Stoichiometry of Polymer Complexes

Polymer complexes have been attracting interest in many scientific and technological fields in recent years. Polymer complexes have found wide applications in bioinorganic industry (Fenger & Le Drian, 1998), wastewater treatment (Mizuta et al., 2000), pollution control (Orazzhanova et al., 2003), hydrometallurgy (Varvara et al., 2004), preconcentration (Ro et al., 2003), anionic polyelectrolyte hydrogels (Varghesa et al., 2001), cation-exchange resins (Ahmed et al., 2004) etc. Moreover, they recently showed potential applications in material science as catalytic, conductive, luminescent, magnetic, porous, chiral or non-linear optical materials (Janiak, 2003; James, 2003; Maspoch et al., 2004; Batten & Murray, 2003).

Although various extensive investigations on polymer complexes have been reported, most of these complexes are too complicated to be discussed quantitatively due to the nonuniformity of their structure. These compounds include not only "complexes of macromolecules" but also the structurally labile "metal complex". Before detailed information can be obtained about the properties of polymer complexes, in particular about the reactivity and the catalytic activity, their structure must be elucidated. A polymer complex possessing a uniform structure may be defined as follows: • The structure within the coordination sphere is uniform, i.e. the species and the composition of the ligand and its configuration are identical in any complex unit existing in the polymer complex; • The primary structure of the polymer ligand is known.

•
If the structure within the coordination sphere is identical in a polymer and in a monomeric complex, their reactivity ought to be the same even though the complex is bound to a polymer chain. However, it is clear that the reactivity is sometimes strongly affected by the polymer ligand that exists outside the coordination sphere surrounding the metal complex. The effect of polymer ligands can be explained in terms of two factors: • the steric effect, which is determined by the conformation and density of the polymer ligand chain; • the special environment constituted by a polymer ligand domain.
Hence, it is possible to prepare polymer complexes having different use and applications by varying the polymer chain, the nature of the ligand and the metal ion.
A polymer complex is composed of synthetic polymer and metal ions, with the metal ions bound to the polymer ligand by a coordinate bond. A polymer ligand contains anchoring sites like nitrogen, oxygen or sulphur obtained either by polymerization of monomer possessing the coordinating site or by a chemical reaction between a polymer and a low molecular weight compound with coordinating ability. The synthesis results in an organic polymer with inorganic functions. The metal atoms attached to the polymer backbone are bound to exhibit a characteristic catalytic behavior, distinctly different from their low molecular weight analogues. Indeed, many synthetic polymer complexes have been found to possess high catalytic activity, in addition to semiconductivity, heat resistance and biomedical potentials.
This review will focus mainly on the stoichiometry and the characterization of polymer complexes structure by using elemental analyses, electronic spectra, magnetic susceptibilities, FT-IR, IR, 1 H-NMR, ESR and thermogravimetric analyses.

Classification of polymer metal complexes
The polymer complexes may be classified into three different groups according to the position occupied by the metal, which is decided by the methods of preparation: 1. Complexation of polymeric ligand with metal ions which could be divided into two categories: a. Pendant metal polymer complexes. b. Inter/intra-molecular bridged polymer complexes. 2. Complexation of multifunctional ligands with a metal. 3. Polymerization of metal containing monomers.

