Bridged dinuclear tripodal tris(amido)phosphane complexes of titanium and zirconium as diligating building blocks for organometallic polymers

Article abstract of DOI:10.1002/ejic.200701015

Appropriate bridging ligands allow for the preparation of bimetallic titanium and zirconium precursors to transition-metal-containing polymers using the formally trianionic P(CH₂NAr^R)₃ ligand (where Ar^R = Ph, and 3,5-Me₂C₆H₃ for a and b, respectively). Lithiation of the known amidophosphane ligand precursors P(CH₂NHAr^R)₃ (1a,b) with 3 equiv. of nBuLi cleanly provided the diethyl ether adducts P(CH₂NAr ^R)₃Li₃(OEt₂J_1.5 (2a,b). The THF adduct P(CH₂NPh)₃-Li₃(THF)₅ (2a-THF) was characterized by X-ray crystallography. Protonolysis reactions were used to prepare the mononuclear titanium complexes P(CH₂NAr ^R)₃TiOC₆H₄tBu (4a,b) and dinuclear species [P(CH₂NPh)₃TiNMe₂]₂-μ-4, 4′{O[3,3′,5,5′-(C₆H₂Me₂) ₂]O} (5a), [P(CH₂NPh)₃Ti]₂(μ-O) (6a), and P(CH₂N-3,5-Me₂C₆H₃) ₃Ti-μ-O-Ti(NMe₂)₃ (7b), from P(CH ₂NAr^R)₃TiNMe₂. The reactions of 1a,b with Zr(NEt₂)₄ afforded metal complexes of the type P(CH₂NAr^R)₃ZrNEt₂ (8a,b). The chloride complexes P(CH₂NAr^R)₃ZrCl(THF) (9a,b) were prepared by treatment of HNEt₃Cl with 1 or 2. The complexes 9a,b reacted with cyclopentadienyllithium (C₅H₅Li) to produce P(CH₂NAr^R)₃ZrCp (10a,b), which were also prepared by the reactions of the lithium salts 2a,b with CpZrCl₃. The dilithium salt of the fulvalene dianion (Li₂C₁₀H ₈) reacts with 9a,b to produce the dinuclear complexes trans-[P(CH₂NAr^R)₃Zr]₂(μ- η⁵:η⁵ -C₁₀H₈) (10a,b), respectively. The facile preparation of transition-metal-containing polymers from the bridged dinuclear complexes was illustrated by the reaction of 6a with half an equivalent of [Rh(CO)₂(μ-Cl)]₂, which precipitated polymeric Cl(CO)Rh[P(CH₂NPh)₃Ti] ₂(μ-O). Wiley-VCH Verlag GmbH & Co. KGaA, 2008.