Novel dinucleating ligand systems containing two adjacent coordination compartments of the potential triamidoamine-type - Nickel(II) and cobalt(II) coordination chemistry

Article abstract of DOI:10.1515/znb-1999-1012

The preparation of novel dinucleating pyrazolate ligands H₅L³ - H₅L⁸ carrying chelating side arms with appending secondary amine functions is reported. Following different synthetic routes, either CH₂

Full text of DOI:10.1515/znb-1999-1012

Novel Dinucleating Ligand Systems Containing Two Adjacent
Coordination Compartments of the Potential Triamidoamine-Type
-
Nickel(II) and Cobalt(II) Coordination Chemistry
Silke Buchler, Franc Meyer*, Albrecht Jacobi, Peter Kircher, and Laszlo Zsolnai
Anorganisch-Chemisches Institut der Universität Heidelberg,
Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany
* Reprint requests to Dr. F. Meyer. Fax: (0049) 6221 545707
E-mail: franc@sunO.urz.uni-heidelberg.de
Z. Naturforsch. 54 b, 1295-1306 (1999); received June 18, 1999
Dinuclear Complexes, N-Ligands, Nickel, Cobalt, Solid-State Structures
The preparation of novel dinucleating pyrazolate ligands H5 L3 - H5 L8 carrying chelating
side arms with appending secondary amine functions is reported. Following different synthetic
routes, either CH2 CF3 , C6 H2 F3 , or CftF? moieties can be introduced as substituents at the termi-
nal nitrogen atoms. These systems are reminiscent of two coupled coordination compartments of
the potential triamidoamine-type. Crystallographic analyses of a series of bimetallic complexes
of the CH2CF3 -substituted ligand H5 L4 with NiCh and C0 CI2 reveal manifold coordination
modes in the solid state, resulting from the facile detachment of a single or several N-donor
sites from the metal centers. Coordination number sets {4/6} (in H5 L4 Co2 CU) and {5/6}
(in H4 L4 Ni2 Cl3, H4 L4 Co2 Cl3 and H5 L4 Ni2CL) are thus observed. In the non-deprotonated
HsL-type systems the remaining protons are found to be scavenged by a pyrazolate-N (in
H5 L4 Ni2 CU) or an amine function of a ligand side arm (in H ^C oiC U ).
R
R
Introduction
Dinuclear transition metal complexes have re-
ceived considerable attention in the past several
years, mainly due to the increasing interest in co-
operative effects between individual metal cen-
ters [1, 2]. One fundamental approach to achieve
this sought-after cooperativity is the design of din-
ucleating ligand matrices that hold the two metal
ions in close proximity by providing adjacent coor-
dination compartments with suitable sets of donor
functions [3]. In this regard we have recently studied
a series of pyrazolate-based bimetallic complexes,
in which the coordination spheres of the metal ions
Scheme 1. Pyrazole-based type I and type II dinucleating
ligand systems.
as well as the accessible range of metal-metal sep- early 3d transition metal ions and for allowing mul-
arations can be selectively altered by appropriate tielectron redox chemistry of the bimetallic site.
changes of the chelating substituents attached to the A class of ligands closely related to the tran sys-
heterocycle [4-6]. Among these, the representative tems are the mononucleating triamidoamine anions
type I ligands HL1 and HL2 can be viewed as two {[RN(CH2 )n]3 N}3- , which have been intensively
tran-type coordination compartments [tran = tris-
studied by Verkade et al. [7], Schrock et al. [8 ], and
(aminoalkyl)amine] coupled by a pyrazole moiety others [9]. These ligands can bind to a variety of
(Scheme 1) [4], However, while these systems gave transition metals in different oxidation states, in par-
ticular in oxidation states 3+ and higher, and turned
rise to a diverse chemistry of dinuclear complexes
of (usually late) divalent 3d transition metals [6 ], out to be especially suited for stabilizing transi-
they proved less suited for stabilizing complexes of tion metals with relatively low d electron count [8 ].
0932-0776/99/1000-1295 $ 06.00 (c) 1999 Verlag der Zeitschrift für Naturforschung, Tübingen • www.znaturforsch.com
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S. Buchler et al. ■Novel Dinucleating Ligand Systems
1296
1) S0CI2
,
NH
R'
Hg
HN—
R'
R’
1a, b (R' = COCF3)
1c,d(R' = C6F5)
2a, b (R' = COCF3)
2c, d (R' = C6F5)
LiAIH4
O
x
F3C
OEt
R
X — NH
H N~x
nNH2
2
or CßFß, N a2C03
V /
\J
NH
R
R
H5L3, H5L4 (R = CH2CF3)
H5L5, H5L6 (R= ^ 0 - F )
Scheme 2. Synthesis of type II ligands
H5L3 - H5L6.
Moreover, the fixation of dinitrogen achieved within ondary amine functions of the employed triamine in
di- and oligonuclear arrangements of such triami- order to selectively react its central N atom with the
doamine molybdenum and uranium complexes un- acid chloride. We first chose the trifluoroacetyl pro-
derlines the special capabilities that cooperating tecting group that is conveniently introduced [1 2 ] by
treating diethylenetriamine or dipropylenetriamine
with ethyl trifluoroacetate to give la, b, respectively.
Its electron withdrawing properties now allow for
a selective coupling of the central N atom of la, b
with the pyrazole moiety to afford 2a, b, and the
subsequent reduction step not only transforms the
newly formed amide linkages but at the same time
reduces the trifluoroacetyl groups to yield the type
II ligands H5L3 and H5L4 carrying trifluoroethyl
substituents at the terminal amine functions.
Altogether the trifluoroacetyl group serves two
purposes, i. e. it first acts as a protecting group
during the coupling reaction and is then converted
into the requisite terminal substituent at the amine
donors without increasing the overall number of
synthetic steps. In addition, the same procedure may
be used to attach long chain fluorinated substituents
at the ligand core by employing appropriate perflu-
oroalkylcarboxy protecting groups (which we have
exemplary proved by starting from the heptafluo-
robutyryl protected triamines), a prospect that might
possibly be of interest in the view of a future modifi-
cation of the solubility of resulting complexes [13].
As electron-withdrawing pentafluorophenyl sub-
metal ions in multinuclear arrangements might offer
for the activation of small substrate molecules [1 0 ].
In this context we intended to prepare novel type
II dinucleating ligand frameworks which have the
potential to provide two adjacent coordination pock-
ets, each bearing similarity to the mononucleating
triamidoamine compartments. The present contri-
bution reports a first synthetic strategy giving access
to such systems II, and it describes the basic coor-
dination behavior of one selected ligand towards
cobalt(II) and nickel(II) chloride in comparison to
the corresponding complexes of L 1 and L2.
Results and Discussion
Ligand synthesis
The known synthetic route for the preparation of
type I ligands L 1 and L2 starts from pyrazole-3,5-
dicarboxylic acid. This is first converted into the
corresponding bis(acid chloride), and subsequently
treated with the appropriate secondary amine. The
resulting bis(amide) is finally reduced using an ex-
cess of LiAlH4 [4, 11], With the aim of limiting the
preparative effort and the number of synthetic steps
we decided to adapt this established strategy also for stituents at the terminal nitrogen atoms proved par-
ticularly useful for the formation of the metal-amido
the synthesis of the new systems II (Scheme 2). This
bond in triamidoamine chemistry [8 , 14], we also
implies the necessity to protect the terminal sec-
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1297
S. Buchler et al. ■Novel Dinucleating Ligand Systems
r
r
/— ' NH
HN-
1) 1c, d / N a 2C03 /CH3CN
2) HCl / EtOH
Scheme 3. Synthesis of type II ligands
H5 L7 and H5 L8.
