Zinc complexes of aldehydes and ketones, 3 aldehyde complexes of zinc halides

Article abstract of DOI:10.1002/(sici)1099-0682(199901)1999:1<129::aid-ejic129>3.0.co;2-p

Aldehyde complexes of the zinc halides were obtained by treating ZnCl₂, ZnBr₂, and ZnI₂ under anhydrous conditions with large excesses of benzaldehyde and various substituted benzaldehydes. Their constitutions were determined by a total of 12 X-ray structure analyses. Three product types were found: ZnHal₂(aldehyde)₂ (A), [ZnHal₂(aldehyde)](proportional to) (B), and [Zn(aldehyde)₆] [Zn₂Hal₆] (C). All three dissolve readily in the corresponding aldehyde or in polar nonprotic solvents indicating the presence of solvated zinc species in solution.

Full text of DOI:10.1002/(sici)1099-0682(199901)1999:1<129::aid-ejic129>3.0.co;2-p

FULL PAPER
Zinc Complexes of Aldehydes and Ketones, 3[°]
Aldehyde Complexes of Zinc Halides
Bodo Müller[a] amd Heinrich Vahrenkamp*[a]
Keywords: Zinc / Aldehyde ligands / Halide ligands / Structural chemistry
Aldehyde complexes of the zinc halides were obtained by
treating ZnCl2, ZnBr2, and ZnI2 under anhydrous conditions
with large excesses of benzaldehyde and various substituted
benzaldehydes. Their constitutions were determined by a
total of 12 X-ray structure analyses. Three product types
were found: ZnHal2(aldehyde)2 (A), [ZnHal2(aldehyde)]ϱ (B),
and [Zn(aldehyde)6] [Zn2Hal6] (C). All three dissolve readily
in the corresponding aldehyde or in polar nonprotic solvents
indicating the presence of solvated zinc species in solution.
In the preceding paper[1] we outlined the motivation for
our studies of zinc complexation by aldehydes and ketones.
The sharp discrepancy between the importance of metal ion
catalysis for reactions of carbonyl-containing compounds
and the scant knowledge on the chemical interactions be-
tween metal ions and carbonyl functions calls for the gath-
ering of basic information upon which mechanistic insight
is to be built. The fact that so little is known about metal
complexes (other than organometallic species) of simple
carbonyl compounds is a reflection of the low donor
strength of these compounds. Thus for their exploration not
only are anhydrous reaction conditions essential but also
are all reaction media of moderate donor strength to be
avoided.
Preparations
In order to obtain the aldehyde complexes as pure, solid
materials the aldehyde had to be present in a large excess
and in a high concentration. In practice this meant using
the aldehyde as the reaction medium which restricted the
reaction to only those aldehydes that are low-melting or
liquid. Pure and crystalline products were obtained with the
following aldehydes:
While catalytic zinc in biochemical systems is never
bound to halides and in fact halide ions are known to be
inhibitors of some zinc enzymes[2], zinc halides are typical
activators for reactions of organic carbonyl compounds.
Examples in which zinc chloride is employed in higher than
stoichiometric amounts are sugar acetylations, the Fischer
indole synthesis, FriedelϪCrafts acetylations, and various
condensations[3]. After studying the coordination of car-
bonyl compounds to halide-free zinc species[1] we therefore
turned to the corresponding studies of the pure zinc halides.
This paper, like the preceding one[1], describes aldehyde
complexes. We are aware of only one related publication,
i.e. one containing some data on ZnCl2•benzaldehyde[4]. We
scanned the coordination abilities of a broad range of alde-
hydes towards the zinc halides ZnCl2, ZnBr2, and ZnI2.
Again we observed that aliphatic aldehydes undergo con-
densation or polymerization reactions after addition of the
zinc halide. Benzaldehyde and various substituted benzal-
dehydes, however, were found to be suitable as ligands. A
preliminary account of our findings was published in
The water-free zinc halides ZnCl2, ZnBr2, and ZnI2 were
prepared in diethyl ether from zinc and HCl, Br2, and HI
prior to use. They were dissolved in the aldehydes. After
complete dissolution an equal volume of dichloromethane
was added. The products precipitated on addition of petro-
leum ether. Crystalline complexes were obtained in lower
yields after careful layering with petroleum ether. The re-
sulting zinc complexes belong to one of the three classes A,
B, and C.
1994[5]
.
