Scientific paper
Anion Change as a Tool for Structure Design: Syntheses and Crystal Structures of Copper(I)
Trifluoracetate and Tetrafluoroborate with 3-[(2-morpholino-4-oxo-4,5-dihydro-1,3-thiazol-5-ylidene)methyl-phenoxy]propene
Evgeny A. Goreshnik,1* Zoran Mazej,1 Volodymyr V. Karpyak2
and Marian G. Mys'kiv2
1 Department of Inorganic Chemistry and Technology, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia 2 Department of Chemistry, Ivan Franko National University, Kyryla & Mefodia, 6, 79005 L'viv, Ukraine * Corresponding author: E-mail: evgeny.goreshnik@ijs.si
Received: 05-02-2008 Dedicated to the memory of Professor Ljubo Golic
Abstract
By alternating-current electrochemical synthesis crystals of two new copper(I) coordination compounds of Cu(CF3COO)Cj7Hj8N2O3S (I) and [Cu(Cj7Hj8N2O3S)2]BF4 (II) composition have been obtained and structurally investigated. In the crystal structure of I the ligand moiety acts as a bridge, being coordinated to one metal center through the C=C-bond of allyl group, and to another Cu atom by nitrogen atom of thiazole ring. Due to such a bridging function dimers of [Cu(CF3COO)Cj7Hj8N2O3S]2 composition appear. The trigonal-planar copper atom coordination sphere includes, besides the nitrogen atom and C=C bond, also one oxygen atom from trifluoroacetate anion. In the structure II two nitrogen atoms from thiazole rings of two ligand moieties form linear surrounding of copper atom resulting in a formation of [Cu(Cj7Hj8N2O3S)2]+ complex cations. The [BF4]- anion is completely disordered. Mentioned dimers in I and complex cations and [BF4]- anions in II are associated by weak interactions only.
Keywords: Copper(I), complex, structure design
1. Introduction
Catalytic properties of the copper(I) halides and a possibility of their olefin n-adducts separation were a basis of the structural chemistry of the copper(I) n-complex-es.1 One may note, that in such adducts halogen atoms occupy usually two or even three places in metal surrounding resulting in polymeric cupro-halide fragments.2' 3' 4 To introduce more active centers of ligand into copper coordination sphere one may use weakly bonded anions such as [ClO4]-' [BF4]- [PFg]-' [CF3COO]-. In copper(I) coordination compounds with such anions, ligand moieties realize fully their coordination abilities and play dominant role in a 3-D network formation.
Recently copper(I) chloride coordination compound with 3-[(2-morpholino-4-oxo-4'5-dihydro-1'3-thiazol-5-
ylidene)methyl-phenoxy]propene has been prepared and structurally investigated.5 In this compound unusual Cu4Cl4 inorganic fragment, included in a formation of complicated organic-inorganic 3-D network, has been found. In order to explore 3-D network formation in cop-per(I) complexes with the same ligand in the presence of weakly bonded anions, compounds Cu(CF3COO) C17H18N2O3S (I) and [Cu(C17H18N2O3S)2]BF4 (II) have been prepared and X-ray structurally investigated.
2. Results and Discussion
In structure I with (CF3COO)- anion the ligand moiety acts as a bridge between two metal centers, being coordinated to one copper atom via n-interaction with
the C16=C17 bond, and to another metal atom via N1 atom of thiazole ring. The major part of the ligand molecule is strictly flat: both benzene and thiazole aromatic rings, as same as non-hydrogen atoms of allyl group and N2 atom of morpholine ring lie in common plane. The CF3COO- anion in I is bound to the only one metal center through the one oxygen atom. Contrary, in earlier studied Cu(CF3COO)(olefin) compounds trifluoracetate-anion acts as a bridge, being connected via both oxygen atoms to two copper(I) cations.6 Due to the above mentioned bridging function of the ligand molecule, dimers of [Cu(CF3COO) L]2 (L = C17H18N2O3S) composition appear. In such dimers two ligand molecules are oriented in "head to tail" mode (Fig. 1). Further association of such dimers is realized by weak interactions (Fig. 2). The copper atom possesses trigonal-planar environment composed of O5 atom of trifluoracetate-anion, N1 atom of thiazole ring of one ligand molecule and the C16=C17-bond of allyl group from another ligand moiety with the Cu-O, Cu-N and Cu-m (m is a mid-point of
C=C-bond) distances of 1.966(4), 1.998(5) and 1.905(7) À, respectively. The deviation of the metal atom and olefin group from the (N1, O5, m) plane does not exceed 0.1 À. Such an orientation of olefin bond in Cu1 coordination sphere is favoured for effective copper-olefin interaction.
