High-yielding synthesis of β-octaalkyl-meso-(bromophenyl)-substituted porphyrins and X-ray study of axial complexes of their zinc complexes with THF and 1,4-dioxane

Article abstract of DOI:10.1002/ejic.201200868

New 5-(4-bromophenyl)-3,7,12,13,17,18-hexamethyl-2,8-dipentyl- and 5,15-bis(4-bromophenyl)-2,8,12,18-tetramethyl-2,8,12,18-tetrapentylporphyrins (H₂P-1 and H₂P-2) and their zinc metal complexes (ZnP-1 and ZnP-2, respectively) were sy

Full text of DOI:10.1002/ejic.201200868

FULL PAPER
DOI: 10.1002/ejic.201200868
High-Yielding Synthesis of β-Octaalkyl-meso-(bromophenyl)-Substituted
Porphyrins and X-ray Study of Axial Complexes of Their Zinc Complexes with
THF and 1,4-Dioxane
Elena A. Mikhalitsyna,[a] Vladimir S. Tyurin,[a] Sergey E. Nefedov,[b] Sergey A. Syrbu,[c]
Aleksandr S. Semeikin,[c] Oskar I. Koifman,[c] and Irina P. Beletskaya*[a]
Keywords: meso-Substituted porphyrins / Metalloporphyrins / Axial coordination / Supramolecular structures / X-ray
diffraction / Porphyrinoids / Zinc
New 5-(4-bromophenyl)-3,7,12,13,17,18-hexamethyl-2,8-di-
pentyl- and 5,15-bis(4-bromophenyl)-2,8,12,18-tetramethyl-
2,8,12,18-tetrapentylporphyrins (H2P-1 and H2P-2) and their
zinc metal complexes (ZnP-1 and ZnP-2, respectively) were
synthesized in high yields by condensation of β-tetraalkyl-
substituted dipyrromethanes with 2-formyl-3,4-dialkylpyr-
roles or 4-bromobenzaldehyde and subsequent metallation.
X-ray analysis data showed the formation of axial complexes
of ZnP-1 and ZnP-2 with the solvent molecules of THF and
dioxane in the solid state. Coordination of ZnP-1 with diox-
ane led to polymer multidecker structures.
sors.[8] Axial coordination of ligands to a metalloporphyrin
affords an additional means for assembly and organization
of supramolecular materials.
Introduction
Among organic chromophores, porphyrins have a special
place owing to their unique structural, redox and photo-
chemical/physical properties,[1] the rigidity of their planar
aromatic frameworks, their high stabilities over a wide
range of temperatures and the significant values of their
oxidation and reduction potentials. This is a reason why
porphyrins and their metal complexes are of remarkable im-
portance in biological systems in nature, being components
of oxygen-carrier heme complexes, cytochrome catalysts
and chlorophyll in light-harvesting photosynthesis
centres.[2] Synthetic metalloporphyrin complexes are there-
fore of particular interest in terms of creating analogues of
natural systems and molecular devices.
Moreover, porphyrins have also been identified as re-
markable building blocks in supramolecular chemistry.[3]
Intensive progress in this area of chemistry has led to the
discovery of new applications of porphyrin systems in mate-
rials science,[4] molecular electronics[5] and nanotechnol-
ogy.[6] The ability to produce sharp changes in their spectral
properties[7] depended on the architectural arrangement of
the chromophores, with their environments playing crucial
roles in the use of metalloporphyrins as receptors and sen-
The main objective of this work is the synthesis of new
soluble porphyrin building blocks based on the unsymmet-
rical 5-(4-bromophenyl)-3,7,12,13,17,18-hexamethyl-2,8-di-
pentylporphyrin (H2P-1, Figure 1) and the symmetrical
5,15-bis(4-bromophenyl)-2,8,12,18-tetramethyl-2,8,12,18-tet-
rapentylporphyrin (H2P-2), which are suitable for further
modification through substitution of their bromine atoms
with an assortment of well-developed transition metal catal-
ysis methods[9] to create functionalized porphyrin deriva-
tives and covalently bound porphyrin arrays. We have re-
cently demonstrated that ditopic ligands such as azacrown-
ether-appended porphyrins could be formed through Pd-
catalysed amination of mono- and bis-meso-bromophenyl-
substituted porphyrins with aza-crown ethers.[10]
In many cases, poor solubilities of porphyrins in nonpo-
lar solvents cause difficulties in their subsequent applica-
tion. High solubilities can be achieved through selection of
suitable substituents and modification of the periphery of
the porphyrin core. For this reason we synthesized new β-
octaalkyl-meso-(bromophenyl)-substituted porphyrins, con-
taining methyl and pentyl substituents in their pyrrole rings
to assist the solubilities of these porphyrins in nonpolar sol-
vents.
[a] IPCE RAS,
Leninskiy prospekt 31–4, Moscow 119071, Russian Federation
Fax: +7-495-939-36-18
The 5-aryl- and 5,15-diaryl-β-octaalkylporphyrins H2P-1
and H2P-2, as well as their zinc complexes ZnP-1 and ZnP-
2, have been successfully synthesized in high yields and
completely characterized by spectral methods and by X-ray
structural analysis. Single crystals of free-base porphyrins
H2P-1 and H2P-2 were easily grown from chloroform/hex-
E-mail: beletska@org.chem.msu.ru
Homepage: http://www.chem.msu.ru/rus/history/acad/
beletskaya.html
[b] IGIC RAS,
Leninskiy prospekt 31, Moscow 119071, Russian Federation
[c] ISCTU,
prospekt F. Engelsa 7, Ivanovo 153000, Russian Federation
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Figure 1. 5-(4-Bromophenyl)-β-octaalkylporphyrin (H2P-1) and 5,15-bis(4-bromophenyl)-β-octaalkylporphyrin (H2P-2).
