The phenomenon of intramolecular attractive S...O interactions: Synthesis and structure of (1,10-phenanthroline)copper(II) complexes with isonitroso-(4-methylthiazol-2-yl)acetamide and isonitroso-(4-methylthiazol-2-yl)-(benzothiazol-2-yl)methanide

Article abstract of DOI:10.1515/znb-1997-0304

Isonitroso-(4-methylthiazol-2-yl)acetamide H(L¹), isonitroso-(4-methylthiazol-2-yl)(benzothiazol-2-yl)methanide H(L²) and their copper(II) complexes of composition [Cu(Phen){L¹}(ClO₄)] (1) and [Cu(Phen){L²}Cl]*C₂H₅OH (2) have been prepared. Crystal and molecular structures of the complexes have been determined from X-ray diffraction data (1: monoclinic, space group P2₁/c, with a = 11.611(2), b = 10.259(2), c = 17.869(4) A, β = 104.67(3)°, V = 2059.1(7) A³, Z = 4; R1 = 0.046 for the 2522 unique reflections with I > 2σ(I). 2: triclinic, space group P1, with a = 8.351(1), b = 10.876(1), c = 14.891(2) A, α = 96.170(8)°, β = 94.201(9)°, γ = 106.721(9)°, V = 1280.1(2) A³, Z = 2; R1 = 0.034 for the 4038 unique reflections with I > 2σ(I)). In the structure of 1 the coordination polyhedron of Cu²⁺ is a distorted square pyramid with an oxygen atom of the ClO₄ counter anion in the apex (Cu-O 2.505(3) A); in complex 2 the copper atom adopts fivefold coordination of a slightly distorted trigonal-bipyramidal geometry with a chlorine atom in the equatorial plane (Cu-Cl 2.3504(9) A). Ethanol of crystallization gives rise to a hydrogen bond at the chlorine atom. In both structures the oximic anions are coordinated to the metal center in a bidentate chelate manner via the nitrogen atom of the nitroso group and the carbonyl oxygen atom (1) or via the benzothiazole nitrogen atom (2) (Cu-O, Cu-N in the range 1.963(2) - 2.031 (2) A). The thiazole group of the ligands takes no part in the coordination. The nitroso oxygen atoms possess short intramolecular contacts with thiazole sulphur atoms, with d〈S...O〉 at 2.605(3) (1) and 2.676(3) A (2), which may be attributed to a strong intraligand interaction.

Full text of DOI:10.1515/znb-1997-0304

The Phenomenon of Intramolecular Attractive S—O Interactions:
Synthesis and Structure of (l,10-Phenanthroline)copper(II) Complexes
with Isonitroso-(4-methylthiazol-2-yl)acetamide and
Isonitroso-(4-methylthiazol-2-yl)-(benzothiazoI-2-yl)methanide
Konstantin V. Domasevitch3, Vera V. Ponomarevaa, Andrey A. Mokhir3,
Eduard B. Rusanov3, Joachim Sielerb, Eberhard Hoyerb
a Department of Inorganic Chemistry, Kyiv Shevchenko University,
Volodimirska St., 64, Kyiv 252033, Ukraine
b Institut für Anorganische Chemie, Universität Leipzig,
Linnestraße 3, D-04103 Leipzig, Deutschland
Z. Naturforsch. 52 b, 323-330 (1997); received September 16, 1996
Copper(II), Oximes, Thiazoles, Benzothiazoles, X-Ray
Isonitroso-(4-methylthiazol-2-yl)acetamide H (L '), isonitroso-(4-methylthiazol-2-yl)(benzo-
thiazol-2-yl)methanide
H(L2) and their copper(II) complexes
of composition
[Cu(Phen){L'}(C104)] (1) and [Cu(Phen){L2}Cl]*C2H5 0 H (2) have been prepared. Crys-
tal and molecular structures of the complexes have been determined from X-ray diffractioon
data (1: monoclinic, space group P2]/c, with a = 11.611(2), b = 10.259(2), c = 17.869(4) Ä,
ß = 104.67(3)°, V = 2059.1(7) Ä3, Z = 4; R\ = 0.046 for the 2522 unique reflections with
I > 2a(I). 2: triclinic, space group PI, with a = 8.351(1), b = 10.876(1), c = 14.891(2) Ä,
a = 96.170(8)°, ß = 94.201(9)°, 7 = 106.721(9)°, V = 1280.1(2) A3, Z = 2; R\ = 0.034 for the
4038 unique reflections with I > 2a(I)). In the structure of 1 the coordination polyhedron of
Cu2+ is a distorted square pyramid with an oxygen atom of the CIO4 counter anion in the apex
(Cu-0 2.505(3) A); in complex 2 the copper atom adopts fivefold coordination of a slightly
distorted trigonal-bipyramidal geometry with a chlorine atom in the equatorial plane (Cu-Cl
2.3504(9) A). Ethanol of crystallization gives rise to a hydrogen bond at the chlorine atom.
