Preparation and characterization of mononuclear Co, Ni, and Zn complexes of dinucleating macrocyclic hexaaza-dithiophenolate ligands and their open-chain derivatives

Article abstract of DOI:10.1039/b603740b

The preparation and characterization of mononuclear complexes of the dinucleating 24-membered hexazadithiophenolate macrocycles H₂L ² and H₂L³ and their open-chain N ₃S₂ analogues H₂

Full text of DOI:10.1039/b603740b

View Article Online / Journal Homepage / Table of Contents for this issue
PAPER
www.rsc.org/dalton | Dalton Transactions
Preparation and characterization of mononuclear Co, Ni, and Zn complexes
of dinucleating macrocyclic hexaaza-dithiophenolate ligands and their
open-chain derivatives
Thorsten Fritz,b Gunther Steinfeld,b Steffen Ka¨ssa and Berthold Kersting*a
Received 13th March 2006, Accepted 9th May 2006
First published as an Advance Article on the web 19th May 2006
DOI: 10.1039/b603740b
The preparation and characterization of mononuclear complexes of the dinucleating 24-membered
hexazadithiophenolate macrocycles H2L2 and H2L3 and their open-chain N3S2 analogues H2L4 and
H2L5 are reported. The highly crystalline compounds [Ni(L4)] (4), [Ni(L5)] (5), [Co(L5)] (6), [NiH2(L2)]2+
(7), [ZnH2(L2)]2+ (8), and [NiH2(L3)]2+ (9) could be readily prepared by stoichiometric complexation
reactions of the hydrochlorides of the free ligands with the corresponding metal(II) dichlorides and
NEt3 in methanolic solution. All complexes were characterized by X-ray crystallography. Monometallic
complexes 4–6 of the pentadentate ligands H2L4 and H2L5 feature distorted square pyramidal MN3S2
structures (s = 0.01 to 0.44). Similar coordination geometries are observed for the macrocyclic
complexes 7–9 of the octadentate ligands H2L2 and H2L3. The two hydrogen atoms in 7–9 are attached
to the noncoordinating benzylic amine functions and are hydrogen bonded to the metal-bound
thiophenolate functions. A comparison of the structures of 4–9 reveals that the macrocycles L2 and L3
have a rather flexible ligand backbone that do not confer unusual coordination geometries on the metal
ions. We also report on the ability of the monometallic complexes 7 and 8 to serve as starting materials
for the preparation of dinuclear complexes.
Introduction
Mononuclear complexes of dinucleating macrocyclic ligands
represent versatile starting materials for the preparation of
heterodinuclear complexes.1–5 The vast majority of such com-
plexes are derived from the tetraaza-diphenolate system H2L1
(Scheme 1), first described by Robson et al.,6 and their countless
derivatives.7–12 Far less is known about the ability of the related
polyaza-dithiophenolate macrocycles to stabilize mononuclear
complexes,13–15 which can be traced to the difficulties encountered
during their synthesis.16
Recently, we have reported the first example for a mononuclear
complex of the permethylated hexaza-dithiophenolate ligand H2L2
(Scheme 1).17 In this paper, we describe the synthesis and character-
ization of several other mononuclear complexes of this macrocycle
and its per-N-propylated derivative H2L3. The preparations of
the corresponding complexes of the open-chain chelate ligands
H2L4 and H2L5 are also described and their structures are
compared with those of the mononuclear macrocyclic complexes.
The ability of the mononuclear complexes to serve as starting
Scheme 1 Structure of the ligands H2L1–H2L5.
materials for homo- and heterodinuclear complexes is described
briefly.
Results and discussion
Synthesis of ligands and complexes
The macrocycles H2L2,18 and H2L3,19 have been reported earlier.
Scheme 2 illustrates the synthetic route to the new acyclic ligands
aInstitut fu¨r Anorganische Chemie, Universita¨t Leipzig, Johannisallee
H2L4 and H2L5.
29, D-04103 Leipzig, Germany. E-mail: b.kersting@uni-leipzig.de;
The thioether 2 was obtained as a pale-yellow oil by a Schiff-
base condensation of 2-(tert-butylthio)benzaldehyde 1 and bis(2-
aminoethyl)amine in an ethanol/dichloromethane mixed solvent
Fax: +49/(0)341-97-36199
bInstitut fu¨r Anorganische und Analytische Chemie, Universita¨t Freiburg,
Albertstr. 21, 79104 Freiburg, Germany
3812 | Dalton Trans., 2006, 3812–3821
This journal is
The Royal Society of Chemistry 2006
©

View Article Online
Scheme 2 Synthesis of H2L4 and H2L5.
system followed by reduction with NaBH4. Reductive methylation
of 2 with formaldehyde and formic acid under Eschweiler–
Clarke conditions gave the permethylated derivative 3 in nearly
quantitative yield. Both the unmethylated and the permethylated
thioether could be converted to the corresponding thiophenols
using sodium in liquid ammonia as reducing agent. Both com-
pounds were isolated as their trihydrochloride salts and stored
under an atmosphere of dry nitrogen. These acyclic ligands could
not be obtained in analytically pure form. Nevertheless, they were
of sufficient purity for metal complex syntheses.
The synthesis of the mononuclear complexes 4–6 is outlined
in Scheme 3. Treatment of H2L4·3HCl with NiCl2·6H2O and
triethylamine in a 1 : 1 : 5 ratio in methanol solution gave
paramagnetic [Ni(L4)] (4) (leff = 2.85 lB) as a green, air-stable,
microcrystalline solid in 77% yield. The permethylated derivative
H2L5·3HCl reacted in a similar manner to afford air-stable [Ni(L5)]
(5) (leff = 2.91 lB) as a red, microcrystalline solid. The dark-
green, air-stable cobalt(II) complex [Co(L5)] (6) (leff = 4.20 lB) was
obtained in the same manner. Complexes 5 and 6 are only slightly
soluble in polar protic solvents, but can be readily dissolved in
polar aprotic solvents (e.g. MeCN, DMSO, DMF). Complex 4 is
insoluble in all common organic solvents.
Scheme 4 Synthesis of complexes 7–9.
H2L2·6HCl is treated with ZnCl2·6H2O and NEt3 in a 1 : 1 :
6 molar ratio in methanolic solution. Similarly, the reaction of
H2L3·6HCl with NiCl2·6H2O and NEt3 in methanol produced red
[NiH2(L3)]2+ (9), which was isolated as its tetraphenylborate salt.
Again all complexes 7–9 are air-stable both in the solid state and
in solution.
Preliminary experiments show that the mononuclear com-
plexes 7 and 8 can be readily converted to homo- and het-
erodinuclear complexes. For example, the reaction of 7 with
Ni(OAc)2·4H2O and triethylamine in a 1 : 1 : 2 molar ratio in
hot methanol proceeded smoothly to give the known dinickel
complex [(LMe)Ni2(OAc)]+ (10) in almost quantitative yield (see
Scheme 5).20 Likewise, when [ZnH2(L2)]2+ (8) was allowed to react
with Zn(OAc)2·2H2O and NEt3 in methanol at room tempera-
ture, the dinuclear zinc complex [(LMe)Zn2(OAc)]+ (11) formed
immediately.20 Finally, the reaction of 8 with Cd(OAc)2·2H2O and
NEt3 in methanol produces a non-statistical 1 : 1 : 8 mixture (by
1H NMR, see below) of the two homo- and the heterodinuclear
[(L2)M1M2(OAc)]+ complexes 11 (M1 = M2 = Zn), 12 (M1 = M2 =
Cd) and 13 (M1 = Zn, M2 = Cd), respectively. No attempt has as
yet been made to further decrease the amounts of 11 and 12 in
this reaction. All compounds gave satisfactory elemental analyses
Scheme 3 Synthesis of complexes 4–6.
The synthesis of the homodinuclear complexes 7–9 is depicted
in Scheme 4. Addition of NiCl2·6H2O to a solution of the
macrocycle H2L2·6HCl in methanol, followed by LiClO4, yields
a dark red, microcrystalline solid of [NiH2(L2)][ClO4]2 (7[ClO4]2)
in ≈70% yield. Salt metathesis of monometallic 7[ClO4]2 with
NaBPh4 in methanol gave 7[BPh4]2. Complex [ZnH2(L2)][ClO4]2
(8[ClO4]2) forms as the only isolable product, when the macrocycle
and were characterized by spectroscopic methods (IR, 1H and 13
NMR spectroscopy) and X-ray crystallography.
