Preparation and characterization of CoII, NiII, and ZnII complexes of sterically demanding hexaazamacrocyclic dithiophenolates

Article abstract of DOI:10.1002/ejic.200500022

N-Alkylated variants of a Robson-type 24-membered hexaazamacrocyclic dinucleating dithiophenolate ligand bearing ethyl and propyl groups have been prepared and their ligating properties towards the 3d elements Ni, Co and Zn have been examined. The new ligands support the formation of dinuclear complexes of the type [(L^R)M^II₂(L′)] ⁺, i.e. [(L^Et)-Ni₂(Cl)]⁺ (7) [(L^Pr)Ni₂(Cl)]⁺ (8), [(L^Et)Ni ₂(OAc)]⁺ (9), [(L^Pr)-Ni₂(OAc)] ⁺ (10), [(L^Et)Ni₂(O₂COMe)] ⁺ (11), [(L^Et)-Ni₂(O₂COEt)] ⁺ (12), [(L^Et)Zn₂(OAc)]⁺ (14), [(L^Et)Co₂(Cl)]⁺ (17), and [(L ^Et)Co₂(OAc)]⁺ (18), the overall structures of which are very similar to the corresponding complexes of the parent permethylated ligand system. The use of the longer alkyl chains expands the binding pocket of the complexes to a more conical, calixarene -like cavity and has allowed for the isolation of the trication [(HL ^Et)Ni₂]³⁺ (13), which is an intermediate in the substitution reactions of 7. Complex 13 reveals a new coordination mode of the supporting ligand with adjacent four- and five-coordinate nickel atoms. Its higher stability is presumably a consequence of the increased steric crowding imposed by the longer alkyl chains of (L^Et)^2-. These results have thus demonstrated that these highly functionalized ligand systems allow for the stabilization of reactive intermediates. This information can now be used as a guide to further modulate the chemical reactivity of these compounds. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.

Full text of DOI:10.1002/ejic.200500022

FULL PAPER
Preparation and Characterization of CoII, NiII, and ZnII Complexes of
Sterically Demanding Hexaazamacrocyclic Dithiophenolates
Mathias Gressenbuch,[a] Vasile Lozan,[a] Gunther Steinfeld,[b] and Berthold Kersting*[a]
Keywords: Binding pockets / Macrocyclic ligands / Cobalt / Nickel / Zinc
N-Alkylated variants of a Robson-type 24-membered hexa-
azamacrocyclic dinucleating dithiophenolate ligand bearing
ethyl and propyl groups have been prepared and their ligat-
ing properties towards the 3d elements Ni, Co and Zn have
been examined. The new ligands support the formation of
dinuclear complexes of the type [(LR)MII2(LЈ)]+, i.e. [(LEt)-
Ni2(Cl)]+ (7), [(LPr)Ni2(Cl)]+ (8), [(LEt)Ni2(OAc)]+ (9), [(LPr)-
the isolation of the trication [(HLEt)Ni2]3+ (13), which is an
intermediate in the substitution reactions of 7. Complex 13
reveals a new coordination mode of the supporting ligand
with adjacent four- and five-coordinate nickel atoms. Its
higher stability is presumably a consequence of the in-
creased steric crowding imposed by the longer alkyl chains
of (LEt)2–. These results have thus demonstrated that these
highly functionalized ligand systems allow for the stabiliza-
tion of reactive intermediates. This information can now be
used as a guide to further modulate the chemical reactivity
of these compounds.
Ni2(OAc)]+
(10),
[(LEt)Ni2(O2COMe)]+
(11),
[(LEt)-
Ni2(O2COEt)]+ (12), [(LEt)Zn2(OAc)]+ (14), [(LEt)Co2(Cl)]+ (17),
and [(LEt)Co2(OAc)]+ (18), the overall structures of which are
very similar to the corresponding complexes of the parent
permethylated ligand system. The use of the longer alkyl
chains expands the binding pocket of the complexes to a
more conical, “calixarene”-like cavity and has allowed for
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
Introduction
Much effort is currently been invested in the design and
development of supporting ligands for the construction of
metal complexes with deep binding pockets.[1] Several suit-
able ligand systems have already been reported, as for in-
stance the calixarenes,[2,3] the cyclodextrines[4,5] and some
highly functionalized chelate ligands.[6,7] Recently, we re-
ported that the Robson-type[8] macrocycles H2LH and its
permethylated derivative H2LMe (see Scheme 1) can also be
employed for this purpose.[9] Both ligands support the for-
mation of [(LR)M2(μ-LЈ)]+ complexes, whose ligand confor-
mations are reminiscent of the “partial cone” and “cone”
conformations of the calixarenes.
It has been observed that the binding pocket influences
the coordination chemistry of the [(LR)M2(μ-LЈ)]+ com-
plexes significantly. For example, the substitution rates of
the bridging coligands (LЈ) are drastically increased.[10]
Likewise, it allows for the activation of small molecules
such as carbon dioxide,[11] and it can mediate the course of
substrate transformations as seen in the highly diastereo-
selective cis-bromination of α,β-unsaturated carboxylate co-
ligands.[12]
[a] Institut für Anorganische Chemie, Universität Leipzig,
Johannisallee 29, 04103 Leipzig, Germany
Fax: + 49-341-97-36199
Scheme 1. Structure of the ligands (H2LR) and schematic represen-
tation of the structures of their corresponding metal complexes
[(LR)M2(μ-LЈ)]+. The cavity representation of the ligands (LR)2–
should not be confused with the one used for cyclodextrins.
E-Mail: b.kersting@uni-leipzig.de
[b] Institut für Anorganische und Analytische Chemie, Universität
Freiburg,
Albertstr. 21, 79104 Freiburg
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DOI: 10.1002/ejic.200500022
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M. Gressenbuch, V. Lozan, G. Steinfeld, B. Kersting
FULL PAPER
These results prompted us to expand the binding pocket macrocycles H2LEt and H2LPr were allowed to react with
of this versatile ligand system by using alkyl groups larger NiCl2·6H2O and triethylamine in 1:2:8 molar ratios in
than methyl and to investigate the effect of this modifica- methanolic solution according to Equation (1). In the case
tion on the ligating properties. In this paper, we describe of the ethylated derivative H2LEt, the complexation reaction
the synthesis and characterization of N-alkylated variants was complete after stirring at ambient temperature for 3 d.
of H2LMe bearing ethyl and propyl groups in place of the Upon addition of LiClO4 to the bright yellow solution, yel-
methyl functions and report on their ligating properties low microcrystals of [(LEt)NiII2(μ-Cl)]ClO4 (7·ClO4) could
towards the 3d elements Ni, Co and Zn (see Scheme 1 for be obtained in 82% yield. The propylated ligand H2LPr re-
abbreviations).
acted similarly, generating the yellow species [(LPr)NiII2(μ-
Cl)]ClO4 (8·ClO4), but stirring for 1 week was necessary to
obtain it in comparable yields. In this respect, the two new
ligands contrast the sterically less bulky ones which form
dinuclear species more quickly. Characterization by elemen-
tal analysis, IR and UV/Vis spectroscopy {previously re-
ported for [(LMe)NiII2(μ-Cl)]ClO4 (5·ClO4)} are indicative
of analogous bioctahedral structures of type A for these
chloro-bridged compounds.
Results and Discussion
Ligand Synthesis
Two new derivatives of the parent hexaazamacrocyclic
dithiophenolate H2LH with ethyl and propyl substituents
were prepared in order to probe the influence of ligand
structural variations on metal ion complexation and metal
complex structures. For the bulkier ethyl and propyl deriva-
tives a reaction sequence similar to that used for the alky-
lation of triazacyclononane[13] and cyclam[14] was used. The
syntheses began with the acylation of known amine 1,[15]
with the anhydrides 2 (Scheme 2). The resulting amides 3
were then reduced with lithium aluminium hydride in re-
fluxing THF solution to give the corresponding amines 4.
The thioether functions of the latter compounds were de-
protected in the usual way[16] with sodium in liquid ammo-
nia to afford the desired ligands which could be readily iso-
lated as hydrochloride salts H2LR·6HCl (R = Et, Pr). All
(1)
Table 1. Synthesized complexes, their labeling and selected struc-
tural data.[a]
new compounds were characterized by elemental analysis, Compound
Structure
[d(M···M)/Å]
Ref.
IR, 1H and 13C NMR spectroscopy. The hydrochloride salts
[10]
[11]
5
[(LMe)NiII2(μ-Cl)]+
[(LMe)NiII2(μ-OAc)]+
[(LEt)NiII2(μ-Cl)]+
[(LPr)NiII2(μ-Cl)]+
[(LEt)NiII2(μ-OAc)]+
[(LPr)NiII2(μ-OAc)]+
A [3.201]
B [3.483]
A[b]
of the ligands could not be obtained in analytically pure
form. However, they were of sufficient purity for metal
complex syntheses.