Scheme 1. Self-assembly of axially coordinated complexes of ZnP-1 and ZnP-2 with oxygen-containing ligands.
ane mixtures, whereas their zinc complexes were crystallized natural porphyrins at the β-pyrrole positions on the por-
from THF or 1,4-dioxane solutions. X-ray studies showed phyrin macrocycle promote the required solubility in non-
the formation of supramolecular structures of the zinc–por- polar solvents. In turn, the synthetic meso-aryl-substituted
phyrins with the oxygen-containing solvent molecules in the porphyrins containing active halogen atoms such as bro-
solid state. Coordination of monodentate oxygen ligands mine on their benzene rings offer the potential for further
such as THF to zinc porphyrins leads to the formation of structural functionalization of the porphyrins. On the other
1:1 axial complexes (ZnP-2·THF, Scheme 1). In this case hand, meso-aryl-substituted porphyrins can be readily ob-
the zinc dication has a coordination number of 5. In con- tained by condensation of pyrrole with the corresponding
trast to this, the bidentate oxygen ligands of 1,4-dioxane benzaldehydes in acidic media.[11] It is therefore evident why
each coordinate to two zinc–porphyrins to form sandwich the synthesis and investigation of the properties of this par-
stacking columns (ZnP-1·C4H8O2, Scheme 1) in which the ticular class of porphyrins has attracted great attention. In-
zinc dications have coordination numbers of 6. Equilibria deed, many synthetic functionalized porphyrin systems are
operating in solutions of zinc–porphyrins with ligands are based on 5,15-diaryl-2,3,7,8,12,13,17,18-octaalkylporphyr-
usually shifted to five-coordinate zinc, but in the solid state ins, due to their ease of preparation, high symmetry and
the packing forces result in the usually less favoured six- thermal stabilities.[12] In some cases, the molecular architec-
coordinate structure.
ture of a 5,15-diarylporphyrin can be more readily manipu-
lated than that of the corresponding meso-tetraarylporphy-
rin.[13]
A rational approach to a trans-meso-substituted por-
phyrin involves consecutive condensation of acetoxymethyl-
Results and Discussion
The obtained meso-(bromophenyl)-substituted β-octa- pyrrole with dipyrromethane, followed by its condensation
alkylporphyrins efficiently combine features of synthetic with an aldehyde, in a process known as MacDonald [2+2]
and natural porphyrins. The alkyl substituents inherent to condensation. Two molecules of dipyrromethane react with
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Zinc Complexes of β-Octaalkyl-meso-(bromophenyl)-Substituted Porphyrins
two molecules of aldehyde to give a trans-symmetrical por-
The next building block needed for the synthesis of por-
phyrin.[14] Although the synthesis of symmetrical por- phyrin H2P-1, 2-formyl-3,4-dimethylpyrrole (12, Scheme 3),
phyrins is well developed, the unsymmetrical meso-mono- was obtained by a three-step process from urethane (8) and
substituted porphyrins are not easily available. Monosubsti- 2,3-dimethylbuta-1,3-diene (9) as shown. Urethane was
tuted porphyrins could be accessible by condensation of al- transformed into N-(ethoxycarbonyl)sulfinylimine in a one-
dehydes with a,c-biladiene,[15] but unsubstituted biladiene is pot reaction by treatment with SO2Cl2 in pyridine. Addition
highly unstable and difficult to obtain, making it an unsuit- of 2,3-dimethylbuta-1,3-diene (9) to the reaction mixture
able component for the synthesis. Senge et al. have recently gave the heterocyclic Diels–Alder adduct2-ethoxycarbonyl-
reported an alternative route based on 2-formylpyrrole as a 4,5-dimethyl-3,6-dihydro-1,2-thiazine-1-oxide (10). This
building block[16] together with dipyrromethane in a con- was transformed into 3,4-dimethylpyrrole (11) with a meth-
densation reaction.[17] We successfully utilized this method anol solution of KOH (excess). Vilsmeier formylation of 11
in the synthesis of H2P-1.
led to the desired 2-formylpyrrole 12.
The starting material for the syntheses both of H2P-1
and of H2P-2 was 4,4Ј-dimethyl-3,3Ј-dipentyldipyrrometh-
ane-2,2Ј (7, Scheme 2), obtained by a five-step synthesis.[17]
The first stage of the synthesis of the unsymmetrical
monosubstituted
methyl-13,17-dipentylporphyrin H2P-1 involved condensa-
tion of 2-formylpyrrole 12 with dipyrromethane
5-(4Ј-bromophenyl)-2,3,7,8,12,18-hexa-
7
(Scheme 4) in methanol containing HBr to afford the inter-
mediate dihydrobromide of 2,3,7,13,17,18-hexamethyl-8,12-
dipentylbiladiene-a,c (13). Interaction of dipyrromethanes
with 2-formylpyrrole in alcohol solutions has usually led to
the formation of byproducts such as corrole 14 and conse-
quently to decreases in the yields of porphyrins. Carrying
out this reaction in butanol at reflux allowed this side reac-
tion to be avoided and H2P-1 to be obtained in a good yield
of 57%. Moreover, the synthesis of H2P-1 was carried out
as a one-pot reaction without isolation of biladiene 13.
The obtained porphyrin was purified by column
chromatography and crystallized from chloroform/hexane.
Single crystals of H2P-1 were studied by X-ray diffraction.
According to the X-ray data, the nitrogen atoms in H2P-1
porphyrin molecules (Figure 2) are situated practically in
the same plane (deviations are Ϯ0.0031 Å).
Similar significant distortions of the macrocycle have
been observed in other mono-meso-aryl-substituted por-
phyrins[18] with one exception in 2,3,7,8,12,13,17,18-octa-
ethyl-5-phenylporphyrin, which has an unexpectedly planar
macrocycle (deviation of atoms from plane N4 0.010 Å),[19]
in spite of the presence of quite weak CH–π contacts
(3.926–3.989 Å) and even though its crystal contained mo-
lecules of dichloromethane solvent.
Scheme 2. Synthesis of 4,4Ј-dimethyl-3,3Ј-dipentyldipyrromethane-
2,2Ј (7).
Alkylation of acetylacetone (1) with 1-iodopentane in the
presence of K2CO3 in DMF gave 3-pentylpentane-2,4-dione
(2). Reductive Knorr cyclocondensation of this with ethyl
2-(hydroxyimino)-3-oxobutanoate (3) and zinc powder in
acetic acid led to the formation of 2-ethoxycarbonyl-3,5-
dimethyl-4-pentylpyrrole (4). Bromination at the α-methyl
unit was then carried out in acetic acid, and simultaneous
nucleophilic substitution of bromine by an acetoxy group
occurred to give α-acetoxymethylpyrrole 5.
The unit cell of H2P-1 is composed of parallel molecules
(angle is 2.9°, Figure 3.) stacked in nominally “head-to-tail”
dimer fragments (distance between the centres of two adja-
cent molecules is 6.410 Å; Figures 3 and 4).
Self-condensation of 5 in methanol and HCl gave 5,5-
diethoxycarbonyldipyrromethane 6 (Scheme 2). Hydrolysis
It is likely that two molecules are bound in such a “di-
with simultaneous decarboxylation under reflux in ethylene mer” by stacking contacts of pyrrole fragments (3.565–
glycol and in the presence of KOH led to the unstable α- 3.972 Å) and shifted relative to each other [the angle be-
unsubstituted dipyrromethane 7, which was used immedi- tween bonds of Br(1)–C(33) is 27°] (Figure 4). The same
ately without purification in the synthesis of porphyrin “head-to-tail” packing is observed in the crystal of β-octa-
H2P-1.
ethyl-meso-phenylporphyrin. Packing effects and observed
Scheme 3. Synthesis of 2-formyl-3,4-dimethylpyrrole (12).