In both structures the oximic anions are coordinated to the metal center in a bidentate chelate
manner via the nitrogen atom of the nitroso group and the carbonyl oxygen atom (1) or via the
benzothiazole nitrogen atom (2) (Cu-O, Cu-N in the range 1.963(2) - 2.031 (2) Ä). The thiazole
group of the ligands takes no part in the coordination. The nitroso oxygen atoms possess short
intramolecular contacts with thiazole sulphur atoms, with d(S—O) at 2.605(3) (1) and 2.676(3)
A (2), which may be attributed to a strong intraligand interaction.
Introduction
CH
3
NC
It is known, that in crystal structures sulphur
atoms in aromatic group often manifest a “hyperva-
lence” by forming short contacts with negative ions
or with electronegative atoms [1]. Lately we have in-
vestigated the crystal structure of Q-thiazolyloximes
and their metal derivatives and have found that in-
tramolecular attractive interactions of the S— O type
strongly enforce a syn configuration of the nitroso-
group with respect to the thiazole sulphur atom
(d (S -O ) 2.47-2.69 A) [2-4]:
However, the factors affecting the stereochem-
istry of these compounds can often be more com-
plicated, and it is difficult to predict the configu-
ration of these species. A similar conclusion has
been reached by Sax for thiamine derivatives [1].
In this context, a-thiazolyloximes have attracted
attention as model compounds in thiazole chem-
istry and biochemistry, especially for the “special
role” of sulphur atom in thiamine and althiomycin,
a highly modified peptide antibiotic [1 -2, 4-6], In
* Reprint requests to Dr. K. V. Domasevitch.
0939-5075/97/300-0323 $ 06.00
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324
K. V. Domasevitch et al. ■The Phenomenon of Intramolecular Attractive S— O Interactions
order to better characterize the phenomenon of the
intramolecular attractive S—O interaction and its
influence on the configuration of organic molecules
complexed with metal ions, it was of interest to
investigate the crystal structure of complexes of po-
tentially ambidentate thiazolyloximes, including re-
lated molecules with two or more different types of
sulphur atoms. In the course of these investigations
we were successful in synthesizing new thiazoly-
loximes and coordination compounds thereof. Here
we describe the preparation and results of X-ray
investigation of copper(II) complexes containing
the new ligands: isonitroso-(4-methythiazol-2-yl)-
acetamide. H(L'), and isonitroso-(4-methylthiazol-
2-yl)(benzothiazol-2-yl)-methanide, H(L2):
started and dry hydrogen sulphide was bubbled through
the hot mixture (60°C) for 3 h. The resulting dark-brown
solution was stored in a refrigerator (0°C) for 12 h, after
which a slightly-yellow solid, 2-benzothiazolylthioacet-
amide, was filtered off and washed with 20 ml of cold
2-propanol and dried in vacuo over CaCl2. Yield 11.0 g
(89 %). m. p. 163°C. 'H NMR spectrum (6, ppm): 4.42 s
(2H, CH2), 7.48 m, 8.02 m (4H, CH), 9.81 s (2H, NH2).
C9H8N2S2 (208.29)
Calcd C 51.89 H 3.87 N 13.45%,
Found C 52.10 H 3.77 N 13.36%.
(4-Methylthiazol-2-yl)(benzothiazol-2-yl)methane(l\\).
To a suspension of 9.0 g (44 mmol) of II in 30 ml of 2-
propanol a solution of 8.0 g (58 mmol) of bromoacetone
in 10 ml of 2-propanol was added dropwise over a 10
min period. The temperature was allowed to rise to about
40°C and the mixture was stirred for additional 2 h and left
overnight. The orange-yellow precipitate, (III)*HBr, was
collected, washed with 10 ml of 2-propanol and dried in
air. Yield 11.5 g (81 % ).1H NMR spectrum (<5, ppm): 2.38
s (3H, CH3), 4.35 s (2H, CH2), 7.35 s (1H, CH thiazole),
7.46 m, 8.05 m (4H. CH benzothiazole).
c h 3
T
\
h 2n
C |2HioN2S2*HBr (327.26)
H{L'}
H{L}
Calcd C 44.04 H 3.39 N 8.56%,
Found C 44.54 H 3.53 N 8.72%.
