Novel synthesis of macrocyclic amine-thiophenolate ligands: X-ray crystal structure of a Ni4 complex of an N8S4 ligand

Article abstract of DOI:10.1002/(SICI)1099-0682(199912)1999:12<2167::AID-EJIC2167>3.0.CO;2-F

A novel route to macrocyclic amine-thiophenolate ligands is described. The new, air-stable thiophenolate precursor 1,2-bis(4-tert-butyl-2,6- diformyl-phenylsulfanyl) ethane (4) is readily condensed with two equivalents of 1,2-ethanediamine or 1,3-propaned

Full text of DOI:10.1002/(SICI)1099-0682(199912)1999:12<2167::AID-EJIC2167>3.0.CO;2-F

FULL PAPER
Novel Synthesis of Macrocyclic Amine-Thiophenolate Ligands:
X-ray Crystal Structure of a Ni4 Complex of an N8S4 Ligand
Berthold Kersting,*[a] Gunther Steinfeld,[a] Thorsten Fritz,[a] and Julia Hausmann[a]
Keywords: Macrocyclic compounds / Amine-Thiolate Donors / Polynuclear Complexes / Nickel / Condensation reactions
A novel route to macrocyclic amine-thiophenolate ligands is
described. The new, air-stable thiophenolate precursor 1,2-
bis(4-tert-butyl-2,6-diformyl-phenylsulfanyl)ethane (4) is
readily condensed with two equivalents of 1,2-
ethanediamine or 1,3-propanediamine under medium to
high dilution conditions to give 2 × 4 condensation products.
The smaller 1 × 2 macrocyclic compounds are not produced
preparation of polynuclear transition metal complexes. With
divalent nickel H46a forms the di- and tetranuclear
complexes [Ni2(6a)] (7) and [Ni4(6a)][ClO4]4 (8). Reaction of
8
with four equivalents of NH4SCN yields the novel
isothiocyanate complex [Ni4II(6a)(NCS)4]·10MeCN (9). The
structure consists of well-separated molecules of the
tetranuclear complex [NiII4(6a)(NCS)4] (Ci symmetry). Two
under these conditions. Subsequent reduction with NaBH4 symmetry-related binuclear [N2Ni(µ2-SR)2NiN4] fragments
(reduction of imine groups) and Na/NH3 (reductive cleavage
of aryl-alkylsulfides) provides the 36- and 40-membered
amine-thiophenolate ligands H46a and H46b. The
composed of thiolate-bridged distorted planar {N2S2Ni}- and
distorted cis-octahedral {(SCN)2N2S2Ni} units reside within
the cavity of the macrocycle. The intramolecular distance
˚
macrocyclic compounds are versatile ligands for the between the two binuclear units is 6.144(1) A.
corresponding imino- and aminothiophenolates.[11][12] This
is true in particular for larger macrocyclic NxSy com-
Introduction
pounds.[13] To the best of our knowledge, all the macro-
cyclic NxSy compounds described to date have been ob-
tained by metal template condensations using the air-sensi-
tive compound 2,6-diformyl-4-methyl-thiophenol as start-
ing material.[14]
We describe here an alternative route to macrocyclic am-
ine-thiophenolate ligands by employing the air-stable thio-
phenolate precursor, 1,2-bis(4-tert-butyl-2,6-diformylphen-
ylsulfanyl)ethane (4). The tetraaldehyde is readily con-
densed with aliphatic α,ω-diamines, and subsequent re-
duction of the intermediate thioether/imine compounds
provides the 36- and 40-membered ligands H46a,b. This is
demonstrated by the solid-state structure of [Ni4-
(6a)(NCS)4]и10MeCN.
One of the most efficient syntheses of macrocyclic amine
phenolate ligands such as H21 (Scheme 1) involves a Schiff
base condensation of 2,6-diformyl-4-methyl-phenol with an
aliphatic α,ω-diamine in the presence of a labile first-row
transition metal ion. Since its discovery by Robson and co-
workers in 1970,[1] this reaction has been applied to a large
variety of such ligands because they are ideally suited to
prepare homo- and heterodinuclear and mixed-valence
complexes.[2Ϫ7] Higher condensation products,[8][9] such as
the 36-membered amine-phenolate ligand H42,[10] can also
be obtained by this method.