Complexation of polymeric ligand with metal ion
Only decades ago polychelats derived from polymeric ligands and transition metal ions attracted the attention of many investigators. Bamford, Jenkins and Johnson (Bamford et al., 1958) were the first who noticed and described that radical polymerization of vinyl monomers is accelerated by addition of an inorganic salt not participating in redox reactions. They showed that the rate of polymerization of acrylonitrile (AN) initiated by azobisisobutyronitrile (AIBN) in dimethyl formamide (DMF), increases when lithium chloride is dissolved in the reaction mixture. According to the kinetic measurements, the effect was ascribed to an increased propagation of the rate constant and explained by the complexation of the nitrile groups at the radicals with lithium chloride.
A number of authors (Tazuke & Okamura, 1966;Tazuke et al. 1966;Tazuke & Okamura, 1967) have studied radical polymerization of this type. From a kinetic point of view methyl methacrylate (MMA) and AN-metal salt (AlCl 3 , AlBr 3 , ZnCl 2 , GaCl 2 , etc) systems were most intensively investigated (Imoto et al., 1963;Bamford et al., 1966a& Zubov et al., 1968. The increased reactivity of the complexed monomer has been attributed to the delocalization of the electrons in the double and triple bonds of the acceptor monomer as a result of the complexation with the electron accepting metal halide ( Fig. 1) (Lazuke et al., 1967 The new electrophilic acceptor monomer has an increased rate constant and an unchanged termination rate constant resulting in a more rapid rate of propagation and in the formation of a higher molecular weight polymer (Banford et al., 1966b). The kinetics of polymerization were extended to methyl acrylate (MA) with transition metal bromides . The presence of Cu(II), Ni(II) and Zn(II) bromides retards the rate of polymerization. This retardation effect of the polymerization of MA is attributable to the formation of addition products, which must be inactive in initiating the polymerization of MA and decrease the rate of polymerization in the order MA-ZnBr 2 < MA-CuBr 2 < MA-NiBr 2 .
The enhanced reactivity of the complex monomer extends to copolymerization with olefinic or allylic monomer, which is poorly responsive to free radical initiated polymerization (Imoto et al., 1965;Serniuk & Thomas, 1965;Serniuk & Thomas, 1966). The free radical initiated copolymerization of such monomers which a metal halide complexed polar monomer results in an increased concentration of olefinic monomer in the polymer as compared with that obtained in the absence of the complexing agent, as well as an increase in the polymer molecular weight.
The reaction of polymer ligands with metal ions usually results in various coordination structures, which are divided into pendant and inter-and/or intra-molecular bridged complexes.

Pendant polymer complexes
The metal ion in a pendant metal complex is attached to the polymer ligand function, which is appended on the polymer chain. Based on the chelating abilities of the ligands, pendant complexes are classified as monodentate or polydentate polymer metal complexes.

a. Monodentate pendant polymer complexes
A metal ion or a metal complex has only one labile ligand, which is easily substituted by a polymeric ligand, and when other coordination sites are substitution inactive, the complex formed has a simple structure of monodentate type as shown in Fig. 2. If the metal ion or metal complex has more than two labile ligands, it is often possible to realize a monodentate complex structure by selecting an appropriate reaction condition (Kaneko & Tsuchide, 1981). Important characteristics of this type of polymer complexes are: i. The coordination is very clear.
ii. The effect of the polymer chain is clearly exhibited. iii. The polymer complex is very often soluble in water or in organic solvents.  (Kurimura et al., 1971;Tsuchide et al., 1974).  Soluble copper chloride complexes of poly(2-vinylpyridine) (P2VPy) were prepared (Lyons et al., 1988) in a methanol-water solution. Solubility was achieved with the proper solvent www.intechopen.com system due to the sterically hindered environment of the ligand, allowing only one pyridine moiety to complex each copper cation. Partial reduction of the cupric cation occurred during sample preparation, as observed by X-ray photoelectron spectroscopy (XPS) and magnetic susceptibility measurements.

b. Polydentate pendant polymer complexes
When the polymer pendant coordination group has a polydentate structure, the coordination structure of the polymer metal complex is very clear, and high stability can be expected as shown in Fig. 4.

Inter-and/or intra-molecular bridging polymer complexes
The reaction of polymer ligands with metal ions very often results in inter-and/or interamolecular bridging (Fig. 5). The coordination structure of the resulting polymer metal complex is not clear in this case, and the polymer complex is sometimes insoluble in water or in organic solvent. It is usually difficult to distinguish between the inter and intra-molecular bridging. The fact that it is not often easy to elucidate the polymer effect in studying the characteristics of the polymer complex. The simplest example of this type of polymer complex is the poly(vinyl alcohol)(PVA)-Cu(II) complex ( Fig. 6) (Hojo & Shiria, 1972

