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A series of bi- and tri-dentate amido phosphine ligands H[Ph-PNP] (bis(2-diphenylphosphinophenyl)amine), H[iPr-PNP] (bis(2-diisopropylphosphino- phenyl)amine), H[Cy-PNP] (bis(2-dicyclohexylphosphinophenyl)amine), H[iPr-NP] (N-(2-diphenylphosphinophenyl)-2,6-diisopropylaniline), and H[Me-NP] (N-(2-diphenylphosphinophenyl)-2,6-dimethylaniline) have been synthesized in high yield. Lithiation of these compounds with n-BuLi in ethereal solutions afforded the corresponding lithium complexes. The metathetical reactions of MCl4(THF)2 (M = Zr, Hf) with [iPr-NP]Li(THF)2 or [Me-NP]Li(THF)2 in toluene produced the corresponding [iPr-NP]MCl3(THF) and [Me-NP]2MCl2, respectively, in high yield. In contrast, attempts to prepare [Me-NP]MCl3(THF) and [iPr-NP]2MCl2 led to the concomitant formation of mono- and bis-ligated complexes, from which purification proved rather ineffective. The solution and solid-state structures of [iPr-NP]MCl3(THF) and [Me-NP]2MCl2 were studied by multinuclear NMR spectroscopy and X-ray crystallography. Treatment of PdCl2(PhCN)2 with [iPr-NP]Li(THF)2 in THF afforded dimeric {[iPr- NP]PdCl}2, which was reacted with tricyclohexylphosphine to produce [iPr-NP]PdCl(PCy3). The two phosphorus donors in [iPr-NP]PdCl(PCy3) are mutually cis as indicated by the solution NMR and X-ray crystallographic studies. Both {[iPr-NP]PdCl}2 and [iPr-NP]PdCl(PCy3) are highly active catalyst precursors for Suzuki coupling reactions of a wide array of aryl halides, including those featuring electronically deactivated and sterically hindered characteristics. The metathetical reaction of NiCl2(DME) (DME = dimethoxyethane) with [iPr-PNP]Li(THF) and [Cy-PNP]Li(THF), respectively, produced the diamagnetic nickel complexes [iPr-PNP]NiCl and [Cy-PNP]NiCl. These nickel chloride complexes were reacted with Grignard reagents to afford thermally stable nickel alkyl and aryl complexes [iPr-PNP]NiR and [Cy-PNP]NiR (R = Me, Et, n-Bu, Ph). A series of divalent nickel alkoxo, amido, thiolate complexes [iPr-PNP]NiX and [Cy-PNP]NiX (X = OPh, NHPh, SPh) were also easily prepared. Reaction of H[Ph-PNP] with Ni(COD)2 (COD = cycloocta-1,5-diene) produced the transient [Ph-PNP]NiH, which underwent COD insertion to give [Ph-PNP]Ni(£b1- cyclooctenyl). Instead, reactions of Ni(COD)2 with H[iPr-PNP] and H[Cy-PNP], respectively, afforded isolable diamagnetic complexes [iPr-PNP]NiH and [Cy-PNP]NiH without alkene insertion. The reactivity of these nickel hydride complexes was investigated.