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Scheme 4. Synthesis of β-octaalkyl-5-(4-bromophenyl)porphyrin H2P-1.
Figure 2. Molecular structure of porphyrin H2P-1 with thermal el-
lipsoids drawn at the 30% probability level.
stacking interactions seemingly result in a deviation of the
acceptor bromo substituent from the porphyrin plane [an
angle between N4 mean plane and C(10)–Br(1) bond vector
is 12.5°], whereas the deviation of Br(1) from the porphyrin
Figure 3. Fragment of packing of molecules of H2P-1: (A) top view,
(B) lateral view.
ring’s mean plane at 1.408 Å and corresponding distortion another molecule and competing steric repulsion at dis-
of the sp2 environment of carbon atom C(9) are related to tances of 3.337–3.998 Å (Figure 4).
CH–π interactions of C(14)–H and C(15)–H hydrogen
The bromophenyl substituent, however, is virtually per-
atoms of the aryl substituent with the pyrrole fragment of pendicular to the porphyrin plane [angle of C(8)C(9)C(16)/
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Zinc Complexes of β-Octaalkyl-meso-(bromophenyl)-Substituted Porphyrins
Figure 4. Short contacts of two adjasent molecules of H2P-1:
(A) top view, (B) lateral view.
Figure 5. Molecular structure of porphyrin H2P-2 with thermal el-
lipsoids drawn at 30% probability level.
C(11)C(10)C(15) is 86.1°], due to the steric repulsion with
the methyl substituents at the pyrrole β-positions (C···Ph is
3.167–3.210 Å).
mophenyl)porphyrin H2P-2 (Figure 5), the nitrogen atoms
The symmetrical trans-disubstituted 5,15-bis(4-bromo- of the porphyrin component of H2P-2 are situated in practi-
phenyl)-3,7,13,17-tetramethyl-2,8,12,18-tetrapentylpor- cally the same plane (deviations are 0 Å), the carbon atoms
phyrin (H2P-2) was obtained in higher yield than the mono- of the “inner” macrocycle (i.e., meso and α-pyrrole atoms)
substituted H2P-1. In the first step, condensation of dipyr- are set almost in the same plane as the nitrogen atoms
romethane 7 with 4-bromobenzaldehyde in the presence of [maximum deviation of atom C(9) is Ϯ0.0755 (centrosym-
TFA in dichloromethane under argon gave intermediate metrical molecule)], whereas the β-pyrrole atoms, corre-
porphyrinogen 15 (Scheme 5), oxygenation of which (p- sponding to methyl and pentyl substitutes, deviate at
chloranil) led to the formation of porphyrin H2P-2.
Porphyrin H2P-2 was purified and isolated in the same
Ϯ0.139 Å [atom C(10)] and at Ϯ0.129 Å [atom C(21)].
The deviations are apparently the result of steric con-
way as porphyrin H2P-1. Single crystals were grown from tacts, arising in the unit cell in “head-to-head” molecule
chloroform/hexane and investigated by X-ray diffraction. packing, which also determine the conformations of aryl
According to the X-ray data for symmetrical 5,15-(4-bro- substituents. The “head-to-head” arrangement of the mole-
Scheme 5. Synthesis of β-octaalkyl-5,15-bis(4Ј-bromophenyl)porphyrin H2P-2.
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cules of H2P-2, as opposed to the “head-to-tail” packing of
Nominally, molecules of porphyrin H2P-2 (Figure 8) can
the asymmetric H2P-1, is possibly the result of the symmet- be regarded as dimer associates (the distance between mole-
ric aryl substitution. Molecules of H2P-2 arrange them- cule centres is 6.878 Å), just as in the case of H2P-1. How-
selves parallel to each other in planes in the crystal (Fig- ever, there appears to be stronger stacking contacts of pyr-
ure 6).
role fragments in H2P-2 than in H2P-1, which can be con-
cluded from the corresponding interatomic distances in the
parallel arrangement of the molecules along the axis per-
pendicular to the porphyrin plane (Figure 8). There are also
competing steric and CH–π contacts of the bromophenyl
substituent with nitrogen and carbon atoms of the pyrrolic
fragment (C–N and C–C distances are 3.347–3.820 Å) that
lead to distortion of the sp2 reference carbon atom of the
bromophenyl fragment [the deviation of C(2) from the
plane of N4 is Ϯ0.129 Å, displacement of atom Br(1) is
1.507 Å, angle of N4/bond Br(1)–C(2) is 13.1°]. meso-Bro-
mophenyl substituents are perpendicular to the porphyrin
plane (angle is 87.7°), which is a consequence, as also in the
case of H2P-1, of steric contacts with β-methyl substituents,
as distinct from the known 5,15-diphenylporphyrin without
β-substitution, which has similar molecular packing in the
unit cell, but this angle is 54.5°.[20] The same perpendicular
arrangement of 5,15-diaryl substituents with respect to the
N4 plane was observed for all porphyrins containing methyl
groups in the 3-, 7-, 13- and 17-positions.[20–25]
Figure 6. Fragment of packing of molecules of H2P-2.
It should be noted that the arrangement of the molecules
in the crystal forms voids that are clearly seen (Figure 7).
Figure 8. Mutual arrangement of two adjacent molecules of H2P-
2: (A) lateral view, pentyl substituents omitted, (B) top view.
It should be noted that the previously characterized
5,15-diphenyl-2,8,12,18-tetraethyl-3,7,13,17-tetramethyl-
porphyrin has a unit cell packing similar to that of H2P-2
and “inner” macrocycle atoms located virtually in one
plane (deviation of the meso atoms in the 5- and 15-posi-
tions bearing phenyl substituents is Ϯ0.047 Å). Only β-pyr-
Figure 7. The arrangement of H2P-2 molecules in the crystal.