[°]
Part 2: Ref.[1]
[a]
Institut für Anorganische und Analytische Chemie der Uni-
versität Freiburg,
Albertstr. 21, D-79104 Freiburg, Germany
Eur. J. Inorg. Chem. 1999, 129Ϫ135
WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1999
1434Ϫ1948/99/0101Ϫ0129 $ 17.50ϩ.50/0
129

B. Müller, H. Vahrenkamp
FULL PAPER
[ZnHal2(aldehyde)2]
[ϪHalϪZnHal(aldehyde)Ϫ]ϱ
Structures
A
B
[Zn(aldehyde)6][Zn2Hal6]
Eight complexes of class A were subjected to structure
determinations. Their molecular shapes are remarkably uni-
form, including the fact that with the exception of 3a they
all have a crystallographic twofold axis. Figure 1 and Table
1 summarize the bonding features. All complexes are dis-
torted tetrahedral with the OϪZnϪO angle typically small
(94Ϫ106°), the HalϪZnϪHal angle typically large
(122Ϫ131°), and the OϪZnϪHal angles close to the tetra-
hedral value (105Ϫ111°). The aldehydes are attached to zinc
in a strictly anti fashion (dihedral angle ZnϪOϪCϪC aver-
age 178°), and the aromatic rings and the CHO groups are
coplanar (dihedral angle OϪCϪCϪC average 175°).
C
Class A type complexes, i.e. monomolecular tetrahedral
ZnHal2(aldehyde)2 species, were obtained from the five al-
dehydes BA, TA, MA, AA, and OA. Compounds 1b to 5c
respesent the total of 12 complexes that were isolated ana-
lytically pure. They are all extremely hygroscopic, and they
should be stored at low temperatures as some of them de-
compose within a few days at room temperature. Eight of
the complexes were subjected to crystal structure determi-
nations; the high structural similarity between them is dis-
cussed below.
[ZnHal2(aldehyde)2]
1b 1c 2b 2c 3a 3b 3c 4a 4b 4c 5b 5c
Hal
aldehyde
Br
I
Br
I
Cl Br
I
Cl Br
I
Br
I
BA BA TA TA MA MA MA AA AA AA OA OA
The alternative class B type complexes, i.e. mono-alde-
hydeϪZnHal2 species, were obtained for almost all cases in
which class A type complexes did not result. Compounds
6aϪ9c were isolated. Structure determinations of three of
them showed them to be halide-bridged polymers in the
solid state (see below). These compounds do not differ in
their behaviour (solubility, hygroscopicity, thermal stability)
from the monomolecular complexes, which indicates inter
alia that they are molecular bis-aldehyde complexes in alde-
hyde solution. So far we have found no indication for the
alternative constitution of the mono-aldehyde complexes as
halide-bridged dimeric units.
Figure 1. Zinc coordination of class A complexes
The zinc halide bond distances are typical and uniform
for ZnϪCl, ZnϪBr, and ZnϪI, cf. Table 1. The ZnϪO bond
˚
lengths vary only 0.03 A about their average value of 2.035
˚
˚
A. Compared to the average value of 2.09 A for octahedral
zinc-aldehyde complexes they are typically shorter. There is
only one reference value in the literature for ZnϪO(al-
dehyde) in tetrahedral complexes: in BochmannЈs
[Zn(SeR)2(AA)]2 it measures 2.06 A[6]. The spread of the
˚
aldehyde CϭO bond lengths is negligible. Relative to the
standard value for aromatic aldehydes of 1.22 A[7] they are
˚
only very slightly elongated due to the coordination to the
metal.
[ZnHal2(aldehyde)]ϱ
6a
7a
8a
9a
9b
9c
Three structures of class B type complexes were deter-
mined. They were found to belong to two different struc-
tural types. Compound 6a has a screw type arrangement of
the polymeric backbone made up of Zn and Cl (Figure 2).
Compounds 7a and 9b crystallize with a linear zig-zag array
of zinc and halide (Figure 3). Table 2 compares the struc-
tural details of the three complexes.
Like the complexes of class A, those of class B are dis-
torted tetrahedral, yet with a different kind of distortion.
Their OϪZnϪHal angles are near the tetrahedral value,
their Hal1ϪZnϪHal2 angles are near 118Ϫ120°, and the
Hal2ϪZnϪHal2Ј angles (i.e. those involving both bridging
halides) are near 102°. The anti orientation of the zinc-
bound aldehydes (dihedral angles 171Ϫ179°) and the co-
planarity of the arene and CHO groups (dihedral angles
171Ϫ176°) are as before. In Table 2 comparison of 6a and
7a shows that the backbone structure of the polymers
(screw-like or zigzag) is not reflected in the basic bond
lengths and angles. The ZnϪHal distances have typical val-
ues for the terminal halides, cf. Table 1, but are characteris-
tically elongated for the bridging halides. The ZnϪO(al-
Hal
Cl
Cl
Cl
Cl
Br
I
aldehyde
BA
MA
FA
CA
CA
CA
Quite unexpectedly, two compounds of composition
ZnHal2 ·2 aldehyde (10b, c) were found to belong to class
C rather than class A. This was proved for 10b by structure
determination and assumed for 10c by analogy of compo-
sition and spectra. 10b and c share the property of all zinc
halide complexes reported here, namely, they contain only
covalently bound halide. There is no obvious reason, how-
ever, why in this case dismutation into a fully aldehyde-co-
ordinated cation and a fully halide-coordinated anion has
occurred. Just like in the cases of benzaldehyde and tolylal-
dehyde, also in the case of fluorobenzaldehyde reaction with
ZnCl2 yields a 1:1 complex (8a) whereas reaction with
ZnBr2 and ZnI2 yield 2:1 (aldehyde/zinc) complexes (10b,
c).
