Methanetrisamidines in coordination chemistry-syntheses, structures and CH-NH tautomerism

Article abstract of DOI:10.1039/c3dt53261e

Methanetrisamidines {HC[C(NR)NHR]₃} (R = i-Pr 1a; Ph 1b) were reacted with different metal complexes. Reaction of 1a with NiCl ₂(H₂O)₆ occurred with protonation of 1a and formation of {[C(C(NHi-Pr)₂)₃]²⁺[NiCl ₄]^2-} 2, whereas the reaction with CuCl gave [C(C(N(i-Pr)CuCl)NHi-Pr)₂(C(NHi-Pr)₂)] 3. The formation of 2 and 3, which contain the N-H tautomeric form of 1a, occurred with H-migration from carbon to nitrogen. In contrast, reactions of 1b with [M(NCMe) ₃(CO)₃] (M = Cr, Mo, W) yielded octahedral complexes fac-[M(CO)₃CH(C(NHPh)NPh)₃] (M = Cr 4a, Mo 4b, W 4c), in which the C-H tautomeric form is preserved. 1b is a rather strong σ-donor ligand as was shown by IR spectroscopy. The structures of 2, 3 and 4a were determined by single crystal X-ray diffraction.

Full text of DOI:10.1039/c3dt53261e

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Methanetrisamidines in coordination chemistry –
syntheses, structures and CH–NH tautomerism†
Cite this: Dalton Trans., 2014, 43,
2907
Benjamin Gutschank, Stephan Schulz,* Dieter Bläser and Christoph Wölper
Methanetrisamidines {HC[C(NR)NHR]3} (R = i-Pr 1a; Ph 1b) were reacted with different metal complexes.
Reaction of 1a with NiCl2(H2O)6 occurred with protonation of 1a and formation of {[C(C(NH-
i-Pr)2)3]2+[NiCl4]2−} 2, whereas the reaction with CuCl gave [C(C(N(i-Pr)CuCl)NHi-Pr)2(C(NHi-Pr)2)] 3. The
formation of 2 and 3, which contain the N–H tautomeric form of 1a, occurred with H-migration from
carbon to nitrogen. In contrast, reactions of 1b with [M(NCMe)3(CO)3] (M = Cr, Mo, W) yielded octahedral
complexes fac-[M(CO)3CH(C(NHPh)NPh)3] (M = Cr 4a, Mo 4b, W 4c), in which the C–H tautomeric form
is preserved. 1b is a rather strong σ-donor ligand as was shown by IR spectroscopy. The structures of 2, 3
and 4a were determined by single crystal X-ray diffraction.
Received 19th November 2013,
Accepted 9th December 2013
DOI: 10.1039/c3dt53261e
www.rsc.org/dalton
the presence of a dynamic equilibrium between the two tauto-
meric forms 1b and 1c, which can be controlled to some
Introduction
C3-symmetric tripodal ligands have a long-standing history in extent by temperature and the solvent polarity. In contrast, no
coordination chemistry. Hydridotris(pyrazolyl)borates (R = H, indication of an analogous tautomeric equilibrium was found
I), which have been initially prepared by Trofimenko in 1966,1 for 1a. The capability of the C3-symmetric ligands 1a and 1b as
as well as their sterically more demanding “organic” deriva- well as that of 1c to react with metal alkyl complexes MRn and
tives (R = alkyl)2 have been intensively used in coordination alkyl metal hydrides HMRn with alkane or hydrogen elimi-
chemistry including bioinorganic chemistry, in which they nation was demonstrated and several homometallic tri- and
were used as supporting ligands for the modelling of various tetranuclear complexes such as {CH[C(Ni-Pr)2AlR2]3} (R = Me,
zinc enzymes. Moreover, other types of tripodal ligands such as i-Bu) were structurally characterized.9 In addition, 1c was
tris-(pyrazolyl)methane (II),3 tris(pyrazolylmethyl)amine (III),4 found to undergo stepwise deprotonation reactions with two
tris-(2-phenylimidazol-4-yl)phosphine (IV),5 tris(benzimidazo- different metal alkyl complexes at different reaction tempera-
lylmethyl)amine (V)6 as well as tris(5-amino-1-pyridylmethyl)- tures, which was successfully used for the synthesis of hetero-
amine VI7 have been investigated in detail (Scheme 1).
metallic tetranuclear complexes {C[C(N(η3-Ph))N(Ph)ZnMe]2-
We recently reported on the synthesis of two C3-symmetric [C(N(Ph)MMe2)2]} (M
=
Al, Ga).10 Herein we report on
methanetrisamidines of the general type {HC[C(NR)NHR]3} our studies on the formation of coordination complexes
(R = i-Pr 1a; Ph 1b),8 which were formed by hydrolysis of tetra- utilizing the multiple coordinative imino sites of neutral
nuclear zinc amidinate complexes {C[C(NR)2ZnMe]4} (R = i-Pr; methanetrisamidines.
Ph).9 In addition, the NH-tautomeric form of the Ph-substi-
tuted derivative, {C[C(NPh)N(Ph)H]2[C(HNPh)2]} 1c (Scheme 2),
was isolated and structurally characterized, whereas the corres-
ponding i-Pr-substituted derivative was not observed.