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Zinc Complexes of β-Octaalkyl-meso-(bromophenyl)-Substituted Porphyrins
role carbon atoms with methyl and ethyl substituents devi- octaethylporphyrinatozinc, bridged by a dioxane molecule
ate from the N4 plane, by Ϯ0.124 Å and Ϯ0.194 Å, respec- (Zn–O 2.240 Å), in which the zinc atoms are in distorted
tively. The phenyl substituents also make contacts (3.517– tetragonal-pyramidal
environments
(Zn–N
2.042–
3.869 Å) with the nitrogen and carbon atoms of the pyrrole 2.055 Å).[27] The second is monomeric 2,3,5,10,12,15,20-tet-
fragments, leading to geometry distortion of the reference raphenylporphyrinatozinc (Zn–N 2.015–2.104), in which
sp2 carbon atom [angle between 5,15-atoms axis and the the oxygen atom occupies the fifth position in the distorted
corresponding benzene carbon atoms axis (C1–C4) is 8.3°, tetragonal-pyramidal environment of zinc [Zn–O 2.274 Å][28]
displacement of the peripheral carbon atom of the phenyl The third complex, a ZnII 4,4Ј-{[10,20-bis(3,5-di-tert-butyl-
substituent from the N4 plane is Ϯ0.664 Å].[26]
phenyl)porphyrin-5,15-diyl]diethyne-2,1-diyl}dibenzoate
It was found out that interaction of Zn(OAc)2·2H2O (ex- with diradical bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl),
cess) with H2P-1 and H2P-2 in chloroform at room tem- like ZnP-1 with dioxane, has a distorted tetragonal-bipy-
perature led to the formation of fine-crystalline red-purple ramidal environment based on four nitrogen atoms (Zn–N
complexes ZnP-1 and ZnP-2 in 94% yield. According to 2.033–2.053 Å) and two oxygen atoms of the coordinated
the data from X-ray analysis of the 1,4-dioxane complex dioxane molecules (Zn–O 2.462, 2.494 Å).[29] A distorted
ZnP-1·C4H8O2 (Figure 9, obtained by slow concentration tetragonal-bipyramidal environment is also observed in a
at room temperature from a heptane/dioxane mixture, the CdII complex of tetraphenylporphyrin containing coordi-
zinc(II) atom has a distorted tetragonal-bipyramidal envi- nated dioxane molecules.[30,31] In all the complexes de-
ronment involving four porphyrin nitrogen atoms [Zn–N scribed, the porphyrin macrocycles are virtually planar, in-
2.050(5)–2.059(5) Å] and two dioxane oxygen atoms [Zn– dependently of the zinc coordination number.
O 2.414(5), 2.499(5) Å]. The axially coordinated bidentate
dioxane ligands connect porphyrin molecules, forming a 1-
D polymer (Figure 9).
Figure 10. Fragment of packing of ZnP-1 molecules.
Recrystallization of complex ZnP-2 from a THF/hexane
mixture resulted in the formation of a complex containing
coordinated THF molecules. From the X-ray analysis data
for the complex ZnP-2·THF (Figure 11), the central zinc
atom is bound to the four nitrogen atoms of the tetrapyrrole
macrocycle [Zn–N 2.046(4)–2.065(4) Å] and the oxygen
Figure 9. Molecular structure of the axial complex of ZnP-1 with
atom of coordinated THF [Zn–O 2.183(3) Å] and has a dis-
dioxane (ZnP-1·C4H8O2) with thermal ellipsoids drawn at 30%
torted tetragonal-pyramidal environment.
probability level..
Molecules of metal–porphyrin complex ZnP-1, like those
of the ligand H2P-1, are packed in a “head-to-tail” arrange-
ment. However, because of the separation by dioxane mole-
cules in ZnP-1, significant steric, stacking and CH–π con-
tacts are absent, leading to a virtually plane geometry of
the macrocycle component (deviation of nitrogen atoms
from the mean N4 plane is Ϯ0.007 Å, displacement of zinc
atom out of the mean N4 plane is 0.009 Å, deviation of
bromine atom from the plane is –0.112 Å, max/min bro-
mine atom deviation is +0.033 Å/–0.074 Å).
It should be pointed out that the obtained complex ZnP-
1 represents the first example of a 1-D polymer structure
formed with a bridging dioxane ligand (Figure 10). There
are three known zinc complexes that contain solvating diox-
ane molecules. The first is a dimer of 2,3,7,8,12,13,17,18- thermal ellipsoids drawn at 30% probability level.
Figure 11. Molecular structure of complex of ZnP-2·THF, with
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The tetrapyrrolic macrocycle is distorted (min/max dis- porphyrins with only two meso substituents have not been
placements of nitrogen and zinc atoms from the mean N4 studied. In zinc complexes containing two coordinated
plane are –0.059/0.06 Å and 0.186 Å, respectively, the devia- THF molecules, the metal atoms were in distorted tetrago-
tion of meso- and α-pyrrolic carbon atoms is –0.219/ nal-bipyramidal environments. The tetrapyrrolic fragments
0.191 Å, and that of β-pyrrolic atoms is as follows: the dis- were always planar regardless of the natures and locations
placements of carbon atoms in methyl substituents are of substituents and also of the presence of solvent mole-
–0.498 and 0.416 Å, and those in pentyl substituents are cules. Metal–oxygen distances were noticeably increased
–0.515 and 0.407 Å). This is apparently a consequence of (2.371–2.555 Å)[43–49] and close to that observed in complex
strong CH–π interactions (C···C distances between bro- ZnP-1.
mophenyl substituents and pyrrole moieties are 3.447–
The features of the geometries of porphyrins H2P-1 and
3.856 Å) observed in two adjacent molecules in the unit cell H2P-2, containing acceptor bromophenyl substituents at
of the complex (Zn···Zn 6.256 Å; Figures 12 and 13). De- their meso positions, and also those of their zinc(II) com-
spite the presence of these contacts, the bromine atoms in plexes are thus mostly determined by the effects of molecu-
the bromophenyl substituents are much less displaced from lar packing in the crystals and the related possibilities of
the N4 mean plane (–0.156, 0.698 Å) than in the cases of stacking interactions, CH–π contacts of meso-aryl substitu-
the distortions observed in H2P-1 and H2P-2. The reference ents with pyrrole fragments and also steric hindrance. The
sp2-carbon atoms of the PhBr fragments are also not in the meso-(bromophenyl) substituents are situated in the planes
N4 plane, which is probably related to distortions of the perpendicular to the tetrapyrrole macrocycle, due to the ste-
macrocycle, as opposed to the protonated porphyrin com- ric contacts with the β-methyl substituents.
ponents.
Crystal data and structure refinement details of H2P-1
and H2P-2 and their metal complexes are listed in Table 1.