H5L7, H5L8 (R = C6F5)
Table I. Selected atom distances [A] and bond angles [c
for L'Ni2 Cl3.
Nil-Nl
Nil-N4
Nil-C12
Ni2-N5
Ni2-C13
N1-N2
1.945(6)
2.104(7)
2.282(2)
2.217(6)
2.288(2)
1.353(8)
2.188(6)
2.406(2)
1.951(6)
2.103(7)
2.422(2)
3.829
Nil-N3
Nil-Cll
Ni2-N2
Ni2-N6
Ni2-Cll
Nil •••Ni2
79.1(2)
87.9(2)
86.7(3)
94.6(2)
102.3(2)
79.2(2)
87.9(2)
8 6 .0 (2 )
95.1(2)
106.3(2)
129.4(4)
104.94(8)
Nl-Nil-N4
Nl-Ni 1-C12
N3-NM-C11
N4-Nil-Cll
Cll-Nil-C12
N2-Ni2-N6
N2-Ni2-C13
N5-Ni2-Cll
N6-Ni2-Cll
Cll-Ni2-C13
Ni2-N2-N 1
99.6(3)
156.8(2)
164.7(2)
103.6(2)
94.21(9)
99.5(3)
153.1(2)
166.0(2)
1 0 1 .6 (2 )
94.06(8)
128.6(4)
Nl-Nil-N3
NI-Nil-Cll
N3-Nil-N4
N3-Nil-C12
N4-Nil-C12
N2-Ni2-N5
N2-Ni2-Cl 1
N5-Ni2-N6
N5-Ni2-C13
N6-Ni2-C13
Nil-Nl-N2
Nil -Cl 1-Ni2
Fig. 1. Molecular structure of L1NiaCb.
A series of novel dinucleating ligand systems
reminescent of two coupled coordination compart-
ments of potential triamidoamine-type are thus
available. A first glance at their coordination poten-
tial is obtained from some coordination compounds
of the selected ligand H5L4, where the ligand acts
as a simple polyamine donor.
set out to introduce C6F5 moieties as R groups in
our type II ligands. The necessary building blocks
lc, d are readily available by reaction of the re-
spective triamine with hexafluorobenzene [15], and
can selectively be attached to the pyrazole nucleus
to give 2c, d. However, the final reduction step in
these cases not only transforms all amide functions,
but simultaneously leads to partial nucleophilic sub-
stitution of the aryl-bound fluoride by hydride. If re-
action conditions are controlled carefully, this can
be limited to a quite selective replacement of solely
the meta-fluorine atoms, thus leading to the 2,4,6-
trifluorophenyl-substituted potential ligands H5L5
and H5L6 in reasonable purity (Scheme 2).
Synthesis and structural characterization o f
cobalt(II) and nickel(Il) complexes
With the aim of probing the coordination poten-
tial of the new systems in comparison to related
complexes of L 1 and L2, we investigated coor-
dination compounds of H5L4 with cobalt(II) and
nickel(II) chloride. The structures of L*Co2Cl3 and
A different route not requiring such a harsh re- L2Co2C13 have been reported previously [4]. We
duction step had to be developed in order to ob- now synthesized the analogous systems L'NioCls
tain the CöFs-substituted compounds. 3,5-bis(chlo- and L2Ni2Cl3 from the respective ligands, which
were deprotonated prior to their subsequent reaction
with NiCl2. The formation of coordination com-
pounds is inferred from the mass spectra, which
romethyl)pyrazole turned out to be a suitable start-
ing material, if the potentially nucleophilic NH
function of the heterocycle is protected by a tetrahy-
dropyranyl (THP) group prior to attaching the side- show dominant peaks corresponding to the frag-
arm components lc, d [16]. The protecting group
is finally removed by treatment with acid to yield
H5L7, H5L8 (Scheme 3).
ment ions [LNi2Cl2]+. The molecular structures of
the new complexes were determined by X-ray crys-
tallography and are depicted in Figs 1 and 2; repre-
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1298
S. Buchler et al. • Novel Dinucleating Ligand Systems
Table II. Selected atom distances [A] and bond angles [°] Table III. Selected atom distances [A] and bond angles
[°] for H4 L4 Ni2Cl3.
forL2 Ni2Cl3.
Nil-Nl
Nil-N4
Nil -C12
Nil - Ni 1#l
1.962(2)
2.083(3)
2.2852(9) N1-N1#I
Nil-N2
Ni 1-Cl 1
2.195(3)
2.4632(8)
1.360(5)
Nil-Nl
1.991(3)
Nil-N3
Nil-N5
Ni 1-C13
Ni2-N6
Ni2-Cll
N1-N2
2.191(3)
2.182(3)
2.347(1)
2.178(3)
2.477(1)
1.360(4)
Nil-N4
Ni 1-Cl 1
Ni2-N2
Ni2-N7
Ni2-C12
Nil- •-Ni2
2.235(3)
2.567(1)
1.973(3)
2.066(3)
2.312(1)
3.991
3.917
Nl-Nil-N2
N 1-Ni 1-Cl 1
N2-Nil-N4
N2-NÜ-C12
N4-Nil-C12
N il-N l-N l#l
78.6(1)
86.3(1)
98.3(1)
93.7(1)
98.8(1)
129.8(1)
Nl-Nil-N4
Nl-Nil-C12
N2-Nil-Cll
N4-Nil-Cll
Cl 1-Ni 1-C12
Ni 1-Cl 1-Ni 1#1
1 0 1 .6 (1 )
159.1(1)
160.4(1)
97.0(1)
96.1(1)
105.3(1)
79.5(1)
93.5(1)
177.0(1)
163.02(8)
88.94(9)
90.8(1)
83.45(9)
97.57(4)
107.56(1)
154.58(9)
94.21(9)
101.46(9)
92.88(4)
Nl-Nil-N4
N 1-Ni 1-Cl 1
N3-Nil-N4
N3-Nil-C13
N4-Ni 1-C13
N5-Ni 1-N4
N5-Ni 1-C13
N2-Ni2-N6
N2-Ni2-Cl 1
N6-Ni2-Cll
N7-Ni2-N6
N7-Ni2-C12
Nl-Nil-N3
Nl-Nil-N5
Nl-Nil-C13
N3-Ni 1-Cl 1
N4-Nil-Cll
N5-Nil-N3
N5-Ni 1-Cl 1
C12- Ni 1-Cl 1
N2-Ni2-N7
N2-Ni2-C12
N6-Ni2-C12
N7-Ni2-Cll
C12-Ni2-Cll
8 8 .6 ( 1 )
84.90(9)
97.3(1)
98.23(9)
89.69(9)
171.9(1)
88.49(9)
79.38(1)
86.51(9)
160.60(8)
95.49(1)
97.48(1)
N3
CM
I
CI2
TN 4tJ
N3
Fig. 2. Molecular structure of L2 Ni2Cl3.
N1
Nil
sentative atom distances and bond angles are listed
in Tables I and II, respectively. L 'r ^ C ^ crystal-
lizes in the monoclinic space group P2\/c with 4
molecular entities in the unit cell, while L2Ni2Cl3
is found to crystallize in the tetragonal space group
7^4 3 212 with 4 molecules in the unit cell.
cn
N5
ci2
Similar to the results for the known cobalt(II)
systems [4], the nickel ions are found to be five-
coordinate with two ligand side arms remaining un-
coordinated. This is in accordance with previous
observations for related mononuclear complexes of
tran-type ligand systems, where in the case of N,N-
dialkylated terminal amino donors the coordination
of the metal centers is restricted to five-coordina-
tion for steric reasons [17]. Referring to the an-
gular structural parameter r = (ß - a)/60, where
a and ß represent two basal angles with ß > a
Fig. 3. Molecular structure of H4 L4 Ni2 Cl3.
