New ligands: Design and coordination chemistry with the transition metals and lanthanides

This thesis deals with three different topics: (i) The synthesis and characterization of cyclopentadienyldiphosphine complexes of zirconium(III), niobium(III), and molybdenuin(III). (ii) The synthesis and characterization of the p -arene complexes of lanthanides. (iii) Coordination chemistry and catalytic activity of mixed donor ligands based on sp2-hybridized nitrogen donors.;The first topic illustrates the organometallic chemistry of the trivalent second row transition metals. With the cyclopentadienyldiphosphine ligand h5 -C5 H3 -1,3 - SiMe2CH2 PR2 2- abbreviated as PR 2Cp where R = i- Pr and Ph. The Zr(IV) complex undergoes reduction with Na/Hg to form the trivalent Zr dichloro complex, which takes part in a metathetical reaction with MeMgBr to yield Pi- Pr2 CpZrMeCl . The reaction of the dichloro complex with excess carbon monoxide results in the disproportionation of the Zr(III) complex to a Zr(IV) complex and a ZR(II) compound. This reaction is reversible.;The niobium(III) starting material (NbCl3(DME)) reacts with [RP2Cp]Li to form [RP2Cp]NbCl 2. These complexes are low spin and diamagnetic. Nb(IV) derivatives are formed via the reaction of [RP2Cp]NbCl 2 with PbCl2 or with PhNCO. These Nb(IV) derivatives are EPR active and their solid state molecular structures show distorted octahedral geometries around the Nb center.;When MoCl3(THF)3 reacts with [RP 2Cp]Li the corresponding Mo(III) complexes of the [RP 2Cp] ligand, [RP2Cp]MoCl2 are formed. These compounds are low-spin, paramagnetic complexes. Their solid state molecular structures show that they stool complexes.;The second topic deals with the formation of the p -arene complexes of the lanthanides incorporating the diamidodiphosphine macrocycle [PhP(CH2SiMe3NSiMe3CH2)PPh] -2 ([P2N2]) as the ancillary ligand. LnCl 3(THF)3 reacts with Li2[P2N2] to form dimeric complexes P2 N2Ln 2m -Cl 2 Ln = Y, Yb, and Lu. It is shown that when P2 N2Y 2m -Cl 2 reacts with biphenyl lithium, a dinuclear complex is formed that is bridged by a bisbiphenyl unit. The [P2N2]Y fragments are p -coordinated to the two middle rings of the bisbiphenyl moiety on the opposite faces. A fluxional process exists in which the two [P2N 2]Y units traverse along all four of the rings.; P2 N2Ln 2m -Cl 2 complexes also react with various polycyclic aromatic hydrocarbons under reducing conditions to form dinuclear complexes in which two [P 2N2]Ln moieties are h4 coordinated on the opposite sides of the different rings of the polycyclic aromatic units. These compounds are fluxional in solution.;Mixed pyridine-oxazoline bidentate ligands 2-(2-oxazolin-2-ylmethyl)pyridine (pymox) are synthesized by the condensation of the appropriate aminoalcohol with 2-pyridylacetonitrile. When 1-methyl-2-amino-1-propanol is used the product is an achiral ligand, Me-pymox. Chirality is introduced at the carbon center next to the nitrogen donor on the oxazoline ring by using chiral aminoalcohols. These ligands react with Rh(I) starting material [Rh(COD)(THF)2]PF 6 to form [Rh(COD)(pymox)]PF6 complexes.;The coordination chemistry of pymox ligands with Pd(II) are also examined. (Abstract shortened by UMI.).