Results and discussion
Temperature dependent 1H NMR spectroscopic studies of
The reaction of 1a with NiCl2(H2O)6 in CH3CN at 80 °C led to
solutions of 1a–c in different solvents (C6D6, CD3CN) revealed
the formation of the dicationic trisamidinium salt {[C(C(NH-
i-Pr)2)3]2+[NiCl4]2−} 2 (Scheme 3). Obviously, the H-atoms of
water molecules of the nickel chloride hydrate are acidic
University of Duisburg-Essen, Universitätsstr. 5–7, S07 S03 C30, 45117 Essen,
enough to protonate the rather strong Lewis-basic tris-
amidine 1a.
Germany. E-mail: stephan.schulz@uni-due.de; Fax: Int (+)201 1833830;
Tel: Int (+)201 1834635
†Electronic supplementary information (ESI) available: Crystallographic data of
2 is insoluble in THF-d8, acetonitrile-d3 and even D2O,
hence preventing
2 from being characterised by NMR-
2, 3, and 4a. CCDC 971997, 886453 and 971998. For ESI and crystallographic
data in CIF or other electronic format see DOI: 10.1039/c3dt53261e
spectroscopy. However, its structure was proven by X-ray
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Scheme 1 Structures of C3-symmetric tripodal ligands typically used in coordination chemistry.
The structure of the dication [C(C(NHi-Pr)2)3]2+ in 2 is
similar to that of the {[C(C(NHPh)2)3]2+ dication, which was
recently observed in [C(C(NHPh)2)3]2+[Ac−]2}.8 Both dications
contain a central sp2-hybridized carbon atom (C1) similar to
the NH-tautomeric form of the free amidine 1c. In contrast to
1c, all nitrogen atoms in 2 carry protons, resulting in the pres-
ence of six NH groups. This result is quite surprising since the
proton originally bound to the central carbon atom (C1) of the
C–H tautomer CH[(CNHi-Pr)Ni-Pr]3 1a has obviously migrated
to an imine centre, yielding the corresponding N–H tautomeric
form. While the formation of the CH- and the NH-tautomers
has previously been reported for the Ph-substituted trisami-
dine (1b and 1c), we have never observed the formation of the
NH-tautomer of 1a before. The resulting change of hybridisa-
Scheme 2 N,C-Tautomeric methanetrisamidines; potentially basic
coordinative imino sites are depicted in red.
crystallography. Single crystals of 3 were obtained upon storage
of a solution of 2 in CH3CN at −30 °C for 12 h. 2 crystallizes in tion state at the central carbon atom from formally sp3 to sp2
ˉ
the cubic space group Pa3 with the anion and the cation allows the resonance stabilization of the twofold positive
charge over the whole C4-moiety. The N–H tautomeric form as
placed on a three-fold axis.
Scheme 3 Formation of dicationic trisamidinium salt 2 with formal tautomerization of 1a.
2908 | Dalton Trans., 2014, 43, 2907–2914
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Scheme 4 Formation of 3 with formal tautomerization of 1a.
observed in the dication in 2 is thus expected to be energeti- C1–C2 1.468(3) Å). The C–N bond lengths of the imino
cally favoured compared to a hypothetical sp3-hybridised dica- groups within the amidine moieties are slightly elongated (C3–
tion (C–H tautomer). The C–C bond lengths within the N3 1.314(3) Å, C2–N1 1.317(3) Å) due to the coordination to
trigonal-planar C4-moiety of 2 are identical (C1–C2 1.4508(14) Å) the Cu(I)Cl fragment, which results in an increased coordi-
due to the C3 symmetry of the ion and in between the typical nation number and the loss of electron density at the nitrogen
values of C–C single and double bonds. The same is true for atoms. CuCl adopts a η1-coordination mode. The N–Cu–Cl
the C–N bond lengths (mean value: 1.3417(25) Å). Additionally bond angles slightly differ from linearity (N1–Cu1–Cl1 175.94
the C2′–C1–C2 bond angle of 119.893(12)° is in accordance (8)°, N3–Cu2–Cl2 171.97(7)°) and the Cu–N bond lengths (N1–
with the sp2 geometry. The structural findings suggest an ideal Cu1 1.893(2) Å, N3–Cu2 1.880(2) Å) are close to the mean value
delocalisation of the twofold positive charge over the planar found for Cl–Cu–N fragments in the CSD.11 Comparable
C4-moiety as was observed for the dication [C(C(NHPh)2)3]2+ in values were reported for Cu(l-PETAEA)CuCl (PETAEA = bis-(2-
{[C(C(NHPh)2)3]2+[Ac−]2}.8
In order to suppress the strong tendency of the Lewis basic 1.9054(15) Å, N–Cu–Cl 174.18(5)°),12 CuCl(hppSiMe3) (hppH =
methanetrisamidine 1a to undergo protonation reactions, 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) (Cu–N
(2-pyridyl)ethyl)-2-(N-toluenesulfonylamino)ethylamine) (N–Cu
further experiments were conducted with hydrate free metal 1.877(2) Å, N–Cu–Cl 176.43(7)°),13 Pt(PPh3)2Br(μ-3,5-Ph2pz)-
salts. The reaction of 1a with two equivalents of copper(I)chloride CuCl (Cu–N 1.86(3) Å, N–Cu–Cl 177.0(8)°),14 and Cp(PPh3)Ru–
in THF led to the formation of [C(C(N(i-Pr)CuCl)NHi-Pr)2- CN–CuCl (Cu–N 1.810(4) Å, N–Cu–Cl 178.7(1)°),15 respectively.