Results and Discussion
Ligand Syntheses
The synthesis of the new octaamine-tetrathiophenol com-
pounds H46a,b·8HCl was accomplished in three steps em-
ploying 4-tert-butyl-2,6-diformylbromobenzene 3 as start-
ing reagent (Scheme 2). In the first step, compound 3 was
reacted with dipotassium 1,2-ethanedithiolate in DMF in a
2:1 stoichiometric ratio to give the tetraaldehyde 4 in nearly
quantitative yield. Condensation of 4 with two equivalents
of 1,2-ethanediamine in a CH2Cl2/MeOH mixed solvent
system under high-dilution conditions, followed by sodium
borohydride reduction of the intermediate imine-thioether
product, gave the amine-thioether compound 5a in yields
greater than 80%. The smaller 1 ϫ 2Ϫcondensation prod-
uct, i.e. the 18-membered N4S2 macrocycle, is not formed
Scheme 1. Macrocyclic N/O-Donor Ligands H21[1] and H42[10a]
In contrast to the large number of macrocyclic amine-
phenolate ligands, there exist only a few examples of the
[a]
Institut für Anorganische und Analytische Chemie,
Universität Freiburg,
Albertstrasse 21, D-79104 Freiburg, Germany
Fax: (internat.) ϩ49-761/203-6001
E-mail: kerstber@sun2.ruf.uni-freiburg.de
Eur. J. Inorg. Chem. 1999, 2167Ϫ2172
WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1999
1434Ϫ1948/99/1212Ϫ2167 $ 17.50ϩ.50/0
2167

B. Kersting, G. Steinfeld, T. Fritz, J. Hausmann
FULL PAPER
under these conditions. Attempts to obtain this compound bon atoms. The macrocyclic structure of H46a·8HCl was
by using more dilute solutions (and longer reaction times) confirmed by an X-ray structure determination of one of
were unsuccessful, but instead resulted in higher yields of its metal complexes (see below).
5a. In the last step, compound 5a was reduced with sodium
The strategy for the synthesis of the macrocyclic amine-
in liquid ammonia (reductive cleavage of the ArSϪCH2- thiophenolate ligands presented in this study differs from
CH2ϪSAr bonds) to give, after hydrolysis with hydrochloric those employed by other groups for related amine-thio-
acid, the hydrochloride salt of the amine-thiolate ligand, phenolate ligands. Such compounds have been prepared al-
H46a·8HCl. A similar reaction sequence was employed to most exclusively by metal-templated condensations between
prepare
the
40-membered
amine-thiolate
ligand 2,6-diformyl-4-methyl-thiophenol and certain α,ω-diamines,
H46b·8HCl. Both ligands were stored as their hydrochloride followed by sodium borohydride reduction of the imine-thi-
salts under an atmosphere of dry nitrogen. The compounds olate complexes and hydrolysis of the resulting amine-thiol-
H46a,b·8HCl are only slightly soluble in water, although the ate complexes. The latter route has also been employed in
ligands dissolve in methanol in the presence of a base such the synthesis of the phenolate analogue of H46a.[10c] Our
as NEt3.
approach makes use of the air-stable tetraaldehyde/dithi-
oether compound 4 which can be condensed with aliphatic
diamines in the absence of metal ions. Since the 2 ϫ 4 con-
densation products are almost exclusively formed under
these conditions, it is likely that the bridging thioether unit
serves as the template for macrocycle formation. However,
the cyclization reactions still demand medium to high-di-
lution conditions (final concentration ഠ 0.01 ), since
otherwise only polymeric material is obtained. It also ap-
pears that the yield of cyclization product (5a: > 92%, 5b:
56%) decreases with increasing chain length of the diamine.