C
This journal is
The Royal Society of Chemistry 2006
Dalton Trans., 2006, 3812–3821 | 3813
©

View Article Online
described below the N configurations of the two benzylic nitrogen
atoms bonded to the zinc are different. The two N-methyl groups
at N(1) and N(2) are oriented below and above the five-membered
N2C2Zn chelate ring (trans orientation), whereas the NMe groups
at N(2) and N(3) are both on the same side of the chelate ring
(cis orientation). These orientations are sensed by the tert-butyl
groups, thereby causing their inequivalence. Finally, the fact that
the cation is a monometallic species renders the two halves of each
thiophenol unit to become inequivalent, such that all the four
aromatic protons are in chemically different environments. The
13C NMR spectrum was of little diagnostic value.
1
The H NMR spectra for the C2v-symmetric dizinc (11) and
dicadmium complexes (12) have been reported previously.20,22
The 1H-NMR spectrum of the ZnCd derivative 13 is not a
simple superposition of the spectra of 11 and 12, a fact that is
fully consistent with its heterodinuclear nature. The most salient
Scheme 5 Synthesis of complexes 10–13.
1
features in the H NMR spectra of these bowl-shaped dications
are the resonances for the acetate methyl protons (see Fig. 1). As
can be seen, for 11 and 12 these resonances occur at d = 0.81 and
d = 0.98 ppm, respectively, whereas for 13 this signal is observed
at d = 0.92. This clearly reflects the heterodinuclear nature of 13.
Spectroscopic characterization of complexes
The most significant features in the IR spectrum of mononuclear
complex 4 are the weak bands at 3046 and 3062 cm−1, which can
be attributed to the N–H stretching vibrations of the coordinated
amine functions.21 The IR spectra of 5 and 6 are identical,
and reveal only the various stretching and bending modes of
the supporting ligand. In agreement with the formulation of
7[ClO4]2 and 8[ClO4]2 the IR spectra display strong bands at
1100 cm−1 for the perchlorate anions. Absorptions due to the N–H
stretching modes of the protonated R3N–H+ functions could not
be detected. The same was true for 9[BPh4]2. The IR spectrum of
the heterodinuclear species 13 reveals two strong absorptions at
1582 and 1425 cm−1 which can be assigned to the symmetric and
asymmetric stretching frequencies of a l1,3-bridging acetate group.
Similar values were previously reported for 11,20 12,22 and other
carboxylato-bridged complexes of the type [(L2)M2(O2CR)]+.23
With the exception of the insoluble compound 4, all Ni and Co
complexes were further characterized by UV/Vis spectroscopy.
The electronic absorption spectra were recorded in the range 300–
1600 nm in acetonitrile solution at ambient temperature. The
spectra of the intense colored nickel complexes 5, 7, and 9 are
dominated by three strong RS− → NiII charge-transfer transitions
in the 350 to 500 nm region. The weak absorptions bands above
500nm (5: 771 nm, 7: 686, 899nm; 9:688, 945nm) can be attributed
to the spin-allowed d–d transitions of a five-coordinated nickel(II)
(S = 1) ion. On the basis of these data, however, it is not possible to
discriminate between a trigonal-pyramidal or a square-pyramidal
coordination, for which five and six spin-allowed d–d transitions
are expected.24 The same is true for the CoII complex 6.25
Fig. 1 Left: Schematic representation of the bowl-shaped structures of
1
the cations 11–13. Right: H NMR spectra of 11, 12, and 13 in CD3CN
solution showing the resonances of the methyl protons of the bridging
acetate groups in the d = 1.0 to 0.5 ppm region. The signals at 0.81 and
0.98 ppm show that 13 is contaminated with 11 and 12 (intensity ratio:
0.8 : 0.1 : 0.1).
It should be noted that the signals for the acetate coligands are
considerably shifted to high-field relative to free sodium acetate
(d = 1.83 ppm). This can be understood in terms of the ring
current. As can be seen from Fig. 1, the methyl protons are
positioned in the binding cavity of the complexes slightly above
the center of the two phenyl rings in the shielding region. We have
previously reported a correlation between the magnitude of the
shielding effect and the angle between the two phenyl rings.25,26 In
the dizinc complex 11, for example, the angle is more acute (80.0◦)
than in the cadmium complex 12 (94.4◦) such that the distance
of the methyl protons to the centre of the phenyl rings is smaller
in 11 thereby causing a more pronounced shielding effect. On the
basis of these data, we can estimate that the angle between the two
phenyl rings in 13 is ≈87–88◦.
The 1H NMR spectrum of the mononuclear zinc complex
8[ClO4]2 in CD3CN solution shows two sharp singlets at 1.28 and
1.30 ppm corresponding to the methyl protons of two inequivalent
t-Bu groups. The methylene and methyl protons appear as broad
and overlapped resonances in the 5.4 to 1.8 ppm region. The spec-
trum at high d is much better resolved, and consists of four equally
intense doublet resonances at 7.39, 7.38, 7.36, and 7.35 ppm (4J =
2.4 Hz) representing the four aromatic CH protons. The broad
resonance at 8.30 ppm is tentatively assigned to the hydrogen
atoms of the protonated R3NH functions. The inequivalence of
the tert-butyl groups and the four aromatic protons indicate that
the solid state structure (see below) is retained in solution. As is
A solution of complex 13 was also characterized by ESI-
MS. The ESI-MS exhibited a strong peak at m/z = 905.3, cor-
responding to the [(L2)ZnCd(l-OAc)]+ cation. Again the presence
of the homodinuclear “impurities” 11 and 12 was also visible in
the mass spectrum, by the weak peaks at m/z = 859.3 and 953.3.
In summary, all experimental data provide sufficient evidence
3814 | Dalton Trans., 2006, 3812–3821
This journal is
The Royal Society of Chemistry 2006
©

View Article Online
for the formulation of 13 as a heterodinuclear ZnCd complex
coligated by a deprotonated acetate ion. Thus, the mononuclear
amine-thiophenolate complexes pave the way to calixarene-like
compounds with a heterobimetallic core.
[NiII(L4)] (4). The neutral complex 4 crystallizes in the mon-
oclinic space group P21/c. The coordination geometry of the Ni
atom is intermediate between trigonal bipyramidal and square
pyramidal, as indicated by the s = value of 0.44.27 The average
˚
Ni–N and Ni–S distances of 2.086(4) and 2.318(1) A compare
well with those reported for [NiII(terpy)(S-2,4,6-(iPr)3C6H2)2]
Description of the crystal structures. The X-ray crystal struc-
tures of 4, 5, 6, 7[ClO4]2·MeOH, 8[ClO4]2·MeOH, and 9[BPh4]2
were determined to establish the geometries about the metal
ions as well as the bonding modes of the supporting ligands.
Experimental crystallographic data are summarized in Table 1.
Selected bond lengths and angles are given in Table 2. ORTEP
views of the structures of the cations are shown in Fig. 2–5. The
atomic numbering scheme used for the central N3S2Ni core in 4 was
adopted for all compounds to facilitate structural comparisons.