The chain linked through complexation of bifunctional ligands with metal ions
When bifunctional ligands form a complex with metal ions having more than two labile ligands, i.e. easily replaceable a polymer complex (Fig. 8) is formed through metal ion bridging.
This type of polymer metal complex has been synthesized as semiconducting organic materials (Katon, 1970), heat resistant organic polymer or polymer catalysts. Bridged ligands able to form polymer metal complexes of this type are classified as follows : (i) compounds having more than two coordinating groups, and (ii) simple compounds having more than two coordinating atoms, or simple ions which are able to function as bridged ligands. When the complex formation of ligands having four coordinating groups induces chemical reaction between the ligands, the resulting polymer complex sometimes has a network structure.

ii-Linked by simple compound or ion
A simple ion or compound can work as a bridging ligand giving a polymeric structure. A metal salt such as cupric chloride forms an associated structure (Fig. 10) in a very concentrated aqueous solution of hydrogen chloride (Wertz & Tyvoll, 1974) with the chloride ions occupying as bridging ligands both the axial and equatorial coordination sites of Cu 2+ .

b. Network-coordinated polymers
The most usual method to prepare this type of complexes is use a "template reaction". This is a reaction between two functional groups of the ligand induced by their coordination to the metal ion, resulting in a chelated-type metal complex (Fig. 11). A typical example is poly(metal phthalocyanine) formed during the reaction of tetracyanobenzene with metal halides catalyzed by urea as shown in Fig. 12 (Epstein & Wildi, 1960).

Formation through polymerization of metal complexes
Polymer containing the metal as part of a pendent or substituent group may be formed when complex possessing functionalized ligands undergo polymerization. The most widely studied are vinyl complexes and their derivatives, formed through radical polymerization of vinyl monomer containing transition metal ions. Vinyl compounds of metal complex are polymerized giving polymer metal complexes as shown in Fig. 13. This type of polymer complex is characterized by its clear coordination structure. Nevertheless, the limitations of the vinyl compounds, and the metal complex tendency to hinder the vinyl polymerization, may constitute an obstacle in this type of polymerization.