Synthesis and Characterization of Nickel Complexes
7؊9
The preparation of nickel(II) complexes of H46a·8HCl
was accomplished by reaction with nickel(II) salts in meth-
anol or acetonitrile in the presence of a base such as tri-
ethylamine. Depending on the metal-to-ligand ratio the me-
talations of H46a·8HCl afforded di- or tetranuclear nickel-
(II) complexes (see Scheme 3). The reaction of H46a·8HCl
with two equivalents of NiCl2·6H2O produced a purple,
microcrystalline solid of composition [Ni2(6a)]·MeOH (7),
whereas the reaction with four equivalents of
Ni(ClO4)2·6H2O yielded the red-brown complex [Ni4(6a)]-
[ClO4]4 (8). Complex 8 could also be obtained by metal-
ation of 7 with two equivalents of Ni(ClO4)2·6H2O.
Scheme 2. Preparation of macrocyclic amine-thiophenolate ligands
H46a,b: (i). HSCH2CH2SH, K2CO3, DMF, 25°C; (ii). 2 equiv.
NH2(CH2)nNH2, 10%MeOH/CH2Cl2; NaBH4; (iii). Na/NH3, HCl
Complex 7 is diamagnetic and exhibits good solubility
in most common organic solvents. Its UV/Vis spectrum in
The new compounds 4, 5a,b, and H46a,b·8HCl were acetonitrile (Figure 1) is very similar to other planar
characterized by 1H NMR, 13C NMR and IR spectroscopy. N2S2Ni complexes,[15][16] indicating that both nickel ions
In the IR spectra of H46a,b·8HCl the NϪH and exhibit planar N2S2 coordination environments in the solu-
1
SϪHstretching vibrations appear as broad bands at 2750 tion state. On the basis of the H NMR spectroscopic data
and 2400 cmϪ1, respectively. The relatively low value for (see Experimental Section) we propose a structure as shown
ν(SϪH) is presumably due to intramolecular hydrogen in Scheme 3 with the two nickel ions occupying diagonally
bonding interactions with adjacent NH protons. According opposite sides of the macrocycle.
1
to the H and 13C NMR spectra, compounds H46a,b·8HCl
The metalation of 7 with nickel(II) perchlorate to form 8
exhibit fourfold symmetry in solution. Compound is accompanied by distinct spectral changes. Isobestic
H46a·8HCl, for example, displays only four resonances at points occurred at 544 and 680 nm. These spectral changes
δ ϭ 7.42, 4.34, 3.44, and 1.19 for the ArH, ArCH2N, were clearly discernible until the ratio of concentrations of
NCH2CH2N, and C(CH3)3 protons, respectively. Due to 7 and Ni2ϩ was 1:2 (see Figure 1). At higher Ni2ϩ concen-
fast H/D exchange, the SH and NH protons are not ob- trations the spectrum remained essentially unchanged, im-
served under these conditions. As expected, the 13C NMR plying that H46a coordinates no more than four Ni2ϩ ions.
spectrum of H46a·8HCl displays eight signals for the 56 car- The IR spectrum of 8 reveals three very strong and sharp
2168
Eur. J. Inorg. Chem. 1999, 2167Ϫ2172

Novel Synthesis of Macrocyclic Amine-Thiophenolate Ligands
FULL PAPER
X-ray Crystal Structure of
[Ni4(6a)(NCS)4]и10CH3CN (9)
The X-ray crystal structure determination of 9 revealed
the structure to consist of well-separated molecules of the
tetranuclear isothiocyanate complex and acetonitrile mol-
ecules of crystallization. Figure 2 shows the molecular
structure of the neutral, centrosymmetric complex [Ni4(6-
a)(NCS)4]. Selected bond lengths and angles are collected
in Table 1.