L2Ni2Cl3 (t = 0 .0 2 ) can be described as predomi-
nantly SPY-5 (a perfect TB-5 structure is associated
with r = 1 , while r = 0 is expected for an ideal
SPY-5 geometry). The distance Ni --Ni amounts to
3.829 (L 'N ^C b) and 3.917 A (L2Ni2Cl3).
As anticipated, treatment of the new ligand H 5 L 4
with two equivalents of NiCb or C0 CI2 in the
presence of an external base affords coordination
[18], the coordination geometry around the nickel compounds H4L4Ni2Cl3 and H4L4Co2Cl3 , whose
ions in L'NioCl^ (r = 0.13/0.22 for Nil/Ni2) and formation is again corroborated by mass spectro-
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S. Buchler et al. • Novel Dinucleating Ligand Systems
Table IV. Selected atom distances [A] and bond angles Table V. UV/Vis data of the complexes; A/nm
(e/IV r'cnT1).
[°] forH4 L4 Co2Cl3.
Col-Nl
Col-N4
Col-Cll
Co2-N2
Co2-N7
Co2-C13
C ol-C o2
2.024(2)
2.240(2)
2.350(8)
1.986(2)
2.117(2)
2.483(9)
3.992
Col-N3
Col-N5
Col-C13
Co2-N6
Co2-C12
N1-N2
2.257(2)
2.282(2)
2.576(9)
2.291(2)
2.316(8)
1.370(3)
410(192), 686(72), 1130(43)
421,690
538 (48), 581 (50), 635 (51)
588, 639, 682
413 (143), 690 (49), 1130 (31)
415,690, 1050
596(117), 639(156), 678(147)
585, 642, 685
H4 L4 Ni,Ch a
H4 L4 Ni,Ch b
H4 L4 Co,Cl\ a
H4 L4 Co.Ch b
H5 L4 Ni7Cl4 a
H5 L4 Ni,Cl4 b
H,L4 CooC14 a
H5 L4 Co,C14 b
Nl-Col-N3
Nl-Col-N5
Nl-Col-C13
N3-Col-Cll
N4-Col-N3
N4-Col-Cll
N5-Col-Cll
Cll-Col-C13
N2-Co2-N7
N2-Co2-C13
N6-Co2-C13
N7-Co2-C12
77.58(8)
89.13(9)
85.74(6)
98.82(6)
89.82(8)
89.35(7)
89.73(7)
98.00(3)
110.75(9)
88.35(6)
161.23(6)
99.38(7)
Nl-Col-N4
N1-Col-Cll
N3-Col-N5
N3-Col-C13
N4-Col-N5
N4-Col-C13
N5-Col-C13
N2-Co2-N6
N2-Co2-C12
N6-Co2-C12
N7-Co2-N6
N7-Co2-C13
92.23(9)
176.06(6)
97.00(8)
162.35(6)
173.17(8)
85.06(6)
88.38(6)
77.00(8)
148.54(7)
92.95(6)
93.14(9)
103.10(7)
a in EtOH;bdispersion in nujol.
some of the differing solvent as used for crystal-
lization is included in the crystal lattice, both com-
pounds are isotypic and crystallize in the monoclinic
space group P2\lc. Their molecular structures are
depicted in Figs 3 and 4, representative atom dis-
tances and bond angles are given in Tables III and IV.
Unexpectedly, both H4L4Ni2Cl3 and H4L4Co2-
Cl3 feature asymmetric dinuclear cores in which
one metal atom [Nil/Col] is six-coordinated in a
distorted OC-6 surrounding while the second metal
center again remains five-coordinate [Ni2/Co2; r =
0.10/0.21] leaving a single side arm dangling. This
finding is surprising, as there is no obvious geomet-
ric or electronic distinction between the two metal
centers spanned by the symmetric dinucleating lig-
and framework that would restrict an increase in
coordination number to only one of them. Further-
more, a related pyrazolate-based dinickel(II) com-
plex providing terminal thioether donor functions at
the ligand side arms gave a symmetric complex with
both metal centers in OC-6 environments [5a], so
that steric reasons appear not to be responsible for
the present results. However, the structural asymme-
try found for H4L4Ni2Cl3 and H4L4Co2Cl3 in the
solid state closely resembles the unusual oligomer-
ization observed for some related dinickel(II) com-
plexes of pyrazolate ligands with fewer chelating
donor functions, also proceeding via a partial in-
crease in coordination number from five to six [2 0 ].
Fig. 4. Molecular structure of H4 L4 Co2 C13.
metry (dominant peaks with m/z corresponding to
[H4L4Ni2Cl2]+ and [H4L4Co2C12]+, respectively).
Magnetic moments per metal ion at room temper-
ature of 2.87 i 0.10 /iB (H4L4Ni2Cl3) and 4.35 ±
0.07 /iß (H4L4Co2C13)confirm the presence of high-
While the UV/Vis spectra of H4L4Ni2Cl3 are
quite similar in solution (EtOH) and in the solid state
(dispersion in nujol), the spectra of H4L4Co2Cl3 un-
spin nickel(II) and cobalt(II), respectively, with the dergo considerable changes upon dissolving of the
common orbital angular momentum contributions complex in EtOH (Table V), indicative of a differ-
ent structure in solution. Closer inspection reveals
tained in crystalline form by slow diffusion of light that the solution optical absorptions of H4L4Co2C13
in the latter case [19]. These complexes can be ob-
bear resemblance to those previously reported for
L2Co2Cl3 [4], thus suggesting detachment of a
petroleum into CH2C12 (H4L4Ni2Cl3) or CHC13
(H4L4Co2C13) solutions. Apart from the fact that
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1300
S. Buchler et al. ■Novel Dinucleating Ligand Systems
Table VI. Selected atom distances [A] and bond angles
[°] for H5 L4 Co2 C13.
R = CH2CF3
Col-Nl
Col-N7
Col-Cll
Co2-N2
Co2-C13
N1-N2
2.049(3)
2.238(3)
2.343(1)
1.998(3)
2.271(1)
1.375(3)
C0 I-N6
C0 I-N8
Col-C12
Co2-C12
Co2-C14
Col •••Co2
2.224(3)
2.223(3)
2.703(1)
2.291(1)
2.224(1)
3.751
Scheme 4. Constitution of HjL^NijCU in the solid state.
further ligand side arm to give two five-coordinated
metal centers in the present case, too.