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Methacrylate monomer coordinated to Co(III) complex, e.g. methacrylato-pentaamine cobalt (III) perchlorate, was radically polymerized giving the polymer (VI) (Fig. 14) (Osada, 1975;Osada, 1976a;Osada, 1976b;Osada & Ishida, 1976). The free radical initiated polymerization of polar monomers containing pendant nitrile and carbonyl groups, e.g. acrylonitrile and methyl methacrylate, in the presence of metal halides such as ZnCl 2 and AlCl 3 is characterized by an increased rate of polymerization. On the contrary, the formation of polymers with considerably higher molecular weight is likely in the absence of the metal halide (Bamford et al, 1957;Bovey, 1960;Arthur & Blouin, 1964). This behavior is similar to the one suggested (Kabanov, 1969) for the polymerization of MMA in presence of inorganic salts such as ZnCl 2 and AlBr 3 .
The polymerization of acrylonitrile (AN) in presence of Cu(I), Cu(II), Co(II), Ni(II) and Cd(II) bromides was studied (El-Sonbati & Diab, 1988b& 1988c. The IR spectrum of the formed AN-Cu(II) bromide polymer complex shows the absence of the C≡N band and the presence of two new bands corresponding to NH 2 and OH groups. These bands are not found with the other metal bromide polymer complexes (Fig. 16). It seem that Cu(II) is reduced to the stable Cu(I) during the polymerization of AN-Cu(II) bromide. Poly(acrylamido-4-aminoantipyrinyl)(PAA) homopolymer and polymer complexes of acrylamido-4-aminoantipyrinyl (AA) with some transition metal bromides and uranyl acetate have been prepared (El-Sonbat et al., 1989)). Dioxouranium(VI) acetate dehydrate reacts with AA in a 1:2 and with CuBr 2 , NiBr 2 and CoBr 2 in 1:1 metal:ligand molar ratios and the polychelates of the types shown in Fig. 18. Poly(2-acrylamidophenol)(PAP) homopolymer and polymer complexes of 2acrylamidophenol (AP) with Cu(II), Ni(II), Co(II), Cd(II) chlorides and uranyl acetate were prepared and characterized (Diab et al., 1988). The phenolic C-O IR band has been shifted of ± 15 cm -1 , indicating that it is involved in the coordination of AP-CuCl 2 and AP-CdCl 2 polymer complexes (Fig. 19). There is a change in the position of NH band to lower frequency, indicating the recruitment of these groups in the coordination of AP-CoCl 2 and AP-NiCl 2 polymer complexes. The possible structures of AP-Cu(II), AP-Ni(II), AP-Co(II), AP-Cd(II) chlorides and uranyl acetate are the following:  Poly(2-acrylamidopyridine)(PAP) homopolymer and polymer complexes of 2acrylamidopyridine (AP) with some transition metal chlorides have been prepared and characterized (Diab et al., 1989a). IR spectrum of PAP homopolymer indicates two tautomeric forms are shown in Fig. 20. The IR spectrum of AP-CuCl 2 polymer complex shows a lowering of the OH stretching frequency by about 10-15 cm -1 indicating that the OH group is involved in the coordination (Fig. 21). An increase in the frequency of the pyridine nitrogen indicates that it takes part in the bond formation. Moreover, new bands appeared in the spectrum assigned to υ(M-O), υ(M-N) and υ(M-Cl). It may be deduced that the probable structure of AP-CuCl 2 polymer complex is: The IR spectra of AP-CoCl 2 , AP-NiCl 2 and AP-CdCl 2 polymer complexes have the characteristic features of coordination between the nitrogen atom of the pyridine ring and the oxygen atom of the hydroxyl group. AP reacts with NiCl 2 , CoCl 2 in a 2:1 ratio and with CdCl 2 in a 1:1 ratio. The possible structures of AP-NiCl 2 , AP-CoCl 2 and AP-CdCl 2 polymer complexes ( Fig. 22) are the following: It was found that poly[bis(2,6-diaminopyridine sulphoxide)](PDPS) homopolymer and polymer complexes of bis(2,6-diaminopyridine sulphoxide)(DPS) with CuCl 2 , CuBr 2 and CuI 2 were prepared and characterized (Diab et al., 1989b). The mode of complexation of the polymer complexes of PDPS with copper halides is derived as shown in Fig. 23. Poly(5-vinyl salicylaldehyde)(PVS) homopolymer and polymer complexes of 5vinylsalicylaldehyde (VS) with CuCl 2 , CoCl 2 , NiCl 2 and uranyl acetate were synthesized and characterized (El-Hendawy, 1989). The IR spectrum of VS-CuCl 2 polymer complex shows a shift of υ(C=O) to a lower frequency by about 15 cm -1 and the υ(C-O) of the phenolic group is shifted to a higher frequency by about 25 cm -1 indicating that both groups are involved in the complexation. From the spectroscopic data, the magnetic moments and the elemental analysis, it is concluded that VS reacts with CuCl 2 , CoCl 2 and NiCl 2 in the ratio 2:1. The possible structure of the polymer complexes VS-CuCl 2 , VS-CoCl 2 and VS-NiCl 2 may be as shown in Fig Polymer complexes of 2-acrylamidobenzoic acid (ABA) with transition metal chlorides and uranyl acetate were prepared and characterized (Diab et al., 1990a). ABA reacts with uranyl ions in a 2:1 molar ratio. The chelation occurs through one of the two oxygens of the carboxylate ion, which is represented as a tautomeric form as shown in Fig. 26. Poly(5-vinylsalicylidene anthranilic acid)(PVSA) homopolymer and polymer complexes of 5-vinylsalicylidene anthranilic acid (VSA) with some transition metal chlorides and uranyl acetate were prepared (Diab et al., 1990b). The IR spectrum of VSA-uranyl acetate polymer complex shows a change in the position of azomethine nitrogen and carboxylate ion groups indicating their involvement in coordination. Elemental analysis and IR spectrum reveal that VSA reacts with uranyl acetate, NiCl 2 , CuCl 2 and CoCl 2 to form the structures shown in Fig. 28. Poly(ethylene glycol)(PEG) reacts with Cu(II), Co(II), Ni(II) and Cd(II) chlorides to form polymer complexes in 2:1, ligand:metal molar ratios (Diab & El-Sonbati, 1990). The IR bands due to C-O are shifted to higher frequencies in the formed polymer complexes. This shift may be due to the increased covalence resulting from metal ion coordination. On the basis of the analytical data, electronic and IR spectral data, PEG reacts with CuCl 2 , CoCl 2 , NiCl 2 and CdCl 2 as shown in Fig. 29. Polymer complexes of 5-vinylsalicylidene aniline (VSA) with Cu(II), Co(II), Ni(II), Cd(II) and UO 2 (II). VSA reacts with uranyl nitrate in a 2:1 ratio and with uranyl acetate in a 1:1 ratio were found (El-Sonbati, 1992). A possible structure for the polymer complexes is shown in Fig. 30. The IR, electronic spectra and elemental analyses data indicate that copper(II) salts react with VSA monomer in a 1:1 molar ratio (Fig. 31). Homopolymer of 5-vinylsalicylidene-2-aminophenol (PVSA) and polymer complexes of 5vinylsalicylidene-2-aminophenol (VSA) with transition metal acetate have been prepared and characterized (El-Sonbati, 1991a). The absence of the phenolic υ(O-H) in the copper(II), nickel(II), cadmium(II) and zinc(II) polymer complexes indicates the phenolic proton is lost upon metal ion complexation VSA appears to react with Cu(II), Ni(II), Cd(II) and Zn(II) acetate in a 1:1 ratio and with Co(II) and uranyl acetate in a 2:1 molar ratio. A possible structure for the polymer complexes is shown in Fig. 33. Polymer complexes derived from 5-vinylsalicylidene hydrazine-S-benzyl dithiocarbocarbazate (VSH) with CuCl 2 , NiCl 2 , CdCl 2 and uranyl acetate were prepared and characterized by elemental analyses, spectroscopic and magnetic measurements (El-Sonbati, 1991b). The IR spectra of VSH-NiCl 2 and VSH-CdCl 2 polymer complexes show the disappearance of the NH group and the appearance of new bands at 1625-1630 cm -1 which could be attributed to the stretching vibrational mode of the conjugated C=N-N=C group. There is a strong broad band at 3460-3350 cm -1 which is attributable to the associated water molecules. The absence of the phenolic υOH is an indication that the phenolic proton is lost upon complexation. Furthermore, it was found that there is a band around 1495 cm -1 , suggesting that the o-hydroxy group has entered into the band formation with metal ions. According to these results beside the electronic spectra and elemental analysis, the possible structure of the products of reaction of VSH with NiCl 2 and CdCl 2 as shown in Fig. 34. The IR spectrum of the VSH-CuCl 2 polymer complex shows the disappearance of the bands attributed to C=S and OH groups, suggesting that enolization occurred through the thioketonic group. The shift of the phenolic υ(C-O) to higher frequencies by about 15-20 cm -1 suggests the formation of an oxygen-bridge structure (Fig. 35). The structure appear to be of the following type: The stoichiometry between uranyl acetate and VSH are in agreement with a 1:2 molar ratio and the following type of structure is proposed (Fig. 36). It was found that, 2-acrylamido-1,2-diaminobenzene (AAB) reacts with Cu(II), Ni(II), Zn(II) and UO 2 (II) chlorides or acetate to give polymer complexes with different stoichiometry (El-Sonbati et.al., 1991), depending on the metal salt and the reaction conditions. The cobalt(II) polymer complexes may be classified into two groups. Those with the 1:1 composition are derived from ADB-Co(II) acetate and those with 1:2 stoichiometry are derived from ADB-Co(II) chloride. All these observations suggest the structures as shown in Fig. 37. www.intechopen.com Polymer complexes of 5-vinylsalicylidene-2-benzothiazoline (VSBH 2 ) with Cu(II), Ni(II), Co(II), Fe(II), Mn(II), Zn(II), Pd(II) and UO 2 (II) were prepared and characterized (El-Sonbati & Hefni, 1993). Two IR bands of medium intensity at 1580 and 1530 cm -1 can be assigned to the thiazolines ring vibration. Therefore, PVSBH 2 homopolymer exists in benzothiazoline form as shown in Fig. 39. Polymer complexes derived from 5-vinylsalicylidene-2-aminomethylpyridine (VSAPH) with some transition metal salts were prepared and characterized (El-Bindary et al., 1993). All the IR and analytical data are commensurate with the structure shown in Fig. 41.