Conclusions
The new porphyrin compounds β-octaalkyl-5-(bro-
mophenyl)- and -5,15-bis(bromophenyl)porphyrins H2P-1
and H2P-2 and their zinc complexes were successfully syn-
thesized with high yields. We have demonstrated that the
coordination structures of zinc–porphyrins ZnP-1 and
ZnP-2 with oxygen-containing ligand molecules of solvents
such as 1,4-dioxane and THF in axial arrangement occur
in the crystal state. Although such axial coordination com-
plexes also exist in solutions, the coordination number of
the zinc atom is usually 5, and only the crystal environment
can give rise to the six-coordinate state. This rare observed
coordination was produced as a consequence of the forma-
tion of a polymeric structure with a bridging 1,4-dioxane
ligand. Note that in the case of the monodentate THF li-
gand, which is not able to form coordination polymers, the
usual 1:1 zinc–porphyrin/ligand complexes with five-coordi-
nate zinc were formed.
Figure 12. Arrangement of adjacent molecules in the unit cell of
the complex ZnP-2·THF.
Experimental Section
General: UV/Vis spectra were recorded with a Lambda 20 spectro-
photometer. 1H (300 MHz, 400 MHz) and 13C (125 MHz) NMR
spectra were recorded with Bruker Avance 300 and 400 spectrome-
ters at room temperature and referenced to the residual proton sig-
nals of the solvent (CDCl3: δ = 7.28 ppm; [D4]MeOH: δ =
4.84 ppm, 3.31 ppm). MALDI-ToF mass spectra were recorded
with an Ultraflex MALDI ToF Bruker Daltonics spectrometer with
a dithranol matrix. High-resolution mass spectra (HRMS) were
measured with a Bruker micrOTOF II instrument by electrospray
ionization (ESI). The measurements were performed in a positive
ion mode (interface capillary voltage –4500 V, end plate offset
–500 V); mass range from m/z = 50 to 6000 Da; external or internal
calibration was achieved with an electrospray calibrant solution
Figure 13. Fragment of molecular packing in a crystal of complex
ZnP-2·THF.
In the previously reported zinc porphyrinates, the metal
atoms were in distorted tetragonal-pyramidal environments
in which the lengths of metal–oxygen bonds varied in the
2.132–2.211 Å range. The geometries of the tetrapyrrole
fragments are determined by the electronic and steric natu-
res of substituents at the meso- and β-positions, and also
by the presence of solvent molecules.[32–42] Complexes of (Fluka). Syringe injection was used for solutions in acetonitrile
5986 Eur. J. Inorg. Chem. 2012, 5979–5990
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Zinc Complexes of β-Octaalkyl-meso-(bromophenyl)-Substituted Porphyrins
(flow rate 3 mLmin–1). Nitrogen was applied as a dry gas; the inter-
face temperature was set at 180 °C. All reactions were monitored by
2.07 (s, 6 H, 4,4Ј-CH3), 1.13 [m, 18 H, OCH2CH3, 3,3Ј-CH2-
(CH2)3CH3], 0.75 [t, J = 8.0 Hz, 6 H, CH2(CH2)3CH3] ppm.
TLC (Macherey–Nagel Alugram SIL G/UV254 silica gel 60 UV254
,
4,4Ј-Dimethyl-3,3Ј-di(n-pentyl)dipyrromethane-2,2Ј (7): A solution
of 6 (2.0 g, 4.36 mol) and KOH (2.0 g, 35.6 mol) in ethylene glycol
(30 mL) was heated at reflux for 1 h. The mixture was diluted with
cooled water (200 mL), and the precipitate was filtered off, washed
with water and dried at room temperature to give 7 (1.28 g, 93%).
The resulting dipyrromethane was further used without purifica-
tion. 1H NMR (CHCl3, 298 K, 400 MHz): δ = 9.97 (br. s, 2 H,
2NH), 6.31 (s, 2 H, pyrrolic CH), 3.70 (s, 2 H, CH2), 2.17 [t, J =
6.82 Hz, 4 H, 3,3Ј-CH2(CH2)3CH3], 2.07 (s, 6 H, 4,4Ј-CH3), 1.13
[m, 4 H, 3,3Ј-CH2(CH2)3CH3], 0.75 [t, J = 8.0 Hz, 6 H, CH2-
(CH2)3CH3] ppm.
CH2Cl2). Column chromatography was performed on silica gel
(Macherey–Nagel 60 0.04–0.063, 230–400 mesh). The X-ray studies
were performed with a SMART APEX II diffractometer. CH2Cl2
was distilled from CaH2; CHCl3 was distilled from P2O5 and was
freed of acids by stirring in the presence of K2CO3. DMF was
distilled from CaH2. Methanol was distilled from magnesium turn-
ings. The starting materials were generally used as received.
Syntheses of Porphyrins and Metalloporphyrins
3-(n-Pentyl)pentane-2,4-dione (2):
A mixture of acetylacetone
(300 mL, 2.91 mol) and 1-iodopentane (380 mL, 2.91 mol) was
gradually added to a stirred suspension of K2CO3 powder in DMF
(500 mL). The reaction mixture was stirred at 100 °C for 8 h; it was
then cooled, the precipitate was filtered off and washed with ace-
tone, and the solvent was evaporated in vacuo. The residue was
diluted with water, the organic layer was collected, and the water
layer was extracted with diethyl ether. The combined organic frac-
tions were concentrated in vacuo to yield the product (272 g, 55%).
1H NMR (CHCl3, 298 K, 400 MHz): δ = 4.00 [t, J = 7.7 Hz,
2,3-Dimethylbuta-1,3-diene (9): A mixture of pinacone (156 g,
1.32 mol) and concentrated HBr (5 mL) in a 500 mL round-bot-
tomed flask fitted with a dumped packing fractionating column
and condenser was heated to reflux and slowly distilled with collec-
tion of the fraction boiling up to 95 °C. The distillate was washed
twice with water, hydroquinone (0.5 g) was added, and drying was
accomplished with CaCl2. The product was distilled, and the frac-
tion with boiling point about 69–72 °C was collected to give 9
1
(47.5 g, 44%). H NMR (CHCl3, 298 K, 300 MHz): δ = 5.06 (s, 2
H, CH2), 4.97 (s, 2 H, CH2), 1.92 (s, 6 H, CH3) ppm.
2
H, CH2(CH2)3CH3], 2.24 (s, 6 H, CH3) 2.21 (m, 2 H,
CH2CH2CH2CH2CH3), 1.74 (m, 2 H, CH2CH2CH2CH2CH3), 1.54
(m, 2 H, CH2CH2CH2CH2CH3), 0.98 (t, J = 7.26 Hz, 3 H,
CH2CH2CH2CH2CH3) ppm.