6
7
this work
this work
this work
this work
this work
this work
this work
8
A[b]
9
B[c]
10
11
12
13
14
15
16
17
18
B [3.513]
[(LEt)NiII2(μ-O2COMe)]+ B[c]
[(LEt)NiII2(μ-O2COEt)]+ B [3.520]
3+
[(HLEt)NiII
]
2
[3.319]
[(LEt)ZnII2(μ-OAc)]+
[(LMe)CoII2(μ-Cl)]+
[(LMe)CoII2(μ-OAc)]+
[(LEt)CoII2(μ-Cl)]+
[(LEt)CoII2(μ-OAc)]+
B [3.459]
A [3.180]
B [3.448]
A[b]
this work
[9b]
[9b]
this work
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B [3.482]
–
–
[a] The complexes were isolated as ClO4 or BPh4 salts. [b] The
experimentally determined structures of 5 and 15 suggest that com-
plexes 7, 8 and 17 adopt the form A. [c] The experimentally deter-
mined structures of 10 and 12 suggest that complexes 9 and 11
adopt the form B.
Scheme 2. Preparation of the ligands H2LEt and H2LPr.
The bridging halide ions in complexes 7 and 8 proved
quite labile. Thus, the reactions of the respective [(L)Ni2(μ-
Cl)]+ cations with sodium acetate proceeded smoothly and
yielded green solutions, from which green crystals of [(LEt)-
Ni2(μ-OAc)]ClO4 (9·ClO4) and [(LPr)Ni2(μ-OAc)]ClO4
Synthesis of Complexes
The synthesized compounds and their labels are collected (10·ClO4) were obtained in good yields [Equation (2)].
in Table 1. Of these, the compounds [(LMe)NiII2(μ-Cl)]ClO4 Later studies revealed that the same compounds can also
(5·ClO4) and [(LMe)NiII2(μ-OAc)]ClO4 (6·ClO4) were re- be directly synthesized from the respective ligands and
ported previously.[10,11] According to these procedures, the Ni(OAc)2·6H2O.
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CoII, NiII, and ZnII Complexes of Hexaazamacrocyclic Dithiophenolates
FULL PAPER
H2LMe results in restricted access to the two metal ions
which are buried inside a sterically more encumbered cavity.
This clearly shows that these highly functionalized macro-
cycles allow for the stabilization of reactive intermediates.
(2)
The methyl carbonate species 11 and its corresponding
ethyl carbonate derivative 12 represent two further exam-
ples of nickel complexes of the ethylated macrocycle. Com-
pound 11 was obtained by a carbonation reaction of the
green μ-hydroxo species [(LEt)NiII2(μ-OH)]+ (prepared in
situ from 7 and sodium hydroxide; Equation (3)] and iso-
lated as the pale-green perchlorate salt 11·ClO4 in 88%
yield. The conversion of the methyl carbonate complex 11
into the ethyl carbonate species 12 was accomplished by a
transesterification reaction with neat ethanol [Equation (4)].
Similar transformations were previously observed for the
nickel complex 5 of the permethylated macrocycle. Thus,
the rate of the substitution reactions and the ability to fix
small molecules is not drastically altered by the longer alkyl
chains.
Scheme 3. Preparation and reactions of 13.
To obtain some preliminary information on the solution
structures, the synthesis of diamagnetic zinc complexes was
devised next. The acetato-bridged dizinc complex 14 was
obtained by the direct reaction of H2LEt·6HCl with
Zn(OAc)2·2H2O and triethylamine in methanol [Equa-
tion (5)]. Attempts to prepare a chloro-bridged complex
such as [(LEt)ZnII2(μ-Cl)]+ were unsuccessful.
(5)
The two CoII complexes 17 and 18 represent the last two
compounds of this study. These were prepared according to
Equations (6) and (7). Both cations were isolated as their
perchlorate salts in 83% and 74% yield, respectively. The
structures of complexes [(LMe)CoII2(μ-Cl)]+ (15) and [(LMe)-
CoII2(μ-OAc)]+ (16) have previously been shown to be of
type A and B, respectively.[18] On the basis of spectroscopic
similarities (vide infra), analogous structures are likely for
the complexes supported by H2LEt. This is confirmed by an
X-ray crystal structure determination of [(LEt)CoII2(μ-
OAc)]BPh4 (18·BPh4, see below).
(3)
(4)
3+
The compound [(HLEt)NiII
]
2
(13) formed rather unex-
pectedly during attempts to prepare a methanolato-bridged
complex [(LEt)NiII2(μ-OMe)]+ (Scheme 3). Instead of the
anticipated compound the dark-green trication 13 was ob-
tained. It could be isolated as the triperchlorate salt
13·(ClO4)3 but only in low yield. This compound differs
from the ones above in several respects. It bears no co-
ligands, reveals a central N2Ni(μ-S)2NiN3 core structure
with adjacent four- and five-coordinate NiII ions and shows
one protonated (non-coordinating) amine function (see be-
low). It reacts readily with Et4NCl to regenerate the parent
complex 7, and produces the acetato-bridged compound 9
upon addition of sodium acetate (Scheme 3). Recall that 7
is a type A species whereas 9 is of the kind B. The reaction
in Equation (2) therefore involves a conformational change
of the macrocycle from A to B. It can be shown that this
requires an inversion of the configurations of the tertiary
(6)
(7)
All new complexes are stable in air both in solution and
nitrogen donor atoms; however, this can only proceed by in the solid state. The perchlorate salts are very soluble in
dissociation of the metal–nitrogen bonds. The crystal struc- a range of common polar organic solvents (CH3CN, EtOH,
ture of 13 reveals such non-coordinating nitrogen donor MeOH). The complexes with the longer alkyl chains also
atoms. Thus, 13 is presumably an intermediate in the above exhibit some solubility in apolar solvents such as cyclohex-
substitution reactions [e.g. Equation (2)]. All attempts to ane or toluene. The new compounds gave satisfactory ele-
isolate the analogous compound of the permethylated mental analyses and were characterized by spectroscopic
macrocylce have failed.[17] Therefore, the isolation of 13 can methods (IR, UV/Vis, 1H and 13C NMR spectroscopy) and
be traced back to the sterically more demanding ethyl func- compounds 10·ClO4, 12·BPh4, 13·(ClO4)3, 14·ClO4, and
tions. As we will show below, the use of H2LEt in place of 18·BPh4 also by X-ray structure analysis.
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M. Gressenbuch, V. Lozan, G. Steinfeld, B. Kersting
FULL PAPER
Spectroscopic Characterization
Infrared Spectroscopy
is observed between 1000 and 1180 nm. These absorptions
can be attributed to the d-d transitions ν2 [3A2g(F) Ǟ
3T1g(F)] and ν1 [3A2g(F) Ǟ 3T2g(F)], respectively, of an octa-
hedral nickel(ii) (d8) ion. For the chloro-bridged com-
pounds the ν1 absorption is split presumably due to lower
symmetry. The higher energy features below 400 nm (not
listed in Table 2) result from π-π* transitions within the
(LR)2– ligands. The slight differences in the position of the
d-d transitions indicate that each complex retains its integ-
rity in solution. This is also supported by the NMR spec-
troscopic data described below for the zinc complex 14.
The infrared spectra of all compounds display the bands
expected for the macrocyclic ligands, counterions, carboxyl-
ate or alkyl carbonate coligands.[19] Selected Infrared data
–
are listed in Table 2. The ClO4 ion gives rise to a broad
band at 1100 cm–1 which is normal for this counterion. The
IR spectra of the acetato-bridged complexes 6, 9, 10, 14,
16, and 18 are very similar. Each spectrum displays two
strong bands around 1590 and 1430 cm–1. These bands are
associated with the asymmetric [νasym(OAc–)] and symmet-
ric stretching modes [νsym(OAc–)] of the carboxylate co-
ligands.[20] The similarities to the IR spectrum of the di-
nickel complex 6 are indicative of μ1,3-bridging acetate
groups. The IR spectra of complexes 7, 8, 15, and 17 lack
these two bands, which is in good agreement with the for-
mulation of the chloro-bridged [(LMe)M2(μ-Cl)]+ cations.
As can be seen in Table 2, the asymmetric and symmetric
stretching modes of the alkyl carbonate complexes 11 and
12 are shifted to higher and lower frequencies, respectively,
when compared with the corresponding values for the acet-
ato-bridged compounds. This trend has also been observed
for the carboxylate and alkyl carbonate complexes of the
permethylated macrocycle.[11] We finally note that the
methyl and ethyl carbonate complexes can be easily distin-
guished by their IR spectra [e.g. by the frequency of the
νsym(O2CR) stretching mode].
As expected, the UV/Vis spectrum of the [(HLEt)-
3+
NiII
]
trication 13 is different from the bioctahedral com-
2
plexes above. The spectrum is dominated by an intense ab-
sorption band at 574 nm, which can be tentatively assigned
to a d-d transition of the planar four-coordinate NiN2S2
chromophore. It is a typical value for complexes containing
planar NiN2S2 units.[21] This intense absorption presumably
obscures the weaker d-d transition bands of the five-coordi-
nate NiN3S2 fragment.[22]
The electronic absorption spectra of the four cobalt(ii)
complexes are again very similar. Each compound reveals a
weak band at ca. 1260 nm which can be readily assigned to
4
4
the T1g(F) Ǟ T2g transition of an octahedral high-spin
cobalt(ii) ion.[23] Further absorption bands are observed in
the 500–600 nm range. These bands are attributable to com-
ponents of the parent octahedral ligand field transitions,
4
4
4
4T1g(F) Ǟ T1g(P) and T1g(F) Ǟ A2g, split by lower sym-
metry. The more intense band at ca. 450 nm most probably
arises from a thiolate-to-cobalt(ii) charge transfer (LMCT)
transition and the feature at ca. 350 nm from a π-π* transi-
tion within the (LR)2– ligand. Again, these spectroscopic
findings clearly show that the coligands remain attached to
the cobalt ions in the solution state.