The main theme of this thesis focuses on the preparation of palladium and platinum phosphine complexes that possess the potential to act as anti-cancer agents. The design of the complexes was based on the known compound, [Au(dppe)2]Cl which was shown to have an anti-mitochondrial mode of action on cancer cells. Major problems were experienced in the synthesis of these novel palladium and platinum compounds as the five phosphine ligands required diverse reaction conditions. Instability was the major hindrance as decomposition occurred during purification. This led to the substitution of the counter-ion (Cl-) with PF6-. The complexes prepared in this study were varied in lipophilicity as the gold complex was found to be non-selective due to high lipophilicity. In total, six compounds were prepared, purified and tested for potency against a panel of cancer cell lines as well as normal cells. The most lipophilic compound, [Au(dppe)2]Cl, was non-selective as it exhibited the highest toxicity to both cancerous and normal cells. In general, in vitro studies showed that palladium complexes were more toxic than the platinum analogues. These novel compounds were also non-toxic to both resting and stimulated lymphocytes signifying high selectivity for cancer cells. Three compounds, Pg 3, Pg 4a and Pg 8 exhibited high toxicity and were hence tested as such on murine cancer cell lines. Pg 8, with intermediate lipophilicity, showed toxicity against a larger number of cancer cell lines and this led to further investigations in an attempt to determine its mode of action. Analysis of the effects of Pg 8 on the mitochodria showed that it did not depolarise the mitochondrial membrane potential. A seven day analysis showed that while it did not have any effect on the mitochondrial membrane potential, it depolarised the plasma membrane potential from day 4. In contrast, [Au(dppe)2]Cl depolarised the mitochondrial membrane potential as expected. Pg 8 was shown to induce apoptosis and necrosis on Jurkat cells after exposure for 48 h. It was also shown to induce cell cycle arrest (after 48 h) as it caused blockade in the S-phase. In contrast, [Au(dppe)2]Cl caused a blockade in the G0/G1 phase. Uptake studies with radiolabelled Pg 8, [103Pd(d2pyrpe)2][PF6]2, showed that it accumulated significantly in Jurkat cells. Biodistribution studies in Wistar rats demonstrated that it was mostly taken up in the spleen followed by the liver. However, it was excreted faster than [198Au(dppe)2]Cl as this latter compound accumulated significantly in the lungs followed by the spleen, small intestine and liver. Acute toxicity studies in Balb/c mice showed that Pg 8 was less toxic than [Au(dppe)2]Cl. The latter compound (at 3 and 6 ìM) caused a significant reduction of total body weight over a 5-day period. Toxicity was evident as it was also shown to cause elevation of liver enzymes (AST and GGT), contrary to the results obtained from the mice treated with Pg 8 (at 3, 6, 12 and 15 ìM). Preparation of a patent for the synthesis as well as anti-cancer properties of the novel compound, [Pd(d2pyrpe)2][PF6]2 (Pg 8) is currently in progress. Copyright / Thesis (PhD)--University of Pretoria, 2009. / Pharmacology / unrestricted

FRANCISCO, Thiago dos Santos. Complexos fosfínicos de rutênio com ligantes o-fenilênicos: síntese, caracterização e aplicação como catalisadores em reação de hidrogenação. 2010. 124 f. Dissertação (Mestrado em química)- Universidade Federal do Ceará, Fortaleza-CE, 2010. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-10-11T18:28:09Z No. of bitstreams: 1 2010_dis_tsfrancisco.pdf: 5070327 bytes, checksum: 96a27bf25acf9e571ef8c69702f2c2da (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2016-10-11T23:46:52Z (GMT) No. of bitstreams: 1 2010_dis_tsfrancisco.pdf: 5070327 bytes, checksum: 96a27bf25acf9e571ef8c69702f2c2da (MD5) / Made available in DSpace on 2016-10-11T23:46:52Z (GMT). No. of bitstreams: 1 2010_dis_tsfrancisco.pdf: 5070327 bytes, checksum: 96a27bf25acf9e571ef8c69702f2c2da (MD5) Previous issue date: 2010 / The dependence on the experimental conditions of the production of phosphine ruthenium complexes containing o-phenylene ligands was analyzed in this work. The reaction between mer-[RuIIICl3(dppb)(H2O)] and [RuIICl2(dppb)(PPh3)] starting complexes, where dppb = 1,4-bis(diphenylphosphine)butane and PPh3 = triphenilphosphine, and 4-cloro-1,2-phenylenediamine (opda-Clcat), 3,3’,4,4’-tetraaminebiphenyl (tabcat,cat), benzenedithiol (bzditiolcat), and 9,10-phenantrequinone (fenantq) species resulted in the production of trans-[RuIICl2(dppb)(opda-Clcat)], cis-[RuIICl2(dppb)(opda-Clq)], trans-[RuIICl2(dppb)(tabq,cat)], cis-[RuIICl2(dppb)(tabq,cat)], trans-[RuIICl2(dppb)(Bzditiolcat)], and