The amido ligand –N(SiiPr3)DIPP (DIPP = 2,6-diisopropylphenyl) has been used to prepare two-coordinate complexes of CrI, CrII, and CrIII. The two-coordinate CrII complex has also been used to prepare a three-coordinate CrIII iodide complex, which can be used to access a stable CrIII methyl species.

The asymmetric borylation of N-tert-butanesulfinyl imines with bis(pinacolato)diboron is achieved using a Cu(II) catalyst and provides access to synthetically useful and pharmaceutically relevant α-amino boronic acid derivatives. The Cu(II)-catalyzed reaction is performed on the benchtop in air at room temperature using commercially available, inexpensive reagents at low catalyst loadings. A variety of N-tert-butanesulfinyl imines, including ketimines, react readily to provide α-sulfinamido boronate esters in good yields and with high stereoselectivity. In addition, this transformation is applied to the straightforward, telescoped synthesis of α-sulfinamido trifluoroborates.

Divalent complexes of vanadium were synthesized employing bulky silyl(aryl)amido ligands −N(Si i Pr 3 )DIPP and −N(Si t Bu 2 Me)DIPP (DIPP = 2,6-i Pr 2 C 6 H 3 ). Solid-state structural characterization revealed that although the ligand −N-(Si i Pr 3 )DIPP supports a monomeric, bis(amido) complex of vanadium, its constitutional isomer −N(Si t Bu 2 Me)DIPP affords a homoleptic complex in which the vanadium center is sandwiched between the arene rings, an unusual binding mode for arylamido ligands. Magnetometry studies indicate that V[N(Si i Pr 3 )DIPP] 2 and V[(η 5 -DIPP)N(Si t Bu 2 Me)] 2 have similar high-spin d 3 electron configurations. However, spectroscopic methods, including electron paramagnetic resonance, nuclear magnetic resonance, infrared, and UV−visible spectroscopies, in addition to cyclic voltammetry and reactivity studies, suggest that V[N(Si i Pr 3 )DIPP] 2 is stereochemically nonrigid in solution, while V[(η 5 -DIPP)N(Si t Bu 2 Me)] 2 is not. This nonrigidity explicitly impacts the reactivity of V[N(Si i Pr 3 )DIPP] 2 , which can be used to access both amido-bound and arene-bound complexes. Moreover, treatment of V[N(Si i Pr 3 )DIPP] 2 with single and multielectron oxidants reveals a range of transformations including an intramolecular sp 3 C−H bond activation.

Low-coordinate organoCr(III) complexes supported by the silylamido ligand -N(SiMe 3 )DIPP (DIPP = 2,6diisopropylphenyl) are ethylene polymerization catalyst precursors without the need of additional cocatalyst. The reaction of CrCl 3 (THF) 3 with 3 or 2 equiv. of LiN(SiMe 3 )DIPP yields either a four-membered cyclometalated Cr complex or Cr[N(SiMe 3 )DIPP] 2 Cl, respectively, with no trace of Cr[N(SiMe 3 )DIPP] 3 . Addition of 1 equiv. of LiN(SiMe 3 )DIPP to Cr[N(SiMe 3 )DIPP] 2 Cl also leads to the four-membered metallacycle, which upon heating transforms to a new sixmembered Cr metallacycle, likely via a r-bond metathesis step. Cr[N(SiMe 3 )DIPP] 2 Cl can be readily converted to bis (amido)Cr(III) vinyl and alkyl complexes Cr[N(SiMe 3 )DIPP] 2 R (R = vinyl, Bn, and Me). All of these structurally characterized low-coordinate Cr(III) complexes with a Cr-C bond initiate the polymerization of ethylene in the absence of activators or cocatalysts, producing ultra-high-molecular weight polyethylene.