UV/Vis Spectroscopy
All new complexes were further characterized by UV/Vis
spectroscopy. The electronic absorption spectra of the com-
plexes were recorded in the 300–1600 nm range in acetoni-
trile solution. Selected spectroscopic data are reported in
Table 2. The data for complexes 5, 6, 15, and 16 have been
reported previously and are included for comparative pur-
poses.
NMR Spectroscopy
The 1H NMR spectrum of the acetato-bridged zinc com-
The spectra of the nickel complexes are similar but not plex 14 displays only one set of signals, indicative of a single
identical. Each compound displays two weak absorption isomer. The four aromatic protons (CAr) and the tert-butyl
bands. One appears in the 620–670 nm range, the other one protons [C(CH3)3] appear as singlets, implying C2v sym-
Table 2. Selected UV/Vis and IR spectroscopic data for compounds 5–18.
Compound
λmax/nm (ε/m–1 cm–1)
νas, νs (O2CR)
5
658 (41), 920 (59), 1002 (80)
649 (28), 1134 (55)
659 (30), 930 (53), 1026 (76)
674 (26), 931 (54), 1023 (74)
660 (29), 1180 (79)
662 (29), 1183 (77)
668 (22), 1136 (84)
668 (28), 1140 (79)
574 (850), 1016 (50)
352 (2290)
357 (1523), 468 (590), 545 (162), 571 sh (137), 1237 (23)
440 (467), 523 (170), 542 (121), 565 sh (64), 608 sh (21), 1262 (33)
342 (2401), 470 (602), 548 (175), 578 sh (162), 1280 (28)
440 (610), 528 (204), 1288 (44)
–
6
1588, 1426
–
–
7
8
9
1589, 1426
1593, 1428
1638, 1330
1637, 1316
–
1584, 1442
–
1587, 1434
–
1588, 1439
10
11
12
13
14
15
16
17
18
[a] The UV/Vis and IR spectra were recorded for the perchlorate salts.[b] Spectra were recorded in CH3CN solution at 295 K. Concentra-
tion of solutions were ca. 1.0×10–3 m.
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CoII, NiII, and ZnII Complexes of Hexaazamacrocyclic Dithiophenolates
FULL PAPER
metry for the [(LEt)Zn2(μ-OAc)]+ cation (i.e. structure type
B). This is further supported by the fact that the [(LEt)-
Zn2]2+ fragment gives rise to only 13 13C signals (9 for the
aliphatic and 4 for the aromatic carbon atoms). The appear-
1
ance of the H NMR signals for the methyl protons of the
bridging acetato coligand at δ = 0.85 ppm is also worth
mentioning. This signal is shifted to high field when com-
pared with free sodium acetate (δ = 1.83 ppm). This can be
understood in terms of the ring current. As can be seen
from Figure 3, the methyl protons of the acetate groups are
positioned in the binding cavity of the [(LEt)Zn2]2+ frag-
ment slightly above the center of the two phenyl rings in
the shielding region. Similar findings have been observed
for the [(LMe)ZnII(μ-OAc)]+ cation.[24] In summary, the
spectroscopic data have clearly established that all com-
plexes exist as discrete and stable species with similar
“cone”- and “partial-cone”-like conformations of the
macrocycles. Thus, with the exception of complex 13, the
ligating properties of the new ligands are not very different
from the parent (LMe 2– and (LH)2– ligands.
)
X-ray Crystallography
The formulations of the new compounds were further
confirmed by X-ray diffraction studies. Single crystals of X-
ray quality were obtained for the perchlorate salts of 10, 13,
and 14 and for the tetraphenylborate salts of 12 and 18.
Selected crystallographic data are listed in Table 4. The
molecular structures of the complexes are displayed in Fig-
ures 1, 2, 3, 4 and 5, and selected bond lengths and angles
are given in Table 3.
Description of the Structures of the Bioctahedral [(LR)-
Figure 1. Two perspective side views of the structure of the dinickel
complex 10 with thermal ellipsoids drawn at the 50% probability
level. Hydrogen atoms are omitted for reasons of clarity.
M2(μ-O2CR)]+ Complexes
The structures of the bioctahedral species 10, 12, 14, and
18 will be discussed first. A common labeling scheme for
the [(LMe)M2]2+ fragments has been used to facilitate struc-
tural comparisons. The structure of the cation [(LMe)-
Ni2II(μ-OAc)]+ (6) has been reported previously, and its
metrical parameters are also given for comparison.
Structure of the [(LR)M2]2+ Fragment
It is appropriate to describe the structures of the [(LR)-
M2]2+ fragments first. The macrocycles adopt the confor-
mation of type B, previously reported for the acetato-
bridged complex 6 (Scheme 1).[11] In each case, the two me-
tal ions are coordinated in a square-pyramidal fashion by
the two fac-N3(μ-S)2 donor sets of the doubly deprotonated
macrocycles. The coordination of the exogenous coligands
generates distorted octahedral environments for the metal
ions. The metrical parameters of the central N3M(μ-S)2(μ-
O2CR)MN3 cores are very similar (see Table 3). The dieth-
ylenetriamine units are fac-coordinated with one larger and
two smaller N–M–N bond angles, which is most commonly
observed in complexes with this tridentate unit.[25] Likewise,
the M–N bonds involving the four benzylic nitrogen donors
are invariably longer (by ca. 0.1 Å) than the ones compris-
Figure 2. Structure of the dinickel complex 12 with thermal ellip-
soids drawn at the 50% probability level. Hydrogen atoms are omit-
ing the central nitrogen atoms of the linking diethylenetri- ted for reasons of clarity.
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M. Gressenbuch, V. Lozan, G. Steinfeld, B. Kersting
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Figure 3. Structure of the dizinc complex 14 with thermal ellipsoids
drawn at the 50% probability level. Only one orientation of the
disordered tert-butyl group is displayed. Hydrogen atoms are omit-
ted for reasons of clarity. Symmetry code used to generate equiva-
lent atoms: 1 – x, y, 0.5 – z (Ј).
Figure 5. Structure of the dinickel complex 13 with thermal ellip-
soids drawn at the 30% probability level. Only one orientation of
the disordered tert-butyl and the N-propyl group is displayed. Se-
lected bond lengths [Å] and angles [°]: Ni(1)···Ni(2) 3.319; Ni(1)–
N(1) 2.051(3), Ni(1)–N(2) 2.138(3), Ni(1)–N(3) 2.060(3), Ni(1)–
S(1) 2.2911(11), Ni(1)–S(2) 2.4065(13), Ni(2)–N(4) 1.991(3), Ni(2)–
N(5) 1.997(3), Ni(2)–S(1) 2.2140(13), Ni(2)–S(2) 2.2129(12); N(5)–
Ni(2)–S(2) 157.83(10), N(4)–Ni(2)–S(1) 171.76(10), N(2)–Ni(1)–
S(2) 176.86(9), N(1)–Ni(1)–S(1) 100.57(9), N(3)–Ni(1)–S(1)
113.77(10), N(1)–Ni(1)–N(3) 145.55(12).
Scheme 4. Schematic representation of the expansion of the bind-
ing pocket of the [(LR)M2(LЈ)]+ complexes upoing going from the
methylated (R = Me) to the propylated ligand system (R = Pr).
Figure 4. Structure of the dicobalt complex 18 with thermal ellip-
soids drawn at the 50% probability level. Hydrogen atoms are omit-
ted for reasons of clarity.
amine units. This is also normal for carboxylato-bridged
structures of this ligand system {e.g. [(LMe)M2(μ-OAc)]+, M pocket entrance, see for example, C(4)···C(26) in 10]. The
= CoII, NiII, and ZnII}. Hence, the differences in the metal– values range from 9.265 to 9.891 Å (Table 3). Two trends
nitrogen bond lengths are due to steric constraints of the are apparent. Firstly, the diameter increases with increasing
macrocycles.
length of the N-alkyl residues (e.g. compare 6 with 10). Sec-
ondly, the distances increase with increasing steric bulk of
the coligand with this latter trend being the more important
one (e.g. compare 10 with 12). This is indicative of intra-
molecular steric repulsions between the residues of the
bowl-shaped hosts and their guests.
Cavity Dimensions
As can be seen from Scheme 4, the four alkyl residues on
the four benzylic nitrogen atoms align with the two phenyl
rings. Thus, upon going from the methylated derivative to
the N-propylated macrocycle the binding pocket of the
[(LR)M2]2+ fragment expands to a sterically more encum-
bered, conical, calixarene-like cavity as schematically illus-
trated in Scheme 4.
Binding Mode of the Coligands
As expected, the acetate and ethyl carbonate coligands
bind to the [(LMe)M2]2+ fragment as bidentate μ1,3-bridges.
The dimensions of the binding cavities of the [(LMe)- Consequently, the M···M separations are almost equidistant
M2]2+ fragments can be described by the intramolecular dis- in these three compounds [average value is 3.491(1) Å]. The
tances between the two opposing aryl ring carbon atoms average metal–ligand bond lengths show no unusual fea-
bearing the tert-butyl groups [e.g. the diameter of the tures and compare well with those in 6.