˚
Table 1. Selected bond lengths [A] and angles [°] in [Ni4(6-
a)(NCS)4]и10CH3CN (9)[a]
Bond lengths
Ni(1)ϪS(1)
Ni(1)ϪS(2a)
Ni(1)ϪN(2)
Ni(1)ϪN(3)
Ni(1)ϪN(5)
Ni(1)ϪN(6)
N(5)ϪC(29)
N(6)ϪC(30)
Ni(1)···Ni(2a)
2.463(2)
2.503(2)
2.091(5)
2.167(4)
2.060(5)
2.071(5)
1.124(8)
1.175(8)
3.147(1)
Ni(2a)ϪS(1)
Ni(2a)ϪS(2a)
Ni(2a)ϪN(1)
Ni(2a)ϪN(4a)
2.212(2)
2.179(2)
1.943(5)
1.935(5)
S(5)ϪC(29)
S(6)ϪC(30)
1.658(7)
1.633(6)
Bond angles
S(1)ϪNi(1)ϪS(2a) 74.63(6)
S(1)ϪNi(1)ϪN(2) 92.80(13)
S(1)ϪNi(1)ϪN(3) 95.38(13)
S(1)ϪNi(1)ϪN(5) 172.2(2)
S(1)ϪNi(1)ϪN(6) 88.62(15)
S(1)ϪNi(2a)ϪS(2a) 86.54(6)
S(1)ϪNi(2a)ϪN(1) 95.7(2)
S(1)ϪNi(2a)ϪN(4a) 178.6(2)
S(2a)ϪNi(2a)ϪN(1) 177.5(2)
S(2a)ϪNi(2a)ϪN(4a) 92.74(15)
S(2a)ϪNi(1)ϪN(2) 166.71(13) N(1)ϪNi(2a)ϪN(4a) 85.0(2)
S(2a)ϪNi(1)ϪN(3) 94.05(13)
Scheme 3. Preparation of dinuclear and tetranuclear nickel comple-
xes of H46a: (i). 2.0 equiv. NiCl2·6H2O, NEt3/MeOH; (ii). 4.0 equiv.
Ni(ClO4)2·6H2O, NEt3/MeOH; (iii). 2 equiv. Ni(ClO4)2и6H2O,
CH3CN; (iv). 4 equiv. NH4SCN, CH3CN
S(2a)ϪNi(1)ϪN(5) 97.6(2)
S(2a)ϪNi(1)ϪN(6) 92.3(2)
N(2)ϪNi(1)ϪN(3) 82.6(2)
N(2)ϪNi(1)ϪN(5) 95.0(2)
N(2)ϪNi(1)ϪN(6) 91.7(2)
N(3)ϪNi(1)ϪN(5) 86.0(2)
N(3)ϪNi(1)ϪN(5) 173.2(2)
N(5)ϪNi(1)ϪN(6) 90.8(2)
Ni(1)ϪN(5)ϪC(29) 170.7(5)
N(5)ϪC(29)ϪS(5) 179.8(6)
Ni(1)ϪN(6)ϪC(30) 165.1(5)
N(6)ϪC(30)ϪS(6) 177.4(7)
[a]
Symmetry transformations used to generate equivalent atoms:
Ni(2a), S(2a), N(4a): 1Ϫx, 2Ϫy, 1Ϫz.
All donor atoms of the 36-membered macrocycle are in-
volved in coordination to the four nickel atoms to give two
four-coordinate N2S2Ni and two six-coordinate N4S2Ni co-
ordination units. Each Ni atom forms a five-membered che-
late ring with one of the four ethanediamine moieties of the
ligand. These N2Ni units are bridged by two thiophenolate
sulfur atoms to give two symmetry-related binuclear
[N2Ni(µ2-SR)2NiN2(NCS)2] units. The average NiϪN and
NiϪS bond lengths within these binuclear units compare
well with those of other N2S2NiII and N4S2NiII complexes,
˚
Figure 1. Titration of [Ni2(6a)]·MeOH (7) ([7] ϭ 1 ϫ 10Ϫ3 ) with
10Ϫ3  Ni(ClO4)2·6H2O in MeCN (0.0Ϫ4.0 added equiv) at 295 K
followed by UV/Vis spectroscopy
although the bond length Ni(1)ϪN(3) at 2.167(4) A is quite
long for an octahedral N4S2NiII complex.[17] The intramol-
ecular distance between the two distorted cis-octahedral
and the two distorted planar nickel atoms at 6.144(1) A and
9.005(1) A, respectively, may be used to describe the dis-
˚
˚
absorptions for ν(ClO) at 1150, 1115, and 1089 cmϪ1 con- tance between the two binuclear subunits.