Experimental
Isonitroso(4-methylthiazol-2-yl)(benzothiazol-2-yl)-
methane (IV). To a vigourously stirred suspension of 9.37
g (29 mmol) of (III)*HBr in 30 ml of 2-propanol and 50
ml of water 2.19 g (32 mmol) of solid N aN 02 was added
over a 20 min period at room temperature. The mixture
was stirred for 5 h and the white precipitate filtered off,
washed with 50 ml of water and dried in vacuo over
H2SO4. After recrystallization from hot water, the yield
was 7.06 g (89 %). 1H NMR spectrum (6, ppm): 2.47 s
(3H, CH3), 7.71 s (1H, CH thiazole), 7.45 m, 8.14 m (4H,
CH benzothiazole), 14.04 s (1H, NOH).
Preparation of ligands
Bromoacetone was distilled twice and stored in a re-
frigerator prior to use. All experiments were carried out
in air.
Isonitroso-(4-methylthiazol-2-yl)(benzothiazol-2-yl)-
methane (IV) was prepared by a three-step method ac-
cording to the scheme:
h 2s
h
2c n
a
h
n h 2
i
C ,2H9N3OS2 (275.34)
Calcd C 52.34 H 3.29 N 15.26%,
Found C 52.18 H 3.50 N 15.16%.
BrCH2C0CH3
H3
Preparation of coordination compounds
,c h 3
In order to characterize the bidentate coordination
mode of the oximes prepared, coordination compounds of
composition Cu(diamine){L}X, where diamine = 2,2-di-
pyridyl, 1,10-phenanthroline were synthesized. A number
of copper(II) oximates of similar stoichiometry have been
reported earlier [8, 9],
Due to easy hydrolysis of the anionic oxime form
{L2}- to give H(L: ), we were not successful in the
preparation of analytically pure samples of alkali metal
oximates, 2,2-dipyridyl or 1,10-phenanthroline and cop-
per(II) salts CuX2 (X = Cl, Br, CIO4). A complex
OH
IV
The preparation of 2-cyanomethylbenzothiazole (I)
was as described previously [7], and the synthesis of iso-
nitroso-(4-methythiazol-2-yl)acetamide was carried out
in a similar fashion starting with cyanoacetamide [3].
2-Benzothiazolylthioacetamide (II). To a hot solution
of 10.4 g (60 mmol) of I in 100 ml of dry 2-propanol
2.0 g (37 mmol) of NaOCH? was added. The stirrer was
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K. V. Domasevitch et al. ■The Phenomenon of Intramolecular Attractive S— O Interactions
325
Table I. Experimental data for [Cu(phen){L'}(C104)] (1) and [Cu(phen){L2}Cl]*C2H5 0 H (2).
1
2
Ci8Hi4ClCuN50 6S
527.4
Monoclinic
c.6h^c1cun50 ,s .
Formula
599.6
Triclinic
Pi
Formula weight
Crystal system
Space group
Unit cell
P2|/c
a = 11.611(2), b = 10.259(2), c = 17.869(4), a = 8.351(1), b = 10.876(1),c = 14.891(2),
a = 90, 0 = 104.67(3),
2059.1(7)
4
7
= 90
a = 96.170(8), ß = 94.201(9),
1280.1(2)
2
7
= 106.721(9)
dimensions (A, °)
v (A3)
z
1.70
1068
1.56
614
Dcaic (g cn T 3)
F(000)
ß (cm-1)
40.79
11.56
Data collection
T(K)
293
293
Diffractometer
Radiation
Wavelength (A)
20max (°)
CAD-4 Enraf Nonius
CuKa
1.54178
STOE
MoKa
0.71069
52.08
119.84
Index ranges
Reflections collected
Unique data
0< h <12, 0< k < 1 1 ,-2 0 < / <19
3223
3053 (/?,m0.033)
-1 0 < h <10, —13< A: < 13, 0 < / < 18
5353
5068 (Rm 0.067)
Observed reflections
Discrimination
2522
2a
4038
2a
Structure refinement
Data used
2869
333
8.6
0.046
0.125
1.073
4263
390
10.9
0.034
0.093
1.065
0.590
Parameters refined
Data to param. ratio
R 1 (obs.)
wR2 (obs.)
