Multiple metal coordinating behaviour of the tetrapodal ligand 1,1,1,1-tetrakis[(salicylaldimino)methyl]methane

Article abstract of DOI:10.1016/j.inoche.2010.06.018

The tetrapodal ligand 1,1,1,1-tetrakis[(salicylaldimino)methyl]methane (H₄tsam) has been introduced for the first time for metal complexation. Two zinc(II) complexes[Zn₂(tsam)] (1) and [Zn ₃(Htsam)₂]?2C₇H₈ (2) have been obtained by reacting zinc acetylacetonate with the ligand in the presence of triethylamine, while a cobalt(III) complex [Co(Htsam)]?CH ₃CN?H₂O (3) is obtained when Co(ClO₄) ₂?6H₂O is reacted in air. All the compounds have been characterized by their elemental analyses and ESI-MS, IR, UV-VIS and ¹H NMR spectra. The X-ray crystal structures of H₄tsam, 2 and 3 have been determined. Compounds 1 and 2 exhibit fluorescence in solution and the lifetimes of their luminescence decay have been measured. Thermal analysis (TGA, DTA) of 2 with regard to loss of encapsulated toluenes and redox behaviour of 3 have been studied.

Full text of DOI:10.1016/j.inoche.2010.06.018

Inorganic Chemistry Communications 13 (2010) 1074–1080
Contents lists available at ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
Multiple metal coordinating behaviour of the tetrapodal ligand 1,1,1,1-tetrakis
[(salicylaldimino)methyl]methane
Supriya Dutta a, Papu Biswas a,b, Ulrich Flörke c, Kamalaksha Nag a,
⁎
a
Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
b
Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 711 103, India
c
Anorganische und Analytische Chemie, Universität Paderborn, D-33098 Paderborn, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
The tetrapodal ligand 1,1,1,1-tetrakis[(salicylaldimino)methyl]methane (H4tsam) has been introduced for
the first time for metal complexation. Two zinc(II) complexes[Zn2(tsam)] (1) and [Zn3(Htsam)2]·2C7H8 (2)
have been obtained by reacting zinc acetylacetonate with the ligand in the presence of triethylamine, while a
cobalt(III) complex [Co(Htsam)]·CH3CN·H2O (3) is obtained when Co(ClO4)2·6H2O is reacted in air. All the
compounds have been characterized by their elemental analyses and ESI-MS, IR, UV-VIS and 1H NMR spectra.
The X-ray crystal structures of H4tsam, 2 and 3 have been determined. Compounds 1 and 2 exhibit
fluorescence in solution and the lifetimes of their luminescence decay have been measured. Thermal analysis
(TGA, DTA) of 2 with regard to loss of encapsulated toluenes and redox behaviour of 3 have been studied.
© 2010 Elsevier B.V. All rights reserved.
Received 4 May 2010
Accepted 10 June 2010
Available online 18 June 2010
Keywords:
Tetrapodal ligand
Configuration and conformation
Crystal structure
Fluorescence
Life time
The role of topology is quintessential for polypodal ligands in
controlling structure, stereochemistry and reactivities of their metal
complexes [1]. Tripodal ligands, in which boron [2], nitrogen [3],
phosphorous [2], or carbon [4] acts as the ligand bridge head, have
extensive coordination chemistry that range from structural and
functional modeling of metalloenzymes [5] to molecular magnetism
[6,7]. Although the chemistry of tetrapodal ligand metal complexes is
relatively less widespread [8], they find important applications, inter
alia, as medical diagnostic probes e.g. MRI contrast agents [9], and
chemotherapeutic agents [10]. Unlike tripodal ligands which have a
single atom as the bridge head, tetrapodal ligands used for metal
complexation have more than one bridge heads. In our effort to
explore the metal complex chemistry of tetrapodal ligands with a
single bridge head, we have designed a number of ligands by
derivatizing 1,1,1,1-tetrakis(2-aminomethyl)methane. Herein we
report the synthesis, structure and physico-chemical properties of
1,1,1,1-tetrakis[(salicylaldimino)methyl]methane (H4tsam) and its
zinc(II) and cobalt(III) complexes.
The ball and stick representation of H4tsam, which crystallizes with
the monoclinic space group C2/c (Z=4) [13], is shown in Fig. 1. The
average values of the C–C–C angles around the central carbon C(9) is
109.7 1.1°. All the phenolic protons are strongly hydrogen-bonded
to their adjacent imine nitrogens with average O····N distances and
O–H····N angles being 2.601(4)Å and 146.9(1)°, respectively.