(C(NHi-Pr)2)] 3 (Scheme 4). 1H and 13C NMR spectroscopic analy- A packing analysis did not show any stabilizing interactions
sis of 3 in THF-d8 showed highly broadened resonances of the between copper and other donor atoms.
i-Pr groups, indicating a dynamic exchange between CuCl moi-
The reactions of 1a with NiCl2(H2O)6 as well as CuCl both
eties and amino protons of the ligand in solution. In addition, occurred with migration of the proton from the carbon to the
the resonance due to the presence of the C–H moiety did not nitrogen atom (CH–NH tautomerism). These findings are in
appear in the 1H NMR spectrum of 3.
remarkable contrast to those recently observed in reactions of
Single crystals of 3 suitable for X-ray crystal analysis were 1a with trialkylalanes AlR3 and dialkylalanes R2AlH, which were
obtained upon storage of a solution of 3 in THF at −30 °C. 3 found to proceed with threefold alkane/hydrogen elimination
crystallizes in the monoclinic space group P21/n with one and preservation of the C–H tautomeric form.8 In contrast, ana-
molecule in the asymmetric unit and an additional disordered logous reactions of 1b with AlR3 occurred with fourfold alkane
THF molecule. As was observed in the protonation reaction of elimination due to the initial formation of the N–H tautomeric
1a with NiCl2(H2O)6, the proton of the central CH-moiety in 1a form.8 We therefore became interested in reactions of 1b with
migrated to one imino group in 3, yielding the corresponding transition metal complexes and reacted 1b with group 6 metal
N–H tautomeric form. The remaining two imino sites each complexes of the general type [M(NCMe)3(CO)3] (M = Cr, Mo,
coordinate to one Cu(I)Cl molecule. These findings prove that W). Reactions of 1b with [M(NCMe)3(CO)3] (M = Cr, Mo, W) in
both the protonation of the imino group as well as the coordi- toluene at 90 °C yielded octahedral complexes fac-[M(CO)3CH-
nation of the imino group to a metal centre such as Cu(I) (C(NHPh)NPh)3] (M = Cr 4a, Mo 4b, W 4c; Scheme 5). The CH
favours the formation of the NH-tautomeric form due to the tautomeric form of 1b is preserved and 1b acts as a tripodal N,N,
migration of the C–H proton to an imino group. The central N-donor to a single metal centre. 1H NMR spectra in THF-d8 (4a,
sp2-hybridised carbon atom C1 in 3 binds to two amidine 4b) and acetone-d6 (4c) each show the characteristic singlet reson-
carbon atoms (C2, C3) and a methylendiamine moiety (C4). ance of the backbone CH moiety (4a: 5.16, 4b: 5.01, 4c:
The C–C bond lengths in 3 are in between the typical values 5.33 ppm), which was confirmed by additional DEPT experiments
for C–C single and CvC double bonds, indicating a delocal- (4a: 43.9, 4b: 46.6, 4c: 46.8 ppm). The equivalent NH groups
ised π-electron system within the planar C4-moiety. The C1–C4 result in one sharp singlet resonance (4a: 7.60, 4b: 7.62, 4c: 8.11).
bond is slightly shortened, which can be attributed to the higher The carbonyl resonances of 4a–c show weak signals at about
double bond character (C1–C4 1.424(4) Å, C1–C3 1.473(3) Å, 230 ppm (4a: 235, 4b: 230.2, 4c: 226.8 ppm) in the 13C NMR
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Scheme 5 Formation of tripodal complexes 4a–c.
spectra, indicating a terminal coordination of the carbonyl NiCl2(H2O)6 with protonation of the Lewis-basic imine centres
ligands to the metal centre.16 This coordination mode was also and with CuCl with formation of [C(C(N(i-Pr)CuCl)NHi-Pr)2-
proven by solid-state IR spectroscopy, showing the absorption (C(NHi-Pr)2)] 3, containing two coordinated CuCl moieties.
bands in 4a–c due to the carbonyl groups (νCO: 1881, 1757 (4a), Both reactions occurred with migration of the proton from the
1881, 1751 (4b), 1869, 1756 cm−1 (4c)) at rather low frequency central carbon atom to an imine centre (CH–NH tautomerism).
numbers. According to these studies, the σ-donor capacity of In contrast, the reaction of 1b with [M(NCMe)3(CO)3] (M = Cr,
methanetrisamidine 1b toward group 6 metal carbonyl com- Mo, W) resulted in the formation of fac-[M(CO)3CH(C(NHPh)-
plexes is comparable to that of typical N,N,N-tripodal donor NPh)3] (M = Cr 4a, Mo 4b, W 4c) containing the central metal
ligands such as trispyrazolylborates, triazacyclononanes or centres in an octahedral coordination mode. The methanetris-
methyltrispyrazolylsilanes (Table 3).
amidine ligand 1b serves as a tripodal chelating N,N,N-donor
Orange crystals of 4a suitable for a single-crystal X-ray ligand, in which the C–H tautomeric form is preserved.