GOF on F2
Largest peak in the final 0.544
difference map (e A
)
Cu(phen){L}Cl*EtOH was prepared by direct synthe-
sis in accordance with the general procedure described
by Skopenko and Kokozay [10]. The following methods
were used:
(20 ml). The resulting dark-green solution was heated
to 70-80°C, quickly filtered and then cooled to room
temperature during the period of 24 h. The dark-green
prismatic crystals of the complex were filtered off and
dried in air at room temperature. The yield was 0.760
g (72 %). The complex is soluble in hot water, aqueous
2-propanol and DMF.
cu(c104)2*6H20 + (Phen*H20 ) + N a{L'}
= [Cu(Phen){L'}(C104)] + NaC104 + 7H20
2Cu + 2(Phen*HCl*H20 ) + 2H(L2) + 2EtOH + 0 2
= 2[Cu(phen){L2}Cl]*EtOH + 4H20
Ci8Hi4ClCuN50 6S (527.39)
Calcd C 40.99 H 2.68 N 13.28 Cu 12.05%,
Found C 40.22 H2.81 N 13.02 Cu 11.75%.
Isonitroso-(4-methylthiazol-2-yl)acetamido-( I,10-phen-
anthroline)-copper(II) perchlorate (I)
Isonitroso(4-methylthiazol-2-yl)(benzothiazol-2-yl)-
methanido-( I,10-phenanthroline)-copper(II)
chloride, ethanol solvate (2)
To a hot solution of 0.370 g (2 mmol) of H(L') in
aqueous 2-propanol (1:1 v/v) (20 ml) 0.106 g (1 mmol)
of Na2CC>3 was added. The mixture was refluxed and
stirred for 10 min and then added to the solution of 0.741
g (2 mmol) of Cu(C104)2*6H20 and 0.396 g (2 mmol) of
phenanthroline hydrate in aqueous 2-propanol (1:1 v/v)
Copper powder (0.0635 g, 1mmol), 1,10-phenanthrol-
ine hydrochloride hydrate (0.2347 g, 1 mmol), H(L: )
(0.2753 g, 1 mmol) and dry ethanol (40 ml) were placed
in a flask; the mixture was stirred and refluxed for 2 h
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326
K. V. Domasevitch et al. ■The Phenomenon of Intramolecular Attractive S— O Interactions
Table II. Selected bond lengths (A) and angles (°) for
[Cu(phen){L'}(C104)] (1).
Table III. Selected bond lengths (A) and angles (°) for
[Cu(phen){L2}Cl]*C2H_<iOH (2).
Cu-0(2)
Cu-N(l)
Cu-N(4)
Cu-N(5)
Cu-0(6)
C(l)-C(2)
C(l)-C(3)
S-C(3)
1.264(4)
1.312(5)
1.313(5)
1.373(4)
1.358(6)
1431(4)
1.345(6)
1.409(3)
1.430(3)
1.420(3)
1.435(3)
2.3504(9)
2.031(2)
1.994(2)
2.145(2)
2.002(2)
1.724(3)
1.736(3)
1.730(3)
1.711(4)
1.281(3)
1.330(3)
1.443(4)
1.963(2)
1.965(3)
2.009(3)
1.987(3)
2.505(3)
1.467(4)
1.437(5)
1.737(3)
1.704(4)
1.292(4)
1.314(4)
0(2)-C(2)
N(2)-C(2)
N(3)-C(3)
N(3)-C(4)
C(4)-C(5)
C(11)-C(12)
C(17)-C(18)
Cl-0(3)
Cu-Cl
C(l)-C(3)
C(2)-N(2)
C(12)-N(2)
C(3)-N(3)
C(4)-N(3)
C(4)-C(5)
C(7)-C(8)
C(7)-C(12)
C(17)-C(18)
C(23)-C(24)
C(25)-0(2)
C(25)-C(26)
1.436(4)
1.321(4)
1.388(3)
1.309(4)
1.376(4)
1.350(5)
1.392(4)