[Zn(FA)6] [Zn2Hal6]
10b: Hal ϭ Br; 10c: Hal ϭ I
130
Eur. J. Inorg. Chem. 1999, 129Ϫ135

Zinc Complexes of Aldehydes and Ketones, 3
FULL PAPER
˚
Table 1. Structural data [A,°] of complexes ZnHal2•2 aldehyde
Hal
ZnϪHal
ZnϪO1
O1ϪC1
ZnϪO1ϪC1
O1ϪC1ϪC2
1b
1c
Br
I
2.334(2)
2.529(1)
2.532(1)
2.202(7)
2.199(2)
2.327(1)
2.525(1)
2.524(1)
2.043(3)
2.046(3)
2.046(5)
2.046(2)
2.016(4)
2.014(3)
2.024(2)
2.041(2)
1.235(5)
1.229(5)
1.226(7)
1.222(8)
1.235(7)
1.228(4)
1.230(3)
1.226(3)
125.5(3)
126.3(3)
127.7(4)
123.7(5)
127.1(4)
126.3(3)
126.2(2)
124.8(2)
118.5(3)
123.2(4)
123.3(6)
124.9(6)
122.0(5)
124.0(3)
124.0(3)
123.5(2)
2c
I
3a[a]
4a
4b
4c
5c
Cl
Cl
Br
I
I
[a] Average of two values each.
by us for 4-fluorobenzaldehyde and 2-chlorobenzaldehyde
Ϫ
with SbCl6 counterions[1]. Its structural features, typically
˚
its ZnϪO bond length of 2.08 A (av.), are as observed be-
2Ϫ
fore[1]. The Zn2Br6 anion of 10b belongs to the well-es-
tablished class of Zn2Hal62Ϫ complexes. While quite a num-
ber of these with Hal ϭ Cl have been structurally charac-
terized[8], there is just one structure each for X ϭ Br[9] and
X ϭ I[10] in the literature. The structural details of the
2Ϫ
Zn2Br6 ion in 10b compare well with the reported ones.
Typically both the terminal and bridging ZnϪBr bonds are
longer than in the neutral complexes like 9b, and the Zn2Br2
rectangle is characterized by rather acute angles both at
zinc and bromine.
Figure 2. Polymer backbone and zinc coordination of complex 6a
Figure 3. Polymer backbone and zinc coordination of complexes
7a and 9b
dehyde) bonds are still a bit shorter than those for class A.
This must be related to the fact that only one aldehyde li-
gand per zinc ion is present and that the donor capacity of
two of the three halide ligands is reduced because of their
bridging nature.
The unexpected class C constitution of complexes 10b
and c became obvious only after the structure determi-
nation of 10b, cf. Figure 4. The hexaaldehydeϪzinc cation
Figure 4. Coordination of zinc in the cation and anion of com-
plex 10b
˚
Bond lengths [A] and angles [°] for the cation: ZnϪO1 2.073(4),
ZnϪO2 2.081(4), ZnϪO3 2.080(4), O1ϪC1 1.224(8), O2ϪC2
1.222(7), O3ϪC3 1.229(7), ZnϪO1ϪC1 124.1(4), ZnϪO2ϪC2
129.5(4), ZnϪO3ϪC3 119.4(4), O1ϪC1ϪC 123.6(6), O2ϪC2ϪC
124.0(6), O3ϪC3ϪC 125.3(6); for the anion: ZnϪBr1 2.335(1),
ZnϪBr2 2.336(1), ZnϪBr3 2.474(1), ZnϪBr3Ј 2.497(1),
of 10b corresponds to the ones structurally characterized Br3ϪZnϪBr3Ј 97.33(4), ZnϪBr3ϪZnЈ 82.67(4).
˚
Table 2. Structural data [A,°] for complexes [ZnHal2•aldehyde]ϱ
Hal ZnϪHal1
ZnϪHal2
ZnЈϪHal2
ZnϪO1
O1ϪC1
ZnϪO1ϪC1 O1ϪC1ϪC2 ZnϪHalϪZn
6a
7a
9b
Cl
Cl
Br
2.172(2)
2.177(1)
2.305(2)
2.293(2)
2.304(2)
2.409(2)
2.300(2)
2.275(2)
2.408(2)
2.009(5)
2.015(2)
2.021(6)
1.225(8)
1.230(4)
1.223(9)
127.8(5)
122.0(2)
125.8(6)
122.8(6)
122.7(3)
120.5(8)
107.92(7)
102.77(3)
99.51(5)
Eur. J. Inorg. Chem. 1999, 129Ϫ135
131

B. Müller, H. Vahrenkamp
FULL PAPER
a tighter binding between the cation and the aldehyde li-
gands.