As it follows from the Dewar-Chatt-Dunkanson concept in olefin copper(I) complexes, the n-bond consists of two components: the (Cu(I)^L)^ donor-acceptor component, arising from overlapping of the occupied olefinic np orbital and the unoccupied 4s0 orbital of Cu(I) atom, and the (Cu(I)^L)n -dative component, formed upon electron-density drawing-off from the 3d10 copper(I) orbitals to the unoccupied antibonding orbital of the C=C-group.7 For a numerical characterization of copper-olefin interaction effectiveness C-Cu-C angle provides the most
Figure 1. [Cu(CF3COO)(Cj7Hj8N2O3S)]2 dimers in structure of I.
suitable parameter being dependent on both C=C-bond elongation and Cu-(C=C) distance shortening. The (Cu(I)^L)^ donor-acceptor component, less sensitive to the olefinic bond orientation, causes at first shortening of the Cu-m (m - a middle of C=C bond) distance, whereas the (Cu(I)^L)n -dative component, being strongly dependent on a proper olefinic group orientation in the met-
Figure 2. Packing diagram of Cu(Cj7Hj8N2O3S)(CF3COO).
al coordination sphere, causes a lengthening of the C=C-bond. Therefore, both components cause an increasing of C-Cu-C angle. In the structure of compound I, in addition to rather short Cu-m distance one may note that C=C double bond, coordinated to the Cu metal atom, is noticeably elongated to 1.385(9) À in comparison to the value of 1.33 À in free olefins.8 The C-Cu-C angle appears to be equal to 39.9(3)°, which is one of the highest values observed in copper(I) n-complexes. One may conclude that copper-C=C n-interaction in I appears to be rather effective.
In structure II with BF4- copper atom is bound to two nitrogen atoms of tiazole rings of two ligand molecules resulting in a formation of centrosymmetric [CuL2]+ complex cation (Fig. 3). Because of the lower coordination number of the metal atom than that in I the Cu-N distances are shortened to 1.88(3) À. Similar copper(I) coordination was found recently in the crystal structure of bis(2-methylbenzimidazole-copper(I) dichlorocupra-
action in I allows the metal center coordination with two ligand molecules. The presence of weakly bonded BF4-anion in II makes the copper cation practically "naked" and, in turn, resulting in a low copper coordination number 2. Contrary to earlier studied Cu4Cl4(C17H18N2O3S)2 compound anions in I and II do not participate in association of building blocks.
4. Experimental Section
4. 1. Synthesis of Ligand
3-[(2-morpholino-4-oxo-4,5-dihydro-1,3-thiazol-5-ylidene)methyl-phenoxy] propene was obtained by re-fluxing of a mixture of 4-allyloxybenzalrhodanine and morpholine in ethanol (2 h), followed by cooling to a room temperature and recrystallization from ethanol. Measured melting point of synthesized ligand equals to 213-214 °C.
C17

03
I C15
/


I
C5V' N /
C4 ;
/ C9 _
'C8

Figure 3. [Cu(Cj7Hj8N2O3S)2]+ cations in structure of [Cu(Cj7Hj8N203S)2]BF4.
V/
M
V, /
/
/ 1
s.
te(I).10 BF4 unit is found on site symmetry inconsistent 4. 2. Synthesis of I and II Compounds with its own, e.g. tetrahedral molecule on an inversion center, so that alternate orientation is generated by a symmetry operation. This positional disorder could be roughly described by pseudo-octahedral model with the occupancy of 0.67 for each F atom. Since the crystal structure of II is of a layer type, epitaxial twinning of crystals could be possible reason for low quality of structural investigation.
3. Conclusions
Two new copper(I) coordination compounds with 3-[(2-morpholino-4-oxo-4,5-dihydro-1,3-thiazol-5-yli-dene)methyl-phenoxy]propene were synthesized and X-ray structurally investigated. Weak Cu+ - CF3C00- inter-
Good quality crystals of I were obtained using the alternating-current electrochemical technique starting from ethanol solution containing copper(II) trifluorac-etate and a ligand.11 Because of low ligand solubility the reaction was performed at 50 °C. The starting mixture was placed into a small test-tube and heated to dissolve a ligand. After that copper-wire electrodes in cork were inserted, and alternating current of 0.30 V tension (frequency 50 Hz) was applied. After heating at 50 °C during 9 h with a reflux condenser, the reactor was allowed to stand at 20 °C (under the tension) for a few days. Orange crystals of the title compound appeared on copper electrodes. The density of I, measured by flotation method in chloroform-bromoform mixture, was found to be 1.7 g cm-3.