In a reaction involving three equivalents of zinc acetylacetonate,
two equivalents H4tsam and six equivalents of N(C2H5)3 in boiling
acetonitrile, a yellow product that precipitated out during reflux was
found to have the composition [Zn2(tsam)] (1) [14]. This compound
was previously obtained in a different way [11]. A second product was
isolated from the filtrate first by evaporating it to dryness, followed by
extraction with benzene and finally with addition of toluene to the hot
benzene concentrate [Zn3(Htsam)2]·2C7H8 (2) [15] separated out as
light yellow crystals. The relative yield of the two products was ca. 60%
(1) and 25% (2). However, when the above reaction was carried with
the reactants in the molar ratio 2:1:4, compound 1 was isolated as the
sole product in 90% yield. Compounds 1 and 2 have been character-
ized by their elemental (C, H and N) analysis, ESI-MS, IR and 1H NMR
spectra. The strongest peak observed in the ESI-MS at m/z=676 for 1
and 1286.5 for 2 correspond to ions [Zn2(tsam)+H]+ and [Zn3
(Htsam)2 +H]+, respectively. As shown in Fig. 2, the observed and
simulated isotopic distribution patterns for both of the cationic
species [1+H]+ and [2+H]+ are in excellent agreement with each
other. Because of poor solubility of 1, diffraction quality crystal of the
compound could not be obtained. Nevertheless, the composition and
the spectroscopic data of [Zn2(tsam)] indicate that each of the metal
centers are coordinated to two salicylaldimine units symmetrically to
obtain ZnN2O2 coordination sphere.
The hydrochloride salt of 1,1,1,1-tetrakis(2-aminomethyl)meth-
ane C(CH2NH2)4·4HCl was prepared by modification of a procedure
reported in literature[11] from pentaerythritol in 45% overall yield
following the protocols outlined in Scheme 1. The ligand H4tsam was
obtained in 80% yield by reacting C(CH2NH2)4·4HCl, N(C2H5)3 and
salicylaldehyde in 1:4:4 molar ratio in methanol [12].
⁎
Corresponding author. Fax: +91 33 2473 2805.
E-mail address: ickn@iacs.res.in (K. Nag).
1387-7003/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2010.06.018

S. Dutta et al. / Inorganic Chemistry Communications 13 (2010) 1074–1080
1075
Scheme 1.
The perspective structural view of [Zn3(Htsam)2] in 2 [16] (Fig. 3a)
shows that out of four salicylaldimines of H4tsam only three are
involved in metal coordination. In the trinuclear core N3Zn(μ-O3)Zn
(μ-O3)ZnN3, the crystallographically equivalent terminal metal cen-
ters [Zn(1)/Zn(1′)] are coordinated to three imine nitrogens and
three phenolate oxygens of three pendant salicylaldimines, while
the central metal Zn(2) obtains ZnO6 coordination sphere as all the
phenolate oxygens act as bridges. Fig. 3b shows the coordination
polyhedra that resulted due to the sharing of the O3 faces of
the terminal and central metal atoms. In the terminal ZnN3O3
coordination sphere, the average value of the largest N–Zn (1/1′)–O
angles [154.5(9)°] indicates its significant distortion from regular
octahedral geometry. On the other hand, for the central Zn(2), all the
three trans O–Zn(2)–O angles are 180°. A closer look of the trigonal
planes of the terminal metal centers reveals that they are prismat-
ically twisted.
Consideration of the Zn(2)–O bond distances indicate that relative to
the four identical equatorial Zn(2)–O(1/1′, 2/2′) bonds [2.096(5)Å], the
two axial Zn(2)–O(3/3′) bond [2.149(5)Å] is longer. Clearly, Zn(2) has an
axially elongated octahedral geometry (D4h). The extent of trigonal
prismatic distortion is given by the twist angle ϕ [17], which is 0° for
perfect trigonal prism (D3h) and 60° for both trigonal antiprism (D3d) and
octahedron (Oh). The average value of ϕ for Zn(1/1′) turns out to be 27.6°,
which indicates that the distortion from regular octahedron to trigonal
prism is 54% complete. Further, the N3 and O3 trigonal planes are
practically parallel to each other (their dihedral angle is 0.28°) and
the distance between the centroids of the two planes is 2.748 Å.