Spectra
The characteristic IR bands of the complexes, i.e. the al-
dehyde ν(CO) bands, are listed in Table 3. A significant shift
to lower wavenumbers occurs upon coordination to zinc.
There is no correlation between this shift and the bonding
type (i.e. classes A, B, and C). Instead it seems to be corre-
lated with the electron density of the aldehydes: for elec-
tron-rich aldehydes (BA, AA), the shift is small, and for
electron-poor aldehydes (FA, CA) it is large. The same ob-
servations were made for zinc-aldehyde complexes with
Discussion
The strict maintenance of anhydrous conditions has
made it possible to isolate zinc halide complexes of seven
different aromatic aldehydes. In all compounds obtained
the halides are attached covalently to zinc. Two compo-
sitions have been observed, represented by the formulae
ZnHal2•aldehyde and ZnHal2•2 aldehyde. They appear in
three structural types, monomolecular ZnHal2•2 aldehyde
(A), polymeric and halide-bridged ZnHal2•aldehyde (B),
and ionic [Zn(aldehyde)6][Zn2Hal6] (C). Notably the di-
meric halide-bridged structural type [ZnHal2•aldehyde]2 is
missing.
The NMR spectra prove the compositions of the prod-
ucts, and the solid-state IR data prove the aldehyde coordi-
nation by large ∆ν values for the aldehyde CO bands. They
give no indication of the complex structures which could
only be obtained by crystal structure determinations. Typi-
cally complex 10b of type C does not differ spectroscopi-
cally from other ZnBr2 complexes like 3b or 5b. Altogether
the uniformity within groups of spectra or structures does
not allow conclusions on structure and bonding to be
drawn.
There seems to be a relation between the composition
of the complexes and the electron-donor properties of the
ligands. Both electron-rich aldehydes (MA, AA) and low-
electronegativity halides (Br, I) favour the ZnHal2•2 alde-
hyde composition. Conversely zinc chloride yields only
polymeric 1:1 complexes with the “normal” aldehydes BA
and TA, and the most electron-poor aldehyde CA appears
only in the polymeric 1:1 complexes. The formation of the
1:1 complexes even in the neat aldehydes is a demonstration
of the low donor strength of the aldehydes, which cannot
compete with bridging halide for the coordination to zinc.
The formation of complexes 10 is an unusual result of this
competition in that both aldehyde and halide get their own
zinc ions.
weakly coordinating anions[1]
.
Table 3. ν(CO) IR bands (KBr, cmϪ1) and their relative shifts
ν(CO) ∆ν ν(CO) ∆ν
1b
1c
2b
2c
3a
3b
3c
4a
4b
4c
1651
1638
1646
1643
1637
1632
1629
1638
1640
1638
Ϫ50
5b
5c
1645
1645
1638
1645
1638
1628
1627
1624
1635
1636
Ϫ57
Ϫ63
Ϫ58
Ϫ61
Ϫ53
Ϫ58
Ϫ61
Ϫ52
Ϫ50
Ϫ52
Ϫ57
Ϫ63
Ϫ59
Ϫ62
Ϫ70
Ϫ71
Ϫ74
Ϫ65
Ϫ64
6a
7a
8a
9a
9b
9c
10b
10c
The characteristic H- and 13C-NMR resonances result
from the aldehyde CHO functions. In the complexes these
resonances are shifted by small, yet significant, amounts.
1
1
The H signals are moved upfield and downfield in an ir-
regular fashion, the 13C signals are all shifted downfield,
as expected due to deshielding resulting from coordination.
While for the zincϪaldehyde complexes with noncoordinat-
ing anions[1] the 1H-NMR shifts were so small that the pos-
sibility of aldehyde substitution by [D6]acetone upon disso-
lution could not be ruled out, this is not the case here. Obvi-
ously the molecular nature and the lower coordination
number of the zinc-halide complexes reported here result in
1
Table 4. H- and 13C-NMR data for the aldehyde CHO functions
(in [D6]acetone, δ)
δ(H)
∆δ
δ(C)
∆δ
With the exception of the cation of 10 all complexes de-
scribed here are tetrahedral. This can be related to the soft
character of the halide ligands, while the homoleptic alde-
hyde complexes in 10 and the other complexes with hard
coligands (water, alcohol, oxoanion) are octahedral[1]. The
tetrahedral complexes are of relevance for zinc-catalyzed re-
actions of organic carbonyl compounds, as in organic syn-
thesis the catalyst is most often ZnCl2[3] and in the enzyme
alcohol dehydrogenase the catalytic zinc has a tetrahedral
1b
1c
2b
2c
3a
3b
3c
4a
4b
4c
5b
5c
6a
7a
8a
9a
9b
9c
10b
10c
9.96
9.96
9.94
9.95
10.45
10.49
10.49
9.83
9.79
9.83
9.97
9.99
9.90
9.94
10.00
10.37
10.31
10.23
9.94
9.96
Ϫ0.10
Ϫ0.10
Ϫ0.04
Ϫ0.03
Ϫ0.03
ϩ0.01
ϩ0.01
Ϫ0.06
Ϫ0.10
Ϫ0.06
ϩ0.01
ϩ0.03
Ϫ0.16
Ϫ0.04
ϩ0.05
ϩ0.01
Ϫ0.05
Ϫ0.13
Ϫ0.01
ϩ0.01
192.8
192.6
192.3
192.3
193.8
193.5
193.6
191.7
192.3
191.9
192.6
192.6
193.0
192.5
191.5
189.7
189.4
188.9
191.2
191.1
ϩ0.1
Ϫ0.1
ϩ0.2
ϩ0.2
ϩ1.2
ϩ0.9
ϩ1.0
ϩ0.7
ϩ1.3
ϩ0.9
ϩ0.2
ϩ0.2
ϩ0.3
ϩ0.4
ϩ0.5
ϩ0.3
±0
ZnNS2O environment[2]
.