NI-C0 I-N6
NI-C0 I-N8
Nl-Col-C12
N6 -C0 I-CII
N7-Col-Cll
N8 -C0 I-N6
N8 -C0 I-CII
Cll-Col-C12
N2-Co2-C13
78.99(10) Nl-Col-N7
94.84(10) N1-Col-Cll
86.03(7)
98.67(7)
89.00(8)
86.37(10)
174.41(8)
98.93(10)
161.70(7)
90.48(8)
170.01(11)
79.72(8)
When H5L4 is treated with the same metal salts
in the absence of an external base, different com-
plexes with empirical formula H4LNi2ClvHCl and
H4LC0 2 CI3 HCI are formed due to the presence
of one additional equivalent of HC1. Again, mag-
netic moments per metal ion at room temperature
N6-Col-N7
N6-Col-C12
N7-Col-C12
91.03(10) N8-Col-N7
N8-Col-C12
N2-Co2-C12
N2-Co2-C14
C14-Co2-C12 114.85(4)
Co2-C12Col 97.04(3)
90.27(8)
97.15(4)
108.25(8)
100.59(8)
1 1 1 .1 1 (8 )
of 3.21 ± 0 .0 1
(H5L4Ni2Cl4) and 4.39 ± 0.05
C13-Co2-C12 112.02(4)
C14-Co2-C13 109.58(5)
(H5L4Co2C14) confirm the presence of high-
spin nickel(II) and cobalt(II), respectively. Unique
structures in the solid state were revealed by X-ray
diffraction analyses for both of these systems.
Single crystals of HsL4Ni2Cl4 are obtained by
layering a solution of the complex in CH2CI2
with Et2 0 . The compound crystallizes in the tri-
clinic space group P\ with eight molecular entities
(four independent bimetallic molecules) in the unit
cell [21]. Unfortunately, the quality of the crystal-
lographic analysis was poor, and we therefore re-
frain from any detailed discussion of the structure.
However, the basic constitution of HsL4Ni2Cl4 in
the solid state could be established unequivocally
and is given in Scheme 4. In this case the pyrazo-
late core has lost its bridging coordination mode
and is detached from one of the nickel ions to be
left in monodentate binding to the second metal
center. The latter is found in an approximate OC-
6 environment, while the detached nickel ion ex-
hibits only five-coordination. The additional proton
is most likely bound to the available second N-atom
of the heterocycle, as depicted in Scheme 4.
Fig. 5. Molecular structure of H5 L4 Co2Cl4 .
donors of one ligand side arm thus remain uncoordi-
Blue crystals of the analogous complex H5L4-
Co2Cl4 are obtained by layering a solution in
CH2CI2 with light petroleum. The compound crys- nated and dangling. Its tertiary nitrogen atom N3 has
tallizes in the triclinic space group P\ with two picked up the surplus proton that could be located
molecular entities in the unit cell. Its molecular as a hydrogen bridge to the cobalt-bound C13 atom
[d(N3--C13) = 3.14 A]. Such hydrogen bonding in-
teractions between N-H donors and metal-bound
chlorine have been recognized to be a common phe-
nomenon [22]. All Co2-Cl distances are very similar
[in the range 2.224( 1) - 2.291(1) Ä], while the bond
structure is depicted in Fig. 5, selected atom dis-
tances and bond angles are given in Table VI.
Interestingly the dinuclear framework consists of
a six-coordinate Col atom (angles between trans
donors in the range 161.7 - 174.4°) next to a four-
coordinate near-tetrahedral Co2 center. All amine length Col-C12 is much longer [2.703(1) A] and
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1301
S. Buchler et al. ■Novel Dinucleating Ligand Systems
causes the Cl-bridge to exhibit distinct asymmetry. base. While five-coordination of the metal centers
The metal-metal distance amounts to 3.75 A, and in the related systems L 'l^ C ^ and L2Ni2Cl3 can
as expected for a rather unstrained bimetallic core be rationalized on the basis of steric constraints,
the two cobalt ions are situated roughly within the the reason for the non-coordination of a single side
plane of the pyrazolate heterocycle (distance 0.08 arm N-donor in both H4L4Ni2Cl3 and H4L4Co2Cl3
and 0.35 Ä).
is less obvious. In the absence of external base an
additional chloride ion coordinates to the bimetallic
system and the surplus proton is scavenged by the
dinuclear core in a variable manner. In H5L4Ni2Cl4
this proton is presumably accommodated by one
of the pyrazolate-N forcing the heterocycle to give
up its bridging coordination mode. On the other
hand, in H5L4Co2Cl4 the proton is bound to one
ligand side arm N-donor, which finally leaves this
side arm completely uncoordinated causing four-
coordination of the respective metal center. Future
work is directed towards the synthesis and study of
amido-metal complexes of the new ligand systems.
A dominant peak in the mass spectrum of
H5L4Co2C14 at m/z =869 corresponding to the com-
position [H4L4Co2C12]+ is indicative of facile loss
of both one equivalent of HC1 and a chloride ion
from the complex. However, the UV/Vis spectrum
is similar in EtOH and for a dispersion in nujol
(Table V), thus suggesting similar structures in so-
lution and in the solid state. Furthermore the solid
state optical absorption spectra of H5L4Co2Cl4, and
H4L4Co2Cl3 (see above) are comparable, and they
thus seem to be dominated by the ligand-field tran-
sitions of the near-octahedral Co(II) ion.
Conclusions
Experim ental
Following a previously established route for the
synthesis of pyrazolate-based multidentate amine
ligands, novel compartemental ligand systems have
been prepared which feature secondary amines at
the appending side arms and thus provide two ad-
jacent coordination compartments reminiscent of
the triamidoamine-type. The crucial synthetic step
is the use of trifluoroacetyl or pentafluorophenyl
moieties as amine protecting groups and at the
same time as precursors for the terminal amine
substituents. Either CH2CF3 or C6H2F3 groups
can be introduced by this way. The related sys-
tems bearing C6F5 substituents at the terminal N
atoms have been made available via an alterna-
tive synthetic strategy. The coordination potential
of one selected new ligand H5L4 towards late tran-
sition metals turned out to be manifold and flexi-
ble because of the facile detachment of a single or
even several donor atoms from the metal centers.
Consequently an unambiguous elucidation of the
structure of these complexes relies on single crys-
tal X-ray crystallography. Coordination numbers
{4/6} (in H5L4Co2Cl4) and {5/6} (in H4L4Ni2Cl3
H4L4Co2Cl3 and H5L4Ni2Cl4) have been observed
in the solid state. However, UV/Vis absorption spec-
tra indicate the likely presence of a different solution
structure in the case of H4L4Co2Cl3 . Complexes
H4L4M2Cl3 form from the ligand and an appro-
priate metal dichloride in the presence of external
General procedures and methods
All manipulations were carried out under an atmo-
sphere of dry nitrogen by employing standard Schlenk
techniques. Solvents were dried according to established
procedures. HL1 and HL2 were synthesized according to
the reported method [4, 11], Microanalyses: Mikroana-
lytische Laboratorien des Organisch-Chemischen Insti-
tuts der Universität Heidelberg. - IR spectra: Perkin-El-
mer 983G. - FAB-MS spectra: Finnigan MAT 8230. -
UV/Vis spectra: Perkin-Elmer Lambda 19. - NMR spec-
tra: Bruker AC 200 at 200.13 (*H) and 50.32 (l3 C) MHz;
solvent signal as chemical shift reference (CDCI3
7.27
6c 77.0; 06-acetone <$h 2.04 Sc 29.8). - Magnetic mea-
surement: Bruker Magnet B-E 15 C8 , field-controller B-
H 15, Sartorius micro balance M 25 D-S. Experimental
susceptibility data were corrected for the underlying dia-
magnetism.
la, b: Ethyl trifluoroacetate was added to a solution
of the triamine [diethylenetriamine (2 . 1 g, 2 0 . 0 mmol) or
dipropylenetriamine (2.7 g, 20.0 mmol), respectively] in
THF and the mixture was heated overnight. After removal
of all volatile material the products la, b remain as white
solids, la [12]: yield (5.9 g (19 mmol, 95%). 'H NMR
(Dft-acetone): 6 = 1.46 (s, 1H, NH), 2.86 (t, VHH=5.9 Hz,
4H, CH2), 3.44 (t, Vhh = 5.9 Hz, 4H, CH2), 7.04 (s, 2H,
NH). 13C{'H} NMR (06-acetone): 6 = 39.7 (CH2), 47.7
(CH2), 116.2 (q, 'Vcf = 286 Hz, CF3), 158.7 (q, 2JCf = 20
Hz, CO). 19F NMR (Dö-acetone): 6 =-11.2. MS (EI) m/z
(%) = 296 (7) [M++l], 169 (87) [M+-CF3 CONHCH2],
140 (100) [CF3 CONHCH2 CH2+],
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1302
S. Buchler et al. ■Novel Dinucleating Ligand Systems
(%) = 627 (100) [M++l], 514(78) [M+-CF3 CH2 NHCH2],
360 (54) [M+-N[(CH2 )2 NHCH2CF3]2],
C 8H ,|F 6N302 (295.2)
Calcd C 32.6 H 3.8 N 14.2%,
Found C 32.0 H 3.9 N 13.6%.