The intermetallic Zn(1)–Zn(2)–Zn(1′) axis is perfectly linear,
while the distance between two adjacent metals Zn(1/1′)····Zn(2) is
2.913(4)Å.
Fig. 1. Ball and stick representation of H4tsam. Selected bond parameters: C(8)–C(9)=
1.531(2), C(9)–C(10)=1.529(2), N(1)–C(7)=1.265(2), N(1)–C(8)=1.459(2), N(2)–C
(10)=1.457(3), N(2)–C(11)=1.276(2), O(1)–C(1)=1.348(2), O(2)–C(17)=1.350(2)Å,
C(10)–C(9)–C(8)=109.41(10), C(10)#1 –C(9)–C(10)=110.80(2), C(10)#1–C(9)–C(8)=
108.46(10), C(8)–C(9)–C(8)#1=110.3(2)°. Symmetry transformations used to generate
equivalent atoms: (–x+1), y, (–z+½).
The stereochemical configuration of the terminal metal centers of
the complex, as obtained by viewing the orientations of the three
Fig. 2. ESI-MS of complexes 1 and 2 showing observed and simulated isotopic abundance patterns for the most strong peaks.

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S. Dutta et al. / Inorganic Chemistry Communications 13 (2010) 1074–1080
Fig. 3. (a) Perspective representation of [Zn3(Htsam)2]·2C7H8 (2). Selected bond parameters: Zn(1)–O(1)=2.094(4), Zn(1)–O(2)=2.107(5), Zn(1)–O(3)=2.124(4), Zn(1)–N(1)=
2.109(6), Zn(1)–N(2)=2.101(6), Zn(1)–N(3)=2.116(6), Zn(2)–O(1)=2.096(4), Zn(2)–O(2)=2.096(5), Zn(2)–O(3)=2.149(5), Zn(1/1′)····Zn(2)=2.913(4)Å: O(1)–Zn(1)–N(3)=155.3
(2), O(2)–Zn(1)–N(1)=153.3(2), O(3)–Zn(1)–N(2)=154.81(19), O(1)–Zn(2)–O(1)#1=180.0°)°. Symmetry transformations used to generate equivalent atoms: (−x+2), (−y+1), −z.
(b). Coordination polyhedra of [Zn3(Htsam)2]·2C7H8. (c). Homochiral (Δ−Δ) configuration of [Zn3(Htsam)2]·2C7H8. (d). Packing diagram showing hydrogen bonds and short contacts in [Zn3
(Htsam)2]·2C7H8 (2).

S. Dutta et al. / Inorganic Chemistry Communications 13 (2010) 1074–1080
1077
j
j
chelate rings N ꢀ C ꢀ C ꢀ C ꢀ O ꢀ Zn along the intermetallic axis
(Fig. 3c), is homochiral Δ–Δ (or Λ–Λ). Moreover, all the three six-
j
j
membered N ꢀ C ꢀ C ꢀ C ꢀ N ꢀ Zn rings have the twisted boat
conformation δδδ. Since compound 2 has a centrosymmetric space
group (P-1), it crystallizes in racemic form.
The packing diagram of [Zn3(Htsam)2]·2C7H8 (Fig. 3d) viewed
along [001] plane shows that the toluenes are trapped between two
layers of complex molecules. As may be noted in Fig. 3d, the C(102)–H
proton of toluene is involved in weak intermolecular hydrogen
bonding with the oxygen atom O(4) of the uncoordinated salicylaldi-
mine moiety and the C(102) ····O(4) distance is 3.52 Å. Again, in the
uncoordinated salicylaldimine, the phenolic O–H and imine nitrogen
are intramolecularly hydrogen-bonded with O(4)····N(4) distance
being 2.574 Å and ∠O(4)–H····N(4) is 147°.
The thermal stability of 2 with regard to the loss of encapsulated
solvent molecules has been studied by thermogravimetric and
differential thermal analyses. Fig. 4 shows that onset of desolvation
takes place at 140°C and completes at 220°C. The observed weight loss
12.35% is in agreement with the value 12.53% expected for the loss of
two toluene molecules from 2.
The absorption and emission spectra of compounds 1 and 2 in
dimethyl sulfoxide and acetonitrile respectively are shown in Fig. 5. The
absorption maxima of the compounds are located at 366 nm for 1
(ε=23,000 M−1 cm−1) and at 353 nm for 2 (ε=25,500 M−1 cm−1).