analysis were obtained from a solution in THF upon storage at
−30 °C for 5 days. 4a crystallizes in the orthorhombic space
group Pna21 with one molecule and one additional, partially
disordered THF molecule in the asymmetric unit. The central
Experimental
sp3 hybridized carbon atom C1 is bonded to three amidine
carbon atoms and one hydrogen atom. The C–C bond lengths
are in the typical range of C–C single bonds (C1–C2 1.517(5),
C1–C3 1.520(5), C1–C4 1.523(5) Å) and the C–C1–C angles are
roughly 110°. The C–N bond lengths within the amidine
moieties are typical of single and double bonds. The central
atom Cr1 is coordinated by three imino nitrogen atoms of the
trisamidine ligand (Cr1–N2 2.138(3), Cr1–N4 2.133(3), Cr1–N6
2.146(3) Å) and three carbonyl ligands (Cr1–C5 1.819(5), C5–O1
1.171(5); Cr1–C6 1.809(4), C6–O2 1.184(5); Cr1–C7 1.823(4),
C7–O3 1.168(5) Å), resulting in an octahedral coordination
mode as was deduced by infrared analysis, exhibiting two
ν(CO) stretching vibrations (A1 and E), vide supra. Each set of
three identical ligands occupies one face of the octahedron
surrounding the metal atom. The bond lengths in 4a are in
good agreement with the structural data of similar tripodal
complexes, e.g. [LCr(CO)3][PF6]-dmf (Cr–C 1.817(4) Å, Cr–N
2.182(4) Å, C–O 1.172(5) Å),20 {HC(CN(2-i-Pr-Ph)Me)3}Cr(CO)3
(Cr–C 1.8336(12) Å, Cr–N 2.1218(19) Å, C–O 1.1673(15) Å),21 cis-
(diethylenediaminechromium)tricarbonyl (Cr–C 1.816 Å, Cr–N
2.185 Å), C–O 1.173 Å)24 and tricarbonyl{N,N′,N″-tris[(S)-1′-
phenylethyl]hexahydro-1,3,5-triazine}chromium (Cr–C 1.799 Å,
C–N 2.209 Å, C–O 1.174 Å).25,26
All manipulations were performed in a glovebox under an Ar
atmosphere or using standard Schlenk techniques. Solvents
were carefully dried over Na/K and degassed prior to use. 1a–c1
27
and M(NCMe)3(CO)3 were prepared according to literature
1
methods. H and 13C NMR spectra were recorded on a Bruker
DMX 300 spectrometer and are referenced to internal THF-d8
(1H: δ = 3.58; 13C: δ = 67.4) and acetone-d6 (1H: δ = 2.04; 13C:
δ = 29.8). IR spectra were recorded on an ALPHA-T FT-IR
spectrometer equipped with a single reflection ATR sampling
module. Melting points were measured in sealed capillaries
and were not corrected. Elemental analyses were performed at
the Elementaranalyse Labor, University of Essen.
{[C(C(NHi-Pr)2)3]2+[NiCl4]2−} 2
0.25 g (0.6 mmol) 1a and 0.30 g (1.3 mmol) NiCl2(H2O)6 were
suspended in 20 ml of acetonitrile and heated under reflux for
2 h. Filtration of the reaction mixture gave a blue coloured fil-
trate, from which pale blue crystals of 2 were formed within
12 h upon storage at −10 °C. Yield: 0.21 g (55%). Mp.: >250 °C.
Elemental analysis calculated (%) for C22H48N6Cl4Ni (M =
597.16 g mol−1): H 8.10, C 44.25, N 14.07; found: H 7.96,
C 44.49, N 13.89. Crystalline 2 is completely insoluble in
common organic solvents; hence solution NMR data could not
be obtained. ATR-IR: ν 3302, 3252, 2966, 2931, 2872, 1642,
Conclusions
Reactions of two methanetrisamidines 1a and 1b with 1574, 1551, 1521, 1459, 1386, 1386, 1365, 1306, 1259, 1121,
different metal complexes were investigated. 1a reacts with 1091, 1009, 979, 870, 797, 674, 618, 559 cm−1
.
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{[C(C(HNi-Pr)2)(C[N(CuCl)i-Pr)NHi-Pr])2]} 3
(75.5 MHz, THF-d8, 25 °C): δ 43.9 (CH), 123.6 (Ar), 123.8 (Ar),
125.3 (Ar), 125.4 (Ar), 129.8 (Ar), 130.0 (Ar), 139.4 (Ar), 151.1
(Ar), 158.4 (N–CvN), 235 (CuO). IR: ν 3358, 3078, 3049, 3019,
1881, 1757, 1624, 1589, 1498, 1483, 1368, 1233, 1203, 1174,
0.25 g 1a (0.6 mmol) and 0.12 g (1.3 mmol) CuCl were sus-
pended in 20 mL of THF and stirred for 1 h at 60 °C. Filtration
of the reaction mixture gave a yellowish solution, from which
yellow crystals of 3 were formed within 5 days upon storage at
−30 °C. Yield: 0.27 g (74%). Mp.: 117 °C (dec.). Elemental
analysis calc. (%) for C22H46N6Cl2Cu2 (M = 592.64 g mol−1):
H 7.82, C 44.59, N 14.18; found: H 7.63, C 44.83, N 13.89.
1H-NMR (300 MHz, THF-d8, 25 °C): δ 1.21 (m (broad), CH-
(CH3)2), 5.02 (m (broad), CH(CH3)2). 13C-NMR (75.5 MHz, THF-
d8, 25 °C): δ 19–23 (CH(CH3)2), 45 (CH(CH3)2), 85 (C(CN2)3),
159 (NCN). ATR-IR: ν 3447, 3371, 3328, 3302, 2957, 2922, 2866,
1630, 1562, 1459, 1418, 1383, 1362, 1309, 1297, 1221, 1165,
1068, 1024, 909, 750, 712, 694, 641, 527, 506, 471 cm−1
.