2228
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 2223–2234

CoII, NiII, and ZnII Complexes of Hexaazamacrocyclic Dithiophenolates
FULL PAPER
Table 3. Selected bond lengths and angles of complexes 6, 10, 12, 14 and 18.
6
10
12
14
18
M(1)–O(1)
M(1)–N(1)
M(1)–N(2)
M(1)–N(3)
M(1)–S(1)
1.998(2)
2.281(2)
2.152(2)
2.251(2)
2.493(1)
2.448(1)
2.008(2)
2.244(2)
2.158(2)
2.295(2)
2.493(1)
2.451(1)
2.003(2)
2.230(2)
2.471(1)
3.483(1)
9.306
79.49(4)
79.45(3)
163.89(7)
170.28(5)
170.09(5)
163.84(7)
170.86(5
169.28(5)
80.8
1.990(6)
2.321(7)
2.158(6)
2.238(9)
2.517(3)
2.423(2)
1.985(5)
2.247(6)
2.174(6)
2.334(7)
2.507(2)
2.423(3)
1.988(6)
2.245(7)
2.468(3)
3.513(1)
9.622[d]
77.94(8)
78.11(8)
162.9(2)
167.4(2)
168.1(2)
160.9(2)
168.2(2)
167.68(16)
88.1
2.020(3)
2.293(4)
2.156(4)
2.291(4)
2.494(1)
2.441(1)
2.030(3)
2.253(4)
2.160(4)
2.340(4)
2.475(1)
2.430(1)
2.025(3)
2.248(4)
2.460(1)
3.520(1)
9.891[e]
78.26(5)
78.83(5)
164.81(14)
168.21(11)
168.31(10)
164.90(14)
169.16(10)
168.08(10
95.2
2.021(3)
2.362(3)
2.193(3)
2.418(3)
1.993(3)
2.292(4)
2.212(4)
2.387(4)
2.495(2)
2.502(2)
2.004(3)
2.313(4)
2.191(6)
2.312(5)
2.492(1)
2.538(2)
1.999(3)
2.285(5)
2.507(2)
3.482(1)
9.563[e]
2.565(1)
M(1)–S(2)
2.535(1) (S1Ј)[b]
2.021(3) (Zn1Ј-O1Ј)[b]
2.362(3) (Zn1Ј-N1Ј)[b]
2.193(3) (Zn1Ј-N2Ј)[b]
2.418(3) (Zn1Ј-N3Ј)[b]
2.565(1) (Zn1Ј-S1)[b]
2.535(1) (Zn1Ј-S1Ј)[b]
2.021(3)
M(2)–O(2)
M(2)–N(4)
M(2)–N(5)
M(2)–N(6)
M(2)–S(1)
M(2)–S(2)
M–O
M–N[a]
2.324(3)
2.550(3)
M–S[a]
M···M
3.459(1) (Zn1–Zn1Ј)[b]
9.265 (C4–C4Ј)[b]
82.20(5) (S1–Zn1–S1Ј)
82.20(5) (S1–Zn1Ј–S1Ј)
159.43(11)
C(4)···C(20)
S(1)–M(1)–S(2)
S(1)–M(2)–S(2)
O(1)–M(1)–N(2)
N(1)–M(1)–S(2)
N(3)–M(1)–S(1)
O(2)–M(2)–N(5)
N(4)–M(2)–S(1)
N(6)–M(2)–S(2)
Ph/Ph[c]
80.17(6
79.55(5)
158.40(15)
169.98(10)
168.51(10)
159.7(2)
169.74(11)
168.47(12)
83.8
172.35(8) (N1–Zn1–S1Ј)
168.60(8)
159.4(1) (O1Ј-Zn1Ј-N2Ј)
172.35(8) (N3Ј-Zn1Ј-S1)
168.60(8) (N1Ј-Zn1Ј-N2Ј)
76.0
[a] Average values. [b] Symmetry code used to generate equivalent atoms: 1 – x, +y, 0.5 – z (Ј). [c] Angle between the normals of the
planes of the two aryl rings. [d] C(4)···C(26). [e] C(4)···C(23).
Description of the Crystal Structure of [(HLEt)Ni2]-
(ClO4)3·3MeOH·H2O [13·(ClO4)3·3MeOH·H2O]
2,2Ј,2ЈЈ-terpyridine; Ni–N 2.057 Å, Ni–S 2.303 Å)[28] and
other trigonal-bipyramidal NiIIN3S2 complexes.[29] The me-
tal–ligand bonds involving the equatorial donor atoms are
shorter than the ones comprising the axial ones; an exactly
analogous situation is found in the terpy complexes. As a
consequence of the shorter metal–ligand bonds, the
metal···metal separation is smaller at 3.319 Å. Finally, it
should be noted that the two nickel(ii) ions are almost com-
pletely surrounded by the apolar N-ethyl substituents from
the macrocycle. This steric crowding about the coordina-
tively unsaturated dinickel site might explain its higher sta-
bility {relative to the very unstable [(HLMe)Ni2]3+ trication
of the permethylated macrocycle}.
¯
This salt crystallizes in the triclinic space group P1. Thes-
tructure revealed the presence of discrete dinuclear [(HLEt)-
Ni2]3+ trications, perchlorate anions, and methanol and
water molecules of solvent of crystallization. As can be seen
in Figure 5, this complex bears no coligands and features
two differently coordinated nickel atoms. One nickel atom
is coordinated in a distorted planar fashion by two cis-ori-
ented nitrogen atoms and two bridging thiophenolate sulfur
atoms. The other nickel ion is five-coordinate. The proton-
ated amine donor N(6) is out of range of bonding interac-
tions with the metal atoms and points away from them.
The coordination geometry of the four-coordinate nickel
ion is significantly distorted from square-planar towards
tetrahedral, as indicated by an N–Ni–N/S–Ni–S dihedral
angle of 23.80(2)° (mean deviation from plane 0.238 Å).
Summary and Conclusion
The following are the main findings of this investigation.
This is a rather large distortion from planarity. Other nickel a) N-Alkylated variants of H2LMe bearing ethyl and propyl
complexes with N2S2 coordination environments are more groups in place of the methyl functions can be readily pre-
rigorously square-planar, the tetrahedral twists from the pared by acylation of the parent hexaamine–dithioether
NiN2S2 planes not exceeding 15°.[26,27]
compound 1 followed by reduction of the amide and thi-
The coordination environment around the five-coordi- oether functions. b) The new ligands support the formation
nate nickel atom is distorted trigonal-bipyramidal with S(1), of dinuclear complexes of the type [(LR)M2(μ-LЈ)] with a
N(1) and N(3) occupying the equatorial and S(2) and N(2) bowl-shaped structure. c) The binding pocket of the com-
the axial positions. The angles in the equatorial plane devi- plexes expands to a more conical, “calixarene”-like cavity
ate by as much as 25.6° [N(1)–Ni(1)–N(3)] from the ideal upon going from the permethylated to the perpropylated
values of a perfect trigonal bipyramid. The average Ni–N ligand system. d) The rate of the substitution reactions and
and Ni–S distances of 2.083 and 2.349 Å are shorter than in the ability to fix small molecules is not drastically altered
the above bioctahedral species but compare well with those by the longer alkyl chains. e) Finally, it has been demon-
reported for [NiII(terpy)(S-2,4,6-(iPr)3C6H2)2] (terpy = strated that these highly functionalized ligand systems allow
Eur. J. Inorg. Chem. 2005, 2223–2234
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2229

M. Gressenbuch, V. Lozan, G. Steinfeld, B. Kersting
Compound H2LEt·6HCl: To
solution of sodium (3.45 g,
FULL PAPER
a
for the stabilization of reactive intermediates. These find-
ings can now be used as a guide to further modulate the
chemical reactivity of these compounds.
150.0 mmol) in liquid ammonia (150 cm3) was added a solution
of compound 4a (3.91 g, 5.00 mmol) in tetrahydrofuran (50 cm3)
dropwise at –78 °C. The resulting blue reaction mixture was stirred
at –78 °C for one additional hour to ensure complete deprotection
of the macrocycle. Solid ammonium chloride was added in small
portions at –78 °C to destroy excess reducing agent. The resulting
colourless suspension was allowed to warm to room temperature.
After 12 h, the remaining solvent was distilled off at reduced pres-
sure. The residue was taken up in water (50 mL) and the pH of the
suspension adjusted to ca. 1 to give a pale-yellow solution of H2LEt
as the hexahydrochloride salt. To remove the inorganic salts, the
solution was concentrated in vacuo to a volume of about 20 mL.
Methanol (ca. 60 mL) was then added and the resulting solution
was filtered from NaCl and NH4Cl. The latter two steps were re-
peated several times in this order, until no more salts precipitated
upon addition of MeOH. A 100-mL portion of ethanol was then
added. Upon standing for 1–2 h, the product precipiated as a pale-
Experimental Section
Materials and Methods: Compound 1 was prepared as described in
the literature.[9] All syntheses were carried out under argon. Melt-
ing points were determined in open glass capillaries and are uncor-
rected. NMR spectra were recorded with a Bruker AVANCE DPX-
200 spectrometer at 300 K. Chemical shifts refer to solvent signals.
Infrared spectra were recorded with a Bruker VECTOR 22 FT-IR
spectrometer and electronic absorption spectra with a Jasco V-570
UV/VIS/NIR spectrometer. Elemental analyses were carried out
with a VARIO EL elemental analyzer. CAUTION: Perchlorate salts
are potentially explosive and should therefore be prepared only in
small quantities and handled with appropriate care!