The two compounds also exhibit a second more intense band (not shown
in Fig. 5) at 265 nm (ε=57,000 M−1 cm−1) for 1 and 258 nm
(ε=59,000 M−1 cm−1) for 2. It appears that the higher energy stronger
band is due to π–π* transition of the aromatic rings, while the lower
energy band is due to C=N π–π* transition. Although the ligand itself
does not show any luminescence spectrum at room temperature, both 1
and 2 exhibit strong luminescence when their C=N absorption bands are
excited. In the case of 1, the luminescence peak occurs at 450 nm, while for
2 this peak is observed at 440 nm.
Fig. 5. Absorption and emission profiles of [Zn2(tsam)] (1) (bold line) in dimethyl
sulfoxide and [Zn3(Htsam)2]·2C7H8 (2) (dotted line) in acetonitrile.
ligand in the metal chelation and the spectator role of the fourth one.
On the other hand, the ESI-MS of 3 indicates the occurrence of
unipositive monomeric as well as dimeric cations in the plasma. As
shown in Fig. 7, in methanol, three peaks due to [Co(Htsam)+H]+
(m/z=605.37, 12%), [Co(Htsam)+Na]+ (m/z=627.37, 100%) and
[{Co(Htsam)}2 +Na]+ (m/z=1231.75, 10%) are observed, whereas
in acetonitrile, the relative abundances of the peaks due to [Co
(Htsam)+H]+ (m/z=604.90), [Co(Htsam)+Na]+ (m/z=626.89)
and [{Co(Htsam)}2 +H]+ (m/z=1208.58) are 100%, 10% and 15%,
respectively. The observation of the dimerized cationic species is
intriguing.
A plausible explanation could be the uncoordinated phenolic OH of
3 in the ESI-MS condition undergoes dimerization as:
It may be noted that the relative intensities of the luminescent band
of the two compounds bear similar relationship to their absorbance
ꢀ
ꢁ
̅
̅
intensities. The Stokes' shift
V abs− V em of the compounds,
Complex 3 is further characterized by the observation of two bands
5100 cm−1 (1) and 5600 cm−1 (2), are also of comparable energies.
The time resolved photoluminescence decay of 1 (in dimethyl
sulfoxide) and 2 (in acetonitrile) are shown in Fig. 6. The lifetime (τ)
values obtained by analyzing single exponential decay curves are
practically same for 1 (13.10 0.10 ns) and 2 (13.20 0.23 ns). The
quantum yield (ϕ) of 1 (in dimethyl sulfoxide) is 0.22, while that of 2
(in acetonitrile) is 0.26.
at 400 and 550 nm in the visible region of the absorption spectrum,
1
which can be attributed to 1A1g →1T2g and T1g transitions, respec-
tively. Further, the compound undergoes quasi-reversible reduction
in acetonitrile with E1/2 =−890 mV and ΔEp =140 mV at a scan rate
of 100 mV s−1
.
The X-ray structure of 3 [19] (Fig. 8) shows a near perfect
octahedral geometry for the [CoN3O3] coordination sphere. All the
Co–O and Co–N distances are almost equal (1.90 0.01 Å), as are
the three O–Co–N trans angles (178 1°). Similar to 2, in this case also
O(4)····N(4) distance is 2.60 Å and O(4)–H····N(4) angle is 146.1°.
The reaction between Co(ClO4)2·6H2O and H4tsam in the
presence of N(C2H5)3 in air led to the isolation of the cobalt(III)
complex [Co(Htsam)]·CH3CN·H2O (3) [18]. The 1H NMR spectrum
of 3 indicates the involvement of three salicylaldimine units of the
Acknowledgments
KN in thankful to the Indian National Science Academy for supporting
him as INSA Senior Scientist. Thanks are due to Mr. Subrata Das, IACS for
TCSPC measurements.
Appendix A. Supplementary material
CCDC 775643–775645 contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
References
Fig. 4. Thermogravimetric and differential analysis of [Zn3(Htsam)2]·2C7H8 (2) under
inert atmosphere at a heating rate of 5 °C/min.