4b: yield: 0.16 g (82.0%). Mp.: >250 °C (dec.). Elemental
analysis calc. (%) for C43H34MoN6O3 (M = 778.73 g mol−1):
H 4.40, C 66.32, N 10.79; found: H 4.36, C 66.10, N 10.65.
1H-NMR (300 MHz, THF-d8, 25 °C): δ 5.01 (s, 1H, HC(CN2)3),
6.78 (m, 6H, Ar), 6.89 (m, 3H, Ar), 6.95 (m, 6H, Ar), 7.09
1124, 1068, 971, 926, 877, 767, 735, 667, 617, 570 cm−1
.
{HC[C(NPh)NHPh]3M(CO)3} 4a–c
0.15 g 1c (0.8 mmol) and 0.8 mmol M(NCMe)3(CO)3 were sus-
pended in 15 mL of toluene. The reaction mixture was then
heated to 90 °C for 4 h, upon which the reaction darkened and
the products 4a–c precipitated. After cooling, the reaction
mixture was filtered off and crude 4a–c were isolated as yellow
to red solids. The crude products were washed with 10 mL of
n-hexane yielding analytically pure 4a–c. Suitable crystals of 4a
for single-crystal diffraction were obtained from a solution in
THF upon storage at −30 °C for 5 days.
4a: yield: 0.14 g (76.1%). Mp.: >250 °C (dec.). Elemental
analysis calc. (%) for C43H34CrN6O3 (M = 734.76 g mol−1):
H 4.66, C 70.29, N 11.44; found: H 4.57, C 69.80, N 11.25.
1H-NMR (300 MHz, THF-d8, 25 °C): δ 5.16 (s, 1H, HC(CN2)3),
6.79 (m, 9H, Ar), 6.91 (m, 6H, Ar), 7.09 (m, 3H, Ar), 7.19
(m, 6H, Ar), 7.36 (m, 6H, Ar), 7.60 (s, 3H, NH). 13C-NMR
Fig. 2 Molecular structure of 3 (thermal ellipsoids at 50% probability
levels, hydrogen atoms at arbitrary radii; i-Pr groups reduced to bonds
and H atoms omitted for clarity).
Fig. 1 Molecular structure of 2 (thermal ellipsoids at 50% probability
levels, hydrogen atoms at arbitrary radii; i-Pr groups reduced to bonds
and H atoms and the anion omitted for clarity).
Fig. 3 Molecular structure of 4a (thermal ellipsoids at 50% probability
levels, hydrogen atoms at arbitrary radii; phenyl groups reduced to
bonds and H atoms omitted for clarity).
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Table 1 Bond lengths (Å) and angles (°) of 2
Ni(1)–Cl(1)
Ni(1)–Cl(2)#1
N(1)–C(2)
N(2)–C(2)
C(1)–C(2)
2.2345(8)
2.2696(5)
1.3449(19)
1.3386(18)
1.4508(14)
Cl(1)–Ni(1)–Cl(2)#1
Cl(2)#1–Ni(1)–Cl(2)#2
C(2)–N(1)–C(3)
C(2)–N(2)–C(6)
C(2)–C(1)–C(2)#1
110.194(14)
108.739(14)
125.26(12)
125.75(13)
119.892(12)
N(2)–C(2)–N(1)
N(2)–C(2)–C(1)
N(1)–C(2)–C(1)
119.42(13)
118.68(13)
121.89(13)
#1 y + 1/2, −z + 1/2, −x + 1; #2 −z + 1, x − 1/2, −y + 1/2.
Table 2 Bond lengths (Å) and angles (°) of 3
Cu(1)–N(1)
Cu(1)–Cl(1)
Cu(2)–N(3)
Cu(2)–Cl(2)
N(1)–C(2)
N(2)–C(2)
N(3)–C(3)
N(4)–C(3)
N(5)–C(4)
1.893(2)
2.0983(8)
1.880(2)
2.1020(8)
1.317(3)
1.351(3)
1.314(3)
1.350(3)
1.360(4)
C(1)–C(4)
C(1)–C(2)
C(1)–C(3)
1.424(4)
1.468(3)
1.473(3)
C(3)–N(3)–C(11)
C(3)–N(3)–Cu(2)
C(11)–N(3)–Cu(2)
C(3)–N(4)–C(14)
C(4)–N(5)–C(17)
C(4)–N(6)–C(20)
C(4)–C(1)–C(2)
C(4)–C(1)–C(3)
C(2)–C(1)–C(3)
119.8(2)
122.90(18)
117.31(17)
127.4(2)
127.4(3)
126.0(3)
119.8(2)
117.2(2)
121.4(2)
N(1)–Cu(1)–Cl(1)
N(3)–Cu(2)–Cl(2)
C(2)–N(1)–C(5)
C(2)–N(1)–Cu(1)
C(5)–N(1)–Cu(1)
175.94(8)
171.97(7)
120.1(2)
119.89(17)
118.39(17)
acetone-d6, 25 °C): δ 46.8 (CH), 123.8 (Ar), 124.3 (Ar), 125.9
(Ar), 126.0 (Ar), 129.9 (Ar), 130.2 (Ar), 138.6 (Ar), 138.7 (Ar),
150.4 (Ar), 158.4 (N–CvN), 226.8 (CuO). IR: ν 3349, 3079,
3049, 3022, 1869, 1756, 1741, 1719, 1616, 1586, 1497, 1483,
1368, 1315, 1233, 1201, 1177, 1068, 1024, 912, 768, 750, 714,
Table 3 IR-data for several group 6 metal carbonyl complexes with
different N,N,N-tripodal ligands
Complexf
ν(CO)/cm−1
Ref.