C2 |H3 4Fi2 N8 (626.5)
lb: yield (6.4 g, 19.8 mmol, 99%). 'H NMR (D6 -ace-
tone): b = 1.54 (s, 1H, NH), 1.77 (quint., VHh = 6.2 Hz,
4H, CH2), 2.76 (t, Vhh = 6.2 Hz, 4H, CH2), 3.48 (t, VHH=
6.2 Hz, 4H, CH2), 8.22 (s, 2H, NH). 13C{1H} NMR (D6-
acetone): 6 = 27.6 (CH2), 38.9 (CH2), 47.6 (CH2), 116.0
(q, '/c f = 286 Hz, CF3), 157.0 (q, 2JCf = 36 Hz, CO). I9F
NMR (D6 -acetone): b =-77.9. MS (EI) m/z (%) = 323 (10)
[M++l], 183 (87) [M+-CF3 CONHCH2CH2], 154 (100)
[CF3 CONH(CH2)3+], 126(100) [CF3 CONHCH2+].
Calcd C 40.3 H 5.5 N 17.9%,
Found C 40.3 H 6.0 N 17.8%.
Ligand H 5 L 4: Starting from pyrazole-3,5-dicarboxylic
acid monohydrate (2,7 g, 15.5 mmol) and lb (10.0 g,
31.0 mmol) the amide 2b (23.0 g, 30.0 mmol) was pre-
pared as described for 2a. 'H NMR (D6 -acetone): b =
1.94 (quint,V = 6.0 Hz, 8 H, CH2), 3.40 (t, V = 6.0 Hz,
8 H, CH2), 3.62, 3.81 (2t, V = 6.0 Hz, 8 H, E-/Z-CH2),
6.99 (s, 1H, pz-H4), 8.60 (s, 4H, NH). 13C{'H} NMR
(D6 -acetone): b = 25.9 (CH2), 37.6 (CH2), 43.9 (CH2),
Ci0 H15F6 N3 O2 (323.2)
46.7 (CH2), 108.9 (pz-C4), 116.9 (q, ' y C F
=
286Hz, CF3),
Calcd C 37.2 H 4.7 N 13.0%,
Found C 36.5 H 4.5 N 12.2%.
143.1 (pz-C3/5), 158.0 (q, 2/ Cf = 30 Hz, COCF3), 162.9
(CO). ,9F NMR (D6 -acetone): b = -77.3. MS (FAB+):
m/z (%) = 767 (100) [M++l], The reduction was car-
ried out analogously to the synthesis of H5L3 to yield
H5L4 (9.5 g, 15.0 mmol). IR (film): z>max/cirT 1 = 3271 (s),
2937(s), 2839(s), 1566(w), 1469(w), 1366(w), 1267(s),
1146(s), 952(m), 827(m), 664(m). 'H NMR (CDC13): b =
1.61 (quint,3/ = 6.5 Hz, 8 H, CH2), 2.45 (t, V = 6.5 Hz,
8 H, CH2), 2.70 (t, V = 6.5 Hz, 8 H, CH2), 3.10 (q, V Hf =
9.4 Hz, 8 H, CH2 CF3), 3.54 (s, 4H, CH2), 5.95 (s, 1H,
pz-H4). I3 C{'H} NMR (CDC13): b = 47.6 (CH2), 47.8
(CH2), 49.9 (CH2), 50.0 (q, 2JCf = 31 Hz, CH2CF3), 51.5
(CH2), 103.5 (pz-C4), 125.2 (q, ‘/ Cf = 277 Hz, CF3). I9F
NMR (CDC13): b = -72.2. MS (FAB+): m/z (%) = 683
(100) [M++l],
Ligand H 5 L 3 : Pyrazole-3,5-dicarboxylic acid mono-
hydrate (2.0 g, 11.5 mmol) was converted into 3,5-bis-
(chloroformyl)pyrazole by the usual reaction with thionyl
chloride (100 cm3). It was taken up in THF (100 ml) and
treated dropwise with a solution of la (7.1 g, 24.0 mmol)
and triethylamine (6 . 6 g, 92 mmol) in THF (100 ml). Af-
ter stirring overnight, a saturated aqueous sodium chlo-
ride solution was added. The phases were separated and
the THF phase was dried over MgS04 and filtered. THF
was removed under vacuum, the oily residue was taken
up in THF and filtered again. After evaporation of the
solvent the product 2 a remained as a yellow solid, 'H
NMR (06-acetone): 6 = 3.62 (t, V = 5.4 Hz, 8 H, CH2),
3.65, 4.00 (2t, V = 5.4 Hz, 8 H, E-/Z-CH2), 7.05 (s, 1H,
pz-H4), 8.81 (s, 4H, NH). 13C{'H} NMR (D6 -acetone):
b = 45.8 (CH2), 46.2 (CH2), 47.7 (CH2), 109.1 (pz-C4),
116.5 (q, '7cf = 285 Hz, CF3), 142.4 (pz-C3/5), 157.5 (q,
2JCf = 36 Hz, COCF3), 163.2 (CO). 19F NMR (D6 -ace-
C2 5 H42N8 FI2 (682.6)
Calcd C 44.0 H 6.2 N 16.4%,
Found C 43.6 H 6.5 N 15.6%.