1
yellow solid (2.82 g, 58%). H NMR (200 MHz, D2O): δ = 1.29 [s,
18 H, ArC(CH3)3], 1.39 (m, 18 H, CH2CH3), 3.33 (m, 12 H,
CH2CH3), 3.75–3.90 [m, 16 H, N(CH2CH2)2], 4.59 (s br, 8 H,
ArCH2N), 7.56 (s, 4 H, ArH) ppm. 13C{1H} NMR (50 MHz,
D2O): δ = 9.09 (CH3), 9.21 (CH3), 31.49 [ArC(CH3)3], 34.90
[ArC(CH3)3], 47.41 (CH2), 48.73 (CH2), 50.19 (CH2), 50.39 (CH2),
Compound 3a: A solution of 1 (9.44 g, 15.4 mmol) in acetic anhy-
dride (90 mL) was stirred at 50 °C for 6 h. After the solvent was
distilled off at reduced pressure, the residue was taken up in aque-
ous potassium hydroxide solution (3 m, 100 mL) and dichlorometh-
ane (100 mL). The layers were separated and the aqueous phase
was extracted with dichloromethane (3×50 mL). The combined or-
ganic layers were washed with water (50 mL) and dried with anhy-
drous sodium sulfate. Evaporation of the solvent gave 3a as a white
solid (13.1 g, 98%). M.p. 236 °C. This material was used in the next
59.44 (CH2), 131.74 (CH), 132.00 (CAr), 147.00 (CAr), 149.00 (CAr
ppm. This compound was pure enough for the preparation of the
)
metal complexes. IR (KBr:) ν = 3407 vs, 2962 vs, 2624 vs, 1690 s,
˜
1630 m, 1451 vs, 1400 vs, 1231 m, 1161 s, 1031 s, 898 vs, 801 vs,
1
565 vs cm–1.
step without further purification. H NMR (200 MHz, CDCl3): δ
= 1.06–1.26 [m, 18 H, ArC(CH3)3], 1.94–2.23 (m, 18 H, NCOCH3),
2.82–3.35 (m, 20 H, NCH2CH2 and SCH2), 4.47–4.74 (m, 8 H,
Compound 3b: The preparation of this compound was analogous
to that of 3a, except that propionic anhydride was used instead of
acetic anhydride. 3b was obtained as a white solid (8.92 g, 94%).
M.p. 170–176 °C. This product was used in the next step without
further purification. 1H NMR (200 MHz, CDCl3): δ = 1.17 (m, 18
H, NCOCH2CH3), 1.25–1.36 [m, 18 H, ArC(CH3)3], 2.70 (m, 12
ArCH ), 6.91–7.10 (m, 4 H, ArH) ppm. IR (KBr): ν = 3456 m,
˜
2
2963 s, 2871 w, 1652 vs. ν(CO), 1559 vw, 1474 m, 1418 s, 1363 m,
1313 vw, 1238 w, 1195 w, 1131 vw, 1094 vw, 1062 vw, 1035 vw,
988 vw, 950 vw, 878 vw, 603 w cm–1. C46H68N6O6S2·CH3CO2H
(865.19 + 60.05): calcd. C 62.31, H 7.99, N 9.52, S 7.26; found C
62.33, H 8.79, N 9.23, S 6.66.
H, NCOCH2CH3), 3.06–3.68 [m, 20 H, N(CH2CH2N)2
+
ArSCH2], 4.90 (s, 8 H, ArCH2N), 7.00–7.06 (m, 4 H, ArH) ppm.
IR (KBr): ν = 3441 w, 2967 m, 2939 m, 2876 w, 1724 vw, 1648 vs,
˜
Compound 4a: A solution of 3a (8.65 g, 10.0 mmol) in tetra-
hydrofuran (50 mL) was added dropwise to a suspension of lithium
aluminium hydride (4.55 g, 120 mmol) in tetrahydrofuran
(200 mL). The reaction mixture was refluxed for 12 h. To the hot
reaction mixture was added water (10 mL) in small portions fol-
lowed by 3 m aqueous potassium hydroxide solution (30 mL). Care
should be taken during this step because of the violent reaction.
The reaction mixture was refluxed for an additional hour to ensure
complete hydrolysation of the aluminum salts. After cooling to
room temperature, the organic layer was decanted from a white
residue. This residue was extracted with boiling tetrahydrofuran
(3×100 mL). The combined organic layers were dried with anhy-
drous sodium sulfate. Evaporation of the solvent gave the title com-
pound as a yellowish oil which was used in the next step without
1563 vw, 1468 s, 1421 s, 1378 w, 1364 w, 1198 m, 1184 m, 1120 vw,
1079 w, 1052 w, 970 vw, 879 vw, 815 vw, 726 vw, 683 vw, 573 vw,
535 vw cm–1. C52H80N6O6S2 (949.36): calcd. C 65.79, H 8.49, N
8.85, S 6.76; found C 65.02, H 8.52, N 8.28, S 6.16.
Compound 4b: The preparation of this compound was analogous
to 3b. Compound 4b was obtained as a yellowish oil which crys-
tallized on standing. Recrystallization from ethanol gave 5.02 g
(58%) of analytically pure material. M.p. 128 °C. 1H NMR
(CDCl3, 200 MHz): δ = 0.77 (t, 3J = 7.2 Hz, 18 H, NCH2CH2CH3),
1.23 [s, 18 H, ArC(CH3)3], 1.14–1.40 (m, 12 H, NCH2CH2CH3),
2.26 (t, 3J = 7.2 Hz, 12 H, NCH2CH2CH3), 2.48 (s, 16 H,
NCH2CH2N), 2.63 (s, 4 H, ArSCH2), 3.60 (s, 8 H, ArCH2N), 7.45
(s, 4 H, ArH) ppm. 13C{1H} NMR (CDCl3, 75 MHz): δ = 12.3
(NCH2CH2CH3), 21.2(NCH2CH2CH3), 21.6 (NCH2CH2CH3),
31.8 [ArC(CH3)3], 35.2 [ArC(CH3)3], 35.7 (ArSCH2), 51.5 (CH2),
52.4 (CH2), 56.1 (CH2), 58.2 (CH2), 59.2 (CH2), 124.7 (CH), 127.7
1
further purification (6.80 g, 87%). H NMR (CDCl3, 200 MHz): δ
= 0.85–1.00 (m, 18 H, NCH2CH3), 1.23 [s, 18 H, ArC(CH3)3], 2.29–
2.55 (m, 28 H, NCH2CH3 and NCH2CH2N), 2.70 (s, 4 H, SCH2),
3.62 (s, 8 H, ArCH2N), 7.41 (s, 4 H, ArH) ppm. 13C{1H}NMR
(50 MHz, CDCl3): δ = 13.6, 13.8 (CH3), 32.5 [ArC(CH3)3], 35.8
[ArC(CH3)3], 37.0 (ArSCH2), 49.0 (CH2), 51.0 (CH2), 52.3 (CH2),
53.0 (CH2), 58.7 (CH2), 125.8 (CH), 129.1 (CAr), 145.0 (CAr), 152.1
(CAr), 144.2 (CAr), 151.4 (CAr) ppm. IR (KBr): ν = 2958 s, 2933 s,
˜
2870 m, 2817 m, 1460 m, 1404 w, 1380 w, 1361 w, 1079 m, 893 w,
647 w cm–1. C52H92N6S2 (865.46): C 72.16, H 10.71, N 9.71, S 7.41;
found C 71.92, H 10.86, N 9.60, S 7.30.
(CAr) ppm. IR (Nujol): ν = 3417 m, 2964 vs, 2869 s, 2809 s,
˜
2354 vw, 2327 vw, 1730 vw, 1713 vw, 1691 vw, 1659 vw, 1642 vw, Compound H2LPr·6HCl: The preparation of this compound was
1631 vw, 1600 w, 1555 vw, 1513 vw, 1463 m, 1383 m, 1363 m, analogous to H2LEt·6HCl, except that 4b (4.32 g, 5.00 mmol) was
1292 w, 1262 s, 1223 w, 1173 w, 1096 s, 1073 s, 865 vw, 802 s,
710 vw, 663 vw cm–1.
used as the starting material. The hydrochloride was obtained as a
pale-yellow solid (3.33 g, 63%). 1H NMR (200 MHz, D2O): δ =
2230
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 2223–2234

CoII, NiII, and ZnII Complexes of Hexaazamacrocyclic Dithiophenolates
0.71 (t, 3J = 7.2 Hz, 18 H, NCH2CH2CH3), 1.04 [s, 18 H, C- [(LEt)Ni2(μ-O2COMe)]ClO4 (11·ClO4): To a solution of 7·ClO4
FULL PAPER
(CH3)3], 1.60–1.35 (m, 12 H, NCH2CH2CH3), 2.87 (m, 12 H,
NCH2CH2CH3), 3.44 (m, 16 H, NCH2CH2N), 4.30 (s, 8 H,
(201 mg, 0.200 mmol) in a mixture of MeOH/H2O (40 mL/ 5 mL)
was added finely ground NaOH (20 mg, 0.50 mmol). The color of
ArCH2N), 7.25 (s, 4 H, ArH) ppm. 13C{1H} NMR (50 MHz, the reaction mixture turned from yellow to green. The reaction
D2O): δ = 10.4 (CH3), 17.2 (CH2), 17.4 (CH2), 30.7 [ArC(CH3)3], mixture was exposed to air and stirred at room temperature for
34.8 [ArC(CH3)3], 35.5 (CH2), 47.3 (CH2), 48.7 (CH2), 56.0 (CH2), 24 h. A solution of LiClO4·3H2O (1.00 g, 6.25 mmol) in methanol
59.6 (CH2), 61.9 (CH2), 131.1 (CH), 134.3 (CAr), 147.9 (CAr), 158.4 (2 mL) was then added. The green microcrystalline solid was iso-
(CAr) ppm. IR (KBr): ν = 3427 w, 2967 vw, 2878 w ν(CH), 2465 w,
1629 s ν(CO), 1471 w, 1384 m, 1364 m, 1300 s, 1200 m, 1150 m,
1051 s, 996 s, 967 s, 806 vs, 755 vs, 601 vs cm–1. This compound was
pure enough for the preparation of the metal complexes.