The challenge to improve this relevance faces two prob-
lems. One of them is the mostly unpredictable composition
and structure of the zinc halide/aldehyde complexes. This
means that reaction intermediates and catalytic pathways of
zinc halide catalyzed carbonyl reactions are equally unpre-
dictable as yet. The other is the weak attachment of the
Ϫ0.5
ϩ0.4
ϩ0.3
132
Eur. J. Inorg. Chem. 1999, 129Ϫ135

Zinc Complexes of Aldehydes and Ketones, 3
Table 5. Reaction details
FULL PAPER
Compl.
ZnHal2
aldehyde
g
yield
m.p.
g
mmol
mL
mmol
g
%
°C
1b
1c
2b
2c
3a
3b
3c
4a
4b
4c
5b
5c
6a
7a
8a
9a
9b
9c
10b
10c
ZnBr2
ZnI2
1.11
1.01
1.69
1.02
0.48
1.57
0.74
0.72
1.13
0.92
1.11
0.79
0.71
0.46
0.44
0.77
1.51
0.93
1.41
1.06
4.93
3.16
7.50
3.20
3.52
6.97
2.32
5.28
5.02
2.88
4.93
2.48
5.21
3.38
3.23
5.65
6.71
2.91
6.26
3.32
BA
BA
TA
TA
MA
MA
MA
AA
AA
AA
OA
OA
BA
TA
FA
5
5.22
5.22
10.19
5.10
10.05
10.05
5.03
11.19
6.71
5.60
8.95
5.60
10.96
5.10
5.79
6.24
9.36
6.24
8.68
5.79
49.19
49.19
84.81
42.41
67.81
67.81
33.91
82.19
49.31
41.09
65.75
41.09
103.30
42.41
46.61
44.39
66.59
44.39
69.91
46.61
2.01
1.57
3.28
1.72
1.13
3.40
1.28
2.08
2.23
1.66
1.67
1.24
0.96
0.76
0.81
1.16
2.10
1.21
2.86
1.70
93
93
94
96
74
94
90
96
89
97
68
85
76
88
96
74
86
90
97
90
115
94
5
ZnBr2
ZnI2
10
5
124
122
120
92
ZnCl2
ZnBr2
ZnI2
ZnCl2
ZnBr2
ZnI2
ZnBr2
ZnI2
10
10
5
136
91
10
6
117
116
92
5
8
5
86
ZnCl2
ZnCl2
ZnCl2
ZnCl2
ZnBr2
ZnI2
10.5
5
117
116
125
132
153
132
65
5
5
CA
CA
CA
FA
7.5
5
ZnBr2
ZnI2
7.5
5
FA
71
aldehydes, which should render ZnNX2O complexes (i.e. Table 6. Analytical characterization
structural models of alcohol dehydrogenase) unstable when
formula
mol. wt.
Analyses calcd./found
N represents a good nitrogen donor. We have been working
to overcome the latter problem, and the succeeding paper
C
H
Zn
Hal
presents one possible solution[11]
.