HC
VSAPH may also act as a bidentate ligand, coordinating to the metal ion via the azomethine nitrogen and phenolic oxygen atoms. Loss in a proton from the latter group would allow formation of a six-membered chelate ring. The uranyl polymer complexes can be formulated as [UO 2 (VSAP) 2 ] and [UO 2 (VSAPH)(OAc) 2 ], indicating a probable coordination number of 6 for the uranium(VI) ion. The following structures are suggested (Fig. 42) for the polymer complexes: www.intechopen.com The presence of coordinated water was confirmed by TG data when a loss in weight corresponding to one water molecule was found for Ni(II) and two water molecules for Cu(II), Co(II) and Ni(II). No coordination water molecules were found in the case of Zn(II), Hg(II) and Cd(II) polymer complexes.
Polymer complexes of N,N`-o-phenylenediamine bis(cinnamaldehyde) (L) with Cu(II), Co(II), Ni II , Zn II ,UO 2 II and Pd II were prepared and characterized (El-Sonbati et al., 1993b). A bidentate methine nitrogen atoms coordination of the ligand is assigned in the isolated complexes. The µ eff values of cobalt(II) and nickel(II) polymer complexes are normal and indicate an octahedral stereochemistry around the metal ion, the moments for the cobalt and nickel complexes are in a range expected for six-coordination metal ions, with much orbital contribution. The electronic spectra are summarized in Table 1, together with the proposed assignments, ligand field parameters, magnetic susceptibilities and suggested geometries.
Mononuclear and binuclear complexes of poly(5-vinylsalicylidene-2-aminopyridine) (PVSA) were prepared by the reaction of the homopolymer with copper(II), cobalt(II), nickel(II), dioxouranium(VI) and palladium(II) salts (El-Sonbati et al., 1994a). Metal(II) acetates and palladium chloride were found to give mononuclear complexes, while cupric chloride gave a binuclear complex. The stereochemistry and the nature of the polymer complexes are markedly dependent upon the molar ratios of the reactants, the pH of the system and the nature of the anions involved. In all of the complexes the homopolymer was chelated to the metal ion through the nitrogen atom of the azomethine group and the oxygen atom of the phenolic group. The stoichiometric of the complexes indicate that the copper(II) complexes fall into two distinct categories.  Poly(5-vinylsalicylidene)-1,2-diaminobenzene (PVSB) homopolymer behaves as a monobasic tridentate chelating ligand and mixed ligand of PVSB and pyridine as a bidentate species. Polymer complexes of these ligands with Cu(II), Fe(II), Co(II), Ni(II), Pd(II), Cd(II) and Zn(II) were prepared and characterized (El-Sonbati & Hefni, 1994). In PVSB homopolymer, the principal IR bands of interest are two strong bands at 3365 and 3175 cm -1 attributed to the symmetric and asymmetric NH 2 stretching vibrations (Fig. 45). The frequencies of these bands are observed at a considerably lower wavenumber in the polymer complexes of the nitrogen atom of the amino group with metal ions. The absence of large systematic shifts of υ as (NH 2 ), υ s (NH 2 ) and δ(NH 2 ) bands in the spectra of mixed ligand polymer complexes, i.e. 2:1 species, implies that there is no interaction between the amino group nitrogen atom and the metal ions. Polymer complexes of 2-acrylamido-1-phenyl-2-aminothiourea (APATH) with Rh(II) and Ru(II) ions in the presence and absence of N-heterocyclic bases as mixed ligand have been prepared and characterized through chemical analyses, thermal, electronic and infrared spectral studies (El-Sonbati et al., 1994b). The homopolymer shows three types of coordination behavior. In the mixed valence paramagnetic trinuclear polymer complexes Rh 3 (APATH) 2 Cl 8 (1) and Ru 3 (APATH) 2 Cl 8 (2), and in the mononuclear polymer compound Ru(APATH) 2 Cl 3 ( 3) it acts as a neutral bidentate ligand coordinating through the thiocarbonyl sulphur and carbonyl oxygen atoms. In the mixed ligand paramagnetic polychelates, which are obtained from the reaction of APATH with  In the other hand, mononuclear and hetero bi-trinuclear polymer complexes of nickel(II), copper (II) and oxovanadium(VI) chloride with APATH monomer derived from amidation of acryloyl chloride with 2-amino-1-phenylthiourea have been prepared (El-Sonbati el al., 1995a). The elemental analyses show that these homonuclear polymer complexes have 2:1 and in bimetallic polymer complexes 2:1:1 (homopolymer: metal: metal), stoichiometry. These indicate that they fall into two distinct categories. The first is mononuclear, while the second is heterobinuclear. The following structures shown in Fig. 47 are suggested: Fig. 47.