trans-[RuIICl2(dppb)(fenantq)] complexes. These compounds were characterized by means of electrochemical techniques, electronic and vibrational spectroscopies, and 31P{1H} nuclear magnetic resonance. The 31P{1H} NMR technique allowed the determination of the cis and trans isomers based on correlation with previously reported data and with the isolated compounds from the syntheses made from the [RuIICl2(dppb)(PPh3)] reduced starting complex. The mechanistic scheme for the reaction between the mer-[RuIIICl3(dppb)(H2O)] complex and the opda-Clcat ligand was proposed based on kinetics experiments acquired by using stopped-flow technique. In accordance with the kinetic results, there is the suggestion of the formation of a binuclear intermediate whose metal centers are reduced through an intra-molecular electron transfer process where the ligand is oxidized. This conclusion reinforces the results reported in the literature for the opda ligand. All the synthesized complexes presented catalytic activity toward the hydrogenation reaction of acetophenone molecule. Among these, based on preliminary results, the cis-[RuIICl2(dppb)(opda-Clq)], trans-[RuIICl2(dppb)(tabq,cat)], and cis-[RuIICl2(dppb)(tabq,cat)] complexes presented a conversion of 100%. Although a more careful study should be done, this result suggests that these compounds are able to act as catalysts in reduction reaction of polar double bonding. / A influência das condições reacionais na formação de complexos fosfínicos de rutênio com ligantes o-fenilênicos foram estudadas neste trabalho. A reação dos complexos mer-[RuIIICl3(dppb)(H2O)] e [RuIICl2(dppb)(PPh3)], onde dppb = 1,4-bis(difenilfosfina)butano e PPh3 = trifenilfosfina, e os ligantes o-fenilênicos 4-cloro-1,2-fenilenodiamina (opda-Clcat), 3,3’,4,4’-tetraaminobifenil (tabcat,cat), benzenoditiol (bzditiolcat) e 9,10-fenantrequinona (fenantq) resultaram na formação dos complexos trans-[RuIICl2(dppb)(opda-Clcat)], cis-[RuIICl2(dppb)(opda-Clq)], trans-[RuIICl2(dppb)(tabq,cat)], cis-[RuIICl2(dppb)(tabq,cat)], trans-[RuIICl2(dppb)(Bzditiolcat)] e trans-[RuIICl2(dppb)(fenantq)]. A caracterização destas espécies foi realizada por técnicas eletroquímicas, espectroscopias eletrônica e vibracional e ressonância magnética nuclear de 31P{1H}. A técnica de RMN 31P{1H} permitiu a identificação dos isômeros cis e trans dos complexos sintetizados através de comparação com dados da literatura e com espectros obtidos para os produtos isolados a partir do complexo reduzido, [RuIICl2(dppb)(PPh3)]. A proposta mecanística para a reação entre o complexo mer-[RuIIICl3(dppb)(H2O)] e o ligante opda-Clcat foi baseada em experimentos cinéticos obtidos através da técnica de stopped-flow. De acordo com os resultados cinéticos, há a sugestão de formação de um intermediário binuclear cujos centros metálicos são reduzidos através de um processo de transferência de elétrons intramolecular onde o ligante sofre oxidação. Esta conclusão reforça os resultados reportados na literatura para o ligante opda. Todos os complexos sintetizados apresentaram atividade catalítica em relação à reação de hidrogenação da molécula de acetofenona sendo que, de acordo com os ensaios realizados, os complexos cis-[RuIICl2(dppb)(opda-Clq)], trans-[RuIICl2(dppb)(tabq,cat)] e cis-[RuIICl2(dppb)(tabq,cat)] apresentaram uma conversão de 100%. Embora seja necessário um estudo mais criterioso, este resultado sugere que estes compostos podem atuar como catalisadores de reação de redução de duplas ligações polares.

No description available.

CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / The dependence on the experimental conditions of the production of phosphine ruthenium complexes containing o-phenylene ligands was analyzed in this work. The reaction between mer-[RuIIICl3(dppb)(H2O)] and [RuIICl2(dppb)(PPh3)] starting complexes, where dppb = 1,4-bis(diphenylphosphine)butane and PPh3 = triphenilphosphine, and 4-cloro-1,2-phenylenediamine (opda-Clcat), 3,3â,4,4â-tetraaminebiphenyl (tabcat,cat), benzenedithiol (bzditiolcat), and 9,10-phenantrequinone (fenantq) species resulted in the production of trans-[RuIICl2(dppb)(opda-Clcat)], cis-[RuIICl2(dppb)(opda-Clq)], trans-[RuIICl2(dppb)(tabq,cat)], cis-[RuIICl2(dppb)(tabq,cat)], trans-[RuIICl2(dppb)(Bzditiolcat)], and trans-[RuIICl2(dppb)(fenantq)] complexes. These compounds were characterized by means of electrochemical techniques, electronic and vibrational spectroscopies, and 31P{1H} nuclear magnetic resonance. The 31P{1H} NMR technique allowed the determination of the cis and trans isomers based on correlation with previously