Structural Analysis of Powder Complex of Tris ( 1 , 10-phenanthroline ) copper ( II ) Trifluoromethane Sulfonate Dihydrate

The powder complex of tris(phenanthroline) copper(II) trifluoromethanesulfonate dihydrate has been synthesized by direct interaction of the corresponding precursors, copper(II) nitrate, phenanthroline, and potassium triflate. The metal content found to be 6.76% corresponds to the theoretical value of 6.77% in [Cu(phen) 3 ](CF 3 SO 3 ) 2 .2H 2 O. The equivalent electrical conductance producing the charge ratio of cation by anion to be 2: 1, should confirm the formula. The magnetic moment, μ eff , of this complex which was to be 1.85-1.90 B.M, indicates that the complex is paramagnetic corresponding to spin-only value for one unpaired electron. UV-Vis spectrum of the complex reveals the only one broad absorption observed at about 681.50 nm (14673.51 cm-1), being associated with the spin allowed transition, Eg → 2T 2g . The extinction coefficient of 48 Lmol1 cm-1 indicates the adoption of octahedral environment in this complex. The infrared spectrum shows absorptions of ligand group which is influenced by the metal-ligand interaction in this complex. The powder XRD of this complex was refined by Le Bail method of Rietica program and found to be fit as triclinic symmetry of space group P1.


INTRODUCTION
The synthesis and characterisation of complexes containing transition metals with phenanthroline (phen) as ligand and various common counter ions such as NO 3 -, BF 4 -, ClO 4 -, PF 6 have been reported long time ago, e.g.Ito et al., 1 Triflate salts were already known as highly ionic since the corresponding acid might be considered as super-acid which is much stronger than sulphuric acid, being Hammett acidity to be -12, e.g.Raamata et al., and Howells and Mc Cown [2][3] .Triflate ionic liquids are hydrolytically stable and in many cases they are the preferred reaction media in comparison to ionic liquids with the hydrolytically unstable (PF 6 ) − or (BF 4 ) − anions 4 .
In the case of copper(II) complex with phenanthroline ligand and triflate anion, the single crystals of six-coordinated site 5 of [Cu(phen) 3 ] [CF 3 SO 3 ] 2 .H 2 O and five-coordinated site 6 of [Cu(phen) 2 OH 2 ][CF 3 SO 3 ] 2 have been analysed.For the two complexes, the triflate anion were found to be uncoordinated to the central atom, Cu(II).The structural cationic complex of the trisphenanthroline, [Cu(phen) 3 ] 2+ , with diferent counter anions (X) have also been solved through a number of other corresponding single crystals, these are for X = (ClO 4 ) 2 7 , S 4 O 6 .5H 2 O 8 , and (TCNQ) 2 9 .It was not surprisingly found that the corresponding tris(phenanthroline)copper(II) cation adopted different space group, triclinic or monoclinic, with various cell parameters.
No electrical, electronic spectral and magnetic data have been reported at least for the tris(phenantroline) copper(II) triflate.Moreover, the determination of lattice parameters for the powder coordination compounds by XRD has been very little attention up to now, but abundantly for the metal oxides.For those reasons, the powder complex has been prepared, the corresponding cell parameters were analysed following PXRD, and this is the main purpose of this work.

Preparation of tris(phenanthroline)copper(II) triflate
About 10 mL of an aqueous solution of 0.1 mmol Cu(NO 3 ) 2 and 5 mL solution of 0.32 mmol phenanthroline in water (with drops of ethanol to disolve) were mixed.The mixture was well stirred and heated to obtain a homogeneous solution.To this solution, an excess of saturated aqueous solution of KCF 3 SO 3 (0.4 mmol in 5 mL of water) was added.The mixture was concentrated on warming, and the obtained powder on cooling was then filtered, rinsed with a minimum of cold water, and then dried in aeration.