Ϫ
sistent with the presence of the ClO4 ions. It was not pos-
An interesting feature to note is the fact that the isothi-
sible to grow single crystals of this product, although the ocyanate ions within each binuclear unit occupy cis posi-
reaction of 8 with NH4SCN in CH3CN yielded single crys- tions at the six-coordinate nickel atom {SCNϪNi(1)ϪNCS
tals of [Ni4(6a)(NCS)4]·10CH3CN (9) suitable for an X-ray at 90.8(2)°}. It is assumed that this coordination mode is
crystal structure determination.
enforced by the short C2 alkyl chain which links the 2,6-
Eur. J. Inorg. Chem. 1999, 2167Ϫ2172
2169

B. Kersting, G. Steinfeld, T. Fritz, J. Hausmann
FULL PAPER
Figure 2. Perspective view of the molecular structure of the tetranuclear isothiocyanate complex [Ni4(6a)(NCS)4] in 9. Hydrogen atoms
and tert-butyl groups are omitted for reasons of clarity
bis(aminomethyl)-4-tert-butylthiophenolate moieties. This
is in marked contrast to coordinatively unsaturated
Conclusion
A new synthetic route to macrocyclic amine-thiolate li-
N2Ni(µ2-SR)2NiN2 complexes in which the thiophenolate
gands has been developed. The air-stable thiophenolate pre-
moieties are connected via a C3 alkyl chain. Here the ex-
cursor
1,2-bis(4-tert-butyl-2,6-diformylphenylsulfanyl)-
ogenous ligands are coordinated in trans-axial positions
ethane can be condensed with aliphatic α,ω-diamines
{NH2(CH2)nNH2} to give the 2 ϫ 4 macrocyclic com-
pounds {4и(7 ϩ n) ring-atoms} in the absence of metal ions.
By varying the building blocks it should be possible to ob-
tain a wide range of polydentate amine-thiolate ligands
which could be useful for the preparation of new polynu-
clear transition metal thiolate complexes
(see Scheme 4).[18][19]
Experimental Section
1
General: H NMR and 13C{1H} NMR spectra were recorded on a
Bruker AVANCE DPX 200 spectrometer. All chemical shifts are
quoted on the δ scale with TMS or the solvent as internal standard.
Coupling constants are expressed in Hz. Melting points were deter-
mined in capillaries and are uncorrected. CHN-Analyses were de-
termined with a PerkinϪElmer Elemental Analyzer 240. IR spectra
were recorded on a Bruker VECTOR 22 FT-IR-spectrophotometer
as KBr pellets. Absorption spectra were recorded on a Jasco V-
570 UV/VIS/NIR spectrometer. Compound 3[20] was prepared as
described in the literature. All other chemicals were of reagent
grade and used without further purification. Solvents were predried
over molecular sieves and freshly distilled from appropriate dry-
ing agents.
Figure 3. Coordination units in the central [N2Ni(µ2-SR)2-
NiN2(NCS)2] core in 9 showing 50% thermal ellipsoids
Compound 4: To
a suspension of 1,2-ethanedithiol (2.50 g,
26.5 mmol) and K2CO3 (8.29 g, 60.0 mmol) in DMF (80 mL) was
added solid 3 (14.3 g, 53.0 mmol), and the reaction mixture was
stirred for 12 h. Water (200 mL) was then added dropwise with stir-
ring. The resulting precipitate was isolated by filtration, washed
with water (3 ϫ 50 mL), and dried in air. The solid was purified by
recrystallization from dichloromethane/cyclohexane to give 11.5 g
(92%) of 4 as pale yellow crystals. M.p. 178° C. Ϫ IR (KBr): ν˜ ϭ
1
2872m (CH), 1687s cmϪ1 (CO). Ϫ H NMR (CDCl3): δ ϭ 10.67
(s, 4 H, CHO), 8.11 (s, 4 H, ArH), 2.96 (s, 4 H, CH2), 1.31 (s, 18
H, CH3). Ϫ 13C{1H} NMR (CDCl3): δ ϭ 191.0 (CHO), 153.9,
138.3, 136.9, 131.3, 38.5, 35.2, 30.9.
