Synthetic Approaches to
(smif)2Ti (smif
= 1,3-di-(2-pyridyl)-2-azaallyl) Reveal Redox Non-Innocence and C–C
Bond-Formation

Frazier, Brenda
A.; Wolczanski, Peter T.; Keresztes, Ivan; DeBeer, Serena; Lobkovsky, Emil B.; Pierpont, Aaron W.; Cundari, Thomas R.

doi:10.1021/ic300590t.s001

ic300590t_si_001.pdf (797.43 kB)

Synthetic Approaches to (smif)₂Ti (smif = 1,3-di-(2-pyridyl)-2-azaallyl) Reveal Redox Non-Innocence and C–C Bond-Formation

journal contribution

posted on 2016-02-20, 15:28 authored by Brenda A. Frazier, Peter T. Wolczanski, Ivan Keresztes, Serena DeBeer, Emil B. Lobkovsky, Aaron W. Pierpont, Thomas R. Cundari

Attempted syntheses of (smif)₂Ti (smif =1,3-di-(2-pyridyl)-2-azaallyl) based on metatheses of TiCl_nL_m (n = 2–4) with M(smif) (M = Li, Na), in the presence of a reducing agent (Na/Hg) when necessary, failed, but several apparent Ti(II) species were identified by X-ray crystallography and multidimensional NMR spectroscopy: (smif){Li(smif-smif)}Ti (1, X-ray), [(smif)Ti]₂(μ-κ³,κ³-N,N(py)₂-smif,smif) (2), (smif)Ti(κ³-N,N(py)₂-smif,(smif)H) (3), and (smif)Ti(dpma) (4, dpma = di-2-pyridylmethyl-amide). NMR spectroscopy and K-edge XAS showed that each compound possesses ligands that are redox noninnnocent, such that d¹ Ti(III) centers AF-couple to ligand radicals: (smif){Li(smif-smif)^2–}Ti^III (1), [(smif^2–)Ti^III]₂(μ-κ³,κ³-N,N(py)₂-smif,smif) (2), [(smif^2–)Ti^III](κ³-N,N(py)₂-smif,(smif)H) (3), and (smif^2–)Ti^III(dpma) (4). The instability of (smif)₂Ti relative to its C–C coupled dimer, 2, is rationalized via the complementary nature of the amide and smif radical dianion ligands, which are also common to 3 and 4. Calculations support this contention.