1b
1c
2b
2c
3a
3b
3c
4a
4b
4c
5b
5c
6a
7a
8a
9a
9b
9c
C14H12Br2O2Zn
437.5
Ϫ
Ϫ
14.95/
14.82
12.30/
12.27
14.05/
14.01
11.69/
11.75
15.11/
15.17
12.54/
12.60
10.62/
10.67
16.00/
15.81
13.14/
13.21
11.06/
11.14
13.14/
13.23
11.06/
11.18
26.97/
27.02
25.50/
25.38
25.11/
25.22
23.62/
23.84
17.88/
17.76
14.22/
14.34
13.81/
13.91
11.52/
11.61
36.53/
36.61
47.76/
47.85
34.33/
34.21
45.36/
45.20
16.39/
16.44
30.64/
30.52
41.23/
41.33
17.35/
17.45
32.12/
32.00
42.91/
42.88
32.12/
31.98
42.91/
43.03
29.25/
29.05
27.65/
27.51
27.23/
27.10
38.42/
38.30
Ϫ
Ϫ
Ϫ
C14H12I2O2Zn
531.5
Ϫ
Ϫ
Ϫ
Ϫ
Experimental Section
C16H16Br2O2Zn
465.5
41.28/
42.00
34.35/
33.52
Ϫ
3.47/
3.11
2.88/
2.77
Ϫ
All preparations required strictly anhydrous conditions. The gen-
eral working and measuring conditions were as in ref.[12], and the
specific ones as in ref.[1]. The aldehydes were obtained commer-
cially and distilled prior to use. The anhydrous zinc halides were
prepared from zinc and HHal or Hal2 in diethyl ether[13][14]. The
new complexes were prepared following the general procedure be-
low, details for which are given in Table 5. When they were too
hygroscopic for ordinary C/H/N analysis, they were also charac-
terized by zinc and halide analyses. Table 6 gives the analytical
characterizations.
C16H16I2O2Zn
559.5
C20H24Cl2O2Zn
432.7
Ϫ
Ϫ
C20H24Br2O2Zn
521.6
46.05/
45.90
39.02/
38.30
47.03/
46.86
38.63/
37.89
32.49/
32.20
38.63/
36.76
32.49/
33.14
34.68/
34.88
37.47/
37.74
Ϫ
4.64/
4.56
3.93/
3.83
3.95/
3.91
3.24/
3.17
2.73/
2.62
3.24/
3.17
2.73/
2.67
2.50/
2.55
3.14/
3.29
Ϫ
C20H24I2O2Zn
615.6
C16H16Cl2O4Zn
408.6
C16H16Br2O4Zn
497.5
C16H16I2O4Zn
591.5
Preparation of the Complexes: The zinc halide was dissolved in a
10Ϫ20 fold excess of the aldehyde with stirring and heating. After
cooling to room temp. 10 mL of dichloromethane was added. By
adding 50 mL of petroleum ether (b.p. 60Ϫ70°C) a colourless pre-
cipitate was obtained, which was filtered off, washed with the petro-
leum ether, and dried in vacuo.
C16H16Br2O4Zn
497.5
C16H16I2O4Zn
591.5
C7H6Cl2OZn
652.8
C8H8Cl2OZn
256.5
Structure Determinations[15]: Crystals were obtained by careful lay-
ering of the reaction solutions with petroleum ether (b.p.
70Ϫ90°C). They were immersed in perfluorinated polyether oil for
protection and attachment to the goniometer head and immedi-
ately subjected to the nitrogen flow of the diffractometerЈs cooling
system. Diffraction data were recorded at low temperatures with
the ω/2θ technique on a Nonius CAD4 diffractometer fitted with
C7H5Cl2FOZn
260.4
C7H5Cl3OZn
276.9
C7H5Br2ClOZn
365.8
C7H5ClI2OZn
459.8
Ϫ
Ϫ
30.37/
29.89
22.99/
22.03
18.29/
16.04
1.82/
2.24
1.38/
1.49
1.10/
1.17
2.13/
2.09
1.78/
2.10
Ϫ
Ϫ
Ϫ
33.76/
33.83
44.73/
44.64
˚
a molybdenum tube (Kα, λ ϭ 0.7107 A) and a graphite mono-
10b C42H30Br6F6O6Zn3 35.52/
chromator. No absorption corrections were applied. The structures
were solved with direct methods and refined anisotropically with
the SHELX program suite[16]. The aldehyde C-H hydrogen atoms