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Poly[1-acrylamido-2(2-pyridyl)ethane)] (PAEPH) homopolymer and polymer complexes of 1-acrylamido-2(2-pyridyl) ethane AEPH with a number of bi and tetravalent transition metals have been prepared and characterized using spectral ( 1 H and 13 C-NMR, IR, UV-Vis) and thermal analysis, and magnetic measurements (El-Sonbati et al., 1995b). The stoiciometries of the polymer complexes have been deduced from their elemental analyses. These indicate that the metal-polymer complexes fall into two distinct categories, namely 1:1 and 1:2 (ligand: metal). PAEPH is mononucleating and hence requires one metal ion for coordination. The formation of the polymer complexes may be represented by the following reactions: The reactions appear to proceed only up to a 1:2 molar ratio. Even on prolonged refluxing (~ 32 h) of 1:3 or 1:4 reaction mixture, replacement of a third chloride group by the homopolymer was not observed. This is probably due to steric factors. Plausible structures (Fig. 48)  The zirconium atoms appear to be hexa-(A, B) and hepta-(B, C) coordinated. In the polymer complexes of zirconyl isopropoxide, zirconium exhibits a coordination number of 5. The [UO 2 (AEP)(AcO)(OH 2 )] polymer complex spectrum exhibits characteristic bands for the monodentate acetate group at 1620 and 1395 cm -1 with Δυ = 235 cm -1 . The spectrum also exhibits three bands at 907, 790 and 275 cm -1 assigned to υ 3 , υ 1 and υ 2 of the dioxouranium ion.
Trying to deepen the knowledge of this ligand, a studied polymer complexes of AEPH with copper(II), nickel(II), cobalt(II) and Zn(II) (El-Sonbati & El-Bindary, 1996). Some binary and ternary novel polymer complexes dioxouranium(VI) with 5vinylsalicylaldehyde (VSH) have been prepared and characterized by various physicochemical techniques (El-Sonbati et al., 2002). Addition of ammonia to an ethanolic solution of uranyl nitrate give uranyl ammine complex which on treatment with VSA result in the formation of the imine complex (C). The reaction of the compound C with 1,2diaminoethane and/or 1,2-diaminobenzene yield symmetrical tetradentate Schiff base complex of type (1C) as shown in Fig. 50 (Fig. 51). This lowering in the ligand field band of [Cu(VSR)] may be due to exchanges in the planarity of (VSR) and also to reduction in strength of Cu-O bond on the formation of second bond with metal(II) halides.