reported data and with the isolated compounds from the syntheses made from the [RuIICl2(dppb)(PPh3)] reduced starting complex. The mechanistic scheme for the reaction between the mer-[RuIIICl3(dppb)(H2O)] complex and the opda-Clcat ligand was proposed based on kinetics experiments acquired by using stopped-flow technique. In accordance with the kinetic results, there is the suggestion of the formation of a binuclear intermediate whose metal centers are reduced through an intra-molecular electron transfer process where the ligand is oxidized. This conclusion reinforces the results reported in the literature for the opda ligand. All the synthesized complexes presented catalytic activity toward the hydrogenation reaction of acetophenone molecule. Among these, based on preliminary results, the cis-[RuIICl2(dppb)(opda-Clq)], trans-[RuIICl2(dppb)(tabq,cat)], and cis-[RuIICl2(dppb)(tabq,cat)] complexes presented a conversion of 100%. Although a more careful study should be done, this result suggests that these compounds are able to act as catalysts in reduction reaction of polar double bonding. / A influÃncia das condiÃÃes reacionais na formaÃÃo de complexos fosfÃnicos de rutÃnio com ligantes o-fenilÃnicos foram estudadas neste trabalho. A reaÃÃo dos complexos mer-[RuIIICl3(dppb)(H2O)] e [RuIICl2(dppb)(PPh3)], onde dppb = 1,4-bis(difenilfosfina)butano e PPh3 = trifenilfosfina, e os ligantes o-fenilÃnicos 4-cloro-1,2-fenilenodiamina (opda-Clcat), 3,3â,4,4â-tetraaminobifenil (tabcat,cat), benzenoditiol (bzditiolcat) e 9,10-fenantrequinona (fenantq) resultaram na formaÃÃo dos complexos trans-[RuIICl2(dppb)(opda-Clcat)], cis-[RuIICl2(dppb)(opda-Clq)], trans-[RuIICl2(dppb)(tabq,cat)], cis-[RuIICl2(dppb)(tabq,cat)], trans-[RuIICl2(dppb)(Bzditiolcat)] e trans-[RuIICl2(dppb)(fenantq)]. A caracterizaÃÃo destas espÃcies foi realizada por tÃcnicas eletroquÃmicas, espectroscopias eletrÃnica e vibracional e ressonÃncia magnÃtica nuclear de 31P{1H}. A tÃcnica de RMN 31P{1H} permitiu a identificaÃÃo dos isÃmeros cis e trans dos complexos sintetizados atravÃs de comparaÃÃo com dados da literatura e com espectros obtidos para os produtos isolados a partir do complexo reduzido, [RuIICl2(dppb)(PPh3)]. A proposta mecanÃstica para a reaÃÃo entre o complexo mer-[RuIIICl3(dppb)(H2O)] e o ligante opda-Clcat foi baseada em experimentos cinÃticos obtidos atravÃs da tÃcnica de stopped-flow. De acordo com os resultados cinÃticos, hà a sugestÃo de formaÃÃo de um intermediÃrio binuclear cujos centros metÃlicos sÃo reduzidos atravÃs de um processo de transferÃncia de elÃtrons intramolecular onde o ligante sofre oxidaÃÃo. Esta conclusÃo reforÃa os resultados reportados na literatura para o ligante opda. Todos os complexos sintetizados apresentaram atividade catalÃtica em relaÃÃo à reaÃÃo de hidrogenaÃÃo da molÃcula de acetofenona sendo que, de acordo com os ensaios realizados, os complexos cis-[RuIICl2(dppb)(opda-Clq)], trans-[RuIICl2(dppb)(tabq,cat)] e cis-[RuIICl2(dppb)(tabq,cat)] apresentaram uma conversÃo de 100%. Embora seja necessÃrio um estudo mais criterioso, este resultado sugere que estes compostos podem atuar como catalisadores de reaÃÃo de reduÃÃo de duplas ligaÃÃes polares.

The major topics discussed are all relevant to the bright phosphorescent emissions of coinage metal complexes (Cu(I), Ag(I) and Au(I)) with an explanation of the theoretical background, computational results and ongoing work on the application in materials and optoelectronic devices. Density functional computations have been performed on the majority of the discussed complexes and determined that the most significant distortion that occurs in Au(I)-phosphine complexes is a near and beyond a T-shape within the P-Au-P angle when the complexes are photoexcited to the lowest phosphorescent excited state. The large distortion is experimentally qualified with the large Stokes' shift that occurs between the excitation and emission spectra and can be as large as 18 000 cm-1 for the neutral Au(I) complexes. The excited state distortion has been thoroughly investigated and it is determined that not only is it pertinent to the efficient luminescence but also for the tunability in the emission. The factors that affect tunability have been determined to be electronics, sterics, rigidity of solution and temperature. The luminescent shifts determined from varying these parameters have been described systematically and have revealed emission colors that span the entire visible spectrum. These astounding features that have been discovered within studies of coinage metal phosphorescent complexes are an asset to applications ranging from materials development to electronics.