were located and refined freely. All other hydrogen atoms were in-
1420.3
C42H30F6I6O6Zn3 29.63/
1702.3 29.59
35.03
10c
Eur. J. Inorg. Chem. 1999, 129Ϫ135
133

B. Müller, H. Vahrenkamp
FULL PAPER
Table 7, part 1. Crystallographic details
1b
1c
2c
3a
4a
4b
formula
C14H12Br2O2Zn
437.43
C14H12I2O2Zn
531.41
1.0 ϫ 0.6 ϫ 0.5
C2/c
C16H16I2O2Zn
559.46
C20H24Cl2O2Zn
432.66
C16H16Cl2O4Zn
408.56
0.5 ϫ 0.5 ϫ 0.5
P21212
2
8.964(4)
19.918(1)
4.776(3)
90
90
90
852.7(8)
1.59
1.53
183(2)
1.77
C16H16Br2O4Zn
497.48
1.2 ϫ 0.5 ϫ 0.3
C2/c
mol. mass
crystal size [mm] 0.6 ϫ 0.2 ϫ 0.1
space group
0.4 ϫ 0.05 ϫ 0.03 0.8 ϫ 0.1 ϫ 0.1
C2/c
4
18.816(2)
4.832(1)
17.030(3)
90
104.51(11)
90
1499.0(5)
1.94
Ϫ
Fdd2
8
19.883(2)
35.747(5)
5.0360(5)
90
90
90
3579.4(7)
2.08
Ϫ
183(2)
4.82
Pca21
4
24.848(2)
4.712(2)
17.279(2)
90
90
90
2023.1(1)
1.42
Ϫ
183(2)
1.49
Z
4
4
˚
a [A]
19.407(2)
5.0240(4)
16.878(1)
90
105.20(1)
90
1588.0(2)
2.22
20.361(3)
5.634(2)
16.859(4)
90
110.79(2)
90
1808.0(7)
1.83
˚
b [A]
c [A]
˚
α [°]
β [°]
γ [°]
3
˚
V [A ]
d(calc.) [g·cmϪ3
]
]
d(obs.) [g·cmϪ3
Ϫ
183(2)
5.43
1.81
183(2)
5.79
temp. [K]
183(2)
6.96
µ(MoKa) [mmϪ1
hkl range
]
h: 0 to 23
k: Ϫ6 to 0
l: Ϫ21 to 20
1550
h: 0 to 26
k: 0 to 7
l: Ϫ23 to 22
2359
h: Ϫ24 to 0
k: Ϫ44 to 0
l: 0 to 6
983
h: 0 to 30
k: Ϫ5 to 0
l: 0 to 21
2051
h: Ϫ11 to 0
k: Ϫ1 to 25
l: Ϫ6 to 6
2007
h: Ϫ23 to 25
k: 0 to 7
l: Ϫ20 to 0
1889
refl. measd.
indep. refl.
1504
2298
983
2049
1846
1821
obs. refl. [I>2σ(I)] 1261
2190
905
1633
1688
1575
parameters
87
88
97
226
105
105
refl. refined
R1 (obs. refl.)
wR2 (all refl.)
1504
0.031
0.083
2298
983
2048
1846
1821
0.032
0.021
0.053
ϩ0.6
Ϫ0.5
0.036
0.104
ϩ1.0
0.053
0.036
0.099
0.163
0.098
residual el. density ϩ0.7
ϩ1.6
ϩ1.1
ϩ1.1
Ϫ3
˚
[e/A
]
Ϫ0.8
Ϫ1.1
Ϫ0.5
Ϫ0.7
Ϫ0.8
Table 7, part 2. Crystallographic details
4c
5c
6a
7a
9b
10b
formula
C16H16I2O4Zn
591.46
C16H16I2O4Zn
591.46
C7H6Cl2OZn
242.39
C8H8Cl2OZn
256.41
C7H5Br2ClOZn
365.75
C42H30Br6F6O6Zn3
·2 C7H5FO
mol. mass
1668.45
crystal size [mm] 0.6 ϫ 0.4 ϫ 0.2 0.6 ϫ 0.2 ϫ 0.1 0.7 ϫ 0.03 ϫ 0.03 0.7 ϫ 0.3 ϫ 0.3 0.4 ϫ 0.2 ϫ 0.1 0.9 ϫ 0.8 ϫ 0.3
space group
C2/c
4
21.303(5)
5.673(1)
17.182(5)
90
111.25(2)
90
1935.4(8)
2.03
1.98
183(2)
4.47
C2/c
4
22.975(1)
5.345(3)
19.026(6)
90
126.54(3)
90
1877.2(2)
2.09
Ϫ
183(2)
4.61
P21/n
4
12.060(3)
4.914(1)
14.560(5)
90
94.96(3)
90
859.6(4)
1.87
Ϫ
183(2)
3.41
Pca21
4
22.047(2)
6.256(1)
7.155(1)
90
90
90
986.9(2)
1.73
Ϫ
183(2)
2.98
Pbca
8
Pbca
4
18.490(4)
15.788(7)
20.707(5)
90
90
90
6045(3)
1.83
1.82
183(2)
5.22
Z
˚
a [A]
7.352(1)
14.026(5)
20.262(7)
90
˚
b [A]
c [A]
˚
α [°]
β [°]
γ [°]
90
90
3
˚
V [A ]
2089.4(11)
2.33
d(calc.) [g·cmϪ3
]
]
d(obs.) [g·cmϪ3
2.29
183(2)
10.21
temp. [K]
µ(MoKa) [mmϪ1
hkl range
]
h: Ϫ28 to 0
k: 0 to 7
l: Ϫ21 to 22
2396
h: Ϫ28 to 22
k: 0 to 6
l: 0 to 23
1911
h: Ϫ14 to 14
k: Ϫ5 to 0
l: Ϫ17 to 0
1678
h: Ϫ27 to 0
k: Ϫ7 to 0
l: Ϫ8 to 0
1051
h: Ϫ9 to 9
k: Ϫ17 to 0
l: Ϫ24 to 24
7706
h: Ϫ22 to 9
k: Ϫ7 to 19
l: 0 to 25
5914
refl. measd.
indep. refl.