Ligand H 5 L 5 : Starting from pyrazole-3,5-dicarboxylic
tone): b =-77.7. MS (FAB+) m/z (%) = 711 (62) [M++l ], acid monohydrate (1.3 g, 7.8 mmol) and lc [15b] (6.7 g,
416 (100) [M+-N[(CH2 )2 NHCOCF3]2. A solution of this
compound 2a (8 .1 g, 11.0 mmol) in THF was added drop-
wise to a suspension of LiAlH4 (1.9 g, 5.0 mmol) in THF
at room temperature. The mixture was heated to reflux
for 4 h, stirred overnight and hydrolysed by the drop-
wise addition of water. The precipitate was filtered off
and washed several times with THF. The combined or-
ganic phases were dried over MgS04 and evaporated to
15.5 mmol) the amide 2c (7.5 g, 7.6 mmol) was prepared
as described for 2a. 'H NMR (D6 -acetone): b = 3.65 (t,
2J = 5.4 Hz, 8 H, CH2), 3.65, 3.91 (2t, V = 5.4 Hz, 8 H, E-
/Z-CH2), 4.51 (s, 4H, NH), 7.10 (s, lH,pz-H4). I3 C{'H}
NMR (D6 -acetone): b = 44.6 (CH2), 47.8 (CH2), 49.7
(CH2), 109.5 (pz-C4), 125.1, 130.7,136.5,141.0(m,Car),
163.1 (CO). I9F NMR (D6 -acetone): 6 = -174.0,-168.0,
-162.0. MS (FAB+) m/z (%) = 991 (16) [M++ 1], 436 (100)
dryness to yield H5 L3 (6.7 g, 10.7 mmol) as a yellow- {NH[CH2CH2 NH(C6 F5)]2++ 1}. The reduction of 2c was
ish oil. IR (film): iW c m - 1 = 3289(s), 2937(s), 2837(s), carried out under the same conditions as above to yield
1566(w), 1454(w), 1351(w), 1268(s), 1161(s), 947(m), H5L5 (6.0 g, 7.4 mmol, 97 %). IR (film): //max/cm_l =
821(m),661(m).1H NMR (CDC13): <5= 1. 8 6 (s, 4H, NH), 3355 (s), 2941/2842 (vs), 1642 (w), 1606 (s), 1516 (s),
1359 (s), 1275/1183 (vs), 1107 (m), 1037 (s), 814 (m), 784
(m), 627 (m). 1H NMR (CDC13): b = 2.85 (t, V = 5.6 Hz,
2.59 (t, V = 5.3 Hz, 8 H, CH2), 2.75 (t, V = 5.3 Hz, CH2),
3.09 (q, V h f = 9.4 Hz, CH2CF3), 3.63 (s, 4H, CH2), 5.95
(s, 1H, pz-H4). 13C{1H} NMR (CDC13): 6 = 46.6 (CH2), 8 H, CH2), 3.10 (t, 3y = 5.6 Hz, 8 H, CH2), 3.72 (s, 4H,
CH2), 5.98 - 6.14 (m, 9H, pz-H4 and Har). i3 C{'H} NMR
(CDC13): b =41.4 (CH2), 50.2 (CH2), 53.9 (CH2). 95.8 (m,
48.5 (CH2), 50.0 (q, 2/ Cf = 31 Hz, CH2CF3), 53.6 (CH2),
102.9 (pz-C4), 125.3 (q, ' / c = 277 Hz, CF3), pz-C3 / 5 not
f
observed. ,9F NMR (CDC13): b = -72.2. MS (FAB+): m/z Car), 104.5 (pz-C4), 129.8, 135.1, 149.3, 154.1 (m, Car).
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1303
S. Buchler et al. • Novel Dinucleating Ligand Systems
5.5 Hz,
4H, CH2), 4.25 (s, 4H, NH),
NMR (CDCI ): 6 = 43.3 (CH2), 49.8 (CH2), 53.6 (CH2),
103.6 (pz-C4), 123.6, 131.0, 135.3, 140.0 (m, Car). I9F
NMR (CDCI ): 6 =-172.3,-164.9,-160.8. MS (FAB+)
m/z (%) = 963 (45) [M++ 1] 766 (100) [M+-CH NHC F5],
8
H, CH2), 3.39 (t, V = 5.5 Hz,
8
H, CH2), 3.71 (s,
l9FNM R (CDCI
(%) = 819 (55) [M++l], 658 (100) [M+-CH
3
): 6 = -176.3,-135.1. MS (FAB+) m/z
NHC ].
6
.10 (s, 1H, pz-H4). 13 C { H}
1
2
6
H
2
F
3
3
C37H3 3 Fi2N (817.7)
8
Calcd C 54.3 H 4.2 N 13.7%,
Found C 53.0 H 4.3 N 12.5%.
3
2
6
Ligand H5L6: Starting from pyrazole-3,5-dicarboxylic
acid monohydrate (1.2 g, 7.1 mmol) and Id (
14.2 mmol) the reaction was carried out as described
above to yield 2d (6.9 g, 6.7 mmol). 'H NMR (CDCI ):
6 = 1.89 (quint, V = 5.6 Hz, H, CH2), 3.38 (t, 3/ = 5.6 Hz,
H, CH2), 3.76 (t, V = 5.6 Hz, H, CH2), 4.35 (s, 4H,
NH), 7.12 (s, 1H, pz-H4). i C{'H} NMR (CDCI ): 6 =
436 (35) {[N(CH
C37H2öF2oN (962.6)
Calcd C 46.2 H 2.7 N l l .
2
CH
2
NHC
6
F
5
)
2
]+}.
6
. 6 g,
8
6
%,
3
Found C 46.2 H 2.9 N 11.4%.
Ligand H5L8: Starting from 2d (1.3 g, 2.8 mmol) and 3
(4.0 g, 1.4 mmol) the synthesis of H LXwas carried out as
described above. Yield (1.1 g, 1.1 mmol, 78%). IR(KBr):
v max/cm = 3229 (s), 2947/2858 (vs), 1655 (s), 1642
8
8
8
3
3
3
27.8 (CH2), 43.1 (CH2), 43.7 (CH2), 45.5 (CH2), 109.6
(pz-C4), 123.3, 131.0, 135.4, 140.3 (m, Car), 161.5 (CO).
“
1
(w), 1510 (s), 1478/1361 (s), 1262/1148 (vs), 1103 (s),
1060 (m), 1018 (s), 991 (s), 791 (m), 739 (m). 'H NMR
19F NMR (CDCI
m/z(%) = 1047 (100) [M++l], 1027 (40) [M+-HF], 864
) [M+-HNC F5], 462 (32) [{N[(CH NHC F5]2}+].
3
): 6 = -172.8, -165.2, -160.4. MS (FAB)
(CDCI
V = 6.4 Hz,
3.65 (s, 4H, CH2), 4.33 (s, 4H, NH), 6.07 (s, 1H, pz-H4).
C{ H} NMR (CDCI ): 6 = 27.0 (CH2), 44.9 (CH2), 49.9
(CH2), 51.8 (CH2), 109.5 (pz-C4), 123.6, 130.4, 135.4,
142.2 (m, Car), 145.5 (pz-C3/5). I9F NMR (CDCI ): 6 =
-172.8,-165.1,-160.1. MS (FAB+) m/z (%) = 1019(65)
[M++l], 557 (100) {M+-N[(CH NHC F5]2}, 464 (75)
[{N[(CH NHC F5]2}+].
3
): 6 = 1.78 (quint, V = 6.4 Hz,
8
H, CH2), 2.57 (t,
(
8
8
6
2
)
3
6
8
H, CH2), 3.36 (t, V = 6.4 Hz,
8
H, CH2),
The reduction was carried out analogously to the syn-
thesis of H5 L3 to yield H5 L6 (5.5 g, 6.3 mmol, 94 %).
IR (film): Pmax/cm_l = 3265 (s), 2939/2839 (vs), 1642
(w), 1606 (s), 1517 (s), 1469/1359 (s), 1284/1181 (vs),
1108 (m), 1037 (s), 813 (m), 786 (m), 627 (m). 1H NMR
I3
1
3
3
(CDCI
3
): 6 = 1.85 (quint, V =
H, CH2), 3.40 (t, V =
(s, 4H, CH2), 6.00 - 6.08 (m, 9H, pz-H4, Har). i
NMR (CDCI ): b = 25.6 (CH2), 42.3 (CH2), 50.0 (CH2),
52.0 (CH2), 95.6 (m, Car), 104.4 (pz-C4), 129.3, 134.0,
149.2, 154.1 (m, Car). ,9F NMR (CDCI ): 6 = -177.0,
-135.0. MS (FAB+) m/z (%) = 875 (40) [M++l], 485
(100) {M+-N[(CH NHC F3l2}.