(Et4N)[(HB(3,5-Me2pz)3Cr(CO)3]
{HC(pz)3}Cr(CO)3
{MeSi(3,5-Me2pz)3}Cr(CO)3
LCr(CO)3
{HC(CN(2-i-Pr-Ph)Me)3}Cr(CO)3
{HC(C(NPh)NHPh)3}Cr(CO)3 4a
(NCP)[HB(pz)3Mo(CO)3]
{HC(3,5-Me2pz)3}Mo(CO)3
{MeSi(3,5-Me2pz)3}Mo(CO)3
LMo(CO)3
{HC(CN(2-i-Pr-Ph)Me)3}Mo(CO)3
{HC(C(NPh)NHPh)3}Mo(CO)3 4b
{MeSi(3,5-Me2pz)3}W(CO)3
LW(CO)3
1891, 1748a
1898, 1758b
1898, 1755c
17
18
697, 635, 615, 553, 541, 506, 476, 414 cm−1
.
19
1903, 1762a
1893, 1796, 1775d
1881, 1757e
20
21
This work
Single crystal X-ray diffraction
1882, 1736c
22
1900, 1760b
1896, 1755c
23
Crystallographic data of 2, 3 and 4a,‡ which were collected
on a Bruker AXS APEX2 diffractometer (MoKα radiation, λ =
0.71073 Å) at 150(1) K (2, 3) and 141(2) K (4a), are summarized
in Table 5. The solid-state structures of 2, 3 and 4a are
shown in Fig. 1–3, bond lengths and angles of 2, 3 and 4a are
summarized in Tables 1, 2 and 4. The structures were solved
by direct methods (SHELXS-97) and refined anisotropically by
full-matrix least-squares on F2 (SHELXL-97).28,29 Absorption
corrections were performed semi-empirically from equivalent
reflections on the basis of multi-scans (Bruker AXS APEX2).
Hydrogen atoms were refined using a riding model or rigid
methyl groups. 3 was refined against data produced by
PLATON/SQUEEZE.30 The complete solvent molecule in 3 and
the disordered part of it in 4a were refined isotropically. The
solvent molecule in 3 was only partially occupied.
19
1907, 1768a
1897, 1787, 1776d
1881, 1751e
20
21
This work
1887, 1747c
19
1897, 1757a
1898, 1785, 1775d
1869, 1756e
20
{HC(CN(2-i-Pr-Ph)Me)3}W(CO)3
{HC(C(NPh)NHPh)3}W(CO)3 4c
21
This work
a Acetonitrile solution. b Nujol. c KBr pellets. d Presence of i-Pr groups
destroys planes of symmetry, hence splitting the E band into a doublet.
e ATR technique. f Ligand abbreviations: pz = pyrazolyl, L = 1,4,7-
tribenzyl-1,4,7-triazacyclononane, NCP = N-methyl-4-cyanopyridinium,
p-NCC5H4NMe+.
(m, 3H, Ar), 7.21 (m, 6H, Ar), 7.33 (m, 6H, Ar), 7.62 (s, 3H, NH).
13C-NMR (75.5 MHz, THF-d8, 25 °C): δ 46.6 (CH), 123.6 (Ar),
124.9 (Ar), 125.6 (Ar), 126.1 (Ar), 130.0 (Ar), 139.4 (Ar), 151.1
(Ar), 158.0 (N–CvN), 230.2 (CuO). IR: ν 3352, 3079, 3052,
3022, 1881, 1751, 1727, 1621, 1589, 1500, 1483, 1365, 1233,
1203, 1177, 1068, 1024, 909, 750, 712, 694, 656, 553, 550, 503,
Acknowledgements
474 cm−1
.
4c: yield: 0.15 g (69.1%). Mp.: >250 °C (dec.). Elemental
analysis calc. (%) for C43H34WN6O3 (M = 866.61 g mol−1): H
3.95, C 59.60, N 9.70; found: H 3.88, C 59.55, N 9.61. H-NMR
St.S. wishes to thank the University of Duisburg-Essen for
financial support.
1
(300 MHz, acetone-d6, 25 °C): δ 5.33 (s, 1H, HC(CN2)3), 6.94
‡The crystallographic data of 2, 3 and 4a (excluding structure factors) have been
(m, 9H, Ar), 6.99 (m, 6H, Ar), 7.09 (m, 3H, Ar), 7.25 (m, 6H,
deposited with the Cambridge Crystallographic Data Centre as supplementary
Ar), 7.36 (m, 6H, Ar), 8.11 (s, 3H, NH). 13C-NMR (75.5 MHz, publication nos. CCDC-971997 (2), CCDC-886453 (3) and CCDC-971998 (4a).