2336
1849
1615
1051
2045
5905
obs. refl. [I>2σ(I)] 2231
1751
1096
993
1093
3991
parameters
105
105
100
109
109
367
refl. refined
R1 (obs. refl.)
wR2 (all refl.)
2336
0.023
0.071
1849
1615
1051
2045
5905
0.019
0.054
ϩ0.8
0.049
0.023
0.075
ϩ0.4
0.050
0.044
0.130
ϩ0.7
0.151
0.145
residual el. density ϩ0.5
ϩ1.1
ϩ1.3
Ϫ3
˚
[e/A
]
Ϫ1.1
Ϫ0.6
Ϫ1.0
Ϫ0.5
Ϫ1.6
Ϫ1.2
cluded with fixed distances and isotropic temperature factors 1.2
times those of their attached atoms. Parameters were refined
against F2. The R values are defined as R1 ϭ Σ Fo Ϫ Fc /ΣFo and
Acknowledgments
2
wR2 ϭ {Σ[w(Fo Ϫ Fc2)2]/Σ[w(Fo2)2]}1/2. Drawings were produced
This work was supported by the Deutsche Forschungsgemein-
schaft.
with SCHAKAL[17]. Table 7 lists the crystallographic data.
134
Eur. J. Inorg. Chem. 1999, 129Ϫ135

Zinc Complexes of Aldehydes and Ketones, 3
FULL PAPER
M. Förster, R. Burth, A. K. Powell, T. Eiche, H. Vahrenkamp,
Chem. Ber. 1993, 126, 2643Ϫ2648.
[1]
[12]
B. Müller, H. Vahrenkamp, Eur. J. Inorg. Chem. 1999, 117Ϫ127,
preceding paper.
[13]
[14]
[2]
R. T. Hamilton, J. A. V. Butler, J. Chem. Soc. 1932, 2283Ϫ2284.
G. Brauer, Handbuch der Präparativen Anorganischen Chemie,
Ferdinand Enke Verlag, Stuttgart, 1978, Band 2, p. 1023Ϫ1026.
The crystallographic data of the structures described in this
paper were deposited with the Cambridge Crystallographic
Data Centre as supplementary publication no. CCDC-102445
(for 3a), 102446 (for 4a), 102447 (for 4b), 102448 (for 4c),
102449 (for 5c), 102450 (for 2c), 102451 (for 1b), 102452 (for
1c), 102453 (for 10b), 102454 (for 7a), 102455 (for 6a), 102456
(for 9b). Copies of these data are available free of charge from
the following address: The Director, CCDC, 12 Union Road,
GB-Cambridge CB2 1EZ (Telefax: Int. ϩ44 (0)1223/ 336 033;
E-mail: deposit@chemcrys.cam.ac.uk). For a limited time they
are also available on the Internet Web Site www.chemie.uni-frei-
burg.de/aoanchem/hv/data.html.
Zinc Enzymes (Ed.: T. G. Spiro) Wiley, New York, 1983.
[3]
[3a] Comprehensive Organc Chemistry, Vol. 1 (Eds.: D.Barton, W.
[3b]
D. Ollis, J. F. Stoddart) Pergamon Press, Oxford, 1979. Ϫ
[15]
[3c]
R. Brettle in ref.[3a], pp. 943Ϫ1016. Ϫ
pp. 1105Ϫ1160.
T. Laird in ref.[3a]
,
[4]
[5]
[6]
[7]
[8]
F. Filippini, B. P. Susz, Helv. Chim. Acta 1971, 54, 835Ϫ
845.
B. Müller, M. Ruf, H. Vahrenkamp, Angew. Chem. 1994, 106,
2164Ϫ2165; Angew. Chem., Int. Ed. Engl. 1994, 33, 2089Ϫ2090.
M. Bochmann, K. J. Webb, M. B. Hursthouse, M. Mazid, J.
Chem. Soc. Chem. Commun. 1991, 1735Ϫ1737.
Taken as the average from 198 structures in the Cambridge
Crystallographic Data File.
for a comparative discussion cf. K. M. Doxsee, J. R. Hagadorn,
T. J. R. Weakley, Inorg. Chem. 1994, 33, 2600Ϫ2606.
A. Bino, D. Gibson, Inorg. Chim. Acta 1982, 65, L37ϪL38.
P. G. Cozzi, T. Carofiglio, C. Floriani, A. Chiesi-Villa, C. Riz-
zoli, Organometallics 1993, 12, 2845Ϫ2848.
[16]
[17]
G. M. Sheldrick, SHELX-86 and SHELXL-93, Programs for
Crystal Structure Determination, Universität Göttingen, 1986
and 1993.
[9]
[10]
E. Keller, Program SCHAKAL, Universität Freiburg, 1997.
Received August 3, 1998
[11]
B. Müller, H. Vahrenkamp, Eur. J. Inorg. Chem. 1999, 137Ϫ144,
succeeding paper.
[I98257]
Eur. J. Inorg. Chem. 1999, 129Ϫ135
135