Scheme 4. Stereochemical courses of reactions of coordinatively
unsaturated nickel complexes containing a [N2Ni(µ2-SR)2NiN2]
core structure: influence of the bridging alkyl chain
Compound 5a:
A
solution of 1,2-ethanediamine (493 mg,
8.20 mmol) in 10% MeOH/CH2Cl2 (100 mL) and a solution of 3
2170
Eur. J. Inorg. Chem. 1999, 2167Ϫ2172

Novel Synthesis of Macrocyclic Amine-Thiophenolate Ligands
(2.05 g, 4.36 mmol) in CH2Cl2 (100 mL) were simultaneously added
FULL PAPER
4
2
2.0 Hz, 4 H, ArH), 6.90 (d, J ϭ 2.0 Hz, 4 H, ArH), 4.42 (d, J ϭ
within 3 h to 300 mL of CH2Cl2 with stirring. After the reaction 12.0 Hz, 4 H, CH2), 3.90 (d, 2J ϭ 12.0 Hz, 4 H, CH2), 3.27 (d,
mixture was stirred for further 12 h at room temperature, the sol-
vents were removed at reduced pressure to obtain a white solid.
2J ϭ 12.0 Hz, 4 H, CH2), 3.04 (m, 8 H, CH2), 2.95 (m, 4 H, CH2),
2.50 (m, 8 H, CH2), 1.26 (s, 36 H, CH3). Ϫ C56H84N8Ni2S4·CH3OH
The solid was dissolved in MeOH/CH2Cl2 (100 mL, 1:1), a solution (1147.00): calcd. C 59.69, H 7.73, N 9.77; found C 59.42, H 7.33,
of NaBH4 (1.20 g, 31.7 mmol) in 50 mL of MeOH was added, and
the resulting homogeneous reaction mixture was stirred for further
2 h. After the excess reducing agent was destroyed by acidification
with 1 HCl, the pH was readjusted to 11 by addition of 2 NaOH
solution, and the aqueous phase extracted with CH2Cl2 (3 ϫ
200 mL). The combined organic phases were dried over K2CO3,
filtered, and the solvent removed under reduced pressure. The pale-
yellow residue was purified by column chromatography (SiO2)
using MeOH/NEt3/CH2Cl2 (10:5:85) as eluting solvent to give
2.12 g (92%) of the product as a white foam. Ϫ IR (KBr): ν˜ ϭ
3310w cmϪ1 (NH). Ϫ 1H NMR (CDCl3): δ ϭ 7.34 (d, 4J ϭ 2.0 Hz,
N, 9.52.
[Ni4(6a)][ClO4]4·3MeOH (8): To
a solution of 7 (115 mg,
0.100 mmol) in MeOH (3 mL) was added Ni(ClO4)2·6H2O (76 mg,
0.20 mmol) in MeOH (1 mL). The brown solution was stirred for
12 h, during which time a microcrystalline precipitate of 8 de-
posited. The crystals were filtered, washed with cold MeOH
(1 mL), and dried in air. Yield: 128 mg (74%). Ϫ IR (KBr): ν˜ ϭ
3200w (NH), 1142, 1113, 1087vs cmϪ1 [ClO4Ϫ, ν3(F2]. Ϫ UV/Vis
(MeCN): λmax (ε) ϭ 586 (204), 1017 nm (10 Ϫ1cmϪ1). Ϫ
C56H84N8Ni4S4·Cl4O16·3CH3OH (1726.27): calcd. C 41.05, H 5.61,
N 6.49; found C 41.32, H 5.45, N 6.36.