ꢀ
ꢀꢀ
28
˚
˚
(terpy = 2,2 ,2 -terpyridine; Ni–N: 2.057 A, Ni–S: 2.303 A),
and other five-coordinate NiIIN3S2 complexes.29–32 The main
difference between the structure of 4 and the compounds des-
cribed below concerns the intermolecular hydrogen bonding
interactions. In the present structure the individual complexes
are linked via intermolecular N–H · · · S hydrogen bonds involving
the thiolate sulfur atoms (S(1), S(2ꢀ)) and the amine hydrogen
atoms (H(1ꢀ), H(3)) to generate one-dimensional infinite chains.33
Table 1 Selected crystallographic data for 4, 5, 6, 7[ClO4]2·MeOH, 7[BPh4]2·MeCN, 8[ClO4]2·MeOH, and 9[BPh4]2
Compound
4
5
6
7[ClO4]2·MeOH
7[BPh4]2·MeCN
8[ClO4]2·MeOH
9[BPh4]2
Formula
C18H23N3NiS2 C21H29N3NiS2 C21H29CoN3S2 C39H70Cl2N6NiO9S2 C88H109B2N7NiS2 C39H70Cl2N6O9S2Zn C98H130B2N6NiS2
Mr/g mol−1
Space group
404.22
P21/c
10.799(2)
13.289 (3)
12.474(2)
90.00
96.68(3)
90.00
1778.0(6)
4
446.30
P21/c
18.320(4)
7.583(2)
15.183(3)
90.00
96.70(3)
90.00
2094.8(8)
4
446.52
P21/c
18.334(4)
7.601(2)
15.163(3)
90.00
96.46(3)
90.00
2099.6(8)
4
960.74
P21/n
14.073(3)
17.070(3)
19.323(4)
90.00
93.04(3)
90.00
4635(2)
4
1409.27
Pbca
18.177(4)
17.826(4)
48.531(10)
90.00
90.00
90.00
15725(6)
8
967.40
P21/n
1536.53
P1
¯
˚
a/A
14.270(3)
16.937(3)
19.708(4)
90.00
94.15(3)
90.00
14.095(3)
15.097(3)
23.640(5)
89.52(3)
75.64(3)
65.07(3)
4393(2)
˚
b/A
˚
c/A
◦
a/
b/
◦
◦
c /
3
˚
V/A
4751(2)
4
Z
d
2
calcd./g cm−3
1.510
1.331
1.415
1.137
1.413
1.027
1.397
0.682
1.191
0.349
1.353
0.773
1.162
0.317
l(Mo Ka)/mm−1
◦
h limits/
1.90–28.33
11219
4239
1.12–28.29
12760
4931
1.12–28.35
12807
4993
1.75–28.30
28635
10921
6237
1.40–28.37
46215
18528
1.59–28.31
29408
11276
1.65–28.34
40508
20741
Measured refl.
Independent refl.
Observed refl.a
2125
2489
3026
4108
7641
8857
No. parameters
R1b (R1 all data)
wR2c (wR2 all data)
217
244
244
560
901
533
1038
0.0507 (0.1291) 0.0524 (0.1336) 0.0481 (0.0963) 0.0463 (0.0948)
0.0885 (0.1137) 0.0956 (0.1270) 0.0885 (0.1106) 0.1096 (0.1319)
0.625 (−0.664) 0.644 (−0.783) 0.688 (−0.664)
0.0566 (0.2973)
0.1272 (0.2099)
0.328 (−0.674)
0.0523 (0.0775)
0.1528 (0.1657)
1.563/−1.022
0.0457 (0.1378)
0.0853 (0.1063)
0.541 (−0.401)
−3
˚
Max., min. peaks/ e A
0.922 (−0.610)
2
1/2
a Observation criterion: I > 2r(I). b R1 = RꢁFo| − |Fcꢁ/R|Fo|. c wR2 = { R[w(Fo − Fc2)2]/R[w(Fo2)2]}
.
Table 2 Selected bond lengths and angles of complexes 4–9 and [(LEt)Ni2]3+
Compound
4
5
6
7[ClO4]2
7[BPh4]2
[(LEt)Ni2]3+
8[ClO4]2
9[BPh4]2
M–S(1)
M–S(2)
M–N(1)
M–N(2)
M–N(3)
M–Na
2.294(1)
2.341(1)
2.104(4)
2.036(3)
2.117(4)
2.086(4)
2.318(1)
2.301(1)
2.292(1)
2.196(4)
2.104(4)
2.275(4)
2.192(4)
2.297(1)
2.269(1)
2.298(1)
2.253(3)
2.130(3)
2.357(3)
2.247(3)
2.284(1)
2.310(1)
2.3041(9)
2.159(3)
2.079(3)
2.233(3)
2.157(3)
2.3069(9)
2.296(2)
2.307(2)
2.152(5)
2.125(5)
2.137(5)
2.138(5)
2.302(2)
2.291(1)
2.407(1)
2.051(3)
2.138(3)
2.060(3)
2.083(3)
2.349(1)
2.3083(9)
2.3221(9)
2.262(3)
2.103(3)
2.368(3)
2.244(3)
2.3151(9)
2.304(1)
2.332(1)
2.137(2)
2.176(2)
2.125(2)
2.146(2)
2.318(1)
M–Sa
N(1)–M–N(3)
N(1)–M–S(1)
N(1)–M–S(2)
N(1)–M–N(2)
N(3)–M–S(1)
N(3)–M–S(2)
N(3)–M–N(2)
S(1)–M–S(2)
S(1)–M–N(2)
S(2)–M–N(2)
166.4(1)
162.3(1)
96.3(1)
92.5(1)
82.7(1)
96.9(1)
93.0(1)
82.3(1)
113.78(6)
106.0(1)
140.2(1)
157.9(1)
96.94(8)
92.52(8)
81.3(1)
100.46(7)
91.59(7)
79.9(1)
116.79(5)
111.10(8)
132.11(8)
162.9(1)
95.61(8)
92.77(7)
83.4(1)
98.42(8)
93.14(7)
82.7(1)
104.42(4)
110.03(8)
145.54(8)
155.7(2)
145.55(12)
100.57(9)
92.33(9)
85.83(13)
113.77(10)
94.68(10)
85.44(13)
82.41(4)
157.7(1)
97.04(7)
92.78(7)
81.4(1)
102.23(8)
91.20(7)
79.8(1)
109.89(3)
117.43(8)
132.67(8)
155.72(8)
99.96(7)
91.26(7)
83.33(8)
102.76(7)
94.19(6)
83.25(8)
97.37(4)
103.25(7)
159.29(6)
93.68(10)
91.00(10)
83.67(14)
91.32(10)
93.28(10)
82.79(14)
139.92(5)
115.2(1)
96.35(14)
93.87(15)
83.0(2)
105.95(14)
91.90(14)
82.28(19)
99.62(7)
104.16(15)
156.21(15)
100.41(9)
176.86(9)
104.9(1)
sb
0.44
0.37
0.43
0.29
0.01
0.52
0.41
0.06
a Mean values; b s is defined as (a − b)/60◦, where a = largest angle, b = second largest angle (s = 1.0 for ideal trigonal bipyramidal; s = 0.0 for ideal
square pyramidal).
This journal is The Royal Society of Chemistry 2006
Dalton Trans., 2006, 3812–3821 | 3815
©

View Article Online
Fig. 3 ORTEP representation of the structure of complex 7 in crys-
tals of 7[ClO4]2·MeOH (top) and 7[BPh4]2·MeCN (bottom). Hydrogen
atoms, except H(4) and H(6), have been omitted for clarity. Selected
◦
˚
bond lengths [A] and angles [ ] (values in square brackets refer to
7[BPh4]2·MeCN): S(1) · · · H(6) 2.489 [2.612], S(1) · · · N(6) 3.153 [3.253],
S(2) · · · H(4) 2.504 [2.713], S(2) · · · N(4) 3.173 [3.308]; S(1) · · · H(6)–N(6)
130.1 [128.1], S(2) · · · H(4)–N(4) 130.7 [123.9].
Fig. 2 Structure of the neutral complexes 4 (top), 5 (middle), and 6
(bottom). Thermal ellipsoids are drawn at the 50% probability level.
Hydrogen atoms are omitted for clarity.
The corresponding distances are normal for N–H · · · S hydrogen
ꢀ
ꢀ
ꢀ
˚
˚
bonds (N(1 )H(1 ) · · · S(1) = 2.484 A, N(1 ) · · · S(1) = 3.297 A,
ꢀ
ꢀ
34–37
˚
˚
N(3)H(3) · · · S(2 ) = 2.785 A, N(3) · · · S(2 ) = 3.639 A).
[NiII(L5)] (5). Crystals of 5 grown from an acetonitrile so-
lution are monoclinic space group P21/c. The crystal structure
determination revealed the presence of discrete molecules of
the neutral complex (Fig. 2). The conformation adopted by the
permethylated ligand (L5)2− resembles that of its parent (L4)2−
in 4. The distortion from trigonal bipyramidal towards square
pyramidal is somewhat more pronounced in 5, as indicated by the
smaller s value of 0.37. The conversion of secondary into tertiary
amines results in an increase of the average Ni–N bond distance
Fig. 4 Overlay of line-drawings of the structures of 5 (solid) and 7
(dashed). The noncoordinating diethylenetriamine unit of (L2)2− in 7 has
been omitted for clarity.
˚
by 0.108 A. Similar effects have been observed for Ni complexes
of other N donor ligands and their methylated derivatives.38 The
closest intermolecular distance between two complexes is observed
ꢀ
between S(1) and a methylene carbon atom H(10 ) (2.828 A). This
[CoII(L5)] (6). The crystal structure determination revealed
6 (Fig. 2) to be isostructural with 5. Again, the coordination
geometry for the Co atom is intermediate between trigonal
˚
value should be compared with the much shorter S · · · H distances
in 4.