Im ersten Teil der Arbeit wird die Synthese neopentyl- und neosilylsubstituierter Phosphane zur Verwendung als Liganden in katalytisch aktiven Palladiumkomplexen beschrieben. Die Aktivität wurde in der Suzuki-Miyaura Kreuzkupplungsreaktion getestet. Während die neosilylsubstituierten Phosphane 2:1 Addukte (5b und 5d) mit geeigneten Palladiumsalzen bilden, welche moderate Katalyseaktivität zeigen, untergehen die neopentylsubstituierten Komplexe schnelle Cyclometalierungsreaktionen in Gegenwart von Basen und bilden die katalytisch wenig aktiven Palladacyclen (6a, 6e, and 6g). Die deaktivierende Cylometallierung konnte durch Darstellung der Palladiumcomplexe ausgehend von Pd(cod)Cl2 in Abwesenheit von Basen vermieden werden. Die erhaltenen 2:1 Phosphaneaddukte zeigten deutlich verbesserte Aktivität. Daraus wurde geschlossen, dass die Cyclomettalierung als Nebenreaktion eine wichtige Deaktiverungsmöglichkeit darstellt, diese Überlegung veranlasste uns Trialkylphosphane mittlerer Größe, mit Substituenten die nur schwer eine Cyclometallierungen eingehen können zu testen. Die Verwendung der Phosphoniumsalze 4h (R = Cy, R‘ = neopentyl) und 4m (R = iPr, R‘ = CH2Cy) führt zu höheren Aktivitäten in der Suzuki-Miyaura Kreuzkupplung, als bestes Katalysatorsystem hat sich die Kombination aus Pd2(dba)3 oder Pd(OAc)2 und entsprechendem Phosphoniumsalz ergeben. Im zweiten Teil dieser Arbeit werden Synthesen zu neuen biphenylbasierten Diphosphanen (70, 71, 76, and 77) vorgestellt. Die Palladiumkomplexe wurden ebenfalls auf ihre Eignung als Katalysatoren in palladiumkatalysierten Suzuki-Miyaura Kreuzkupplungen getestet und zeigen für diese Klasse von Komplexen gute Aktivität. Das Tetraphosphan 82 wurde für die Synthese des zweikernigen Palladium(II)-komplex 83 eingesetzt. Durch die Koordination des D2h-symmetrischen Tetraphosphanes an die Palladiumatome wird die Symmetrie des Moleküls erniedrigt und folglich erhält man den formal D2-symmetrischen Komplex 83. / In the first part of this thesis, the synthesis and catalytic activity of neopentyl and neosilyl substituted phosphine palladium complexes is described. The complexes have been tested in the Suzuki-Miyaura cross-coupling reaction. Whereas the neosilyl substituted phosphines form 2:1 adducts (5b and 5d) with Palladium salts which showed moderate activity, the neopentyl complexes quickly undergo cyclometallation in presence of bases to form Palladacycles (6a, 6e, and 6g) which showed only moderate catalytic activity. Cyclometallation could be avoided by the preparation starting from Pd(cod)Cl2 in the absence of bases. The obtained 2:1 phosphine adducts showed superior activity. We concluded that cyclometallation process is an important deactivation pathway, this prompted us to test trialkyl phosphine ligands with medium size but substituents not reliable to cyclometallation. We have been pleased to find that 4h (R = Cy, R‘ = neopentyl) and 4m (R = iPr, R‘ = CH2Cy) showed good activity in the Suzuki-Miyaura cross-coupling reaction. The best results have been obtained by in situ preparation of active catalyst from Pd2(dba)3 or Pd(OAc)2 and the appropriate phosphonium salt. In the second part of this thesis, the first synthesis of a new family of biphenyl based bisphosphine ligands (70, 71, 76, and 77) has been reported. Their palladium complexes were successfully tested as catalyst in the Suzuki cross-coupling reaction. Within the class of bisphosphine based palladium complexes they show good activity in Suzuki-Miyaura cross-coupling reaction. Systematically, was expanded our synthesis strategy and we were able to introduce the first synthesis of a highly symmetric 2,2',6,6'-tetraphosphinobiphenyl. Tetraphosphine 82 was used as ligand in a dinuclear palladium(II) complex 83. Upon complexation the D2h symmetric 2,2’,6,6’-tetraphosphine lead to a chiral D2 symmetric complex 83.