lated by filtration, washed with methanol and dried in vacuo. The
yield was 182 mg (87%). M.p. 284–285 °C (decomp.). UV/Vis
˜
(CH3CN): λmax (ε) = 670 (20), 1138 nm (49 m–1 cm–1). IR (KBr): ν
˜
= 3446 m, 2964 vs, 2901 m, 2357 vs, 1716 vw, 1638 vs νasym(CH3-
–
–
OCO2 ), 1450 vs, 1384 m, 1331 vs νsym(CH3OCO2 ), 1261 w,
[(LEt)Ni2(Cl)]ClO4 (7·ClO4): To a suspension of H2LEt·6HCl
(974 mg, 1.00 mmol) in methanol (40 mL) was added a solution of
NiCl2·6H2O (475 mg, 2.00 mmol) in methanol (2 mL). A solution
of Et3N (810 mg, 8.00 mmol) in methanol (2 mL) was then added
to give a dark red solution. After stirring at room temperature for
3 d, the product was precipitated by the addition of solid
LiClO4·3H2O (2.50 g, 15.6 mmol). The yellow microcrystalline so-
lid was isolated by filtration, washed with 5 mL of cold ethanol
and 5 mL of ether, and dried in vacuo. This material was recrys-
tallized once from a few milliliters of acetonitrile. Yield: 824 mg
–
1232 w, 1101 vs, ν(ClO4 ), 987 vw, 950 vw, 908 vw, 979 vw, 785 s,
625 m, 581 vw, 560 vw cm–1. UV/Vis (CH3CN): λmax (ε) = 350
(2384), 668 (22), 1136 nm (84 m–1 cm–1). C46H79ClN6Ni2O7S2
(1045.13): calcd. C 52.86, H 7.62, N 8.04, S 6.14; found C 52.26,
H 7.67, N 7.90, S 5.71.
[(LEt)Ni2(μ-O2COEt)]ClO4 (12·ClO4): The complex 11·ClO4
(105 mg, 0.100 mmol) was dissolved in acetonitrile (20 mL). To the
green solution was added ethanol (20 mL) and the reaction mixture
was stirred at room temperature for 24 h. The solution was concen-
trated in vacuo to about 5 mL whereupon a pale-green precipitate
formed. The precipitate was filtered, washed with a few milliliters
of cold ethanol and dried in air. Yield: 75 mg (71%). M.p. 295 °C
(82%). M.p. 305 °C (decomp.). IR (KBr) ν = 3445 m, 2961 m,
˜
–
2894 w, 2361 vw, 1631 w, 1460 m, 1381 w, 1100 vs ν(ClO4 ), 912 w,
884 w, 778 w, 733 w, 627 m cm–1. UV/Vis (CH3CN): λmax (ε) = 384
(2070), 480 sh (430), 659 (30), 930 (53), 1026 nm (76 m–1 cm–1).
C44H76Cl2N6Ni2O4S2 (1005.53): calcd. C 52.56, H 7.62, N 8.36, S
6.38; found C 52.40, H 7.47, N 8.42, S 6.49.
(decomp.). IR (KBr): ν = 3453 m, 2965 vs ν(CH), 2900 s, 1638 vs
˜
–
νasym(CH3CH2OCO2 ), 1449 vs, 1384 m, 1330 vw, 1316 vs
–
νsym(CH3CH2OCO2 ), 1248 w, 1231 m, 1187 w, 1151 m, 1101 vs
–
ν(ClO4 ), 1056 s, 987 vw, 949 vw, 908 vw, 878 vw, 806 w, 785 m,
[(LPr)Ni2(Cl)]ClO4 (8·ClO4): The preparation of this compound
was similar to that of 7·ClO4, except that the reaction mixture was
stirred for 1 week. The compound was obtained as yellow micro-
crystals and purified by recrystallization from acetonitrile. Yield:
756 w, 628 m, 582 vs, 560 vs cm–1. UV/Vis (CH3CN): λmax (ε) =
350 (2550), 668 (28), 1140 nm (79 m–1 cm–1). C47H81ClN6Ni2O7S2
(1059.15): calcd. C 53.30, H 7.71, N 7.93, S 6.05; found C 52.48,
H 7.65, N 7.76, S 5.85. The tetraphenylborate salt, [(LEt)Ni2(μ-
O2COEt)]BPh4 (12·BPh4), was prepared by adding NaBPh4
(342 mg, 1.00 mmol) to a solution of [(LEt)Ni2(μ-O2COEt)]ClO4
(106 mg, 0.100 mmol) in methanol (40 mL). The pale-green micro-
crystalline solid was isolated by filtration, washed with ethanol and
dried in air. Yield: 116 mg (91%). M.p. 293–294 °C (decomp). IR
37%. M.p. 274 °C (decomp.). IR (KBr): ν = 3435 vs, 2964 vs,
˜
2874 s, 2741 vw, 2665 vw, 2381 vw, 2179 vw, 2061 s, 1732 vw, 1630 s,
1607 s, 1464 s, 1365 m, 1328 vw, 1261 w, 1233 w, 1108 vs, 926 w,
912 w, 882 w, 805 m, 751 w, 629 s, 559 m cm–1. UV/Vis (CH3CN):
λmax (ε)
=
674 (26), 931 (54), 1023 nm (74 m–1 cm–1).
C50H88Cl2N6Ni2O4S2·CH3CN·3H2O (1089.69 + 41.05 + 54.06):
calcd. C 52.71, H 8.25, N 8.28; found C 52.90, H 8.35, N 8.17.
(KBr): ν = 3442 s ν(OH), 3056 s ν(ArH), 2968 vs ν(CH), 2903 s
˜
–
ν(CH), 1634 vs νasym(CH3CH2OCO2 ), 1579 m, 1478 s, 1463 s,
1427 m, 1397 m, 1373 m, 1316 vs νsym(CH3CH2OCO2 ), 1261 w,
[(LEt)Ni2(OAc)]ClO4 (9·ClO4): To a solution of 7·ClO4 (97.4 mg,
0.100 mmol) in methanol (25 mL) was added a solution of sodium
acetate (16.4 mg, 0.200 mmol) in methanol (10 mL). After stirring
for 2 h, solid LiClO4·3H2O (160 mg, 1.00 mmol) was added. The
resulting pale-green precipitate was isolated by filtration, washed
with methanol and dried in air. This material was recrystallized
once from a mixed acetonitrile/ethanol solvent system. Yield:
–
1231 w, 1185 m, 1154 m, 1102 s, 1056 s, 948 vw, 909 vw, 879 vw,
–
–
854 vw, 803 w, 744 vs ν(BPh4 ), 715 vs ν(BPh4 ), 628 w, 612 w,
560 w cm–1. UV/Vis (CH3CN): λmax (ε) = 668 (27), 1140 nm
(70 m–1 cm–1). The tetraphenylborate salt was additionally charac-
terized by X-ray crystal structure analysis.
[(HLEt)Ni2](ClO4)3 (13·(ClO4)3): To a solution of 7·ClO4 (101 mg,
0.100 mmol) in MeOH (30 mL) was added Pb(ClO4)2 (40.6 mg,
0.100 mmol). The resulting dark green solution was stored at room
temperature for 12 h during which a few crystals of the title com-
pound precipitated as dark green crystals. Yield: 16 mg (13%). The
1H NMR spectra obtained for the trication are broad with chemi-
cal shifts ranging from δ = +200 to –50 ppm and almost completely
collapse into the base line, indicative of a paramagnetic species.
UV/Vis (CH3CN): λmax (ε) = 574 (850), 1016 nm (50 m–1 cm–1).
This compound was additionally characterized by X-ray crystal
structure analysis.
73.5 mg (66%). M.p. 332 °C (decomp.). IR (KBr): ν = 3446 m,
˜
2964 vs, 2900 s, 2359 vw, 1714 vw, 1589 s νasym(OAc–), 1426 s
νsym(OAc–), 1383 s, 1326 w, 1313 w, 1248 w, 1231 m, 1202 vw,
–
1187 vw, 1151 m, 1101 vs ν(ClO4 ), 987 w, 949 w, 928 vw, 907 w,
878 w, 783 m, 756 vw, 664 w, 623 s, 581 vw, 558 vw cm–1. UV/Vis
(CH3CN): λmax (ε) = 345 (1596), 660 (29), 1180 nm (79 m–1 cm–1).