3816 | Dalton Trans., 2006, 3812–3821
This journal is
The Royal Society of Chemistry 2006
©

View Article Online
pyramidal. The two hydrogen atoms H(4) and H(6) bonded
to the benzylic amine nitrogens N(4) and N(6) were located
unambiguously from final Fourier maps. These hydrogen atoms
are intramolecularly hydrogen bonded to the thiolate sulfur atoms
˚
˚
(S(1) · · · H(6) 2.489 A, S(2) · · · H4 2.504 A). A similar situation
has been observed in [CrH2(L2)(OAc)]2+ (S(2) · · · H(5) 2.559), the
only other mononuclear transition metal complex of (L2)2− that
has been structurally characterized so far.17 The average Ni–S
˚
bond lengths in 5 and 7 differ by only 0.01 A, indicating that the
bonding properties of the thiolate donors in 7 are not markedly
affected by the intramolecular hydrogen bonding interactions.
These values should be compared with those in the dinuclear
[Ni2H(LEt)]3+ complex,19 where the two hydrogens are displaced
by a four-coordinate NiII center. The Ni–S bond distances in this
˚
compound are significantly longer (by ca. 0.05 A) than in 7 (see
Table 2).
It is also worth mentioning that the respective bond angles
around the Ni centers in 5 and 7 are very similar. The same is
true for the ligand conformations. This is illustrated in Fig. 4,
representing an overlay of the line-drawings of the two structures.
With the exception of the noncoordinating diethylenetriamine
linker in 7, the two structures are almost superimposable. Even
the configurations of the tertiary nitrogen donors are identical.
This is indicative of a rather flexible ligand backbone of (L2)2−
that does not confer an unusual coordination geometry on the
nickel atom.
[NiH2(L2)][BPh4]2·MeCN (7[BPh4]2·MeCN). The crystal
structure of the tetraphenylborate salt of complex 7 was also
determined. Crystals of 7[BPh4]2·MeCN grown from acetonitrile
are orthorhombic space group Pbca. The structure contains
discrete [NiH2(L2)]2+ dications, two tetraphenylborate anions
and acetonitrile molecules of solvent of crystallization. The
conformation adopted by (L2)2− in 7[BPh4]2 is very similar to that
in 7[ClO4]2 (see Fig. 3). The most significant structural difference
concerns the coordination geometry of the Ni atom. In contrast
to 7[ClO4]2 (s = 0.29) the Ni atom in 7[BPh4]2 reveals an almost
perfect square pyramidal coordination geometry (s = 0.01), with
S(2), N(1), N(2) and N(3) forming the equatorial plane. The Ni
Fig. 5 ORTEP representation of the structures of complexes 8 (top) and
9 (bottom) at 50% probability ellipsoids. Hydrogen atoms, except H(4)
and H(6), have been omitted for clarity. The terminal CH3CH2-groups
of the N-propyl groups in 9 have also be◦en omitted for reasons of
˚
clarity. Selected bond lengths [A] and angles [ ] (values in square brackets
refer to 9[BPh4]2): S(1) · · · H(6) 2.509 [2.563], S(1) · · · N(6) 3.143 [3.223],
S(2) · · · H(4) 2.624 [2.354], S(2) · · · N(4) 3.262 [3.082]; S(1) · · · H(6)–N(6)
127.1 [129.9], S(2) · · · H(4)–N(4) 127.8 [137.0].
˚
atom lies slightly above this plane and is displaced 0.43 A toward
S(1), which constitutes the axial donor. It should be noted in this
respect that five-coordinate NiII complexes are stereochemically
non-rigid as the trigonal bipyramidal and square pyramidal
coordination geometries are energetically close to one another.43
This is nicely illustrated by [Cr(en)3][Ni(CN)5].44 In this salt there
are two independent [Ni(CN)5]3− ions per unit cell, one of which
is a distorted trigonal bipyramid and the other a distorted square
pyramid.
bipyramidal and square pyramidal (s = 0.43). The distortions
from the ideal trigonal bipyramidal geometry are manifested in
the L–Co–L bond angles, which deviate by as much as 22.1◦ (N(1)–
˚
Co–N(3)) from their ideal values. The average Co–S (2.247 A)
˚
and Co–N bond lengths (2.284 A) are normal for five-coordinate
Co(II) complexes with N3S2 coordination.39 Co(III) complexes
reveal much shorter bond lengths.40,41 As expected, the metal–
ligand bond lengths in 6 are larger than those in 5. The mean
It should be noted that we have not been able to locate the
two hydrogen atoms in the case of 7[BPh4]2·MeCN. However,
the distances between N(4) · · · S(2) at 3.308 and N(6) · · · S(1)
˚
difference of 0.03 A is close to the difference of the ionic radii of
II
II
42
˚
˚
the two elements (Co : 0.885 A, Ni : 0.83 A).
˚
at 3.253 A are very similar to those in 7[ClO4]2, indicative of
protonated N(4) and N(6) donors and intramolecular N(4)–
H(4) · · · S(4) and N(6)–H(6) · · · S(6) hydrogen bonds.
[ZnH2(L2)][ClO4]2·MeOH (8[ClO4]2·MeOH). The crystal
structure of 8[ClO4]2·MeOH consists of [ZnH2(L2)]2+ complexes
(Fig. 5), perchlorate anions and methanol solvate molecules.
Complex 8 is isostructural with 7. The Zn atom is five-coordinate,
the coordination geometry being intermediate between trigonal
[NiH2(L2)][ClO4]2 (7[ClO4]2). This salt crystallizes in the
monoclinic space group P21/n. The structure contains discrete
[NiH2(L2)]2+ dications (Fig. 3), two perchlorate anions and a
methanol molecule of solvent of crystallization. The Ni atom
is five-coordinate, being coordinated by two sulfur and three
nitrogen atoms. On the basis of the s criterion (s = 0.29),
the coordination geometry is best described as distorted square
This journal is
The Royal Society of Chemistry 2006
Dalton Trans., 2006, 3812–3821 | 3817
©

View Article Online
bipyramidal and square pyramidal. The s value of 0.41 is slightly
higher than in 7[ClO4]2. Again, the hydrogen atoms H(4) and H(6)
are intramolecularly hydrogen bonded to the thiolate sulfur atoms,
absorption spectra were measured on a Jasco V-570 UV/VIS/NIR
spectrometer. ESI-FTICR mass spectra were recorded with a
Bruker Apex II instrument using dilute acetonitrile solutions.
Room temperature magnetic susceptibility measurements were
determined with a Johnson Matthey model Mark II magnetic
susceptibility balance. 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.
˚
with similar S · · · H distances of 2.509 (S(1) · · · H(6)) and 2.624 A
(S(2) · · · H(4)). As expected, the metal–ligand bond lengths in 8
˚
are larger than those in 7. The mean difference of 0.03 A is also
close to the difference of the ionic radii of the two elements (NiII:
II
˚
˚
0.83 A, Zn : 0.88 A). It should be noted that the methyl groups
bonded to N(1) and N(2) are oriented below and above the five-
membered chelate ring, whereas at N(2) and N(3) they are in
trans configuration. This situation is observed for all complexes
described in this study.
N,Nꢀꢀ-Bis(2-tert-butylthiobenzyl)-diethylenetriamine (2). To a
solution of 2-tert-butylthiobenzaldehyde 1 (10.0 g, 51.5 mmol) in
ethanol (100 mL) was added a solution of bis(2-aminoethyl)amine
(2.65 g, 25.7 mmol). After the reaction mixture was stirred
for 24 h, sodium borohydride (3.00 g, 79.3 mmol) was added.
The reaction mixture was stirred for a further 24 h, water was
added (50 mL), and the pH of the solution adjusted to 1 by
addition of conc. hydrochloric acid. After all volatiles had been
distilled off, the residue was taken up in 3 M aqueous potassium
hydroxide solution (100 mL) and dichloromethane (100 mL). The
layers were separated and the aqueous layer was extracted with
dichloromethane (3 × 50 mL). The combined organic layers were
washed with water (50 mL) and dried with anhydrous potassium
carbonate. Evaporation of the solvent gave compound 2 as a
colourless oil. This material was used in the next step without
further purification (10.9 g, 92%). 1H NMR (200 MHz, CD3OD):
d = 1.27 (s, 9 H, tBu), 3.52 (s, 8 H, NCH2CH2N), 4.64 (s, 4 H,
ArCH2), 7.57 (m, 6 H, ArH), 7.61 ppm (m, 2 H, ArH). 13C NMR
(50 MHz, CD3OD): d = 32.1 (C(CH3)3), 48.5 (SC(CH3)3), 49.4
(NCH2), 50.0 (NCH2), 53.5 (ArCH2), 128.8, 130.9, 131.4, 133.9,
140.6, 146.3 ppm.