6
. 6 Hz,
8
H, CH2), 2.55 (t,
H, CH2), 6.62
C{'H}
2
)
3
6
V=
6
. 6 Hz,
8
6
. 6 Hz,
8
2
)
3
6
3
3
C4iH34F2oN8 (1018.7)
Calcd C 48.3 H 3.4 N ll.0 % ,
Found C 48.1 H 3.6 N 10.1%.
3
Complex L'N iiC b:
A
solution of HL
1
(0.27 g,
2
)
3
6
H
2
0.52 mmol) in THF (20 ml) was treated with one equiva-
lent of BuLi (2.5 M in hexane). After evaporation to dry-
C4 |H42F,2 N 8 (874.8)
ness, EtOH (30 ml) and NiCl
2
•6 H20 (0.13 g, 1.04 mmol)
Calcd C 56.3 H 4.8 N 12.8%,
Found C 55.2 H 5.3 N 11.2%.
were added and the reaction mixture stirred at room tem-
perature for 5 d. All volatile material was then removed
Ligand H5L7: Na
2
C
0
3
(1.2 g, 11.4 mmol) was dried
under vacuum and the residue taken up in CHCI (30 ml)
3
by heating to 100 °C under vacuum for 1 h. A solution
of the amine 2c (1.0 g, 2.3 mmol) and the tetrahydropy-
ranyl (THP) protected 3,5-bis(chloromethyl)pyrazole 3
[16] (0.3 g, 1.1 mmol) in acetonitrile (50 ml) was added.
The mixture was refluxed for 24 h, filtered and the solvent
removed under vacuum, yielding the THP-protected lig-
and as a pale yellow oil. For deprotection ethanolic HC1
(50 ml) was added and the mixture stirred for 1 h at room
temperature. Addition of diethylether caused the ligand
H5L7 to precipitate as the hydrochloride salt, which was
filtered off and dried under vacuum. Aqueous NaOH was
and filtered. The volume of the resulting green solution
was reduced to ~ 15 ml and layered with light petroleum
to gradually afford green crystals of L'N i
2
Cl
3
-2
CHCl
3
(0.25 g, 0.25 mmol, 49%). The solvent molecules are lost
upon storage in air. MS (FAB+, nibeol): m/z (%) = 709
(100) [L'Ni
2
Cl2+], 672(40) [L'Ni Cl+], IR (KBr pellet):
2
Pmax/cm~' = 2966 (m), 1467 (s), 1382 (m), 1097 (s),
1054 (s).
C
2 9
H
6
iCl
3
N
8
Ni2 (745.6)
Calcd C 46.7 H 8.3 N 15.0%,
Found C 45.7 H 7.9 N 14.8%.
added and extracted two times with 50 ml of CH
combined organic phase was dried over MgS
2
CI
2
. The
0
4
. After
Complex L2Ni2Cb: This compound was prepared in
evaporation of the solvent the ligand H5 L7 was obtained
as a pale yellow oil (0.9 g, 0.9 mmol, 78%). IR (KBr):
tw /c m - 1 = 3340 (s), 2950/2844 (vs), 1656 (s), 1642
(w), 1516 (s), 1349 (s), 1263/1148 (vs), 1099 (s), 1014
(s), 795 (m), 678 (m ).1H NMR (CDCI3): 6 = 2.80 (t, V =
close analogy to the preparation of L'N i
ing from HL2 (0.23 g, 0.49 mmol) to afford green crys-
tals of L Ni Cl (0.25 g, 0.25 mmol, 49%). MS (FAB+,
nibeol): m/z (%) = 653 (100) [L Ni Cl2+], IR (KBr pellet):
/>max/c irr' = 2922 (m), 1472 (s), 1306 (m).
2
Cl
3
, but start-
2
2
3
2
2
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1304
S. Buchler et al. ■Novel Dinucleating Ligand Systems
Table VII. Crystal data and refinement details.
L'Ni2Cl3
L2Ni2Cl3
H4L4 Ni2Cl3
H4 L4 Co2Cl3
H5L4Co2Cl4
Formula
C25H53Cl3N8Ni2
Ci^PL] Cl3F |2N8Ni2 C2^H4 |Cl3F|2N8Ni?0
C29H6iCl3N8Ni2
• 2 CHC13
745.6
C25H42C14-
Co2F12Ng
942.3
• c h ci3
905.9
• ÖJ5CH2C12
905.4
689.5
Mr
Crystal size [mm]
Crystal system
Space group
a [A]
b[A]
cl A]
a [°]
ß [°]
7 t°]
V[A3]
0.25x0.20x0.30 0.40x0.30x0.20
0.15x0.15x0.10
monoclinic
P2\/c
11.629(2)
12.139(2)
27.496(6)
90
98.25(3)
90
3841(1)
1.676
0.20x0.10x0.15
monoclinic
P2\/c
11.697(2)
12.269(3)
27.481(6)
90
97.69(3)
90
6908( 1)
1.741
0.20x0.20x0.20
triclinic
P\
monoclinic
P2\lc
12.33(2)
21.29(1)
17.30(1)
90
tetragonal
P432 |2
9.338(1)
9.338(1)
37.527(3)
90
9.407(2)
11.515(1)
17.692(2)
87.13(1)
79.77(1)
85.96(1)
1880(1)
1.665
90.36(7)
90
90
90
4543(1)
1.439
4
3272(1)
1.400
4
Pealed, [gem 3]
Z
4
4
2
F(0 0 0 ) [e]
2056
1464
1974
2072
956
200
200
200
200
200
T [K]
jii (Mo-Ka ) [mm ']
1.39
1.42
1.38
1.35
1.258
hkl Range
±14, -7 -2 5 , ±19 0 - 1 1 , 0 - 1 1 , 0 - 4 6 ±14, ±14, ±33
±14, ±15, ±33
3.0-52.0
59867
7699 (0.078)
6045
0 - 10, ±13, ±21
4.2 - 50.0
6513
6061 (0.020)
4652
2.4 - 49.9
7703
26 Range [°]
Measured refl.
Unique refl. (/?int)
4.3 - 52.0
3665
3.0 - 52.0
58284
7095 (0.042)
3227 (0.028)
2747
7481 (0.109)
5140
Observed refl. I > 2a(l) 5527
Refined parameters
Resididual electron
density [eA- 3 ]
R1
479
0.97/-0.76
182
0.26/-0.35
484
0.79/-0.48
502
0.37/-0.52
484
0.89/-0.85
0.061
0.033
0.083
1.355
0.047
0.109
1.044
0.036
0.081
1.034
0.039
0.079
1.210
wR2 (refinement on F2) 0.164
1.082
Goodness-of-fit
C
2 5
H
5 3 Cl
3
N
8
Ni
2
(689.5)
excess of triethylamine (0.52 g, 5.20 mmol) the prepara-
tion was carried out analogously to that for H Ni Cl to
yield a blue powder. Layering a solution of the crude com-
plex in CHC1 with diethylether affords dark blue crystals
(0.38 g, 0.39 mmol, 71%). MS (FAB+, nibeol): m/z (%) =
869 (100) [H Co C12+]. IR (KBr pellet): z W c n T
Calcd C 43.6 H 7.8 N 16.3%,
Found C 43.2 H 7.8 N 15.1%.