Instruments
Magnetism.The magnetic data for solid sample were obtained only at room temperature by using Magnetic Susceptibility Balance (MSB) of Auto Sherwood Scientific 10169 model, calibrated with CuSO 4 .5H 2 O.The molar magnetic susceptibility data were then corrected for diamagnetism calculated using Pascal's constant 10 .The corresponding effective magnetic moment (μ eff ) was then calculated from the corrected molar magnetic susceptibility following the general formula, μ eff = 2.828 √(χ M .T) BM.

Electronic and Infrared Spectra.
The electronic spectrum of the solid sample was recorded on Pharmaspec UV 1700 Spectro-photometer.Whereas in solution it was recorded on Spektrofotometer UV-Vis Shimadzu 2400 PC Series.The powders were spread on a 2x2 cm particular thin glass adhered with ethanol.The fitting was then placed in the cell holder and the spectrum was recorded at 400-1000 nm.The infrared spectrum of the powdered sample which were pressed on the cell was recorded on an infrared spectrophotometer FTIR Shimadzu Prestige 21 at 500 -4000 cm -1 .

Metal Content and Ionic Property.
The metal content in the sample was calculated based on the data recorded using an Atomic Absorption Spectrophotometer of Shimadzu AA-6650 model.While the ionic property was estimated by recording the electrical (equivalent) conductance by using a conductometer calibrated with an aqueous solution of 1 M potassium chloride at 25 0 .The obtained data of sample was compared to those of known ionic solutions, NH 4 Cl, CaCl 2 , Ni(NO 3 ) 2 , and AlCl 3 , which were also recorded with the same conductometer.

Powder X-Ray Diffraction
The diffractogram of the complex was recorded on a Rigaku Miniflex Benchtop Diffractometer, CuK á : λ=1.5406Å.The powdered sample was spread on the glass plate and then was placed on the cell holder.The reflection data were recorded in scan mode at 2-90 degree of 2θ with interval of 0.02 and rate of 10.The resulting diffractogram was then analysed by Rietica program of Le Bail method at 5-60 degree of 2θ, which was run within 30 cycles.

Chemical formula of the complex
Phenanthroline is generally known as stable compound when complexation in various solvents, and thus no decomposition to others is expected.Therefore, direct interactions of phenanthroline and copper(II) salt in solution should produce the blue cationic phenanthroline complex which could be precipitated on the addition of triflate salt.The electrical conductance of this complex was recorded with respect to the known ionic simple compounds in aqueous solution, and the result is shown in Table .1.It suggests that the corresponding value is very close to the range of those containing three ions per molecule, and thus the possible empirical formula of Cu(phen) n (CF 3 SO 3 ) 2 .xH 2 O was then proposed for this powdered complex.
Metal content obtained from atomic absorption spectral data (6.76%)suggests that the number of phenanthroline molecules, n, and the number of hydrates, x, could then be estimated, and the formula of Cu(phen) 3 (CF 3 SO 3 ) 2 .2H 2 O as in Table 2, might satisfy as expected from the stoichiometric preparation.The conductivity data of this complex confirms the highly ionic property of the triflate salts 2,4,11 .

The magnetic moment
The magnetic susceptibility data obtained on the measurement (Table .3)were then calculated to the magnetic moment based on the estimated formula as in Table 2, and the result of the three samples separatedly preparared in fact to be paramagnet, 1.85-1.90BM.It is a slightly higher than the spin-only value for the one unpaired electron in the d 9 electrons of Cu(II), as also observed in the corresponding hexafluoro-phosphate, 1.85 BM, which was reported to obey the Curie-Weiss law 12 .