[NiH2(L3)][BPh4]2 (9[BPh4]2). This salt crystallizes in the tri-
¯
clinic space group P1. The structure revealed the presence of
mononuclear [NiH2(L3)]2+ complexes (Fig. 5) and tetraphenyl-
borate anions. The overall structure of 9 is similar to that of 7.
Both macrocycles adopt similar conformations. The coordination
geometry of the nickel is again best described as square pyramidal.
This is manifested by the relatively small s value of 0.06. The mean
deviation from the plane through the equatorial atoms S(2), N(1),
˚
N(2), and N(3) is 0.004 A. The Ni atom lies again slightly above
˚
this plane and is displaced by 0.408 A toward S(1). Of all the
complexes presented in this study 9 features the shortest S · · · H
˚
bonds. In particular, the short S(2) · · · H(4) distance at 2.354 A and
the large N(4)–H(4) · · · S(2) angle at 137◦ indicate that NH+ · · · S−
hydrogen bonding is more significant in 9. This may be traced back
to hydrophobic effects. Thus, the longer n-propyl groups of (L3)2−
create a more lipophilic microenvironment about the NH+ · · · S−
functions which in turn results in a lower local dielectric constant
that strengthens the electrostatic interactions in 9.
Conclusion
N,Nꢀꢀ -Bis(2-tert-butylthiobenzyl)-N,Nꢀ,Nꢀꢀ -trimethyl-diethyl-
enetriamine (3). The amine-thioether 2 (4.00 g, 8.70 mmol) was
dissolved in 96% formic acid (9.02 g, 0.188 mol). To the clear
solution was added a 35% aqueous solution of formaldehyde
(8.74 g, 102 mmol). The reaction mixture was heated under reflux
for 20 h. The reaction mixture was concentrated in vacuo to about
10 mL. Water (50 mL) and dichloromethane (100 mL) were added
to the slicky residue, the pH of the aqueous phase was adjusted
to 13 by the addition of 3 M aqueous potassium hydroxide
solution and the heterogeneous mixture was stirred vigorously
for 30 min. The layers were separated and the aqueous phase
was extracted with dichloromethane (3 × 100 mL). The combined
organic fractions were dried over K2CO3 and filtered. Evaporation
of the solvent gave compound 3 as a colourless oil which was used
In the present study it was demonstrated that the 24-membered
hexaazadithiophenolate ligands H2L2 and H2L3 support the
formation of mononuclear complexes of the type [MH2(L)]2+.
The metal atoms are five-coordinate with coordination geometries
intermediate between distorted trigonal-bipyramidal and square
pyramidal. Each structure is further stabilized by two intramolec-
ular NH+ · · · S− hydrogen bonds. A comparison with the structures
of the neutral [M(L)] complexes of the open-chain N3S2 ligands
(L4)2− and (L5)2− reveals that the macrocycles are rather flexible
systems that do not confer unusual coordination geometries on
the metal atoms. The ability of the macrocyclic complexes 8 and
9 to form homo- and heterodinuclear complexes has also been
demonstrated. This sort of chemistry can now be further exploited.
1
in the next step without further purification (4.28 g, 98%). H
NMR (200 MHz, CD3OD): d = 1.16 (s, 18 H, C(CH3)3), 2.06 (s,
6 H, NCH3), 2.11 (s, 3 H, NCH3), 2.46 (s, 8 H, NCH2CH2N),
3.76 (s, 4 H, ArCH2), 7.14–7.27 (m, 4 H, ArH), 7.43–7.48 ppm
Experimental
Materials and methods
1
(m, 4 H, ArH). 13C{ H} NMR (50.3 MHz, CD3OD): d = 32.2
All preparations were carried out under a protective atmosphere
of argon. Reagent grade solvents were used throughout. 2-tert-
Butylthiobenzaldehyde,45 H2L2·6HCl,46 and H2L3·6HCl,19 were
prepared as previously described. All other reagents were obtained
from standard commercial sources and used without further
purification. Melting points were determined in open glass
capillaries and are uncorrected. Infrared spectra were recorded
on a Bruker VECTOR 22 FT-IR-spectrometer. The electronic
(C(CH3)3), 43.6 (NCH3), 43.9 (NCH3), 48.3 (SC(CH3)3), 56.3
(NCH2), 56.8 (NCH2), 61.8 (ArCH2), 128.5 (CH), 130.6 (CH),
132.0 (CH), 134.6, 140.4 (CH), 145.5 ppm.
N,Nꢀꢀ-Bis(2-mercaptobenzyl)-diethylenetriamine (H2L4·3HCl).
To a solution of sodium (3.45 g, 150.0 mmol) in liquid ammonia
(150 mL) was added a solution of compound 2 (2.30 g, 5.00 mmol)
in tetrahydrofuran (50 mL) dropwise at −78 ◦C. The resulting blue
3818 | Dalton Trans., 2006, 3812–3821
This journal is
The Royal Society of Chemistry 2006
©

View Article Online
reaction mixture was stirred at −78 ◦C for a further 1 h to ensure
complete deprotection of the thiolate functions. 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 pressure. The residue was taken up in water
(50 mL) and the pH of the suspension adjusted to ≈1 to give a pale-
yellow solution of H2L3 as the trihydrochloride salt. To remove
the inorganic salts the solution was concentrated in a vacuum to
a volume of ≈20 mL. Methanol (ca. 60 mL) was then added and
the resulting solution was filtered off from NaCl and NH4Cl. The
latter two steps were repeated several times in this order, until no
more salts precipitated upon addition of MeOH. Concentration of
the solution afforded the title compound as a pale-yellow powder
(1.55 g, 68%). 1H NMR (200 MHz, D2O/CD3OD): d = 3.32 (m,
8 H, NCH2CH2N), 4.34 (s, 4 H, ArCH2), 7.43–7.30 ppm (m, 8 H,
ArH).
[Co(L5)] (6). To a solution of H2L5·3HCl (499 mg, 1.00 mmol)
in methanol (20 mL) was added CoCl2·6H2O (238 mg, 1.00 mmol).
To the resulting pale-green solution was added a solution of
triethylamine (505 mg, 5.00 mmol) in methanol (2 mL). The
resulting green solid was isolated by filtration, washed with a
few millilitres of methanol and dried in air. An analytical sample
was obtained by recrystallization from acetonitrile. Yield: 287 mg
(64%). Mp 224 ◦C; IR (KBr, cm−1): m˜ = 3048(m), 2991(s), 2962(s),
2857(s), 2810(m), 1583(w), 1558(m), 1463(s), 1433(m), 1069(m),
1044(m), 996(m), 941(m), 909(m), 819(w), 795(w), 747(m), 685(m).
UV/Vis (CH3CN): kmax (e) = 280 (10800), 314 (8560), 398 (3990),
596 (163), 760 (43) nm (M−1 cm−1). Elemental analysis (%) calcd
for C21H29N3NiS2 (446.30): C 56.51, H 6.55, N 9.42; found: C
56.49, H 6.70, N 9.44.
[NiH2(L2)][ClO4]2 (7[ClO4]2). To a suspension of H2L2·6HCl
(500 mg, 0.562 mmol) in methanol (20 mL) was added a solution
of Ni(ClO4)2·6H2O (205 mg, 0.562 mmol) in methanol (5 mL).
To the reaction mixture was added a solution of triethylamine
(405 mg, 4.00 mmol) in methanol (2 mL). The resulting dark
red solution was stirred for a further 30 min. Then LiClO4·3H2O
(2.00 g, 12.5 mmol) was added to give a red microcrystalline solid.
The precipitate was filtered and recrystallized from methanol.
Large red blocks. Yield: 450 mg (86%). Mp 265–266 ◦C (decomp.).