Table 1 Details of experimental and crystallographic data for I and II compounds
Compound	I	II
Empirical formula	C19H18CuF6N2O5S	C34H36BCuF4N4O6S,
Formula weight	506.95	811.14
Crystal size, mm	0.2 X 0.15 X 0.1	0.08 X 0.03 X 0.02
Temperature, K	293	293
Radiation	MoKa	MoKa
Color, shape	Orange prism	Colourless needle
sp. gr.	P1	P1
Unit cell dimentions		
a, À	7.2458(18)	8.227 (15)
b, À	9.549 (2)	10.055 (17)
c, À	15.255 (4)	10.894 (19)
a, °	90.140 (3)	91.991 (17)
ß, °	99.173 (2)	97.77 (2)
Y, °	109.24 (3)	97.13 (2)
y, À3	982.1 (4)	885 (3)
Z	2	1
Dc g/cm3	1.714	1.521
Dmmg/cm3	1.7	1.5
mm 1	1.28	0.81
F(000)	516	418
Scan range 0, °	2.57,29.21	1.89-27.5
Measured reflections	5353	1275
Used (I > 2a(I))	2730	901
Parameters refined	280	158
R (F)	0.071	0.145
R (F)^; F > 4a(F)	0.188	0.327
Goodness-of-fit	1.05	1.29
Similar synthetic route, using Cu(BF4)26H2O as a starting copper(II) salt, produces crystals II. Their density equals to 1.5 g cm-3.
4. 3. Crystallography
Single-crystal data were collected on a Rigaku AFC7 diffractometer equipped by Mercury CCD area detector using graphite monochromatized MoKa radiation. Data treatments were performed using Rigaku Cry-stalClear software suite program package.12 All structures were solved by direct methods using SIR-92 program,13 implemented in teXan crystallographic software package of Molecular Structure Corporation,14 and refined with
SHELXL-97 software,15 implemented in program package WinGX.16 The figures were prepared using DIAMOND 3.1 software.17
5. Acknowledgement
E. G., Z. M. and M. M. thanks to Slovenian Research Agency (ARRS) and Ukrainian Ministry for Science and Higher Education for financial support (bilateral project BI-UA/07-08-003' M/107-2007)
6. References
1.	M. Herberhold. Metal n-Complexes Elsevier, Amsterdam. 1972.
2.	E. A. Goreshnik, M. G. Mys'kiv. Polish J. Chem. 1999, 73, 1245-1252.
3.	E. A. Goreshnik, D. Schollmeyer, M.G. Myskiv. Z. anorg. allg. Chem. 2002, 628, 2118-2122.
4.	E. A. Goreshnik, L. Z. Ciunik, Yu. K. Gorelenko, M. G. Mys'kiv. Z. anorg. allg. Chem. 2004, 630, 2743-2748.
5.	E. Goreshnik, V. Karpyak, M. Mys'kiv. Acta Cryst. 2005, C 61, m390-m392.
6.	G. Pampaloni, R. Peloso, C. Graiff, A. Tiripicchio. Organo-metallics 2005, 24, 4475-4482.
7.	A. K. Barnard. Theoretical Bases of Inorganic Chemistry, New-York, McGraw-Hill, 1965.
8.	H. V. R. Dias, J. Wu. Eur. J. Inorg. Chem. 2008, 509-522.
9.	E. Goreshnik, D. Schollmeyer, M. Mys'kiv. Acta Cryst. 2004, E 60, m279-m281.
10.	B. M. Mykhalichko M.G. Mys'kiv 1998. Ukrainian Patent UA 25450A, Bull. No. 6.
11.	CrystalClear: Rigaku Corporation, The Woodlands, Texas, USA, 1999.
12.	A. Altomare, M. Cascarano, M., C. Giacovazzo, A. Guagliar-di, J. Appl. Cryst. 1993, 26, 343.
13.TeXan	for Windows, version 1.06: Crystal Structure Analysis, Package, Molecular Structure Corporation, (1997-9).
14.	G. M. Scheldrick, SHELXL-97, University of Göttingen, Germany, 1997.
15.	L. J. Farrugia. J. Appl. Cryst. 1999, 32, 837-838.
16.	DIAMOND v3.1. 2004-2005 Crystal Impact GbR, Bonn, Germany
Povzetek
Dve novi bakrovi(I) koordinacijski spojini sta bili sintetizirani z elektrokemijskim postopkom: Cu(CF3COO) • C17H18N2O3S (I) in [Cu(C17H18N2O3S)2]BF4 (II). V spojini (I) mostovni ligand povezuje preko C=C-vezi alilne skupine in dušikovega atoma tiazolnega obroča dva kovinska centra. Tvorijo se dimeri (CF3COO) • C17H18N2O3S]2. V spojini (II) dva dušikova atoma dveh tiazolnih obročev tvorijo linearno okolico bakrovemu ionu in nastane [Cu(C17H18N2O3S)2]+ kompleksni kation. Anion [BF4]-je v neurejenem stanju.