1.397(4)
1.340(6)
1.425(4)
1.335(6)
1.513(8)
Cu-N(l)
Cu-N(2)
Cu-N(4)
Cu-N(5)
S(1)-C(2)
S(1)-C(7)
S(2)-C(3)
S(2)-C(5)
N(l)-0(1)
C(l)-N(l)
C(1)-C(2)
S-C(5)
0(1)-N(1)
N(l)-C(l)
Cl-0(4)
0-0(5)
0-0(6)
0(2)-Cu-N(1)
0(2)-Cu-N(5)
N(l)-Cu-N(4)
N(l)-Cu-N(5)
N(4)-Cu-N(5)
N(l)-Cu-0(6)
0(2)-Cu-0(6)
Cu-0(6)-Cl
81.7(1)
95.4(1)
100.7(1)
176.8(1)
82.3(1)
91.1(1)
88.7(1)
127.3(2)
114.5(2)
112.5(2)
88.9(2)
119.2(3)
111.6(3)
123.0(3)
123.8(3)
119.1(3)
111.8(3)
113.8(3)
122.1(3)
122(5)
C(3)-S-C(5)
172.1(1)
80.94(9)
93.7(1)
0(1)-N(1)-C(1)
N(1)-C(1)-C(2)
N(l)-C(l)-C(3)
C(1)-C(3)-N(3)
C(1)-C(2)-0(2)
C(3)-N(3)-C(4)
N(3)-C(4)-C(5)
0(2)-C(2)-N(2)
H(l)-N(2)-H(2)
N(2)-Cu-N(5)
N(2)-Cu-N(1)
N(5)-Cu-N(1)
N(2)-Cu-N(4)
N(5)-Cu-N(4)
N(l)-Cu-N(4)
N(1)-Cu-Cl
N(2)-Cu-Cl
N(4)-Cu-Cl
N(5)-Cu-Cl
N(2)-C(2)-C(1)
C(2)-N(2)-C(12)
N(2)-C(2)-S(l)
N(3)-C(3)-S(2)
C(1)-C(3)-S(2)
C(5)-C(4)-N(3)
C(4)-C(5)-S(2)
C(2)-S(l)-C(7)
C(5)-S(2)-C(3)
N(l)-C(l)-C(3)
N(l)-C(l)-C(2)
C(3)-N(3)-C(4)
N(2)-C(12)-C(7)
119.4(2)
111.8(2)
115.2(2)
114.3(2)
123.8(2)
114.3(3)
111.4(3)
89.2(1)
98.07(9)
79.90(9)
123.20(9)
128.87(7)
96.51(7)
107.79(7)
91.40(8)
114.3(2)
112.3(2)
118.7(2)
C(l)-N(l)-Cu
C(2)-0(2)-Cu
88.7(2)
123.8(3)
113.0(2)
111.3(3)
113.2(3)
C(l)-N(l)-Cu
C(2)-N(2)-Cu
0(1)-N(1)-C(1)
untill total dissolution of copper was observed. To the
cold mixture 5 ml of water was added and a small amount
of a brown solid was filtered off. The clear, dark-green
solution was allowed to stand at room temperature in a
vacuum desiccator over H2SO4 for a few days, then dark-
green crystals were collected and dried in air. Yield 0.324
g (54 %). The compound is soluble in ethanol, acetone,
CHCI3 and DMF and insoluble in water.
the difference-Fourier syntheses and refined isotropically.
The aliphatic CH2 and CH3 hydrogen atoms were placed
at calculated positions with their isotropic U values set
invariant at 0.08 A2. Refinements were terminated with
all non-hydrogen parameter shifts < 0.20 cr; the weighting
schemes were w_l = cr(F2) + (aP)2 + bP, where 3P =
(2FC2 + F02) and a and b are constants adjusted by the
program. Convergence was obtained at the values given
in Table I. The principal interatomic distances and angles
are listed in Tables II and III. Full crystallographic data
have been deposited at the Cambridge Crystallographic
Data Centre [13].
C26H22CICUN5O2S2 (599.60)
Calcd C 52.08 H 3.70 N 11.68 Cu 10.60%,
Found C 51.89 H 3.45 N 11.82 Cu 11.02%.
Measurements
1H NMR spectra were recorded on a Bruker CXP-200
spectrometer (200.14 MHz) in DMSO-d6 using tetram-
ethylsilane as an internal standard.
