In this thesis, phosphorus ylides [PhY] and [BrY] have been synthesized through the formation of phosphonium salt and dehydrogenation. The ortho-metalated complexes [Pd(C 6 H 4 CH 2 NRR')XY](R, R'=H, Me, Et, t-Bu. X=Cl, Br. Y=PPh 3 , 4-Picoline, sym-Collidine), can be prepared by refluxing equimolecular amounts of Pd (OAc) 2 and [C 6 H 5 CH 2 NRR`](R, R`=H, Me, Et, t-Bu) in benzene for 24 h, followed by addition of NaX(X=Cl, Br) in MeOH. The halogeno-bridges in dimeric ortho-palladated complexes containing secondary and tertiary aryl-alkylamines are easily cleaved by various neutral ligands, including 4-Picoline, sym-Collidine, PPh 3 , to afford mononuclear metallacycles. These complexes can be used as the starting material for the synthesis of cyclo-palladated coplexes O-coordination and C-coordination [Pd(C 6 H 4 CH 2 NRR')(XY)Y](X= Ph , Br. R, R'=H, Me, Et, t-Bu. X= Cl , Br. Y=PPh 3 , 4-Picoline, sym- Collidine), with ylide [XY](X=PH, X) and AgTfO reaction in THF. The ?(CO) band which is sensitive to complexation occurs from 1507 to 1519 cm -1 in the parent phosphorus ylides. The IR absorption band observed for these complexes show a lowering of ?(CO), indicating coordination of the ylide oxygen for these complexes. The 1 H NMR spectrum of the O-bound complexes showed only one signal for the CH methine at near to that of the free ylides and for C-bound complexes the CH methine at down-field. The 31 P NMR spectra shows a sharp signal resonance shifted slightly up-field relative to the free ylide and is again in agreement with O-coordination, because C-coordination would result in a down-field shift of about 10 ppm of the ylide resonance. In the 13 C NMR spectrum complexes 1a-3c the resonance CH 2 in five-membered ring in the range 48.81-56.60 ppm have been observed.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 [PhYH + ]TfO - and [PdCl(PhY)PPh 3 ] suitable for X-ray crystallography, were obtained. The palladium atom of complex [PdCl(PhY)PPh 3 ] are located in distorted square planer environments. The palladium complexes 1a-3c and [PdCl(PhY)PPh 3 ] have been experimented as catalyst in Suzuki reaction.