Fig. 51.
Novel seven, nine and ten-coordinated rare earth polymer complexes of N-acryloyl-1phenyl-2-thiourea (APT) of the composition [Ln(NO 3 ) 3 (APT) 2 ] n (Ln = La, Sm, Tb, Pr and Nd) and [Ln(NCS) 3 (APT) x ] n (where Ln = La or Pr at X = 2 and Ln = Nd, Sm and Tb at X = 3) have been prepared and characterized on the basis of their chemical analyses, magnetic measurements, conductance, visible and IR spectral data . The data of elemental analysis indicate that the stoichiometric ratio for the reaction of monomer with various LnX 3 is 1:2 and 1:3 (Ln: monomer). The polymer complexes do not contain any water of coordination are all occupied by donor centers from the ligand groups. Therefore, the reaction between LnX 3 and ligand can be represented as follows: These data suggest that three nitrato and isothiocyanato ions are within the coordination sphere.
The build-up of polymer metallic supramolecules based on homopolymer 1-acrylamido-2-(2-pyridyl)ethane (AEPH) and ruthenium, rhodium, palladium as well as platinum complexes has been pursued with great interest (El-Sonbati et al., 2003a). AEPH is found to be a polyfunctional planar molecule with a delocalized π electronic system, with two nitrogen atoms which may act as basic centers and two labile N-H bands. The molecule may present in several tautomers and conformers. The equivalent conformers are the principle contributors to the molecular structure of this molecular in solution; they are in equilibrium and established by intramolecular hydrogen bonds. In the solid state reveals widely used intramolecular hydrogen bonding, which gives rise to six-membered ring (Fig. 52). Monomeric distorted octahedral or trimeric chlorine-bridged, approximately octahedral structures are proposed for these polymer complexes.
From the spectroscopic investigation of the rhodium complexes, it was concluded that the rhodium atom in each complex exists in an octahedral environments (Fig. 54). Two novel supramolecular complexes of types UO 2 (L)(H 2 L)(OH 2 ) 2 and UO 2 (HL n ) 2 (OAc) 2 (H 2 L is a potential four-dentate ligand derived from hydrazine hydrate and malonylchloride and HLn is a potential bidentate ligand derived from coupling of allylazo--diketone have been synthesized and characterized by elemental analyses, conductance and spectral measurements (El-Sonbati et al., 2004a). Alcoholic solutions of uranyl acetate and malonic dihydrazide were refluxed for 8-9 h forms uranyldihydrazide complex as shown in Fig. 56.
The magnetic measurements of the dioxouranium(VI) polymer complexes are independent from field strength and temperature and the ground states of dioxouranium(VI) compounds contain no unpaired electrons. Allyl propenyl-2-(4derivatives phenylazo) butan-3-one (HL n ) is a ligand whose reactivity towards metal ions varies as a function of the 4-substituents. The products, which are usually neutral, have two coplanar O,O metal-chelate rings in an O,O(O,O) trans geometry. Consequently, in the UO 2 2+ case, the uranyl atom should be a six-coordinate octahedral with the oxygen atom in the apical position (Fig. 62).

