Preparation and Characterization of some Transition Metal Complexes with Two Mixed Ligands Macrocyclic and Ligands PPh3

A new ligand (3,4,6,14,15,17,23,24-octaazatricyclo [17.3.1.1 8 ,12] tetracosa-1(23),8(24),9,11, 19, 21hexaene 2,5,7,13,16,18 – hexaone), (CHT) was been prepared from the reaction of pyridine-2,6-dicarboxylic acid with semicarbazide using microwave irradiation in solid state. The ligand is reacted with some transition metal(II) ions to form complexes of the type [Co(CHT)]Cl2, [Fe(CHT) Cl]Cl and [M(CHT)Cl2] where (M=Mn(II), Ni(II), Cu(II) and Zn(II)). Complexes of the type [Ni(CHT)(PPh3)]Cl2 and [M(CHT)(PPh3)Cl]Cl where (M=Mn(II), Fe(II), Co(II), Cu(II) and Zn(II)), were prepared by the reaction of the above complexes with triphenylphosphine(PPh3) in a 1:1 molar ratio. All the complexes were characterized by (C,H,N) analysis, metal content analysis, molar conductance, magnetic moment measurements, electronic and IR spectroscopy, as well as the ligand was characterized by 1 H , 13 C -NMR. The electronic spectra and magnetic measurements indicate that the complexes have octahedral environment around the metal ions, except cobalt complex have square planer geometry.


INTRODUCTION
Macrocyclic compounds received much attention by many author's Robson macrocyclic (Lever, 1970;Dawood et al., 2013;Xiaoqi et al., 2018;Al-Daher et al., 2018). Owing to their metal coordinating properties, metal ions are able in several favorable cases, to organize reacting molecular fragments according to specific geometry and drive the reaction toward the formation of cyclic compound. Transition metal macrocyclic compound have an active part of metalloenzymes as bionomic model compounds due to their resemblance with natural proteins like hemerythrin and enzymes (Zhang et al., 2012).
Poly aza macrocyclic compounds modified with tetraamide and hexaamide function a cyclic tetra peptide moieties in capsulate bind metal ions without deprotonation process of the amide group and are capable to stabilize even the low oxidation states of the metal ions (Kantekin et al., 2010). On other hand not only the above macro molecules ligands form complexes with transition metals but also they were mixed with the phosphine. Macrocyclic phosphine hold promise as incredibly stable ligands for applications requiring robust complexes such as radio active transition metal complexes for use as radiopharmaceuticals. Because of this possibility, these ligand and their complexes have been synthetic targets since soon after the macrocyclic effect was discovered (Rajesh et al., 2012).
Microwave techniques for preparation of organic substances have received a great deal of attention due to their various advantages such as selectivity, rapid and direct controllable internal reactions. This technique has been used to prepare an eighteen member ring ligand and it's reaction with transition metal ion's to form a new complexes of different geometries (Lever et al., 1970).
In view of these interesting results and as continuation of our studies on transition metal complexes with macrocyclic ligand (Dawood, 2010;Dawood et al., 2011;Dawood et al ., 2012), we have prepared new types of complexes containing different donor atoms using microwave technique.

Materials and Methods
All chemicals used as supplied from BDH and Fluka companies. IR spectra were recorded on a Fourier-Transform (FT.IR) Spectrophotometer Tensor 27 Co. Brucker in the range (400 -4000 cm -1 ) using KBr discs. The CHN analysis carried out by (Euro Vactor Model E A 3000( in AL-Albeit University -Jordan. element analysis of the ligand and its complexes (PYE UNICAM SP9-Atomic Absorption Spectrophotometer) at the Department of Biology, Mosul University. Conductivity measurements were carried out on 10 -3 M solution of the complexes in DMSO using (Conductivity Meter Model PCM3-JENWAY), electronic spectra were recorded on (Shimadzu-UV-Visible recording, UV-1650PC-spectrophotometer), using 10 -3 M of the complexes in DMSO. The magnetic susceptibility were measured at 25 °C by Farady's method using Bruker BM6 instrument. 1 H-NMR and 13 C-NMR were carried out by(BRUKER 300 MHz (Switzerland )) and shimadzu QP 5050 A(JAPAN) at Al-Albeit University -Jordan. The ligands prepared in solid state using microwave oven type morph Richards EM 820 CPT. Melting points of all compounds were measured using electro thermal 9300 engineering apparatus and were uncorrected.