C46H79ClN6Ni2O6S2 (1029.13): calcd. C 53.69, H 7.74, N 8.17, S
6.23; found C 53.34, H 7.72, N 8.10, S 6.08.
[(LPr)Ni2(μ-O2CCH3)]ClO4 (10·ClO4): This compound was pre-
pared by the method detailed above for 9·ClO4. Yield: 75.7 mg
(68%). M.p. 319 °C (decomp.). IR (KBr): ν = 3445 m, 2963 vs,
˜
2872 m, 1589 s νasym(OAc–), 1457 m, 1428 m νsym(OAc–), 1365 w,
[(LEt)Zn2(OAc)]ClO4 (14·ClO4): To a suspension of H2LEt·6HCl
–
1312 w, 1332 w, 1151 m, 1092 vs νs(ClO4 ), 1061 vs, 937 w, 911 w, (974 mg, 1.00 mmol) in methanol (50 mL) was added a solution of
876 w, 813 w, 755 w, 663 w, 626 m, 529 w cm–1. UV/Vis (CH3CN): Zn(OAc)2·2H2O (439 mg, 2.00 mmol) in methanol (5 mL). A solu-
λmax (ε) = 662 (29), 1183 nm (77 m–1 cm–1). C52H91ClNi2N6O6S2
(1113.29): calcd. C 56.10, H 8.24, N 7.55, S 5.76; found C 56.49,
H 8.42, N 7.17, S 5.48.
tion of triethylamine (810 mg, 8.00 mmol) in methanol (1 mL) was
added and the resulting clear solution was stirred at room tempera-
turefor 12 h. Solid LiClO4·3H2O (1.60 g, 10.0 mmol) was then
Eur. J. Inorg. Chem. 2005, 2223–2234
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M. Gressenbuch, V. Lozan, G. Steinfeld, B. Kersting
FULL PAPER
added. The resulting colorless precipitate was isolated by filtration,
washed with methanol and dried in air. Yield: 830 mg (80%). M.p.
776 m, 732 vw, 674 vw, 624 m cm–1. UV/Vis (CH3CN): λmax (ε) =
342 (2401), 470 (602), 548 sh (174), 578 (161), 1280 nm
(28 m–1 cm–1). C44H76Cl2Co2N6O4S2·H2O (1006.01 + 18.02): calcd.
282–284 °C (decomp.). IR (KBr): ν = 3442 m, 2964 vs, 2899 s,
˜
1585 s νasym(OAc–), 1464 s, 1442 vw νsym(OAc–), 1385 m, 1329 w, C 51.61, H 7.68, N 8.21, S 6.26; found C 51.20, H 7.39, N 8.37, S
–
1252 w, 1230 w, 1149 m, 1100 vs ν(ClO4 ), 1056 vs, 947 vw, 906 w, 6.25.
884 w, 782 w, 656 vw, 625 s, 578 vw, 553 vw cm–1. 1H NMR
[(LEt)Co2(OAc)]ClO4 (18·ClO4): A solution of sodium acetate
(41 mg, 0.50 mmol) in methanol (5 mL) was added to a solution of
[(LEt)Co2(μ-Cl)]ClO4 (202 mg, 0.200 mmol) in methanol (40 mL).
The mixture was stirred for 1 h, during which the color of the solu-
tion turned to light brown. A solution of LiClO4·3H2O (320 mg,
2.00 mmol) in methanol (2 mL) was added. The resulting light
brown solid was isolated by filtration, washed with cold methanol
and dried in air. This compound was recrystallized once from a
mixed acetonitrile/ethanol (1:1) solvent system. Yield: 152 mg
(300 MHz, CD3CN, 25 °C, TMS): δ = 7.13 (s, 4 H, ArH), 4.12 (d,
2
2J = 12.0 Hz, 4 H, ArCH2), 3.21 (d, J = 12.0 Hz, 4 H, ArCH2),
3
3.60–2.60 (m, 28 H, NCH2CH2 + NCH2), 1.25 (t, J = 7.0 Hz, 6
H, NCH2CH3), 1.23 [s, 18 H, C(CH3)3], 1.16, (t, 3J = 7.0 Hz, 12 H,
NCH2CH3), 0.83 (s, 3 H, CO2CH3) ppm. 13C{1H} NMR (75 MHz,
CD3CN, 25 °C, TMS): δ = 174.74 (C=O), 145.96 (C), 143.85 (C),
135.65 (C), 128.30 (CH), 54.96, 54.17, 53.47, 53.16, 47.53 (all CH2),
34.53 [C(CH3)3], 31.55 [C(CH3)], 23.12 (COCH3), 6.87
(ArCH2NCH2CH3), 4.58 (NCH2CH3). The tetraphenylborate salt,
[(LEt)Zn2(OAc)]BPh4 (14·BPh4), was prepared by adding NaBPh4
(342 mg, 1.00 mmol) to a solution of [(LEt)Zn2(OAc)]ClO4 (104 mg,
0.100 mmol) in methanol (50 mL). The colorless, microcrystalline
solid was isolated by filtration, washed with methanol and dried in
(74%). M.p. 337–338 °C (decomp.). IR (KBr): ν = 3442 m, 2964 vs,
˜
2898 s, 1588 vs νasym(OAc–), 1440 vs νsym(OAc–), 1384 s, 1361 m,
–
1326 w, 1314 w, 1249 w, 1230 s, 1187 vw, 1152 m, 1100 vs ν(ClO4 ),
1055 s, 986 w, 948 w, 928 w, 906 w, 880 w, 783 m, 755 vw, 653 w,
626 s cm–1. UV/Vis (CH3CN): λmax (ε) = 338 (2203), 440 (610), 528
(204), 1288 nm (44 m–1 cm–1). CV (CH3CN, 295 K, 0.1 m
air. Yield: 115 mg (91%). M.p. 246–248 °C (decomp.). IR (KBr): ν
˜
–
= 1582 s νasym(OAc–), 1440 s νsym(OAc–), 703, 732 ν(BPh4 ) cm–1.
nBu4NPF6, ν = 100 mV/s; E (vs. SCE): E1 = +0.27 V (ΔEp
=
1/2
0.126 V), E2 = +0.64 V (ΔEp = 0.131 V). The tetraphenylborate
C70H99BN6O2S2Zn2 (1262.30): calcd. C 66.60, H 7.91, N 6.66, S
5.08; found C 66.89, H 7.85, N 6.45, S 4.84. Compound 14·ClO4
was also characterized by X-ray crystal structure analysis.
1/2
salt, [(LEt)Co2(OAc)] BPh4 (18·BPh4), was prepared by adding
NaBPh4 (342 mg, 1.00 mmol) to
a
solution of [(LEt)Co2(μ-
[(LEt)Co2(μ-Cl)]ClO4 (17·ClO4): To a suspension of H2LEt·6HCl
(974 mg, 1.00 mmol) in methanol (40 mL) was added a solution of
CoCl2·6H2O (476 mg, 2.00 mmol) in methanol (2 mL). A solution
of Et3N (810 mg, 8.00 mmol) in methanol (2 mL) was then added
to give a dark red solution. After stirring at room temperature for
3 d, the product was precipitated by the addition of solid
LiClO4·3H2O (2.50 g, 15.6 mmol). The red microcrystalline solid
was isolated by filtration, washed with 5 mL of cold ethanol and
5 mL of ether, and dried in vacuo. This material was recrystallized
once from a few milliliters of acetonitrile. Yield: 765 mg (76%).
O2CCH3)] ClO4 (103 mg, 0.100 mmol) in methanol (50 mL). The
light brown microcrystalline solid was isolated by filtration, washed
with methanol and dried in air. Yield: 113 mg (90%). M.p. 318–
319 °C (decomp.). IR (KBr): ν = 3437 m, 3055 s ν(Ar), 2968 vs,
˜
2866 s, 1582 vs νasym(OAc–), 1440 vs νsym(OAc–), 1383 m, 1326 w,
1310 w, 1248 w, 1231 w, 1185 vw, 1154 w, 1100 m, 1057 vs, 1033 w,
–
987 vw, 951 vw, 909 w, 882 w, 844 vw, 780 m, 732 s ν(BPh4 ), 704 vs
–
ν(BPh4 ), 653 vw, 626 w, 612 m, 579 vw, 557 vw cm–1. UV/Vis
(CH3CN): λmax (ε) = 442 (597), 528 (196), 1294 nm (43 m–1 cm–1).
C70H99BCo2N6O2S2 (1249.38): calcd. C 67.29, H 7.99, N 6.73, S
5.13; found C 66.96, H 7.73, N 7.03, S 4.95.
M.p. 313 °C (decomp.). IR (KBr): ν = 3443 s, 2963 vs, 2867 s,
˜
2354 vw, 1730 vw, 1696 vw, 1634 w, 1556 vw, 1540 vw, 1518 vw, Crystal Structure Determinations: Single crystals of [(LPr)Ni2(OAc)]·
1478 s, 1463 s, 1382 m, 1327 w, 1278 vw, 1251 w, 1231 w, 1202 vw, ClO4·MeOH (10·ClO4·MeOH), [(HLEt)Ni2]·3ClO4·3MeOH·H2O
1159 m, 1099 vs ν(ClO4 ), 987 vw, 956 vw, 913 vw, 884 w, 803 vw, (13·3ClO4·3MeOH·H2O)
and
[(LEt)Zn2(OAc)]·ClO4·MeOH
–
Table 4. Crystallographic data for complexes 10, 12, 13, 14, and 18.