IR (KBr) m˜ = 3445(s), 3012(sh), 2959(s), 2905(w), 2869(m),
1629(m), 1464(s), 1396(w), 1343(sh), 1302(w), 1262(m), 1231(m),
1199 (w), 1096(vs, m(ClO4−)), 976(w), 891(w), 819(w), 794(w),
624(s). UV/Vis (MeCN): kmax (e) = 341 (2673), 425 (574), 504
(758), 688 (38), 901 nm (11 M−1 cm−1). Elemental analysis (%)
calcd for C38H66Cl2N6NiO8S2·2H2O (928.70 + 36.03): C 47.13, H
7.31, N 8.71, S 6.65; found: C 47.00, H 7.16, N 8.42, S 6.77.
The tetraphenylborate salt, 7[BPh4]2, was prepared by adding a
solution of NaBPh4 (180 mg, 5.26 mmol) in methanol (5 mL)
to a solution of 7[ClO4]2 (50 mg, 5.4 mmol) in methanol (20 mL).
The resulting solid was filtered and recrystallized from acetonitrile.
Yield: 55 mg (74%). Mp 239–240 ◦C (decomp.). Elemental analysis
(%) calcd for C86H106B2N6NiS2 H2O (1368.25 + 18.02): C 74.51, H
7.85, N 6.06, S 4.63; found: C 74.51, H 8.18, N 6.58, S 4.47.
IR (KBr): m˜ = 3159(w), 3120(w), 3053(s), 3036(sh), 3027 (m),
3011(w), 2999(m), 2980(m), 2965(s), 2907(m), 2868(m), 1612(w),
1580(m), 1478(s), 1455(s), 1427(m), 1395(w), 1366(m), 1297(w),
1268(w), 1227(w), 1216(w), 1200(w), 1174(w), 1149(w), 1117(w),
1074(w), 1053(m), 1032(m), 1013(w), 966(w), 949(w), 921(w),
910(w), 894(w), 883(w), 846(w), 821(w), 791(w), 732(vs) (m(BH4−)),
706(s) (m(BH4−)), 625(w), 613(s), 542(w), 479(w).
N,Nꢀꢀ -Bis(2-mercaptobenzyl)-N,Nꢀ,Nꢀꢀ -trimethyl-diethylene-
triamine (H2L5·3HCl). This compound was prepared by the
deprotection of compound 3 (2.03 g, 4.05 mmol) with sodium
(0.800 g, 34.8 mmol) in liquid ammonia (100 mL) by the procedure
detailed above for H2L4·3HCl. The trihydrochloride salt was
obtained as an impure pale-yellow powder. Nevertheless, the
purity is sufficient for the preparation of the metal complexes.
Yield: 1.99 g (98%). 1H NMR (200 MHz, D2O/CD3OD): d = 2.83
(s, 6 H, NCH3), 2.88 (s, 3 H, NCH3), 3.69 (s, 8 H, NCH2CH2N),
4.47 (s, 4 H, ArCH2), 7.28–7.57 ppm (m, 8 H, ArH). 13C NMR
(50.3 MHz, CD3OD): d = 41.5 (NCH3), 41.8 (NCH3), 48.3, 54.2
(NCH2), 54.7 (NCH2), 60.8 (ArCH2), 128.5, 130.3, 132.5, 134.7,
134.8, 135.2 ppm (ArC).
[Ni(L4)] (4). To a solution of H2L4·3HCl (457 mg, 1.00 mmol)
in methanol (20 mL) was added 1.00 mL of a 1.0 M solution of
NiCl2·6H2O in methanol. To the resulting pale-green solution was
added a solution of triethylamine (505 mg, 5.00 mmol) in methanol
(2 mL). The resulting green solid was isolated by filtration, washed
with a few mL of methanol and dried in air. An analytical sample
was obtained by◦recrystallization from acetonitrile. Yield: 364 mg
(90%). Mp 238 C; IR (KBr, cm−1): m˜ = 3062(m), 3046(m) m(N–
H). UV/Vis (MeOH): kmax (e) = 352(1533), 450(1137), 660(658)
nm (M−1 cm−1). Elemental analysis (%) calcd for C18H23N3NiS2
(404.22): C 53.48, H 5.74, N 10.40; found: C 53.65, H 5.75, N
10.34.
[Ni(L5)] (5). To a solution of H2L5·3HCl (499 mg, 1.00 mmol)
in methanol (20 mL) was added 1.00 mL of a 1.0 M solution of
NiCl2·6H2O in methanol. To the resulting pale-green solution was
added a solution of triethylamine (505 mg, 5.00 mmol) in methanol
(2 mL). The resulting red solid was isolated by filtration, washed
with a few millilitres of methanol and dried in air. An analytical
sample was obtained by recrystallization from acetonitrile. Yield:
[ZnH2(L2)][ClO4]2 (8[ClO4]2). This compound was prepared
from H2L2·6HCl (500 mg, 0.562 mmol), Zn(ClO4)2(H2O)6 (209 mg,
0.562 mmol) and triethylamine by the procedure detailed above
for 7[ClO4]2. Yield: 480 mg (91%). Mp 274–275 ◦C (decomp.).
IR (KBr) m˜ = 3445(s), 3057(m), 2985(s), 2869(m), 1631(w),
1458(s), 1365(m), 1344(w), 1304(m), 1230(m), 1180(w), 1099(vs)
(m(ClO4−)), 969 (m), 933(m), 896(w), 808(w), 756(w), 624(s),
564(w), 533(w), 512(w), 494(w). Elemental analysis (%) calcd for
C38H66Cl2N6O8S2Zn·H2O (935.39 + 18.02): C 47.87, H 7.19, N
◦
312 mg (70%). Mp 224 C; IR (KBr, cm−1): m˜ = 3047(m),
2996(s), 2964(s), 2861(s), 2809(m), 1583(w), 1557(m), 1464(s),
1433(m), 1071(m), 1036(w), 994(m), 939(m), 912(m), 818(w),
794(w), 746(m), 688(m). UV/Vis (CH3CN): kmax (e) = 347(2456),
460(1322), 490(1324), 766(71) nm (M−1 cm−1). Elemental analysis
(%) calcd for C21H29N3NiS2 (446.30): C 56.51, H 6.55, N 9.42;
found: C 56.49, H 6.70, N 9.44.
1
8.81, S 6.73; found: C 48.20, H 7.50, N 8.41, S 6.84. H NMR
◦
(400 MHz, CD3CN, 25 C, TMS): d = 1.28 (s, 9 H, ArC(CH3)),
1.30 (s, 9 H, ArC(CH3)), 7.35 (d, 4J = 2.4 Hz, 1 H, ArH), 7.36 (d,
This journal is
The Royal Society of Chemistry 2006
Dalton Trans., 2006, 3812–3821 | 3819
©

View Article Online
4J = 2.4 Hz, 1 H, ArH), 7.38 (d, 4J = 2.4 Hz, 1 H, ArH), 7.39 (d,
4J = 2.4 Hz, 1 H, ArH), 8.30 ppm (s br, 2 H, NH). The methylene
and methyl protons appear as broad and overlapped resonances in
the 5.4 to 1.8 ppm region. 13C{ H} NMR (125 MHz, CDCl3, 25 C,
TMS): d = 31.75 ArC(CH3), 31.79 ArC(CH3), 35.23 ArC(CH3),
35.25 ArC(CH3), 40.68, 42.26, 42.86, 47.18, 50.24, 52.87, 53.81,
56.51, 57.44, 64.51, 65.27, 65.95, 130.29, 130.72, 132.02, 132.16,
132.37, 133.44, 141.25, 141.81, 147.92, 148.47 ppm.
2962(s), 2903(w), 2868(m), 2837(w), 2806(w), 1582(s) (mas(OAc−)),
1477(w), 1458(s), 1425(s) (msym(OAc−)), 1396(w), 1364(m), 1315(w),
1293(m), 1267(m), 1233(m), 1205(m), 1169(w), 1156(w), 1117(w),
1093(vs) (m(ClO4−)), 1053(w), 1043(w), 1012(w), 983(w), 926(w),
910(m), 884(m), 819(m), 803(w), 746(m), 688(w), 653(w), 626(s).
1H-NMR (200 MHz, CD3CN, 25 ◦C, TMS): d = 7.11 (m, 2 H,
◦
1
2
ArH), 7.10 (m, 2 H, ArH), 4.50 (d, J(H,H) = 11.6 Hz, 2 H,
2
ArCH2), 4.44 (d, J(H,H) = 11.6 Hz, 2 H, ArCH2), 3.52 (m, 2
H, CH2), 3.39 (m, 2 H, CH2), 3.19 (m, 4 H, NCH3), 2.87 (s, 3 H,
NCH3), 2.83 (s, 3 H, NCH3), 2.82 (m, 4 H, CH2), 2.68 (m, 4 H,
ArCH2), 2.43 (m, 4 H, CH2), 2.42 (s, 6 H, NBzCH3), 2.38 (s, 6 H,
NBzCH3), 1.24 (s, 18 H, CH3), 0.92 ppm (s, 3 H, O2CCH3). ESI-MS:
m/z 905.3 ([(L3)ZnCd(l-OAc)]+; 100), 859.3 ([(L3)Zn2(l-OAc)]+;
10), 953.3 ([(L3)Cd2(l-OAc)]+; 10).
