Trianionic pincer ligands are an emerging class of ligands that constrain three anionic metal-ligand bonds to the meridonal plane and are capable of supporting highly reactive metal species exploitable for alkene and alkyne polymerization.  Treating CrMeCl2(THF)3 with the dilithio salt pincer ligand precursor {[2,6-iPrNCHN]Li2}2 (1 ) provides the CrIV complex [2,6-iPrNCN]CrIV(Me)THF (2 ) supported by the NCN3- trianionic pincer ligand.  Upon activation with triisobutylaluminum (35 equiv.), complex 2  polymerizes ethylene with catalytic activities up to 7.02x106 g PE (molCr)-1h-1.  Treating (tBuO)3W=CC(CH3)3 with [tBuOCO]H3  (3 ) followed by Ph3P=CH2 then MeOTf provides the first trianionic ligand supported alkylidyne complex [tBuOCO]W=CC(CH3)3(THF) (4 ).  Complex 4  is an active catalyst for the polymerization of functionalized phenyacetylenes (4-RC6H5C=CH, R = H, F, OMe).  Using 4-fluorophenylacetylene, complex 4  (cat. loading = 0.02%) achieves an 87% yield and TON = 4.3x103.

Trianionic NCN<sup>3-</sup> pincer complex of chromium and OCO<sup>3-</sup> pincer complex of tungsten: Catalysts for alkene and alkyne polymerization

243rd National Meeting (2012)

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Trianionic NCN3- pincer complex of chromium and OCO3- pincer complex of tungsten: Catalysts for alkene and alkyne polymerization

Trianionic NCN^3- pincer complex of chromium and OCO^3- pincer complex of tungsten: Catalysts for alkene and alkyne polymerization