Im ersten Teil der Arbeit wird die Synthese neopentyl- und neosilylsubstituierter Phosphane zur Verwendung als Liganden in katalytisch aktiven Palladiumkomplexen beschrieben. Die Aktivität wurde in der Suzuki-Miyaura Kreuzkupplungsreaktion getestet. Während die neosilylsubstituierten Phosphane 2:1 Addukte (5b und 5d) mit geeigneten Palladiumsalzen bilden, welche moderate Katalyseaktivität zeigen, untergehen die neopentylsubstituierten Komplexe schnelle Cyclometalierungsreaktionen in Gegenwart von Basen und bilden die katalytisch wenig aktiven Palladacyclen (6a, 6e, and 6g). Die deaktivierende Cylometallierung konnte durch Darstellung der Palladiumcomplexe ausgehend von Pd(cod)Cl2 in Abwesenheit von Basen vermieden werden. Die erhaltenen 2:1 Phosphaneaddukte zeigten deutlich verbesserte Aktivität. Daraus wurde geschlossen, dass die Cyclomettalierung als Nebenreaktion eine wichtige Deaktiverungsmöglichkeit darstellt, diese Überlegung veranlasste uns Trialkylphosphane mittlerer Größe, mit Substituenten die nur schwer eine Cyclometallierungen eingehen können zu testen. Die Verwendung der Phosphoniumsalze 4h (R = Cy, R‘ = neopentyl) und 4m (R = iPr, R‘ = CH2Cy) führt zu höheren Aktivitäten in der Suzuki-Miyaura Kreuzkupplung, als bestes Katalysatorsystem hat sich die Kombination aus Pd2(dba)3 oder Pd(OAc)2 und entsprechendem Phosphoniumsalz ergeben. Im zweiten Teil dieser Arbeit werden Synthesen zu neuen biphenylbasierten Diphosphanen (70, 71, 76, and 77) vorgestellt. Die Palladiumkomplexe wurden ebenfalls auf ihre Eignung als Katalysatoren in palladiumkatalysierten Suzuki-Miyaura Kreuzkupplungen getestet und zeigen für diese Klasse von Komplexen gute Aktivität. Das Tetraphosphan 82 wurde für die Synthese des zweikernigen Palladium(II)-komplex 83 eingesetzt. Durch die Koordination des D2h-symmetrischen Tetraphosphanes an die Palladiumatome wird die Symmetrie des Moleküls erniedrigt und folglich erhält man den formal D2-symmetrischen Komplex 83. / In the first part of this thesis, the synthesis and catalytic activity of neopentyl and neosilyl substituted phosphine palladium complexes is described. The complexes have been tested in the Suzuki-Miyaura cross-coupling reaction. Whereas the neosilyl substituted phosphines form 2:1 adducts (5b and 5d) with Palladium salts which showed moderate activity, the neopentyl complexes quickly undergo cyclometallation in presence of bases to form Palladacycles (6a, 6e, and 6g) which showed only moderate catalytic activity. Cyclometallation could be avoided by the preparation starting from Pd(cod)Cl2 in the absence of bases. The obtained 2:1 phosphine adducts showed superior activity. We concluded that cyclometallation process is an important deactivation pathway, this prompted us to test trialkyl phosphine ligands with medium size but substituents not reliable to cyclometallation. We have been pleased to find that 4h (R = Cy, R‘ = neopentyl) and 4m (R = iPr, R‘ = CH2Cy) showed good activity in the Suzuki-Miyaura cross-coupling reaction. The best results have been obtained by in situ preparation of active catalyst from Pd2(dba)3 or Pd(OAc)2 and the appropriate phosphonium salt. In the second part of this thesis, the first synthesis of a new family of biphenyl based bisphosphine ligands (70, 71, 76, and 77) has been reported. Their palladium complexes were successfully tested as catalyst in the Suzuki cross-coupling reaction. Within the class of bisphosphine based palladium complexes they show good activity in Suzuki-Miyaura cross-coupling reaction. Systematically, was expanded our synthesis strategy and we were able to introduce the first synthesis of a highly symmetric 2,2',6,6'-tetraphosphinobiphenyl. Tetraphosphine 82 was used as ligand in a dinuclear palladium(II) complex 83. Upon complexation the D2h symmetric 2,2’,6,6’-tetraphosphine lead to a chiral D2 symmetric complex 83.