2912 | Dalton Trans., 2014, 43, 2907–2914
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Table 4 Bond lengths (Å) and angles (°) of 4a
Cr(1)–C(6)
Cr(1)–C(5)
Cr(1)–C(7)
Cr(1)–N(4)
Cr(1)–N(2)
Cr(1)–N(6)
N(1)–C(2)
N(2)–C(2)
N(3)–C(3)
N(4)–C(3)
N(5)–C(4)
N(6)–C(4)
O(1)–C(5)
O(2)–C(6)
O(3)–C(7)
C(1)–C(2)
C(1)–C(3)
C(1)–C(4)
1.809(4)
1.819(5)
1.823(5)
2.133(3)
2.138(3)
2.146(3)
1.366(5)
1.294(5)
1.358(5)
1.289(5)
1.368(5)
1.290(5)
1.171(5)
1.184(5)
1.168(5)
1.517(5)
1.520(5)
1.523(5)
C(6)–Cr(1)–C(5)
C(6)–Cr(1)–C(7)
C(5)–Cr(1)–C(7)
C(6)–Cr(1)–N(4)
C(5)–Cr(1)–N(4)
C(7)–Cr(1)–N(4)
C(6)–Cr(1)–N(2)
C(5)–Cr(1)–N(2)
C(7)–Cr(1)–N(2)
N(4)–Cr(1)–N(2)
C(6)–Cr(1)–N(6)
C(5)–Cr(1)–N(6)
C(7)–Cr(1)–N(6)
N(4)–Cr(1)–N(6)
N(2)–Cr(1)–N(6)
83.69(19)
85.72(19)
85.63(19)
176.68(16)
98.30(16)
91.77(15)
95.21(16)
175.10(16)
99.06(16)
83.03(12)
99.97(15)
93.01(17)
173.98(17)
82.62(12)
82.47(13)
C(2)–N(1)–C(11)
C(2)–N(2)–C(21)
C(2)–N(2)–Cr(1)
C(21)–N(2)–Cr(1)
C(3)–N(3)–C(31)
C(3)–N(4)–C(41)
C(3)–N(4)–Cr(1)
C(41)–N(4)–Cr(1)
C(4)–N(5)–C(51)
C(4)–N(6)–C(61)
C(4)–N(6)–Cr(1)
C(61)–N(6)–Cr(1)
C(2)–C(1)–C(3)
C(2)–C(1)–C(4)
C(3)–C(1)–C(4)
131.9(4)
115.4(3)
121.2(3)
122.8(2)
126.2(3)
117.3(3)
121.7(3)
120.2(2)
121.1(3)
118.3(3)
120.5(3)
120.0(2)
110.6(3)
108.9(3)
110.3(3)
Table 5 Crystallographic data of 2, 3, 4a
2
3
4a
Empirical formula
M
C22H48Cl4N6Ni
597.17
C25.42H52.88Cl2Cu2N6O0.86
664.73
C47H42CrN6O4
806.86
Crystal size [mm]
T [K]
0.18 × 0.16 × 0.12
100(1)
0.32 × 0.23 × 0.17
100(1)
0.150 × 0.120 × 0.030
180(1)
Crystal system
Space group
a [Å]
b [Å]
c [Å]
Cubic
Pa3
18.5823(18)
18.5823(18)
18.5823(18)
90
Monoclinic
P21/n
9.8688(3)
25.3571(7)
14.0716(4)
90
Orthorhombic
Pna21
24.6646(14)
14.2926(7)
11.5541(7)
90
ˉ
α [°]
β [°]
90
90
94.1590(10)
90
3512.06(18)
4
1.257
1.389
90
90
4073.1(4)
4
1.316
0.333
0.75/0.66
1688
γ [°]
V [Å3]
Z
6416.5(11)
8
1.236
0.958
0.75/0.64
2544
Dcalc [g cm−1
]
μ(MoKα [mm−1])
Transmissions
F(000)
0.75/0.60
1385
Index ranges
−25 ≤ h ≤ 25
−25 ≤ k ≤ 24
−22 ≤ l ≤ 17
29.48
−13 ≤ h ≤ 13
0 ≤ k ≤ 34
0 ≤ l ≤ 18
28.73
−31 ≤ h ≤ 31
−18 ≤ k ≤ 12
−14 ≤ l ≤ 14
27.169
θmax [°]
Reflections collected
Independent reflections
Rint
Refined parameters
R1 [I > 2σ(I)]
wR2 [all data]
x(Flack)
40 041
2961
0.0506
100
0.0296
0.0813
52 732
8907
0.0312
310
0.0497
0.1560
32 293
8839
0.0607
522
0.0443
0.0961
0.016(12)
1.010
0.311/−0.353
GooF
1.137
0.387/−0.255
1.082
1.513/−0.809
Δρfinal (max/min) [e Å−3
]
4 G. J. van Driel, W. L. Driessen and J. Reedijk, Inorg. Chem.,
1985, 24, 2919–2925.
Notes and references
1 S. Trofimenko, J. Am. Chem. Soc., 1966, 88, 1842–1844.
2 J. C. Calabrese, S. Trofimenko and J. S. Thompson, J. Chem.
Soc., Chem. Commun., 1986, 1122–1123; S. Trofimenko,
J. C. Calabrese and J. S. Thompson, Inorg. Chem., 1987, 26,
1507–1514.
5 P. C. Kunz and W. Kläui, Collect. Czech. Chem. Commun.,
2007, 72, 492–502.