For the X-ray diffraction study dark-green prismatic
crystals of the dimensions 0.30x0.27x0.20 mm (1) and
0.32x0.27x0.19 mm ( 2 ) were used. Lattice parameters
and the orientation matrix for data collection were ob-
tained from least square refinement of the setting angles
of 24 reflections with 12 < 0 < 15°. Semi-empirical ab-
sorption corrections based on ?/> scans were applied. Ta-
ble I lists details of cell parameters, data acquisition and
structure refinement. The structures were solved by direct
methods and subsequent Fourier difference techniques
and refined by full-matrix least-squares techniques in the
anisotropic approximation for all non-hydrogen atoms
using SHELXS-86 and SHELXL-93 [11,12].Vhe NH2,
OH and aromatic CH hydrogen atoms were located from
Results and Discussion
The molecular structure of
[Cu(Phen){L'}(C104)] (1) is presented in Fig. 1,
which demonstrates a nearly square planar config-
uration at the copper atom with two phenanthroline
nitrogen atoms (Cu-N(4) and Cu-N(5) at 2.009(3)
and 1.987(3) A, respectively) and nitrogen N (l) and
oxygen 0(2) atoms (Cu-N( 1) at 1.965(3) A and Cu-
0(2) at 1.963(2) A, Table II). The mean planes of the
phenanthroline molecule and the group {L1} inter-
sect at an angle of ca. 6.8( 1)°, so that the structure
of the fragment Cu(Phen){L'} is actually planar.
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327
K. V. Domasevitch et al. ■The Phenomenon of Intramolecular Attractive S— O Interactions
0(3)
Fig. 1. Perspective view, with
40% probability ellipsoids, of the
[Cu(phen){L'}(C104)] complex
(1), showing the atom numbering
scheme.
Fig. 2. Fragment of the crystal struc-
ture of the [Cu(phen){L'}(C104)] com-
plex (1).
In both five-membered chelate rings (Fig. 1) the
oxygen atom of a perchlorate counter anion in the
angles about the copper atom, N(l)-Cu-0(2) and apex of a distorted square pyramid. The Cu-0(6)
N(4)-Cu-N(5) of ca. 81.7(1) and 82.3(1)°, respec-
tively, are typical for related systems [8, 9, 14]. The typical for the weak Cu-O and Cu-F interactions in
atoms of each metallocycle, CuN(l)C(l)C(2)0(2) copper(II) perchlorate and tetrafluoroborate com-
and CuN(4)C(l 1)C(12)N(5), are practically copla- plexes with chelating ligands [14].
bond length is found to be 2.505(3) A, which is
nar (the maximum deviation from the least squares
planes does not exceed 0.021(1) A) and the copper
atom resides exactly in the mean plane of atoms
N(l), 0(2), N(4), N(5). The [4+1] coordination en-
vironment of the copper is completed by the 0(6)
The complex units [Cu(Phen){lJ }(C104)] pack
forming “dimers” (Fig. 2), in which the units
are connected by Cu—0(1 a) (2-jc, -y , 1-z) in-
teractions at 2.967(3) A, and the bonds Cu-0(6)
and Cu—0(1 a) practically colinear. These dis-
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328
K. V. Domasevitch et al. ■The Phenomenon of Intramolecular Attractive S— O Interactions
tances are much longer than the usual values from that of [Cu(Phen){L'}(C104)] (Fig. 1)
and similarly composed copper(II) oximate com-
pounds [Cu(Dipy){0NC(C0NH2)2}Cl]*H20 and
[Cu(dipy){ONC(CN)CSNH2}Br]*2( 1,4-Diox)
studied earlier [8, 9]. Unlike 2, these species have a
square-pyramidal (4+1) coordination geometry. Ap-
parently, the Cu(phen){L2}Cl molecular configura-
tion in this case is strongly affected by steric influ-
ences. Thus, the phenanthroline carbon atom C(13)
for hexacoordinated (4+2 or 4+1 + 1) copper(II)
complexes of a distorted square bipyramidal ge-
ometry [14] and, indicate weak van der Waals
interactions [14]. Thus, the geometry is similar
to that found in complexes with isonitrosoma-
lonodiamide [Cu(Dipy){0NC(C0NH2)2}Cl]*H20
[9] and isonitrosothiocyanoacetamide
[Cu(Dipy){ONC(CN)CSNH2}Br] *2( 1,4-Diox) [8].