DMF DMF
www.intechopen.com  (6) and Ho (7) have been prepared and characterized on the basis of their chemical analyses, magnetic measurements, conductance, visible and IR spectral data (El-Sonbati et al., 2009). The IR spectrum of the ligand leads to assume the structure shown in Fig. 63. The spectral data show that all these act as tetradentate ligand. Electronic spectra indicate weak covalent character in the metal-ligand bond.

Conclusions
The coordination polymer research field of study is a vast and one of the fastest growing areas of chemistry in recent times, with important work being done on a large variety of different aspects. Polymer complexes are an important class of new materials due to the coupling of the chemical, optical and electronic properties of the metal moiety to those of the polymer. This review, however, provides a uniquely broad overview of the stoichiometry of polymer complexes by using elemental analyses, FT-IR and IR spectra. The geometry of the polymer complexes was evaluated by electronic spectra (UV.-Vis.) and magnetic moment measurements. The aim of this book is to provide an overview of the importance of stoichiometry in the biomedical field. It proposes a collection of selected research articles and reviews which provide up-to-date information related to stoichiometry at various levels. The first section deals with host-guest chemistry, focusing on selected calixarenes, cyclodextrins and crown ethers derivatives. In the second and third sections the book presents some issues concerning stoichiometry of metal complexes and lipids and polymers architecture. The fourth section aims to clarify the role of stoichiometry in the determination of protein interactions, while in the fifth section some selected experimental techniques applied to specific systems are introduced. The last section of the book is an attempt at showing some interesting connections between biomedicine and the environment, introducing the concept of biological stoichiometry. On this basis, the present volume would definitely be an ideal source of scientific information to researchers and scientists involved in biomedicine, biochemistry and other areas involving stoichiometry evaluation.