
C3 in C6H4), 127.3 (s, C5 in C6H4), 137.8 (s, C2 in C6H4), 153.3 (s,
C1 in C6H4). MS: m/z 315.6 (M+-ZnCl2-THF). Found: C, 57.10; H,
7.87; N, 2.66%. Calcd. for C25H41Cl2NO2Zn (523.89): C, 57.32; H,
7.89; N, 2.67%.
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A similar procedure to that described for 4 was used here, ex-
cept 1-HOCPh2CH2-2-NMe2C6H4 (3) (0.51, 1.6 mmol) was em-
ployed instead of
1 and the product was obtained from
tetrahydrofuran at 20 °C in 80% yield. Mp. 190–192 °C. 1H NMR
(DMSO, d/ppm): 1.77 (m, 4H, CH2 (THF)), 2.49 (s, 6H, N(CH3)2),
3.61 (m, 4H, CH2O (THF)), 3.73 (s, 2H, CH2), 7.14 (s, 1H, OH),
7.16–7.45 (m, vbr, 14H, C6H4 and C6H5). 13C {1H} NMR (DMSO,
d/ppm): 21.0 (THF), 44.7 (CH2), 45.0 (N(CH3)2), 67.0 (THF), 77.0
(C–O), 124.5 (s, C6 in C6H4), 125.4 (s, C4 in C6H4), 126.1 (s, C3 in
C6H4), 127.6 (s, C5 in C6H4), 128.4 (s, p-C in C6H5), 130.0 (s, m-C
in C6H5), 130.9 (s, o-C in C6H5), 142.0 (s, C2 in C6H4), 148.0 (s, C1
in C6H4), 152.3 (s, ipso-C in C6H5). MS: m/z 317.3 (M+-ZnCl2-THF).
Found: C, 59.37; H, 5.94; N, 2.65%. Calcd. for C26H31Cl2NO2Zn
(525.83): C, 59.39; H, 5.94; N, 2.66%.
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