The electronic spectrum
The electronic spectrum of the complex in solution was recorded at 400-1000 nm and shown in Fig. 1 (inset) together with that of starting material, the copper(II) nitrate (1a).It reveals clearly that the main band was definitely shifted to higher energy (about 14673 cm -1 ) in the phenantroline-copper(II) complex (1b) from the lower energy (about 12000 cm -1 ) in the starting material.This indicates that the phenanthroline has replaced the aqueouscopper(II) resulting in a stronger ligand field band.The extinction coefficient of about 48,1 L mol -1 cm -1 suggests the octahedral environment of central atom, and therefore, the band might be attributed to the spin allowed transition 2 E g → 2 T 2g in copper(II).This band is quite comparable to the corresponding perchlorate 13 , 14815 cm -1 .This reflects the presence of ligand field strength of phenanthroline surrounding Cu(II) metal ion, and thus supports the formula proposed.
In powder (Fig. 1c) the spectrum shows clearly a more asymmetric shoulder band that is likely split into two bands concentrated at about 14085 cm -1 and at 15380 cm -1 , indicating a strongly octahedral distortion, being associated with Jahn-Teller effect.The distorted octahedral configuration is so common in copper(II) complexes as reported from single crystal sructure of the corresponding perchlorate 7 , the hexafluorophosphate 12 , and of the triscyanomethanide 14 .The infrared spectrum In general, the spectral shape of the phen and bipy complexes is quite similar 14 .Thus, the effect of chelation has been reported to shift the absorption bands of the functional group in the two ligands [15][16] .In this work as shown in Fig. 2, the infrared spectrum of this complex recorded at 500-4000 cm -1 reveals the ring modes (ν C-C and ν C-N ) of phen at about 3067, 2299-1925, 1510, 1427, 1350 and 1215 cm -1 , and the ring deformation near 725 cm -1 , being quite similar to those observed in chelation of another Cu(II)-phen complex 16 .
In the case of triflate ion, the infrared of some metallic triflate salts are used as comparison 15,18 , and therefore, the corresponding infrared spectrum can be readily assigned.The modes of vibrations observed at 1280 and 1149 cm -1 are to be SO 3 and CF 3 asymmetric stretching modes, respectively, while those at 1030 and 1225 cm -1 are SO 3 and CF 3 symmetric stretching modes, respectively.The bands at 780 and 636 cm -1 are likely deformation symmetry of CF 3 and SO 3 , respectively, and the bands at 580 and 517 cm -1 are deformation asymmetry of CF 3 and of SO 3 , repectively.Therefore, the infrared data strongly suggest that the complex sample should contain the chelation of phen to copper(II) and free triflate anion.
The occurence of lattice water is likely indicated in the spectrum 19 .Thus, the mode observed at about 1624 cm -1 in the spectrum might be due to free molecule of (bending) H 2 O 5 as also proposed by Sinha 15 .Moreover, broad absorption at about 3500-3600 cm -1 should be clearly due to symmetric-antisymetric streching mode of -OH of H 2 O 5,19 .The powder X-Ray diffaction and structural analysis The single crystals of cation [Cu(phen) 3 ] 2+ with some particular anions have been reported 5,[7][8][9]12,14 . The ttrathionate pentadydrate 8 adpots triclinic symmetry of the space group, P1, and similarly for the tetracyanoquinodimethanide monoethanol 9 .Both of them, however, show much different in the cell parameters (Table 3). Wile for the tricyanomethanide 14 and the perchlorate 7 , they are monoclinic symmetry but with different space group of P 21 /n for the former and of C2/c(15) for the latter.Again the cell parameters are quite different between the two.For the hexafluorophosphate 12 , it is also monoclinic of space group C2/c but with much longer in a direction compared to the perchlorate, resulting in much bigger in volume of the cell. Aother single crystal of the triflate monohydrate 5 ,[Cu(phen) 3 ](CF 3 SO 3 ) 2 .H 2 O, in fact has also been reported and it was found to be triclinic system of the space group, P1.The cell parameters are quite similar to the corresponding tetrathionate pentahydrate.The cationic complex with those various counter anions confirm that the tris-chelate phenantroline ligands were coordinated to the metal atom.It has been reported that two single crystals of another complexes, [Cu(bipy) 3 ] (ClO 4 ) 2 have been separately produced 13,20 to have significantly difference in cell parameters, though they are the same symmetry and space group.