4
4 H, ArH), 7.24 (d, J ϭ 2.0 Hz, 4 H, ArH), 4.02 (s, 8 H, BzCH2),
[Ni4(6a)(NCS)4]и10CH3CN (9): To
a solution of 8 (36 mg,
3.97 (s, 8 H, BzCH2), 3.25 (s, 8 H, SCH2), 2.91 (s, 8 H, NHCH2),
2.81 (s, 8 H, NHCH2), 1.90 (s br, 8 H, NH), 1.30 (s, 36 H, CH3).
0.021 mmol) in MeCN (5 mL) was added a solution of NH4SCN
(6.5 mg, 0.085 mmol) in MeOH (1 mL). The brown solution was
filtered and kept at room temp. for 12 h, during which time the
tetranuclear isothiocyanate complex 9 deposited as brown-red crys-
tals. Yield: 25 mg (63%). Crystals of 9 quickly lose the MeCN mol-
ecules of crystallization upon storage in air at 298 K. Ϫ IR (KBr):
ν˜ ϭ 3200w (NH), 2075vs cmϪ1 (CN). Ϫ UV/Vis (DMF): λmax (ε) ϭ
520sh (317), 975 nm (65 Ϫ1cmϪ1). Ϫ C60H84N12Ni4S8 (1464.65):
C 49.20, H 5.78, N 11.48; found C 48.93, H 5.31, N 11.01.
Ϫ
13C NMR (CDCl3): δ ϭ 151.7, 144.3, 144.0, 130.3, 127.0, 126.4,
53.9, 53.3, 48.7, 37.4, 34.4, 31.1.
Compound 5b: Analogously to the preparation of 5a, compound 5b
was prepared from 3 (2.05 g, 4.36 mmol) and 1,3-propanediamine
(608 mg, 8.20 mmol). Yield: 1.35 g (56%). Ϫ IR (KBr): ν˜ ϭ 3295w
1
4
cmϪ1 (NH). Ϫ H NMR (CDCl3): δ ϭ 7.25 (d, J ϭ 2.0 Hz, 4 H,
4
ArH), 7.14 (d, J ϭ 2.0 Hz, 4 H, ArH), 3.95 (s, 8 H, BzCH2), 3.85
(s, 8 H, BzCH2), 3.03 (s, 8 H, SCH2), 2.73 (m, 16 H, NHCH2), 1.72
(m, 8 H, NHCH2), 1.23 (s, 36 H, CH3). Ϫ 13C NMR (D2O/
2%DCl): δ ϭ 155.9, 136.9, 136.6, 131.9, 130.8, 126.3, 50.7, 49.9,
45.4, 44.6, 37.8, 34.9, 30.5, 23.0, 20.9.
X-ray Crystal Structure Determination: Single crystals of complex
9 were obtained by the procedure described above. A red-brown
crystal of [Ni4(6a)(NCS)4]·10MeCN measuring 0.42 ϫ 0.35 ϫ
0.09 mm was mounted with some mother-liquor in a glass capillary.
Intensity data were collected at Ϫ60°C using a STOE IPDS dif-
fractometer with graphite-monochromatized Mo Kα radiation
Compound H46a·8HCl: To a solution of sodium (1.00 g, 43.0 mmol)
in liquid ammonia (100 mL) was added a solution of 5a (2.00 g,
1.90 mmol) in THF (30 mL) and the deep-blue reaction mixture
was stirred for 1 h. After the excess reducing equivalents were de-
stroyed by careful addition of NH4Cl, the suspension was evapo-
rated to dryness, and the resulting pale yellow residue was taken
up in water (40 mL). The yellow solution was cooled to 0° C, and
the pH of the solution adjusted to 1 by addition of 12 hydro-
chloric acid. The pale yellow solid was collected by filtration and
recrystallized from 1 HCl to give H46aи8HCl (1.79 g, 73%) as
white crystals. Ϫ IR (KBr): ν˜ ϭ 3423, 2750br (NϪH), 2400br cmϪ1
˚
(λ ϭ 0.71073 A). The data were corrected for Lorentz and polariz-
ation effects. An empirical absorption correction was applied. Of
8518 unique reflections 5890 measured Fo > 4σ(Fo). Structure solu-
tion (direct methods) and refinements were carried out with
SHELXS-86 and SHELXL-93 software,[21] respectively. The com-
plex [Ni4(6a)(NCS)4]·10MeCN crystallizes in the triclinic space
Table 2. Crystal data and structure refinement for [Ni4(6a)-
(NCS)4]·10CH3CN
1
(SϪH). Ϫ H NMR (D2O): δ ϭ 7.41 (s, 8 H, ArH), 4.36 (s, 16 H,
BzCH2N), 3.45 (s, 16 H, NCH2), 1.23 (s, 36 H, CH3). Ϫ 13C NMR
(D2O): δ ϭ 152.0, 133.9, 131.9 (CH), 130.7, 51.5, 43.0, 34.5, 30.7.