Compound
10·ClO4·MeOH
12·BPh4·MeCN·EtOH
13·(ClO4)3·3MeOH·H2O 14·ClO4·2MeOH
18·BPh4·EtOH
Empirical formula
Mr [g/mol]
Space group
a [Å]
b [Å]
c [Å]
C53H95ClN6Ni2O7S2
1145.34
P21/n
14.810(3)
20.793(4)
21.376(4)
90
108.78(3)
90
6232(2)
4
1.221
0.45×0.30×0.30
0.764
3.50–56.76
39885
C75H110BN7Ni2O4S2
1366.05
P21/n
16.346(3)
29.155(6)
16.945(3)
90
114.22(3)
90
7365(2)
C47H91Cl3N6Ni2O16S2
1284.15
P1
13.551(3)
14.076(3)
16.661(3)
77.77(3)
89.92(3)
75.24(3)
2999(1)
C47H83ClN6O7S2Zn2
1074.50
C2/c
16.385(3)
29.778(6)
13.310(3)
90
123.56(3)
90
5412(2)
4
1.358
0.35×0.26×0.18
1.064
4.58–56.70
17437
C72H102BCo2N7O2S2
1290.40
P21/c
15.734(3)
26.293(5)
18.319(4)
90.00
112.14(3)
90.00
7019.7(24)
4
1.221
0.30×0.20×0.20
0.580
2.80–56.62
44376
¯
α [°]
β [°]
γ [°]
V [Å3]
Z
4
2
dcalcd. [g/cm3]
Crystal size [mm]
1.232
0.30×0.15×0.15
0.620
2.80–56.66
46840
1.421
0.20×0.20×0.20
0.899
3.06–56.62
27268
μ(Mo-Kα) [mm–1
2θ limits [°]
]
Measured reflections
Independent reflections 15063
17670
8078
791
0.0779 (0.1497)
0.1966 (0.2369)
1.129/–1.888
14028
7533
697
0.0540 (0.1117)
0.1229 (0.1529)
0.770/–0.742
6519
2860
341
0.0434 (0.1373)
0.0858 (0.1133)
0.386/–0.523
16817
6415
748
0.0717 (0.1676)
0.1805 (0.2100)
1.583/–0.672
Observed reflections[a]
Number of parameters
R1[b] (R1 all data)
3609
604
0.0774 (0.2867)
0.1928 (0.2636)
1.237/–0.653
wR2[c] (wR2 all data)
Max/min peaks [e/Å3]
[a] Observation criterion: I Ͼ 2σ(I). [b] R1 = Σ||Fo| – |Fc||/Σ|Fo|. [c] wR2 = {Σ[w(Fo – Fc ) ]/Σ[w(Fo2)2]}1/2
.
2
2 2
2232
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Inorg. Chem. 2005, 2223–2234

CoII, NiII, and ZnII Complexes of Hexaazamacrocyclic Dithiophenolates
FULL PAPER
37, 2732–2735; b) Y. Rondelez, G. Bertho, O. Reinaud, Angew.
Chem. 2002, 114, 1086–1088; Angew. Chem. Int. Ed. 2002, 41,
1044–1046.
(14·ClO4·MeOH) were taken directly from the reaction mixtures.
Crystals of [(LEt)Ni2(O2COEt)]BPh4·MeCN·EtOH (12·BPh4·
MeCN·EtOH) and [(LEt)Co2(OAc)]BPh4·EtOH (18·BPh4·EtOH)
were grown by recrystallization from an acetonitrile/ethanol (1:1)
mixed solvent system. The crystals were mounted on glass fibers
using perfluoropolyether oil. Intensity data were collected at
210(2) K, using a Bruker SMART CCD diffractometer. Graphite-
[4] a) M. T. Reetz, S. R. Waldvogel, Angew. Chem. 1997, 109, 870–
873; Angew. Chem. Int. Ed. Engl. 1997, 36, 865–867; b) M. T.
Reetz, Catal. Today 1998, 42, 399.
[5] For reviews of cyclodextrins, see: Chem. Rev. 1998, 98, 1741–
2076 (special issue).
monochromated Mo-Kα radiation (λ = 0.71073 Å) was used
throughout. Crystallographic data of the compounds are listed in
Table 4. The data were processed with SAINT[30] and corrected for
absorption using SADABS[31] [transmission factors: 1.00–0.92 (10,
13), 1.00–0.89 (12, 18), 1.00–0.87 (14)]. The structures were solved
by using the program SHELXS-86.[32] Refinements were carried
out with the program SHELXL-97.[33] PLATON was used to se-
arch for higher symmetry.[34] ORTEP-3 was used for the artwork of
the structures.[35] Where appropriate, all non-hydrogen atoms were
refined anisotropically. Hydrogen atoms were assigned to idealized
positions and given isotropic thermal parameters 1.2 times (1.5
times for CH3 groups) the thermal parameter of the atoms to which
they were attached. In the crystal structure of 10·ClO4·MeOH a
[6]
a) N. Kitajima, W. B. Tolman, Prog. Inorg. Chem. 1995, 43,
419–531; b) S. Trofimenko, Scorpionates: The Coordination
Chemistry of Polypyrazolylborate Ligands; Imperial College
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[10] B. Kersting, G. Steinfeld, Chem. Commun. 2001, 1376–1377.
[11] B. Kersting, Angew. Chem. 2001, 113, 4109–4112; Angew.
Chem. Int. Ed. 2001, 40, 3987–3990.
[12] G. Steinfeld, V. Lozan, B. Kersting, Angew. Chem. 2003, 115,
2363–2365; Angew. Chem. Int. Ed. 2003, 42, 2261–2263.
[13] K. Wieghardt, P. Chaudhuri, B. Nuber, J. Weiss, Inorg. Chem.
1982, 21, 3086–90.
–
propyl group, a tert-butyl group and a ClO4 ion were found to be
disordered over two positions. The site occupancies of the respec-
tive positions were refined as follows: C(18a)–C(20A)/C(18b)–
C(20b) 0.50(2)/0.50(2); C(48a)–C(50a)/C(48b)–C(50b): 0.55(2)/
0.45(2); O(3a)–O(6a)/O(3b)–O(6b) 0.70(1)/0.30(1). The C and O
atoms of the disordered groups and the solvate molecules were re-
fined isotropically. In the crystal structure of 12·BPh4·MeCN·EtOH
the C, N, and O atoms of the solvate molecules were refined iso-
tropically. In the crystal structure of 13·3ClO4·3MeOH·H2O one
tert-butyl group and two methanol molecules of solvent of crystalli-
zation were found to be disordered over two positions [C(42a)–
C(44a)/C(42b)–C(44b) 0.53(2)/0.47(2); O(14)–C(45a)/O(14)–C(45b)
0.57(2)/0.43(2), and O(15a)–C(46a)/O(15b)–C(46b) 0.47(2)/0.53(2)].
In the crystal structure of 14·ClO4·MeOH a tert-butyl group and
the counteranion were found to be disordered over two positions
[14]
[15]
[16]
N. W. Alcock, A. C. Benninston, S. J. Grant, H. A. A. Omar,
P. Moore, J. Chem. Soc. Chem. Commun. 1991, 1573–1575.
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Chem. 2003, 629, 2083–2090.
[17]
Complex 5·ClO4 is also readily dehalogenated with Pb(ClO4)2.
However, the resulting [(HLMe)Ni2]3+ intermediate reacts in-
–
stantaneously with a ClO4 anion to give the perchlorate com-
plex [(LMe)Ni2(μ1,3-ClO4)]+. The structure of this compound
will be reported elsewhere.
[C(20a)–C(22a)/C(20b)–C(22b)
0.47(2)/0.53(2);
O(2a),O(3a)/
(O2b),O(3b) 0.71(2)/0.29(2)]. In the crystal structure of
18·BPh4·EtOH one tert-butyl group was found to be disordered
over two positions at site occupancies of 0.53(2) [C(42a)-C(44a)]
and of 0.47(2) [C(42b)-C(44b)]. The C and O atoms of the solvate
molecule and the disordered groups were refined isotropically.
CCDC-259281 (10), -259282 (12), -259283 (13), -259284 (14) and
-259285 (18) contains the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
[18]
[19]
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B. Kersting, G. Steinfeld, Inorg. Chem. 2002, 41, 1140–1150.
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7
The high-spin d configuration for the present cobalt(ii) com-
plexes is also supported by temperature-dependent magnetic
susceptibility measurements. The results of these studies will be
reported in due course.
J. Hausmann, S. Käss, S. Klod, E. Kleinpeter, B. Kersting, Eur.
J. Inorg. Chem. 2004, 4402–4411.
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Am. Chem. Soc. 1991, 113, 1421–1423; c) R. M. Buonomo, I.
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Acknowledgments
[24]
[25]
We are particularly grateful to Prof. Dr. H. Vahrenkamp for provid-
ing facilities for NMR and X-ray crystallographic measurements.
Financial support of this work from the Deutsche Forschungsge-
meinschaft (Priority programme “Sekundäre Wechselwirkungen”,
KE 585/3-1,2) is gratefully acknowledged.
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Eur. J. Inorg. Chem. 2005, 2223–2234
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