3,4-Dimethylpyrrole (11):
A solution of urethane 8 (39.2 g,
0.44 mol) in dry benzene (220 mL) was mixed simultaneously with
dry pyridine (72 mL, 0.89 mol) and freshly distilled SO2Cl2 (32 mL,
0.45 mol) in a 1 L round-bottomed flask, with cooling of the mix-
ture to maintain a temperature of below 45 °C. The mixture was
stirred for about a further 1 h, and 9 (50 mL, 0.44 mol) was added.
After that, the mixture was heated to reflux with stirring for 1 h
and left at room temperature overnight. The precipitate of pyridine
hydrochloride was filtered off and washed with benzene, and the
combined solutions were concentrated in vacuo. The concentrated
residue was added with cooling and stirring to a solution of KOH
(198 g, 3.53 mol) in methanol (440 mL). The resulting mixture was
heated at reflux for 2 h, and the product was steam-distilled. The
distillate was extracted twice with dichloromethane, washed with
water and dried with Na2SO4. The solution was distilled in vacuo,
with collection of the fraction with boiling point about 70 °C. The
yield of 11 was 34.6 g (41%). M.p. 33–34 °C. 1H NMR (CCl4,
298 K, 300 MHz): δ = 7.17 (br. s, 1 H, NH), 6.18 (s, 2 H, 2,5-H),
1.88 (s, 6 H, 3,4-CH3) ppm.
5-(Ethoxycarbonyl)-2,4-dimethyl-3-(n-pentyl)pyrrole (4): A solution
of NaNO2 (111 g, 1.61 mol) in water (180 mL) was added gradually
with stirring and cooling at –35 °C to a mixture of ethyl acetoacet-
ate (203 mL, 1.60 mol) and acetic acid (400 mL). The solution was
stirred at room temperature overnight. After that, it was added to
a solution of 2 (777 g, 1.60 mol) in acetic acid (700 mL, tempera-
ture was about 90 °C) simultaneously with steady addition of zinc
powder (420 g, 6.43 mol). This mixture was stirred at 95 °C for 1 h
and diluted with water (11 L). The precipitated pyrrole was filtered
off, washed with water and dissolved in dichloromethane. The solu-
tion was filtered to remove inorganic solids and washed with water,
and dichloromethane was evaporated in vacuo. The resulting pyr-
role was dried in vacuo to give crude product (357 g, 94%). Purifi-
cation was performed by recrystallization from aqueous methanol:
the crude product (100 g) was dissolved in methanol at reflux
(150 mL), water (60 mL) was added to this solution up to turbidity,
and the mixture was cooled with stirring. The precipitate was fil-
tered off and dried in vacuo to yield pure 4 (236 g, 62%). M.p.
73 °C. 1H NMR (CCl4, 298 K, 300 MHz): δ = 9.83 (br. s, 1 H,
NH), 4.10 (q, J = 6.97 Hz, 2 H OCH2CH3), 2.10 [m, 8 H, 3,5-CH3,
4-CH2(CH2)3CH3], 1.23 (t, J = 6.97 Hz, 3 H, OCH2CH3), 1.12 [m,
6 H, 4-CH2(CH2)3CH3], 0.75 [t, J = 8.0 Hz, 3 H, 4-CH2(CH2)3CH3]
ppm.
2-Formyl-3,4-dimethylpyrrole (12): POCl3 (36.6 mL, 0.4 mol) was
added to a solution of 11 (28.5 g, 0.3 mol) in DMF (200 mL) with
stirring and maintenance of the temperature below 15 °C. The reac-
tion mixture was stirred at room temperature for 1.5 h and then
diluted with water (900 mL), and a solution of KOH (20%, about
2.4 mol) was added. The resulting precipitate was filtered off,
washed with water and dried to yield 12 (28.9 g, 78%). M.p. 142–
143 °C. 1H NMR (CCl4, 298 K, 300 MHz): δ = 9.63 (br. s, 1 H,
NH), 9.40 (s, 1 H, CHO), 6.75 (s, 1 H, 5-H), 2.18 (s, 3 H, 3-CH3),
1.93 (s, 3 H, 4-CH3) ppm.
5,5-Bis(ethoxycarbonyl)-4,4Ј-dimethyl-3,3Ј-di(n-pentyl)dipyrro-
methane-2,2Ј (6): Bromine (21.6 mL, 0.42 mol) was added gradually
with stirring and cooling by water to suspension of 4 (100 g,
0.42 mol) and anhydrous CH3COONa (69 g, 0.84 mol) in acetic
acid (500 mL). This suspension was stirred for 30 min and diluted
3:1 with cooled water. The precipitate was filtered off, washed with
water and heated at reflux with stirring in a 1 L flask with methanol
(500 mL) and concentrated HCl (10 mL) for 3 h. After cooling of
the reaction mixture, the residue was stirred overnight and filtered,
washed with methanol and dried, yielding 48 g (50%). The crude
5-(4-Bromophenyl)-2,3,7,8,12,18-hexamethyl-13,17-di(n-pentyl)-
porphyrin (H2P-1): Initially, concentrated HBr (2 mL, 16.6 mmol)
was added at room temperature with stirring to a solution of 7
(1.28 g, 4.07 mmol) and 12 (1.0 g, 8.14 mmol) in butanol (100 mL),
after which a precipitate settled. 4-Bromobenzaldehyde (4.0 g,
21.6 mmol) was added after 1 h, and the reaction mixture was
heated to reflux. The mixture was kept at reflux for 4 h, iodine
product was purified by recrystallization from methanol to give 6
1
(35.2 g, 37%). M.p. 124 °C. H NMR (CCl4, 298 K, 300 MHz): δ (1.0 g, 3.9 mmol) was then added, and the mixture was stirred for
= 9.97 (br. s, 2 H, NH), 4.00 (q, J = 6.97 Hz, 4 H, OCH2CH3), 10 min. After that, the reaction mixture was allowed to cool, and
3.70 (s, 2 H, CH2), 2.17 [t, J = 6.82 Hz, 4 H, 3,3Ј-CH2(CH2)3CH3],
concentrated ammonia solution (4 mL) was added gradually. The
Eur. J. Inorg. Chem. 2012, 5979–5990
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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5987