empirical formula
formula weight
crystal size, mm3
T,°C
C80H114N22Ni4S8
1875.26
0.42 ϫ 0.35 ϫ 0.09
Ϫ60
Compound H46b·8HCl: Analogously to the preparation of
H46a·8HCl, this compound was prepared by reduction of 5b
(2.11 g, 1.90 mmol) with sodium (1.00 g, 43.0 mmol) in liquid am-
monia (100 mL). Recrystallization from 1 HCl afforded
H46b·8HCl (1.56 g, 61%) as white crystals. Ϫ 1H NMR (D2O): δ ϭ
¯
space group
P1
˚
a, A
11.217(2)
14.862(3)
15.342(3)
78.26(3)
˚
b, A
˚
c, A
α, deg
β, deg
γ, deg
3
7.47 (s, 8 H, ArH), 4.38 (s, 16 H, BzCH2N), 3.12 (t, J ϭ 7.5 Hz,
70.90(3)
16 H, NCH2), 2.17 (qnt, 3J ϭ 7.5 Hz, 8 H, CH2), 1.16 (s, 36 H,
CH3). Ϫ 13C NMR (CD3OD): δ ϭ 154.1, 136.6, 131.8 (CH), 129.3,
51.5, 45.8, 35.8, 31.4, 23.9.
85.35(3)
3
˚
V, A
2366.0(8)
1
Z
density, g·cmϪ3
µ(Mo Kα), mmϪ1
θ range, deg
reflections collected
1.316
1.013
[Ni2(6a)]·MeOH (7): To
a solution of H46a·8HCl (129 mg,
4.48Ϫ25.92
18381
0.100 mmol) in MeOH (3 mL) was added NiCl2·6H2O (47 mg,
0.200 mmol) in MeOH (1 mL) and NEt3 (121 mg, 1.20 mmol). The unique reflections
8518 (Rint ϭ 0.1403)
5890 (Fo > 4σ(Fo))
0.0817, 0.1975[a]
0.1144, 0.2246[a]
1.095
observed reflections
R1, wR2 [Fo > 4σ(Fo)]
R1, wR2 (all data)
purple solution was stirred overnight, during which time a purple,
microcrystalline precipitate of 7 deposited. The crystals were fil-
tered, washed with cold MeOH (1 mL), and dried in vacuum.
goodness-of-fit on F2
Yield: 58 mg (51%). Ϫ IR (KBr): ν˜ ϭ 3129w cmϪ1 (NH). Ϫ resid. elect. density, eA
0.903/Ϫ0.696
Ϫ3
˚
UV/Vis (MeCN): λmax (εM) ϭ 495 (270), 588 nm (298 Ϫ1cmϪ1).
w ϭ 1/[σ2(Fo2) ϩ (0.1182P)2 ϩ 2.7688P], P ϭ (Fo ϩ 2Fc )/3.
[a]
2
2
Ϫ
1H NMR (200 MHz, CDCl3/CD3OD, 1:1): δ ϭ 7.22 (d, 4J ϭ
Eur. J. Inorg. Chem. 1999, 2167Ϫ2172
2171

B. Kersting, G. Steinfeld, T. Fritz, J. Hausmann
FULL PAPER
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[7b]
1835Ϫ1844.
2554Ϫ2562.
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2172
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