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[12] Anal. Calcd for C33H32N4O4: C, 72.26; H, 5.84; N, 10.21. Found: C, 72.20; H,5.79; N,
10.17. IR (KBr, υ/cm−1): 1631 (υC = N). 1H NMR (300 MHz, CDCl3) δ/ppm 13.22 (s,
4H, PhOH); 8.43 (s, 4H, CH=N); 7.34 (t, 4H, J1 =8.54 Hz, J2 =8.53 Hz, Ar); 7.25
(d, 4H, J=9.05 Hz, Ar); 6.98 (d, 4H, J=8.23 Hz, Ar); 6.90 (t, 4H, J1 =7.53 Hz,
J2 =7.28 Hz, Ar); 3.78 (s, 8H, CH2)
[13] H4tsam: C33H32N4O4, M=548.63, colourless needle, Monoclinic, space group
C2/c, a = 17.143(2), b = 11.2269(14), c = 15.689(2)Å, β = 105.965(3)°,
Fig. 6. Steady state decay profiles of [Zn2(tsam)] (1) (a) and [Zn3(Htsam)2]·2C7H8 (2) (b) in dimethyl sulfoxide and acetonitrile respectively.

S. Dutta et al. / Inorganic Chemistry Communications 13 (2010) 1074–1080
1079
}
Fig. 6 (continued).
(Mo–Kα) = 0.084 mm− 1
U = 2903.0(6) Å3, Z = 4, Dc = 1.255 Mg m− 3
,
μ
,
indices[IN2σ (I)]: R1=0.0616, wR2=0.0843, R indices (all data): R1=0.2056,
wR2=0.1240
T=123(2) K, F(000)=1160, h, k, l limiting indices: −22 b=h b=22, −14
b=k b=14, −20 b=l b=20, crystal size/mm3 =0.40 x 0.10 x 0.08, no. of
data =3339, restrains =0, params =188, no.of reflns [I N2σ (I)] = 3339,
gof=0.834, final R indices[IN2σ (I)]: R1=0.0425, wR2=0.0820, R indices
(all data): R1=0.1098, wR2=0.0980.
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[14] Anal. Calcd for C33H28N4O4Zn2: C, 58.67; H, 4.15; N, 8.29. Found: C, 58.55; H, 4.20;
N, 8.25. FT-IR (KBr, υ/cm−1): 3202(w), 2902 (w), 1627 (s), 2598 (m), 1542 (m),
1471 (m), 1448 (m), 1402 (w), 1317 (m), 1195 (m), 1153 (w), 796 (w), 756 (m),
588 (w). ESI-MS (positive) in CH3CN: m/z=676 [Zn2(tsam)+H]+ (100%). 1H
NMR (300 MHz, (CD3)2SO) δ/ppm 8.12 (s, 4H, CH=N); 7.13 (t, 4H, J1 =6.93 Hz,
J2 =7.01 Hz, Ar); 7.01 (d, 4H, J=7.61 Hz, Ar); 6.58 (d, 4H, J=8.41 Hz, Ar); 6.37 (t,
4H, J1 =7.13 Hz, J2 =7.22 Hz, Ar); 3.59 (s, 8H, CH2)
[15] Anal. Calcd for C80H74N8O8Zn3: C, 65.28; H, 5.03; N, 7.61. Found: C, 65.40; H, 5.13;
N, 7.55. FT-IR (KBr, υ/cm−1): 3464 (w, br), 2891 (w), 1630 (s), 1599 (w), 1543
(m), 1471 (s), 1446 (m), 1402 (m), 1319 (m), 1196 (m), 1155 (w), 1033 (w),
1005 (w), 889 (w), 794 (w), 758 (m), 686 (w), 590 (w). ESI-MS (positive) in
CH3CN: m/z=1286.5 [Zn3(Htsam)2 +H]+ (100%). 1H NMR (300 MHz, CDCl3): δ
8.11 (s, 8H, CH=N); 6.89 (d, 4H, J=6.15 Hz, Ar); 6.79 (d, 4H, J=8.26 Hz, Ar);
6.44 (t, 4H, J1 =6.86 Hz, J2 =6.93 Hz, Ar); 6.18 (t, 4H, J1 =7.26 Hz, J2 =7.24 Hz,
Ar); 3.76 (s, 8H, CH2)
(d) K.R. Dymock, G.J. Palenik, Inorg. Chem. 14 (1975) 1220.