I. P. Beletskaya et al.
FULL PAPER
precipitate was filtered off, washed with methanol and dried at
70 °C. The crude product was purified by column chromatography
on silica gel with dichloromethane as eluent to yield H2P-1 (1.6 g,
10.27 (s, 2 H, 10,20-H), 7.95 (d, J = 8.08 Hz, 4 H, 2,6-H), 7.90 (d,
J = 8.34 Hz, 4 H, 3,5-H), 4.00 [t, J = 7.7 Hz, 8 H, 2,8,12,18-
CH2(CH2)3CH3], 2.63 (s, 12 H, 3,7,13,17-CH3), 2.21 (m, 8 H,
2,8,12,18-CH2CH2CH2CH2CH3), 1.74 (m, 8 H, 2,8,12,18-
1
57%). Rf [benzene/hexane (3:1)] = 0.53. H NMR (CDCl3, 298 K,
400 MHz): δ = 10.17 (s, 2 H, 10,20-H), 9.95 (s, 1 H, 15-H), 7.88 (s, C H 2 C H 2 C H 2 C H 2 C H 3 ) , 1 . 5 4 ( m , 8 H , 2 , 8 , 1 2 , 1 8 -
4 H, 2Ј,3Ј,5Ј,6Ј-H-Ar), 4.03 [t, J = 6.82 Hz, 4 H, 13,17-CH2(CH2)3- CH2CH2CH2CH2CH3), 0.98 (t, J = 7.26 Hz, 12 H, 2,8,12,18-
CH3], 3.67 (s, 6 H, 12,18-CH3), 3.55 (s, 6 H, 2,8-CH3), 2.48 (s, 6 CH2CH2CH2CH2CH3), –2.43 (br. s, 2 H, NH) ppm. UV/Vis
H, 3,7-CH3), 2.32 (m, 4 H, 13,17-CH2CH2CH2CH2CH3), 1.76 (m,
4 H, 13,17-CH2 CH2 CH2 CH2CH3 ), 1.57 (m, 4 H, 13,17-
(CHCl3): λ [log(ε/m–1 cm–1)] = 626 [3.49], 574 [3.96], 542 [3.87], 508
[4.30], 410 nm [5.40]. HRMS (ESI): calcd. for [C56H69Br2N4]+
CH2CH2CH2CH2CH3), 1.00 (t, J = 7.20 Hz, 6 H, 13,17- 956.3790 [M + H]+; found 956.3913.
CH2CH2CH2CH2CH3), –3.19 (s, 1 H, NH), –3.32 (s, 1 H, NH)
Zinc 5-(4-Bromophenyl)-2,3,7,8,12,18-hexamethyl-13,17-di(n-
ppm. UV/Vis (CHCl3): λ [log(ε/m–1 cm–1)] = 624 [3.57], 571 [3.88],
537 [3.92], 503 [4.21], 404 nm [5.29]. HRMS (ESI): calcd. for
[C42H49BrN4]+ 688.3141 [M + H]+; found 688.3239.
pentyl)porphyrinate (ZnP-1): Zinc acetate (0.438 g, 2 mmol, excess)
was added to a solution of porphyrin H2P-1 (69 mg, 0.1 mmol)
in CHCl3 (30 mL). The mixture was stirred at room temperature
overnight, and the solvent was removed in vacuo. The resulting
powder was dissolved in CHCl3, and the solution was filtered and
directly loaded onto a silica gel chromatography column. The ex-
pected compound (eluted with CHCl3) was obtained as a crimson
solid. It was precipitated from chloroform solution by addition of
methanol and washed with methanol to yield ZnP-1 (0.8 mg, 94%).
1H NMR (CDCl3, 298 K, 400 MHz): δ = 9.90 (s, 2 H, 10,20-H),
9.52 (s, 1 H, 15-H), 7.90 (s, 4 H, 2Ј,3Ј,5Ј,6Ј-H-Ar), 3.79 [t, J =
6.82 Hz, 4 H, CH2(CH2)3CH3], 3.48 (s, 12 H, 12,18-CH3, 2,8-CH3),
2.44 (s, 6 H, 3,7-CH3), 2.18 (m, 4 H, 13,17-CH2CH2CH2CH2CH3),
1.71 (m, 4 H, 13,17-CH2CH2CH2CH2CH3), 1.55 (m, 4 H, 13,17-
CH2CH2CH2CH2CH3), 1.01 (t, J = 7.20 Hz, 6 H, 13,17-
CH2CH2CH2CH2CH3) ppm. UV/Vis (CHCl3): λ [log(ε/m–1 cm–1)]
= 536 [3.98], 572 [3.95], 406 [5.56). HRMS (ESI): calcd. for
[C42H49BrN4Zn]+ 751.2354 [M + H]+; found 751.2256.
5,15-Bis(4-bromophenyl)-3,7,13,17-tetramethyl-2,8,12,18-tetra(n-
pentyl)porphyrin (H2P-2): Initially, a solution of trifluoroacetic acid
(0.4 mL, 5.38 mmol) in dichloromethane (30 mL) was added with
stirring at room temperature under argon to a solution of 12
(1.28 g, 4.07 mmol) and 4-bromobenzaldehyde (0.8 g, 4.32 mmol)
in dichloromethane (450 mL). The mixture was stirred for 4 h, p-
chloranil (1.6 g, 6.51 mmol) was then added, and the reaction mix-
ture was left at room temperature overnight. The solvent was then
evaporated in vacuo, and the residue was washed with aqueous
KOH and water and dried at 70 °C. The solid was dissolved in
dichloromethane and purified by column chromatography on silica
gel. The solution after chromatography was concentrated, and the
product was precipitated by addition of methanol. The product was
filtered off, washed with methanol and dried at 70 °C. Rf [benzene/
hexane (3:1)] = 0.76. 1H NMR (CDCl3, 298 K, 400 MHz): δ =
Table 1. Crystal data and structure refinement for porphyrin compounds.
