• Guddekoppa S Ananthnag

      Articles written in Journal of Chemical Sciences

    • Allyl functionalized phosphinite and phosphonite ligands: Synthesis, transition metal chemistry and orthopalladation reactions

      Singappagudem Govindaraju Guddekoppa S Ananthnag Susmita Naik Shaikh M Mobin Maravanji S Balakrishn

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      Allyl functionalized phosphinite PPh2(OAr) [Ar=C6H4(𝑜-C3H5)] (1) and phosphonite PPh(OAr)2 (2) ligands were prepared by the reactions of 2-allylphenol with PPh2Cl and PPhCl2, respectively. The ruthenium(II) complexes, [Ru($\eta^6$-𝑝-cymene)(PPh2(OAr))Cl2] (3) and [Ru($\eta^6$-𝑝-cymene)(PPh(OAr)2Cl2)] (4) were obtained by reacting 1 or 2 with [Ru($\eta^6$-𝑝-cymene)Cl2]2 in 2:1 molar ratios, respectively. Reactions of 1 or 2 with AuCl(SMe2) gave [Au{PPh2(OAr)}Cl] (5) or [Au{PPh(OAr)2}Cl] (6) in good yield. The palladium complex, [Pd{PPh(OAr)2}2Cl2] (7) was prepared by reacting Pd(COD)Cl2 with 2 in 1:2 molar ratio. The reaction between Pd(COD)Cl2 and 1 yielded a mixture of orthopalladated cis- and trans-[Pd(Ph2P(OAr))Cl]2 (8a and 8b). The treatment of 8 with PPh3 and Ph2PCH2PPh2 resulted in the cleavage of chloro bridge to give respectively, [Ph2(OAr)PPd(PPh3)Cl] (9) and [Ph2(ArO)PPd($\eta^2$-dppm)]OTf (10). Single crystal X-ray structure of the ruthenium complex 3 is described.

    • A mixed-valent cyclodiphosphazane: Transition metal chemistry and cis/trans isomerisation

      Guddekoppa S Ananthnag Joel T Mague Maravanji S Balakrishna

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      The hydrolysis of cis-{ClP(𝜇-N$^t$Bu)2P(NH$^t$Bu)} (1) produced a mixed PIII/PV derivative of cyclodiphosphazane, cis-{($^t$BuNH)P(𝜇-N$^t$Bu)2P(O)H} (2). The treatment of 2 with elemental selenium resulted in the formation of the monoselenide, trans-{($^t$BuNH)P(Se)(𝜇-N$^t$Bu)2P(O)H} (3) in good yield. The reactions of two equivalent of 2 with [Pd(𝜇-Cl)(𝜂3-C3H5)]2 or [Ru(𝜂6-𝑝-cymene)(𝜇-Cl)Cl]2 in dichloromethane afforded corresponding mononuclear complexes, [(𝜂3-C3H5)PdCl{($^t$BuNH)P(𝜇-N$^t$Bu)2P(O)H}] (4) and [((𝜂6-𝑝-cymene)RuCl2){($^t$BuNH)P(𝜇-N$^t$Bu)2P(O)H}] (5). The treatment of 2 with M(COD)Cl2 (M = Pd and Pt) in dichloromethane at room temperature gave [MCl2{($^t$BuNH)P(𝜇-N$^t$Bu)2P(O)H}2] (6 M = Pd; 7 M = Pt) in good yield. Owing to the cis/trans isomerisation of the cyclodiphosphazane rings, the complexes 6 and 7 exist as a mixture of two isomers. Various NMR spectroscopic techniques were employed for structural elucidation. The molecular structures of 5 and 7 were established by single crystal X-ray crystallographic studies.

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