4
L
4
2
3
3
Complex H
0.30 mmol) in THF (50 ml) was treated with an ex-
cess of triethylamine (0.21 g, 2.01 mmol) and NiCl -6H20
4
L
4
Ni
2
Cl3: A solution of H
5
L
4
(0.21 g,
4
L
4
2
1
=
2
3441 (m), 2953 (m), 1624 (m), 1461 (m), 1379(m), 1263
(s), 1157 (s), 1102 (s), 1038 (s), 973 (w), 901 (w), 823
(w), 678 (m).
(0.15 g, 0.60 mmol) was added. The resulting green sus-
pension was stirred at room temperature for 12 h. Then the
inorganic salts were filtered off and the resulting green so-
lution was evaporated to dryness to yield a green powder.
Green crystals (0.22 g, 0.23 mmol, 75%) were obtained
by layering a solution of the complex in CHoCL with
diethylether. MS (FAB+, nibeol): m/z (%) = 869 (100)
C
2
5H4iCl
Calcd C 31.7 H 4.3 Cl 16.5 N l l .
Found C 32.1 H 4.8 Cl 16.2 N ll.7 % .
Complex HsL4Ni Cl4: A solution of H
1.03 mmol) in THF (50 ml) was treated with two equiv-
alents of NiCl -6H20 (0.49 g, 2.06 mmol) and stirred at
3
Fi2N
8
Co2-0.5 CHC1
3
(1025.2)
6
%,
2
5
L4 (0.70 g,
[H
4
L
4
Ni2 Cl2+]. IR (KBr pellet) z W c m - 1 = 3437 (m),
3293 (m), 3183 (m), 2937 (s), 2733 (m), 2671 (m), 2598
(m), 2489 (m), 1622 (w), 1468 (m), 1379 (m), 1263 (s),
1157 (s), 1102 (s), 1035 (m), 986 (m), 905 (m), 865 (w),
680 (m).
2
room temperature for 12 h. The resulting green solution
was evaporated to dryness to yield a green powder which
was washed with diethylether to remove unreacted or-
ganic compounds and finally dried under vacuum. Green
C25H4iCl3F,2N8Ni2-0.75 CH
2
C12 (969.1)
Calcd C 31.9 H 4.4 Cl 16.5 N ll.7 % ,
Found C 31.5 H 4.5 Cl 17.5 N ll.3 % .
crystals (
solution of the complex in CH
(FAB+, nibeol): m/z (%) = 867 (100) [H
(KBr pellet): =3213 (m), 3193 (m), 2957 (m),
0
. 6
6
g,
6
8
%) could be obtained by layering a
CI with diethylether. MS
Ni Cl2+]. IR
2
2
Complex H
4
L
4
Co
2
Cl3: Starting from H5 L4 (0.35 g,
O (0.25 g, 1.04 mmol) and an
4
L
4
2
0.52 mmol), C
0
CI
2
6
H
2
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S. Buchler et al. • Novel Dinucleating Ligand Systems
1305
1620 (m), 1554 (m), 1468 (m), 1382 (m), 1337 (w), 1266
(s), 1156 (s), 1098 (s), 1039 (m), 975 (m), 905 (m), 824
(w), 681 (m).
L
H
2
Ni
2
Cl3] or SHELXS-97 [complexes
H
5
4
L
4
4
Ni
2
2
Cl3,
C14]
4
L
4
Co C13, H Ni Cl4, H Ni Cl and H
2
5
L
3
2
5
L
4
2
4
L
Co
and refined with the SHELXL-93 or SHELXL-97 pro-
gram, respectively [23]. In the case of L Ni Cl a twinned
1
2
3
C
2 5
H
4 2 Cl
4
F
1 2
N
8
Ni2 (941.8)
Calcd C 31.9 H 4.5 CI 15.1 N I 1.9%,
Found C 32.6 H 5.0 CI 14.7 N 11.7%.
crystal had been examined and was refined using the
TWIN routine (BASF 0.30844). Atomic coordinates and
thermal parameters of the non-hydrogen atoms were re-
fined in fully or partially anisotropic models by full-
matrix least-squares calculation based on F2. In general
the hydrogen atoms were placed at calculated positions
and allowed to ride on the atoms they are attached to. In the
Complex H
0.52 mmol) and CoC1
the preparation was carried out analogously to that of
HsL Ni Cl to yield a blue powder. Layering a solution of
the crude complex in CH C1 with diethylether afforded
dark blue crystals (0.45 g, 91%). MS (FAB+, nibeol):
m/z (%) = 869 (100) [H Co Cl2+], IR (KBr pellet):
5
L4Co
2
CLi: Starting from H
5
L
4
(0.35 g,
2
-6H20 (0.25 g, 1.03 mmol)
4
2
3
2
2
cases of H
4
L
4
Co
2
C13
and H
5
L
4
Co C14 the N-bound pro-
2
tons could be located in the difference Fourier synthesis
and refined. In Table VII the data for the structure deter-
minations are compiled. Crystallographic data (excluding
structure factors) for the structures reported in this paper
4
L
4
2
v max/cm- 1 = 3438 (m), 3293 (m), 2957 (m), 1620 (m),
1460 (m), 1379 (m), 1262 (s), 1152 (s), 1100 (s), 1040
(s), 976 (m), 901 (m), 823 (w), 678 (m).
(except for HsL
4
Ni
2
Cl4 [21]) have been deposited with
C
2 5
H
4 2 C1
4
F
1 2
N
8
Co (942.3)
2
the Cambridge Crystallographic Data Centre as supple-
mentary publication no. CCDC 114054, 114055, 114057,
and 114059. Copies of the data can be obtained free of
charge on application to CCDC, 12 Union Road, Cam-
bridge CB2 1EZ, UK [fax: (+44) 1223 336-033; e-mail:
deposit@ccdc.cam.ac.uk].
Calcd C 31.9 H 4.5 Cl 15.1 N ll.9 % ,
Found C 31.8 H 4.8 Cl 15.8 N 11.8%.
X-ray crystallography
The measurements were carried out on a Nonius
Kappa CCD diffractometer [complexes
Co C13, and H Ni Cl4] or a Siemens P4 four-
circle diffractometer [complexes L Ni Cl3, L Ni Cl3, and
H<;L Co C14] using graphite-monochromated Mo-Ka ra-
diation. For the latter three complexes the intensities of
three check reflections (measured every 1 0 reflections)
H
4
L
4
Ni2 Cl3,
H
4
L
4
2
5
L
4
2
1
2
2
2
Acknowledgements
4
2
We are grateful to Prof. Dr. G. Huttner for his gen-
erous and continuous support of our work. Acknow-
ledgement of financial support is made to the Deutsche
Forschungsgemeinschaft (Graduiertenkollegsstipendium
for S. B., Habilitandenstipendium for F. M.) and the
Fonds der Chemischen Industrie. Dr. H. Pritzkow is sin-
cerely thanked for help with the structure determination
0
remained constant throughout the data collection (thus
indicating crystal and electronic stability) and an absorp-
tion correction (i/> scan, Axp = 10°) was applied to the
data. All calculations were performed using the SHELXT
PLUS software package. Structures were solved by direct
methods with the SHELXS-93 [complexes L'N i
2
Cl
3
and
of H
5
L
4
Ni2 Cl4.
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1306
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[
2
1
] C25H42Cl4F,2N8Ni2 : 0.75CH
clinic, space group P\ , a - 14.884(3),/? = 22.743(5),
c = 26.454(5), q = 91.54(3), ß = 91.03(3),
106.34(3); V = 8587; Z = ; 0max = 52.0°; 31612
2
C1
2
• 0.5 Et 0 ; tri-
2
7
=
8
unique reflections, 11965 observed [I> 2a(I)],R \ =
0.086, wR2 = 0.229.
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