Significant deviations of the copper atom from the has a short van der Waals contact with the nitroso
base of the square pyramid towards the apical chlo- oxygen atom, C(13)—0(1) 3.090(3) A (Fig. 3).
rine (0.258(3) A [9]) or bromine (0.35(1) Ä [8])
atoms suggest relatively strong interactions of Cu2+
with the apical ligands Cl or Br [14].
The Cu-N(l) (2.031(2) A), Cu-N(2) (1.994(2) A)
and Cu-N(5) (2.002(2) A) separations are typical
for pentacoordinated copper(II) complexes with ni-
trogen donor ligands [14, 16], the Cu-N(4) distance
of 2.145(2) A is slightly longer. The coordination
around Cu2+ is completed by a chlorine atom at a
distance of 2.3504(9) A.
The shortest intermolecular contact in the struc-
ture (1), N(2)—0(5b) (2-x, \-y , 1-z) at 3.105(5) A
(Fig. 2) possibly reflects very weak hydrogen
bonding.
The molecular structure of
There are two five-membered chelate rings and
[Cu(Phen){L2}C1]*C2H5 0 H (2) and the atom num- the mean planes of phenanthroline and oximic lig-
bering scheme are shown in Fig. 3. Only one close and groups intersect at an angle of 54.7(1)°. In the
contact between neighbouring molecules has been metallocycles the angles N(2)-Cu-N(l) 80.94(9)°
detected, 0(1)—C(21a) (-1+x, y, z) of 3.056(4) A.
This distance may also be attributed to a very weak the data for 1 (Table II) and the isonitrosomalonodi-
and N(4)-Cu-N(5) 79.90(9)°, are consistent with
intermolecular hydrogen bond [15].
amide complex [9]. The hydroxyl hydrogen atom of
the ethanol molecule forms a hydrogen bond with
a chlorine atom (Fij*. 3): Cl—H-0(2) 3.231(8) A,
d(Cl—H) 2.08(7) A and the angle Cl— H-0(2) is
ca. 169(5)°.
The configuration of the oximate anions {L1} and
{L2} and the modes of their coordination are the
most important observations in these structures. As
The copper atom adopts five fold coordina-
tion of a slightly distorted trigonal-bipyramidal
geometry with equatorial chlorine and nitro-
gen N(l), N(4) atoms and axial nitrogens N(2)
and N(5) (Fig. 3). The copper atom deviates
by 0.047(1)
A from the equatorial plane to-
wards N(2). The structure differs essentially
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K. V. Domasevitch et al. ■The Phenomenon of Intramolecular Attractive S— O Interactions
329
Table IV. Geometry of the 2-isonitrosoheteryl derivatives H{ONC(R')(R2)} (H{X}) in the crystal structures.
R 1
Configuration3
R2
Compound
Separations, A
Ref.
S—O
C-Cb
4-Methylthiazol-2-yl CN
H{X}
syn
syn
syn
syn
anti
anti
anti
anti
anti
anti
anti
syn
syn
syn
syn
2.701(6) 1.449(6)
[4]
[2]
[4]
[4]
Tl( 18-crown-6){X}
Pb( 18-crown-6){X}2
Cs( 18-crown-6)2{H(X)2}
Tl( 18-crown-6){H(X)2}
Cs{H(X).}*H?0
H{X}
H{X}
Cs{X}
Tl( 18-crown-6){X}
Ni{H(X)2}(C104)*3H ,0
H{X}
2.69(1)
2.69(1)
2.78(2)
1.442(9)
1.42(2)
1.43(1)
—
—
—
—
—
—
—
Benzothiazol-2-yl
CN
1.446(6) [20]
1.443(8)
1.480(2) [22]
1.474(4) [22]
1.459(4)
[21]
[21]
CN
CN
2-Pyridyl
2-Quinolyl
Z^2-Thiazolin-2-yl
zA2-Thiazolin-2-yl
4-Methylthiazol-2-yl
CN
CONH2
CONH2
1.47(1)
1.485(2)
[4]
[19]
[3]
[18]
This
2.633(2) 1.456(2)
2.477(2) 1.452(3)
2.605(3) 1.437(5)
[Ph4As] {X }*4H20
Cu(Phen){X}(C104)
Cu(Phen){X}Cl*EtOH
4-Methylthiazol-2-yl Benzothiazol-2-yl
2.676(3) 1.436(4) paper
a Configuration of the nitroso group with respect to the R 1 substitute;b bond lengths O N C -Q R 1].