[NiH2(L3)][BPh4]2 (9[BPh4]2). To a suspension of H2L3·6HCl
(106 mg, 0.100 mmol) in methanol (20 mL) was added a solution
of Ni(ClO4)2·6H2O (36.6 mg, 0.100 mmol) in methanol (5 mL).
To the reaction mixture was added a solution of triethylamine
(50.5 mg, 0.500 mmol) in methanol (2 mL). The resulting dark
red solution was stirred for a further 30 min. Then LiClO4·3H2O
(160 mg, 1.00 mmol) was added to give a red microcrystalline solid.
The precipitate was filtered and redissolved in methanol (100 mL).
To this solution was added NaBPh4 (342 mg, 1.00 mmol).
The resulting red solid was filtered, washed with methanol and
recrystallized from acetonitrile. Fine red needles. Yield: 82 mg
(53%). Mp 242–246 ◦C (decomp.). IR (KBr) m˜ = 3445(s), 3056(m),
2965(s), 2874(m), 1652(w), 1579(m), 1558(m), 1460(s), 1362(m),
1229(w), 1183(w), 1149(w), 1061(w), 1033(w), 1011(w), 843(w),
733(s) (m(BPh4−)), 704(s) (m(BPh4−)), 612(s). UV/Vis (MeCN): kmax
(e) = 344 (2670), 428 (715), 507 (844), 688 nm (64 M−1 cm−1).
Elemental analysis (%) calcd for C98H130B2N6NiS2·H2O (1536.57 +
18.02): C 75.71, H 8.56, N 5.41, S 4.13; found: C 75.76, H 8.64,
N 5.40, S 3.90.
X-Ray crystallography
Crystals of 4–6, 7[BPh4]2·MeCN, and 9[BPh4]2 suitable for X-
ray crystallography were obtained from acetonitrile. Crystals
of 7[ClO4]2·MeOH and 8[ClO4]2·MeOH were obtained from
methanol. Crystal data and collection details are reported in
Table 1. The diffraction experiments were carried out at 210(2)
K on a BRUKER CCD X-ray diffractometer using Mo Ka
radiation. The data were processed with SAINT47 and corrected
for absorption using SADABS.48 Structures were solved by direct
methods and refined by full-matrix least-squares on the basis of
all data against F2 using SHELXL-97.49 H atoms were placed in
calculated positions and treated isotropically using the 1.2-fold
Uiso value of the parent atom except methyl H atoms, which were
assigned the 1.5-fold Uiso value of the parent C atoms. All non-
hydrogen atoms were refined anisotropically.
In the crystal structure of 7[ClO4]2·MeOH one ClO4− anion was
found to be disordered over two positions. The two orientations
could be successfully refined by using the SADI instruction (equal
Cl–O and O · · · O distances, respectively) implemented in the
SHELXL97 program to give site occupancies of 0.57(2) (for
O(5)O(6a)–O(8a)) and 0.43(2) (for O(5)O(8b)–O(11b)). No hydro-
gen atoms were calculated for the O and C atoms of the MeOH
solvate molecules in 7[ClO4]2·MeOH and 8[ClO4]2·MeOH. In the
crystal structure of 9[BPh4]2 the tert-butyl groups were found to
be disordered over two positions. The two orientations were also
refined by using the SADI instruction (equal C–C and C · · · C dis-
tances, respectively) to give site occupancies of 0.61(1)/0.39(1) (for
C(44a)–C(46a)/C(44b)–C(46b)) and 0.52(1)/0.48(1) for C(48a)–
C(50a)/C(48b)–C(50b).
[(L2)Ni2(l-OAc)][ClO4] (10[ClO4]). To a solution of 7[ClO4]2
(92.8 mg, 0.100 mmol) in methanol (20 mL) was added a solution
of NEt3 (20.2 mg, 0.200 mmol) in methanol (2 mL). To the red
solution was added a solution of Ni(OAc)2(H2O)4 (24.9 mg, 0.100)
in methanol (5 mL). The reaction mixture was heated for 6 min to
give a pale-green solution. The solution was concentrated in vacuo
to ca. 5 mL to give a green precipitate. The solid was filtered,
washed with a few mL of methanol and dried in air. Yield: 76 mg
(86%). The analytical data for this compound are identical with
those reported previously for 10[ClO4].20
[(L2)Zn2(l-OAc)][ClO4] (11[ClO4]). To a solution of 8[ClO4]2
(93.5 mg, 0.100 mmol) in methanol (20 mL) was added a solution
of NEt3 (20.2 mg, 0.200 mmol) in methanol (2 mL). To the
colourless solution was added a solution of Zn(OAc)2(H2O)2
(22.0 mg, 0.100) in methanol (5 mL). After the reaction mixture
was stirred for 30 min, it was concentrated in vacuo to ca. 10 mL
to give a colourless precipitate. The solid was filtered, washed
with a few mL of methanol and dried in air. Yield: 83 mg, (92%).
The analytical material for this compound are identical with those
reported previously for 11[ClO4].20
CCDC reference numbers 601289 (4), 601290 (5), 601291
(6), 601292 (7[ClO4]2·MeOH), 601293 (7[BPh4]2·MeCN), 601294
(8[ClO4]2·MeOH), and 601295 (9[BPh4]2)
For crystallographic data in CIF or other electronic format see
DOI: 10.1039/b603740b
[(L2)ZnCd(l-OAc)][ClO4] (13[ClO4]). To
a
solution of
8[ClO4]2 (93.5 mg, 0.100 mmol) in methanol (20 mL) was
added a solution of NEt3 (20.2 mg, 0.200 mmol) in methanol
(2 mL). To the colourless solution was added a solution of
Cd(OAc)2(H2O)2 (26.7 mg, 0.100) in methanol (5 mL). After the
reaction mixture was stirred for 30 min, it was concentrated in
vacuo to ca. 10 mL to give a colourless precipitate. The solid
was filtered, washed with a few mL of methanol and dried in air.
Yield: 85 mg, (90%). IR (KBr) m˜ = 3445(s), 3048(w), 3011(w),
Acknowledgements
This work was supported by the Deutsche Forschungsge-
meinschaft (project KE 585/3-1,2,3). We thank Prof. Dr
H. Vahrenkamp for providing facilities for X-ray crystallographic
measurements.
3820 | Dalton Trans., 2006, 3812–3821
This journal is
The Royal Society of Chemistry 2006
©

View Article Online
24 (a) M. Ciampoli, Inorg. Chem., 1966, 5, 35–40; (b) R. Morassi, I. Bertini
and L. Sacconi, Coord. Chem. Rev., 1973, 11, 343–387.
25 (a) M. Ciampoli and G. P. Speroni, Inorg. Chem., 1977, 5, 41–44; (b) M.
Ciampoli and G. P. Speroni, Inorg. Chem., 1966, 5, 45–49.
26 J. Hausmann, S. Ka¨ss, B. Kersting, S. Klod and E. Kleinpeter,
Eur. J. Inorg. Chem., 2004, 4402–4411.
References
1 H. Okawa, H. Furutachi and D. E. Fenton, Coord. Chem. Rev., 1998,
174, 51–75.
2 D. Fenton, Chem. Soc. Rev., 1999, 28, 159–168.
3 R. R. Gagne, C. L. Spiro, T. J. Smith, C. A. Hamann, W. R. Thies and
A. K. Shiemke, J. Am. Chem. Soc., 1981, 103, 4073–4081.
4 S. L. Lambert, C. L. Spiro, R. R. Gagne and D. N. Hendrickson, Inorg.
Chem., 1982, 21, 68–72.
5 D. G. McCollum, G. P. A. Yap, A. L. Rheingold and B. Bosnich, J. Am.
Chem. Soc., 1996, 118, 1365–1379.
6 N. H. Pilkington and R. Robson, Aust. J. Chem., 1970, 23, 2225–
2236.
