The
ability to copolymerize monomers vastly increases the range
of accessible material properties for a specific monomer. We investigate
the radical copolymerization of the lactone monomer (3-ethylidene-6-vinyltetrahydro-2H-pyran-2-one) (EVP) made from butadiene and carbon dioxide.
The unique bicyclic structure provided by the EVP unit resulted in
an elevation of the glass transition temperature across a range of
commodity polymers and enabled the incorporation of functionality
into EVP-based copolymers.
Lithium diphenyliridate complexes bearing cycloocta-1,5-diene (COD) as a ligand were synthesized by treating [IrCl(cod)] 2 with phenyllithium and subsequent recrystallization. Xray crystallographic analysis of the complexes showed both contact ion pair and solvent-separated ion pair structures depending on the coordination environment around the Li cation. Natural bond orbital analysis revealed that the anionic charge formally described on Ir efficiently delocalizes to not only the phenyl moieties but also the COD ligand. This result contrasts to the rhodium-analogues, where the anionic charge is more localized at the metal center, suggesting stronger π-back-donation from Ir to ligands than that of Rh.
Anionic
homoleptic organo–transition metal complexes can
be prepared from organolithium reagents and transition metal salts
and are key reactive intermediates in C–C bond formation. However,
the interaction between the anionic component and cationic counterparts
of multianionic homoleptic organo–transition metal complexes
in solution remains unclear, unlike well-studied monoanionic complexes
such as organocuprates. Here we have prepared and structurally characterized
lithium hexaphenylrhodate(III) and -iridate(III) complexes, [Li(12-crown-4)2][MPh6{Li(thf)}2] (M = Rh and Ir), as
the first examples of hexaaryl complexes of d6 metals.
In the crystals, two Li cations contact the trianionic MPh6 moiety, while the other exists as a solvent-separated ion pair.
In THF, hexaphenylrhodate decomposed within 1 h. In contrast, the
Ir analog was stable. 7Li NMR and X-ray absorption fine
structure analysis revealed the solution-phase structure of hexaphenyliridate,
which maintained a partially contacted ion pair structure even in
THF, a coordinating solvent.
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