in the isonitrosomalonodiamide derivatives [9, 17], which is significantly less than the standard S—O
the configuration of {L1} is such that the nitroso van der Waals separation (r(0(van der Waals)) 1.5;
nitrogen N (l) and carbonyl oxygen 0(2) atoms
can chelate the metal atom in the ligand plane and
an amide hydrogen atom gives rise to intramolec-
ular hydrogen bond as shown (Fig. 1): N(2)—
N(3) 2.756(5) A, N(2)-H(l) 0.90(5) A, H(l)-~N(3)
2.02(5) A, angle N(2)-H(l)~-N(3) 138(4)°. How-
ever, unlike the symmetrical isonitrosomalonodi-
amide, in the present case two different possibilities
for the ligand chelation are to be expected:
r(S(van der Waals) 1.85 Ä [14]).
The value agrees with those of the {L1} group
and related 2-thiazolyloximes reported earlier [2 - 4,
18] (Table IV). It may be assumed, that the prefer-
able configuration of isonitroso-(4-methylthiazol-2-
yl)(benzothiazol-2-yl)methanide [{L2}] is such that
the nitroso oxygen atom can maintain an effective
contact S6+—O6- with the thiazole sulphur atom,
but not with the benzothiazole one. Therefore, de-
spite the somewhat weaker donor properties of the
benzothiazole nitrogen atom compared with thia-
zole [15], the following chelate coordination mode
is expected,
In the latter configuration steric hindrance may
arise for the 4-methyl group (Fig. 1), however, the
configurations of the non-coordinated oxime H {L '}
[3] and the anion in the tetraphenylarsonium salt
[Ph4As]{L1}*4H20 [18] are the same, suggesting
an important role of intraligand interactions. This
as confirmed by the present study.
In 2 the ambidentate ligand {L2} is coordinated
may be rationalized in terms of a strong attractive via the nitrogen atoms of nitroso [N( 1)] and ben-
zothiazole [N(2)] groups (Fig. 3). Unlike {L1}
sulphur atoms: SÄ+—O6- [1-4]. The separation (Fig. 1), the steric hindrances on both alternative
donor centers are nearly the same (C(6) in the
interaction between the nitroso oxygen and thiazole
S (l)—0(1) in compound 1 is found at 2.605(3) A,
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330
K. V. Domasevitch et al. • The Phenomenon of Intramolecular Attractive S— O Interactions
a-position to N(3) and C(1 l)-to N(2)). For (2) the
intraligand contact S(2)—0(1) is found to be ca.
2.676(3) A.
and C(l)-C(2) of 1.443(4) A and C(l)-C(3) of
1.436(4) A (2) (Table II) are less than the stan-
dard C(sp2)-C(sp2) distance of 1.48 A [14], re-
flecting the conjugation between the appropriate
functional groups. The C(NO)-C(thiazole) as well
as C(NO)-C(benzothiazole) bond lengths agree
with the data reported earlier [ca. 1.44(1)-1.45(1)
A, Table IV] and in each case are slightly less
than the similar parameters in the 2-pyridyl-, 2-
quinolyl and carbamoyloximes. Thus, the C(NO)-
CONHo bond lengths in isonitrosocyanoacetamide
HONC(CN)CONH2 [H(X)] were found to be
The geometrical parameters of the oximate an-
ions {L1}- and {L2}~ allow a direct comparison
with structural analogues reported earlier [3, 9,17-
19]. The anions are actually planar and suggest
the considerable 7r-electron delocalization involv-
ing nitroso, thiazole and carbamoyl (benzothiazole
in {L2}) groups [17]. The dihedral angle between
mean planes of thiazole ring and the exocyclic car-
bamoyloxime fragment in {L1} is 3.6(3)°. In the
anion {L2}~ the corresponding dihedral angle be-
tween mean planes of the thiazole cycle and ben-
zothiazolyloxime fragment is 5.0(2)°.
1.494(7)
A for H(X)*(18-crown-6)*H.O [23];
1.47(1), 1.474(9) A for Ph6Te30 2{X}2 [24] and
the appropriate parameters for isonitrosomalonodi-
amide in the copper(II) complex [9] are 1.469(2)
and 1.486(2) A.
The carbon-carbon separations, C(l)-C(2) of
1.467(4) A and C(l)-C(3) of 1.437(5)
Ä (1)
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