in this thesis, phosphorus ylides [phbppy], [no2bppy] and [brbppy] have been synthesized through the formation of phosphonium salt and dihydrogenation, followed by the reaction of pd(oac)2 and the orthopalladated dinuclear complexes [pd(?-cl)(phbppy)]2, [pd(?-cl)(no2bppy)]2 and [pd(?-cl)(brbppy)]2 have been produced. the reaction of dinuclear complexes and bidentate ligands [l = bipy (2,2-bipyridine), phen (phenanthroline), dppe (bis(diphenylphosphino)ethane), dppp (bis(diphenylphosphino)propane)] giving the stabilized mononuclear orthopalladated complexes pd(phen)(xbppy)], [pd(bipy)(xbppy)], [pd(dppe)(xbppy)] and [pd(dppp)(xbppy)], (x = ph, no2, br) in endo position. the complexes were chractrized by ft-ir, nmr, chn, conductivity and x-ray diffraction study of pd(phen)(brbppy)], [pd(bipy)(brbppy)], [pd(dppe)(no2bppy)]. the ?(co) band which is sensitive to complexation occurs from 1505 to 1515 cm-1 in the parent ylides. these bands appear at lower energies compared to that found in the phosphonium salts, due to the charge delocalization present in such compounds. coordination of ylide through the carbon atom causes an increase in the ?(co) band, whereas for o-coordination a lowering of the ?(co) band is expected. the ir spectra of all complexes show a strong absorption in the range of 1620-1630 cm-1, which have been shifted to higher frequency with respect to the parent ylides, meaning that the ylides are c-bonded to the palladium center. the ?(p-c) band frequencies occur at 881, 860 and 883 cm-1 in the parent ylides [phbppy], [no2bppy] and [brbppy] respectively, and are shifted to lower frequencies for the complexes, suggesting some removal of the electron density of the p-c bonds. the 1h nmr signals for the pch group of complexes are shifted downfiled compared to that of the free ylides, as a consequence of the inductive effect of the metal center. in the 1h nmr spectra for dinuclear complexes, the signals due to the methinic proton were broad (minor) or broad doublets (major). the presence of two lines of different intensity on each spectrum can be originated from the presence of two diasteroisomers (rr/ss and rs/sr), as a result of the c-bonding of the ylide and the dinuclear nature of ([pd(?-cl)(phbppy)]2, [pd(?-cl)(no2bppy)]2 and [pd(?-cl)(brbppy)]2). in the 31p {1h} nmr spectra of all complexes the presence of one signal group, confirm a single isomer for each complexes. the 31p nmr spectra of the bidentate diphosphine have one signal, while the 31p nmr spectra of pd(ii) complexes with a bidentate diphosphine show two signal due to different trans effect of arylic and ylidic carbons. the results of conductivity show that the molar activity of orthopalladated complexes are within the range for 1:1 electrolytes, which demonstrate the existence of the tfo as counter ion in the solution. single crystals of pd(phen){c6h4(pph2ch-c(o)c6h4(br)-?-c,c)-2}], pd(bipy){c6h4(pph2ch-c(o)c6h4(br)-?-c,c)-2}] and pd(dppe){c6h4(pph2ch-c(o)c6h4(no2)-?-c,c)-2}, suitable for x-ray crystallography, were obtained. the palladium atoms of complexes are located in disorted square planer environments. in complexe pd(dppe){c6h4(pph2ch-c(o)c6h4(no2)-?-c,c)-2} the pd – p(2) bond length is shorter than pd – p(3), due to different trans effect of arylic and ylidic carbons. the ortep diagram of the complexes demonstrate the orthopalladation occuring at the ph rings of the phosphine unit in endo position. in the crystal structure of complexes, cations, anions and solvent molecules are linked into a network by intra-intermolecular hydrogen bonds.