6 A. G. Blackman, Polyhedron, 2005, 24, 1–39.
7 J. C. Mareque-Rivas, R. Prabaharan and S. Parsons, Dalton
Trans., 2004, 1648–1655.
3 H. R. Bigmore, S. C. Lawrence, P. Mountford and
C. S. Tredget, Dalton Trans., 2005, 635–651.
8 B. Gutschank, S. Schulz, M. Marcinkowski, G. Jansen,
H. Bandmann, D. Bläser and C. Wölper, Angew. Chem.,
This journal is © The Royal Society of Chemistry 2014
Dalton Trans., 2014, 43, 2907–2914 | 2913

View Article Online
Paper
Dalton Transactions
2012, 124, 11051–11055, (Angew. Chem. Int. Ed., 2012, 51, 20 T. Beissel, B. S. P. C. Della Vedova, K. Wieghardt and
10893–10897). R. Boese, Inorg. Chem., 1990, 29, 1736–1741.
9 (a) M. Münch, U. Flörke, M. Bolte, S. Schulz and D. Gudat, 21 D. Barnes, G. L. Brown, M. Brownhill, I. German, C. J. Herbert,
Angew. Chem., 2008, 120, 1535–1537, (Angew. Chem. Int. Ed.,
2008, 47, 1512–1514); (b) S. Schmidt, S. Gondzik, S. Schulz,
D. Bläser and R. Boese, Organometallics, 2009, 28, 4371–
A. Jolleys, A. R. Kennedy, B. Liu, K. McBride, F. S. Mair,
R. G. Pritchard, A. Sanders and J. E. Warren, Eur. J. Inorg.
Chem., 2009, 1219–1233.
4376; (c) S. Schmidt, B. Gutschank, S. Schulz, D. Bläser, 22 T. M. Bockman and J. K. Kochi, New J. Chem., 1992, 16, 39–49.
R. Boese and C. Wölper, Eur. J. Inorg. Chem., 2011, 28, 23 I. K. Dhawan, M. A. Bruck, B. Schilling, C. Grittini and
4464–4470.
10 B. Gutschank, M. Bayram, S. Schulz, D. Bläser and 24 H. Brunner, A. Winter and B. Nuber, J. Organomet. Chem.,
C. Wölper, Eur. J. Inorg. Chem., 2013, 5495–5502. 1998, 558, 213–218.
11 Cambridge Structural Database, Version 5.34, see also; 25 F. A. Cotton and D. C. Richardson, Inorg. Chem., 1966, 5,
F. H. Allen, Acta Crystallogr., Sect. B: Struct. Sci., 2002, 58, 1851–1854.
380–388. Bonds were set to “any” type. The search yielded 26 Cambridge Structural Database, Version 5.34, see also;
J. H. Enemark, Inorg. Chem., 1995, 34, 3801–3808.
38 hits with 53 bonds. The mean Cu–N bond length was
found to be 1.909(61) Å (min 1.803 Å, max 2.102 Å).
12 J. M. Goodwin, P.-C. Chiang, M. Brynda, K. Penkina,
M. M. Olmstead and T. E. Patten, Dalton Trans., 2007,
3086–3092.
F. H. Allen, Acta Crystallogr., Sect. B: Struct. Sci., 2002, 58,
380–388. A search for a CrNNN fragment with “any” bonds
and coordination number of Cr equal to 6 yielded 998 hits
with 26 670 Cr–N bonds. Mean 2.055(66) Å, min 1.544 Å,
max 2.67 Å.
13 S. H. Oakley, M. P. Coles and P. B. Hitchcock, Inorg. Chem., 27 (a) D. P. Tate, W. R. Knipple and J. M. Augl, Inorg. Chem.,
2004, 43, 5168–5170.
14 J. P. Fackler Jr., R. G. Raptis and H. H. Murray, Inorg. Chim.
Acta, 1992, 193, 173–183.
15 V. Comte and H. Vahrenkamp, J. Organomet. Chem., 2001,
627, 153–158.
16 C. A. Tolman, Chem. Rev., 1977, 77, 313–348.
17 S. Trofimenko, J. Am. Chem. Soc., 1969, 91, 588–595.
18 S. Trofimenko, J. Am. Chem. Soc., 1970, 92, 5118–5126.
1962, 1, 433–434; (b) H. Werner, K. Deckelmann and
U. Schönenberger, Helv. Chim. Acta, 1970, 53, 2002–2009.
28 SHELXS-97: G. M. Sheldrick, Acta Crystallogr., Sect. A:
Fundam. Crystallogr., 1990, 46, 467–473.
29 G. M. Sheldrick, SHELXL-97, Program for Crystal Structure
Refinement, Universität Göttingen, 1997. See also;
G. M. Sheldrick, Acta Crystallogr., Sect. A: Fundam. Crystal-
logr., 2008, 64, 112–122.
19 E. E. Pullen, D. Rabinovich, C. D. Incarvito, T. E. Concolino 30 PLATON/SQUEEZE: P. van der Sluis and A. L. Spek, Acta
and A. L. Rheingold, Inorg. Chem., 2000, 39, 1561–1567.
Crystallogr., Sect. A: Fundam. Crystallogr., 1990, 46, 194–201.
2914 | Dalton Trans., 2014, 43, 2907–2914
This journal is © The Royal Society of Chemistry 2014