7 P. A. Vigato, S. Tamburini and D. E. Fenton, Coord. Chem. Rev., 1990,
106, 25–170.
8 A. J. Atkins, D. Black, A. J. Blake, A. Marin-Becerra, S. Parsons,
L. Ruiz-Ramirez and M. Schro¨der, Chem. Commun., 1996, 457–
464.
9 (a) H. Okawa, J. Nishio, M. Ohba, M. Tadokoro, N. Matsumoto, M.
Koikawa, S. Kida and D. E. Fenton, Inorg. Chem., 1993, 32, 2949–
2957; (b) M. Yamami, H. Furutachi, T. Ykoyama and H. Okawa, Inorg.
Chem., 1998, 37, 6832–6838.
27 s is defined as (a − b)/60◦, where a = largest angle, b = second largest
angle (s = 1.0 for ideal trigonal bipyramidal; s = 0.0 for ideal square
pyramidal); A. W. Addison, T. N. Rao, J. Reedijk, J. Van Rijn and G. C.
Verschoor, J. Chem. Soc., Dalton Trans., 1984, 1349–1356.
28 C. A. Marganian, H. Vazir, N. Baidya, M. M. Olmstead and P. K.
Mascharak, J. Am. Chem. Soc., 1995, 117, 1584–1594.
29 N. Baidya, M. M. Olmstead, J. P. Whitehead, C. Bagyinka, M. J.
Maroney and P. K. Mascharak, Inorg. Chem., 1992, 31, 3612–3619.
30 P. Stavropoulos, M. C. Muetterties, M. Carrie and R. H. Holm, J. Am.
Chem. Soc., 1991, 113, 8485–8492.
31 (a) T. L. James, D. M. Smith and R. H. Holm, Inorg. Chem., 1994, 33,
4869–4877; (b) G. Fallani, R. Morassi and F. Zanobini, Inorg. Chim.
Acta, 1975, 12, 147–154; (c) F. Osterloh, W. Saak and S. Pohl, J. Am.
Chem. Soc., 1997, 119, 5648–5656.
32 M. D. Santana, G. Garcia, A. Rufete, M. C. Ramirez de Arellano and
G. Lopez, J. Chem. Soc., Dalton Trans., 2000, 619–625.
33 Symmetry code used to generate equivalent atoms: x, 0.5 − y, −0.5 +
z.
10 M. Yonemura, Y. Matsumura, H. Furutachi, M. Ohba, H. Okawa and
D. E. Fenton, Inorg. Chem., 1997, 36, 2711–2717.
11 H. He, A. E. Martell, R. J. Motekaitis and J. H. Reibenspies, Inorg.
Chem., 2000, 39, 1586–1592.
12 J. Nishio, H. Okawa, S. Ohtsuka and M. Tomono, Inorg. Chim. Acta,
1994, 218, 27–32.
34 J. E. Huheey, E. A. Keiter and R. L. Keiter, Anorganische Chemie, 2.
Aufl., Walter de Gruyter, Berlin, 1995, p. 347.
35 T. Steiner, Angew. Chem., 2002, 114, 50–80; T. Steiner, Angew. Chem.,
Int. Ed., 2002, 41, 48–76.
13 (a) S. Brooker and P. D. Croucher, J. Chem. Soc., Chem. Commun.,
1995, 1493–1494; (b) S. Brooker and P. D. Croucher, J. Chem. Soc.,
Chem. Commun., 1995, 2075–2076; (c) S. Brooker, P. D. Croucher and
F. M. Roxburgh, J. Chem. Soc., Dalton Trans., 1996, 3031–3037; (d) S.
Brooker and P. D. Croucher, Chem. Commun., 1997, 459–460; (e) S.
Brooker, P. D. Croucher, T. C. Davidson, G. S. Dunbar, C. U. Beck and
S. Subramanian, Eur. J. Inorg. Chem., 2000, 169–179; (f) S. Brooker,
P. D. Croucher, T. C. Davidson, G. S. Dunbar, A. J. McQuillan and
G. B. Jameson, Chem. Commun., 1998, 2131–2132.
36 B. Krebs, Angew. Chem., 1983, 95, 113–134; B. Krebs, Angew. Chem.,
Int. Ed. Engl., 1983, 22, 113–134.
37 T. Ueno, N. Nishikawa, S. Moriyama, S. Adachi, K. Lee, T. Okamura,
N. Ueyama and A. Nakamura, Inorg. Chem., 1999, 38, 1199–1210.
38 (a) E. K. Barefield, G. M. Freeman and D. G. VanDerveer, Inorg.
Chem., 1986, 25, 552–558; (b) P. Chaudhuri and K. Wieghardt, Prog.
Inorg. Chem., 1987, 35, 329–436.
39 T. Komuro, T. Matsuo, H. Kawaguchi and K. Tatsumi, Inorg. Chem.,
2003, 42, 5340–5347.
14 A. C. Marr, D. J. E. Spencer and M. Schro¨der, Coord. Chem. Rev., 2001,
219–221, 1055–1074.
40 I. Kung, D. Schweitzer, J. Shearer, W. D. Taylor, H. L. Jackson, S. Lovell
and J. A. Kovacs, J. Am. Chem. Soc., 2000, 122, 8299–8300.
41 L. A. Tyler, J. C. Noveron, M. M. Olmstead and P. K. Mascharak,
Inorg. Chem., 2003, 42, 5751–5761.
42 (a) R. D. Shannon and C. T. Prewitt, Acta Crystallogr., Sect. B, 1969,
25, 925–946; (b) R. D. Shannon, Acta Crystallogr., Sect. A, 1976, 32,
751–767.
43 F. A. Cotton, G. Wilkinson, C. A. Murillo and M. Bochmann, Advanced
Inorganic Chemistry, 6th edn, John-Wiley & Sons, Weinheim, 1999,
p. 13.
15 (a) A. J. Atkins, A. J. Blake and M. Schro¨der, J. Chem. Soc., Chem.
Commun., 1993, 1662–1665; (b) N. D. J. Branscombe, A. J. Blake, A.
Marin-Becerra, W.-S. Li, S. Parsons, L. Ruiz-Ramirez and M. Schro¨der,
Chem. Commun., 1996, 2573–2574; (c) N. D. J. Branscombe, A. J.
Atkins, A. Marin-Becerra, E. J. L. McInnes, F. E. Mabbs, J. McMaster
and M. Schro¨der, Chem. Commun., 2003, 1098–1099.
16 S. Brooker, Coord. Chem. Rev., 2001, 222, 33–56.
17 T. Glaser, Y. Journaux, G. Steinfeld, V. Lozan and B. Kersting, Dalton
Trans., 2006, 1738–1748.
18 B. Kersting and G. Steinfeld, Chem. Commun., 2001, 1376–1377.
19 M. Gressenbuch, V. Lozan, G. Steinfeld and B. Kersting, Eur. J. Inorg.
Chem., 2005, 2223–2234.
20 B. Kersting, Angew. Chem., 2001, 113, 4110–4112; B. Kersting, Angew.
Chem., Int. Ed., 2001, 40, 3988–3990.
44 K. N. Raymond, P. W. R. Corfield and J. Ibers, Inorg. Chem., 1968, 7,
1362–1369.
45 O. Meth-Cohn and B. Tarnowski, Synthesis, 1978, 56–58.
46 (a) M. H. Klingele, G. Steinfeld and B. Kersting, Z. Naturforsch., 2001,
56b, 901–907; (b) G. Siedle and B. Kersting, Z. Anorg. Allg. Chem.,
2003, 629, 2083–2090.
21 B. Kersting and D. Siebert, Inorg. Chem., 1998, 37, 3820–3828.
22 V. Lozan and B. Kersting, Eur. J. Inorg. Chem., 2005, 504–512.
23 S. Ka¨ss, T. Gregor and B. Kersting, Angew. Chem., 2006, 118, 107–110;
S. Ka¨ss, T. Gregor and B. Kersting, Angew. Chem., Int. Ed., 2006, 45,
101–104.
47 SAINT+, V6.02, Bruker AXS, Madison, WI, 1999.
48 Sheldrick, SADABS, Area-Detector Absorption Correction; University
of Go¨ttingen, Go¨ttingen, Germany, 1996.
49 G. M. Sheldrick, SHELXL-97, Computer program for crystal structure
refinement, University of Go¨ttingen, Go¨ttingen, Germany, 1997.
This journal is
The Royal Society of Chemistry 2006
Dalton Trans., 2006, 3812–3821 | 3821
©