H2P-1
H2P-2
ZnP-1·C4H8O2
ZnP-2·THF
Empirical formula
Formula mass
C42H49BrN4
689.76
C56H68Br2N4
956.96
C46H55BrN4O2Zn
841.22
C60H74Br2N4OZn
1092.42
Colour
T [K]
red
173(2)
red
173(2)
red
173(2)
red
173(2)
Crystal system
Space group
monoclinic
P2/c
triclinic
P1
triclinic
P1
triclinic
P1
¯
¯
¯
a [Å]
b [Å]
c [Å]
α [°]
14.9705(11)
13.0783(10)
18.5991(14)
90
96.3170(10)
90
3619.4(5)
4
1.266
6.8777(9)
12.8756(18)
15.354(2)
67.982(2)
77.252(2)
87.795(2)
1227.9(3)
1
8.675(5)
10.300(3)
16.247(4)
16.690(5)
83.775(4)
89.870(4)
73.886(4)
2666.1(13)
2
14.398(9)
18.172(11)
68.026(10)
78.351(10)
79.909(10)
2049(2)
β [°]
γ [°]
V [Å3]
Z
2
d(calcd.) [Mgm–3]
1.493
1.691
1.363
1.617
1.361
2.003
µ [mm–1]
1.171
F(000)
1456
502
880
1140
Crystal size [mm]
θ range for data collection [°]
Index ranges
0.14ϫ0.12ϫ0.10
2.28–28.00
–19 Յ h Յ 19
–17 Յ k Յ 17
–24 Յ l Յ 24
30890
0.16ϫ0.14ϫ0.12
2.79–28.00
–9 Յ h Յ 9
–16 Յ k Յ 16
–20 Յ l Յ 20
12490
0.14ϫ0.12ϫ0.10
2.27–26.00
–10 Յ h Յ 10
–17 Յ k Յ 17
–22 Յ l Յ 22
17303
0.14ϫ0.12ϫ0.10
2.40–27.00
–13 Յ h Յ 13
–20 Յ k Յ 20
–21 Յ l Յ 21
25191
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [IϾ2σ(I)][a]
8636 [R(int) = 0.0414] 5815 [R(int) = 0.0272] 7912 [R(int) = 0.0994] 11514 [R(int) = 0.0628]
8636/0/449
1.005
5815/0/272
1.040
R1 = 0.0473,
wR2 = 0.1155
R1 = 0.0650,
wR2 = 0.1243
1.125/–1.336
7912/1/459
1.023
R1 = 0.0821,
wR2 = 0.1838
R1 = 0.1650,
wR2 = 0.2252
1.530/–1.224
11514/1/609
0.993
R1 = 0.0633,
wR2 = 0.1518
R1 = 0.1303,
wR2 = 0.1864
1.337/–1.445
R1 = 0.0482,
wR2 = 0.1127
R1 = 0.0847,
wR2 = 0.1308
R indices (all data)[a]
Largest difference peak/hole [eA–3][b] 1.313/–0.795
[a] R1 = Σ||Fo| – |Fc||/Σ|Fo|; wR2 = {Σ[w(Fo – Fc ) ]/Σw(Fo2)2}1/2. [b] In all structures the largest difference peak is observed in the vicinity
2
2 2
of the heavy atom.
5988
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Eur. J. Inorg. Chem. 2012, 5979–5990

Zinc Complexes of β-Octaalkyl-meso-(bromophenyl)-Substituted Porphyrins
phyrin Handbook (Eds.: K. M. Kadish, K. M. Smith, R. Guil-
ard), Academic Press, London, 2000, vol. 3, pp. 1–48.
a) J. A. A. W. Elemans, R. Hameren, R. J. M. Nolte, A. E.
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N. A. Rakow, M. E. Kosal, J.-H. Chou, J. Porphyrins Phthalo-
cyanines 2000, 4, 407–413; c) E. Deiters, V. Bulach, M. W. Hos-
seini, Chem. Commun. 2005, 3906–3908; d) P. Bhyrappa, S. R.
Wilson, K. S. Suslick, J. Am. Chem. Soc. 1997, 119, 492–8502;
e) S. George, I. Goldberg, Cryst. Growth Des. 2006, 6, 755–762;
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Mater. 2002, 1, 118–121.
a) J. M. Tour, Acc. Chem. Res. 2000, 33, 791–804; b) T. Malin-
ski in The Porphyrin Handbook (Eds.: K. M. Kadish, K. M.
Smith, R. Guilard), Academic Press, San Diego, CA, 2000, vol.
6. pp. 231–256; c) S. Fukuzumi in The Porphyrin Handbook
(Eds.: K. M. Kadish, K. M. Smith, R. Guilard), Academic
Press, San Diego, CA, 2000, vol. 8, pp. 115–152.
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Zinc 5,15-Bis(4-bromophenyl)-3,7,13,17-tetramethyl-2,8,12,18-tet-
ra(n-pentyl)porphyrinate (ZnP-2): The synthesis of ZnP-2 is similar
to that of ZnP-1. A solution of H2P-2 (95.7 mg, 0.1 mmol) in
CHCl3 (30 mL) was mixed with zinc acetate (0.438 g, 2 mmol, ex-
cess). The yield of ZnP-2 was 95.7 mg (94%). 1H NMR (CDCl3,
298 K, 400 MHz): δ = 10.15 (s, 2 H, 10,20-H), 8.00 (d, J = 8.08 Hz,
4 H, 2,6-H), 7.90 (d, J = 8.34 Hz, 4 H, 3,5-H), 3.98 [t, J = 7.71 Hz,
8 H, 2,8,12,18-CH2(CH2)3CH3], 2.50 (s, 12 H, 3,7,13,17-CH3), 2.18
(m, 8 H, 2,8,12,18-CH2CH2CH2CH2CH3), 1.73 (qv, 8 H,
CH2CH2CH2CH2CH3), 1.55 (sc, 8 H, 13,17-H2CH2CH2CH2CH3),
[4]
[5]
0.99 (t, J = 7.26 Hz, 12 H, 13,17-CH2CH2CH2CH2CH3) ppm. UV/
Vis (CHCl3): λ [log(ε/m–1 cm–1)] = 575 [3.16], 540 [3.38], 412 nm
[4.68]. HRMS (ESI): calcd. for [C56H69Br2N4Zn]+ 1021.3160 [M +
H]+; found 1021.3280.
X-ray Diffraction Analysis: The data collection and structure-re-
finement data for compounds H2P-1, H2P-2, ZnP-1, ZnP-2 are
[6]
presented in Table 1. Single-crystal X-ray diffraction experiments
were carried out with a Bruker SMART APEX II diffractometer
and a CCD area detector (graphite monochromator, Mo-Kα radia-
tion, λ = 0.71073 Å, ω-scans). The semiempirical method SAD-
ABS[50] was applied for the absorption correction. The structures
were solved by direct methods and refined by the full-matrix, least-
squares technique against F2 with anisotropic displacement param-
eters for all non-hydrogen atoms. In compounds H2P-1 and ZnP-
2, carbon atoms C(38)–C(40) and C(42)–C(46) of the pentyl sub-
stituents are disordered over two sites with occupancies of 0.7:0.3
and 0.6:0.4, respectively. All the hydrogen atoms in the complexes
were placed geometrically and included in the structure-factor cal-
culations in the riding-motion approximation. All the data re-
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This work was supported by the Russian Foundation for Basic Re-
search (grant#11-03-12160-ofi-m-2011), the Russian Academy of
Sciences (Program of Division of Chemistry and Materials Science
N6 “Chemistry and Physical Chemistry of Supramolecular Systems
and Atomic Clusters”) and the Ministry of Education and Science
of the Russian Federation.
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Received: July 30, 2012
Published Online: October 29, 2012
5990
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© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 5979–5990