From those facts, the powder X-ray diffraction of [Cu(phen) 3 ](CF 3 SO 3 ) 2 •2H 2 O was then recorded, and the diffractogram together with its refinement following Le Bail method of Rietica program is shown in Figure 3.The black signs (+) represent the observed experimental data, the red full line is the refinement at 5-55 degree of 2 theta for the expected model of triclinic symmetry of space group P1 which are the blue bar-lines, and the green curve indicates the difference between the observed diffractogram and the analysis result.It is clear that the red full line does almost pass through the black observed data, and it is demonstrated by the almost flat green curve, indicating that the corresponding analysis might be considered very good with the Goodness of Fitting (GOF) to be 28.58 and derived Bragg R-Factor of 0.03.Detailed results of cell parameters of the crystal structure are presented in Table 4 together with the known single crystal data of the same cation of those anions discussed.
It has been stated that the application of Rietica program has not been performed to many powdered complexes.The first fitting might come from Zhu, Wu, and Le Bail himself 21 (1999) who demonstrated the fitting for powdered of cobalt complex containing monodentate of ammine.It resulted in very low R factors, being 0.053 for R Bragg , 0.1 for R p , 0.119 for R wp and 0.04 for R exp leading to 8.85 for X 2 (GOF).The next application was performed on powdered complexes containing bipy partially 22 in 2008 with reasonably good fittings resulted in derived Bragg R-factors of 0.0048-0.0128and X 2 of 1.9-9.75.The application of Le Bail method was also performed on oxcalate complexes 23 in 2009, and in fact resulting in much high values of R factors, being 16.4-17.9for R p , 13.3-13.58for R wp and high values of 279.36-290 for (R wp /R exp ) 2 or X 2 .Recently 24 , Sugiyarto et al. (2017) reported the powder XRD for the complex of [Mn(phen) 3 ](CF 3 SO 3 ) 2 .6.5H 2 O, with the R values of 3.67 (R p ), 7.34 (R wp ) and 3.61(R exp ) leading to X 2 value of 4.13, and 0.16 (R Bragg ).Concerning how low of R factors, "How good is good enough" of the fitting 25 is in fact still not so easy to conclude as discussed by Toby (2006).Quite recently 26 , Kusumawardani et al., (2017) reported the powder XRD for the complex of Cu(bipy) 3 (CF 3 SO 3 ) 2 .(0.5-1) H 2 O, with the R values of 5.50 (R p ), 9.94 (R wp ) and 2.68 (R exp ) leading to X 2 of 13.72, and 0.02 (R Bragg ).From those reasons, there is no doubt that the complex in this work might be considered to adopt triclinic symmetry of the space group, P1, with the R's values of being reasonably low.(e) 14 (f) 7 (g)

REFERENCES
In principle, it is possible and promising to draw the molecular structure of the (cationic) complex based on the hkl produced by the fitting, however, it is still very hard struggling

CONCLUSION
The powder complex of [Cu(phen) 3 ] (CF 3 SO 3 ) 2 •2H 2 O has been synthesized.The magnetic moment was found to be 1.85-1.90BM, being normal paramagnet for an unpaired electron of Cu(II).In solution the electronic spectral property show a slight asymmetry band concentrated at about 14673 cm -1 , but in the powder it reveals an asymmetry shoulder band concentrated at about 14085 cm -1 and 15380 cm -1 which is attributed to the spin allowed transition, 2 E → 2 T 2 .The infrared spectrum of the complex shows the typical vibrations of the functional groups of phen and the corresponding uncoordinated triflate anion.The Powder X-Ray Diffraction analysed by Rietica program of Le Bail method suggests that the complex adopts triclinic symmetry of space group P1 with the derived Bragg R-factor, 0.03.