[18] Anal. Calcd for C35H34N5O5Co: C, 63.29; H, 5.12; N, 10.54. Found: C, 63.23; H, 5.07; N,
10.60. ESI-MS (positive) in CH3OH: m/z=605.37 [Co(Htsam)+H]+ (12%), 627.37
[Co(Htsam)+Na]+ (100%), 1231.75 [{Co(Htsam)}2+Na]+ (10%). ESI-MS (positive)
in CH3CN: 604.90 [Co(Htsam)+H]+ (100%), 626.89 [Co(Htsam)+Na]+ (10%),
1208.58 [{Co(Htsam)}2+H]+ (15%). FT-IR (KBr, υ/ cm−1): 3446 (m, br), 1626 (s),
1601 (s), 1537 (m), 1468 (m),1448 (s), 1396 (w), 1352 (w), 1321 (m), 1205 (m),
1151 (m), 1027 (w), 904 (w), 758 (m), 617 (w). 1H NMR (300 MHz, CDCl3): δ/ppm
12.46 (s, 1H, Ar-OH); 8.47 (s, 4H, CH=N); 7.47 (s, 4H, Ar-H); 7.13 (t, 4H, J=7.82 Hz,
Ar-H); 7.03 (d, 4H, J=7.50 Hz, Ar-H); 6.45 (t, 4H, J=7.28 Hz, Ar-H); 3.94 (d, 3H,
J=12.60 Hz, coordinated CH2 (ax/eq)); 3.31 (d, 3H, J=12.42 Hz, coordinated CH2
(eq/ax)); 3.74 (s, 2H, uncoordinated CH2)
[19]
C35H34N5O5Co, M= 663.60, red prism, Monoclinic, space group P2(1)/c,
a = 12.1943(10), b = 14.8165(12), c = 17.1925(14)Å, β = 90.222(2)°,
U =3106.3(4) Å3, Z=4, Dc = 1.419 Mg m− 3, μ =0.604 mm− 1, T = 123(2) K,
F(000) =1384, h, k, l limiting indices: −15 b= h b=16, −18 b= k b=19,
−22 b=l b= 23, crystal size/mm3 = 0.45x 0.20 x 0.20, no. of data =7816,
restrains =0, params =417, no.of reflns [I N2σ (I)] =7816, gof =0.888, final R
[16] 2: C80H74N8O8Zn3, M=1471.58, colourless prism, Triclinic, space group P-1,
a=10.262(3), b=12.539(3), c=14.318(4)Å, α=66.245(8), β=81.688(7),
γ=87.230(8)°, U=1668.5(8) Å3, Z=1, Dc =1.465 Mg m−3, μ=1.137 mm−1
,
T=120(2) K, F(000)=764, h, k, l limiting indices: −12 b=h b=11, −9 b=k
b=15, −11 b=l b=17, crystal size/mm3 =0.15x 0.08 x 0.03, no. of data=6431,
restrains=5, params=450, no.of reflns [IN2σ (I)]=6431, gof=0.657, final R
indices[I N2σ (I)]: R1 = 0.0563, wR2 = 0.1164, R indices (all data):
R1 = 0.1000, wR2= 0.1354.

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S. Dutta et al. / Inorganic Chemistry Communications 13 (2010) 1074–1080
Fig. 7. ESI-MS spectra of [CoIII(Htsam)] (3) in CH3OH (a) and CH3CN (b).
Fig. 8. Ball and stick representation of [CoIII(Htsam)]∙CH3CN∙H2O (3) Selected bond parameters: Co–N(1)=1.905(3), Co–N(2)=1.909(2), Co–N(3)=1.899(2), Co–O(1)=1.910(19),
Co–O(2)=1.893(2), Co–O(3)=1.886(19)Å; N(1)–Co–O(1)=92.31(9), N(1)–Co–O(2)=176.73(9), N(1)–Co–O(3)=91.10(9), N(2)–Co–O(1)=89.97(9), N(2)–Co–O(2)=93.09(10),
N(2)–Co–O(3)=176.48(9), N(3)–Co–O(1)=178.91(9), N(3)–Co–O(2)=90.15(9), N(3)–Co–O(3)=94.20(9), N(1)–Co–N(2)=89.82(10), N(1)–Co–N(3)=88.41(10), N(2)–Co–N(3)=
89.22(10), O(1)–Co–O(2)=89.17(9), O(1)–Co–O(3)=86.60(8), O(2)–Co–O(3)=86.08(9)°. Water of crystallization is shown as O(100).