Preparation of the Ligand (CHT):
The ligand (CHT), (Scheme 1), Fig. (1), has been synthesized according to the following equation in below and procedure (Neerja et al., 2010). A solid pyridine-2,6-dicarboxylic acid (3.34 g, 0.002 mol) was mixed with solid (0.15 g, 0.002 mol) semicarbazide and (0.005 g, 0.0001mol) of cerium ammonium nitrate (CAN) as a catalyst. The solid mixture was irradiated using a microwave 800 W for 10 minutes. The mixture cooled at room temperature, then ethyl acetate (20 ml) was added and the mixture stirred for about 1hr to dissolve the CAN which separated from the mixture by filtration, the gray precipitate was washed with n-hexane, ethanol and dried under vacuum for several hours. The physical properties are listed in (Table 1).

RESULTS AND DISCUSSION
Microwave irradiation of a mixture of the semicarbazid, dicarboxylic acid and CAN catalyst afforded the ligand (CHT) in 90% Yield, which is stable in air, non-hydroscopic at room temperature. C.H.N analyses, melting point, and other physical properties for the ligand are listed in (Table 1). The complexes and the mixed ligand complexes are stable ,non-hydroscopic and have high melting points , the physical properties are listed in (Table 1).
The IR spectrum data of (CHT). Table (4) exhibited absorption frequencies assignable to ( N -H ) stretching as a strong band at (3250 cm -1 ), δ)(N-H) appears at (1306 cm -1 ), ( N-N) stretching vibration appears at (1001 cm -1 ), and the frequency assignable to (C=O) band at ( 1708 cm -1 ) as medium intensity (Nakamoto, 1997). The IR spectrum characteristic to (N-N), (CO -NH-CO) and (C = O) stretching frequencies confirm the condensation reaction between the carboxylic acid and semicarbazide, to form a 20 membered hexa amide macrocycle CHT, as shown in Fig. (1). On complication, the stretching frequencies of (N-H), δ(CO -NH-CO) and (N-N) shifted to lower frequency, which may indicate the coordination of two (NH) from the semicarbazide group Fig. (1), other support of this coordination comes from the appearance of new bands attributed to  (M-N) stretching at (434 -492 cm -1 ). However, the position of (C=O) stretching vibration has not been shifted frequencies in all complexes (Sulekh, 2005 ;Zafar, 2004). New bands in the spectrum of the complexes appeared between (434 -501 ) cm -1 vibration of (M-N) group in all complexes may prove the coordination nitrogen atoms with metal ions.

Fig .3 : 13 C-NMR for CHT ligand Electronic Spectra and Magnetic Measurements
The magnetic moments and electronic spectra data for all the complexes are given in (Table 5). The spectrum of the CHT ligand has bands in the U.V spectra at (45871 and 36760 cm -1 ), assigned to   * and n  * transition, respectively. These values are shifted to lower frequencies ( 328 -1229 ; 264 -4080 ) cm-1 respectively in the spectrum of the complexes.
The magnetic moment of the Cu(II) complexes number (5,11) lie in the range ( 2.16,1.94 B.M), corresponding to one unpaired electron and electronic spectra have a band in the range (16667 , 17391 cm -1 ) assigned to the 2 E 2 g(F ) 2 T 2 g,(32051 , 32679 cm -1 ) which may be due to charge transfer , indicating distorted octahedral environment (Lever et al., 1970).
The µ eff values of the two Zn(II) complexes number (6, 12) were diamagnetic as expected, while the U.Vvisible spectrum show bands at (30121, 37962 cm-1 ), ( 33121, 41025 cm-1 ) which may be due to charge transfer, indicating an octahedral environment around the Zn (II)ions