EPR of Powder Copper Phthalocyaninate Substituted with Eight Tetraazamacrocycles and its Nonanuclear Ni2+, Co2+, Zn2+ and Cu2+ Complexes{ Fevzi Ko ¡ì ksal,a Fatih Ucun,a Erbil AgI ar*b and I . brahim Kartala aDepartment of Physics, Faculty of Arts and Sciences, OndokuzMayis University, Samsun,Turkey bDepartment of Chemistry, Faculty of Arts and Sciences, OndokuzMayis University, Samsun,Turkey Variations of the electron paramagnetic resonance parameters of the copper phthalocyaninates due to the paramagnetic and diamagnetic metal ions substituted into the outer cells of eight 12-membered tetraazamacrocycles are found to be very slight and this slight difference is attributed to the electronegativity of the substitutedmetal.Electron paramagnetic resonance (EPR) spectra of the copper phthalocyanine (CuPc) have been studied pre- viously.1¡¾3 However, so far, Cu2+ phthalocyaninate sub- stituted with eight 12-membered tetraazamacrocycles and its nonanuclear Ni2+, Co2+, Zn2+ and Cu2+ complexes have not been studied.It is the purpose of this study to investi- gate the EPR parameters of these complexes. The cells and the synthesis of the complexes shown in Fig. 1 are given in an earlier study.4 The energy level picture of the CuPc5 is shown in Fig. 2. According to this orbital picture, the unpaired electron of the Cu2+ ion of CuPc is in the antibonding dx2¢§y2 orbital. If a is the coe.cient of dx2¢§y2 in the antibonding orbital and l is the spin¡¾orbit coupling constant for a 3d electron, the Ak and A? components of the hyper¢çne structure constant are given as:5 Ak a P 4 7 a2 ¢§ Ogk ¢§ 2U ¢§ 3 7 Og? ¢§ 2U a K A? a P 2 7 a2 a 11 14 Og? ¢§ 2U ¢§ K O1U where K is the Fermi contact parameter describing the s-electron e€ect on the Cu nucleus and P =2bgNbNhr¢§3i is the dipolar hyper¢çne coupling parameter of the unpaired electron (P = 0.036 cm¢§1).In this study, assuming both Ak and A? are negative and assuming P = 0.036 cm¢§1 5,6 and the experimental gk, g? values, we obtained the K and a2 values from eqn.(1). Figure 3 shows the EPR spectrum of CuPc with eight 12-membered tetraazamacrocycles that are devoid of metal ions; the spectra in the presence of various paramagnetic and diamagnetic ions in the centres of the outer cells (Fig. 1) are similar to this. The upper spectrum is a simulation of the lower one. The spectra are axially symmetric and exhibit the nine superhyper¢çne structure lines from the four nearest N nuclei with an approximate intensity distribution of 1:4:10:16::19:16:10:4:1.The superhyper¢çne coupling con- stant of N is approximately 16 G. The CuPcCu8 sample gives only one EPR line, g= 2.146, without hyper¢çne and J. Chem. Research (S), 1998, 96¡¾97$ Fig. 1 NonanuclearM2+ complexes of copper phthalocyaninate substitutedwith eight tetraazamacrocycles Fig. 2 Bonding picture of CuPc $This is a Short Paper as de¢çned in the Instructions for Authors, Section 5.0 [see J.Chem. Research (S), 1998, Issue 1]; there is there- fore no corresponding material in J. Chem. Research (M). *To receive any correspondence. 96 J. CHEM. RESEARCH (S), 1998superhyper®ne lines and has a width of 0200 G. The line- width does not change very much with decreasing tempera- ture (down to 113 K) and should be the result of the dipolar and exchange interactions between the copper ions. Neimann and Kivelson7 have shown that even in the presence of only diamagnetic metal ions the Pc complexes exhibit a strong characteristic EPR line, which they attributed to a free radical.We have also observed this line for all of our samples and it is indicated with an arrow in Fig. 3. The g value of this line is g32.0037 and is in complete agreement with that of the literature.7 The EPR parameters were obtained by simulating the spectra with the Bruker Win-EPR program. The results for the various copper phthalocyaninates are given in Table 1.As seen from Table 1, the hyper®ne coupling (a) values decrease slightly as the substituted ion is varied, in the order f, Zn, Co and Ni. This order is the same as the electro- negativity order Cu (1.9) >Co3Ni (1.8) >jn (1.6) > f. The numbers in parentheses are the electronegativities of the elements.8 Therefore, it may be stated that the ions in the outer cells of the CuPcs in this study attract the central unpaired electron according to their electronegativity. Within the limits of the experimental errors, the values of g in Table 1 do not appear to vary.The calculated results of K and a2 values given in Table 2 seem to support the above conclusion since they decrease as the electronegativity increases, indicating an increase in the covalent character of the unpaired electron. Experimental The spectra were recorded at room temperature with a Varian E-109C model EPR spectrometer using 100 kHz modulation.The modulation amplitude was 0.6 G and the microwave power was around 2 mW. The low temperature measurements were made using a Varian temperature controller. The g factors were determined by comparison with a diphenylpicrylhydrazyl sample of g =2.0036. Received, 21st April 1997; Accepted, 22nd October 1997 Paper E/7/02705B References 1 E. M. Roberts and W. S. Koski, J. Am. Chem. Soc., 1961, 83, 1865. 2 M. Abkowitz, I. Chen and J. H. Sharp, J. Chem. Phys., 1967, 48, 4561. 3 S. E. Harrison and J. M. Assour, J. Chem. Phys., 1964, 40, 365. 4 E. Ag Ï ar, B. Bat , E. Erdem and M. O È zdemir, J. Chem. Res. (S), 1995, 16. 5 T. F. Gibson, D. J. E. Ingram and D. Scholand, Discuss. Faraday Soc., 1958, 26, 72. 6 J. M. Assour, J. Chem. Phys., 1965, 43, 2477. 7 R. Neimann and D. Kivelson, J. Chem. Phys., 1961, 35, 162. 8 L. Pauling, 1960, The Nature of the Chemical Bond, Cornell University Press. Table 1 The experimental EPR parameters of powder copper phthalocyaninate substitutedwith eight tetraazamacrocycles and its nonanuclear Zn2+, Co2+, Ni2+ and Cu2+ complexes (Dg = 0.002, Da = 0.4G) Acronym M' gk g? Ak/G A?/G g aG CuPc(f) f 2.154 2.052 212.0 17.0 2.086 82.0 CuPcZn8 Zn 2.152 2.053 209.3 16.8 2.086 81.0 CuPcCo8 Co 2.148 2.052 209.3 16.0 2.084 80.4 CuPcNi8 Ni 2.148 2.052 209.3 16.0 2.084 80.4 CuPcCu8 Cu ^ ^ ^ ^ 2.146 ^ Table 2 The calculated EPR parameters of powder copper phthalocyaninate substituted with eight tetraazamacrocycles and its nonanuclear Zn2+, Co2+ and Ni2+ complexes Complex K a2 CuPc(f) 0.314 0.797 CuPcZn8 0.311 0.785 CuPcCo8 0.308 0.781 CuPcNi8 0.308 0.781 Fig. 3 EPR spectrumof CuPcwith empty outer cells at room temperature; the upper spectrumis a simulation of the lower using the BrukerWin-EPR program J. CHEM. RESEARCH (S), 1998 97