Chemistry of reduced monomeric and dimeric cobalt complexes supported by a PNP pincer ligand

Sergio S Rozenel; Rosa Padilla; John Arnold

doi:10.1021/ic4018882

Chemistry of reduced monomeric and dimeric cobalt complexes supported by a PNP pincer ligand

Inorg Chem. 2013 Oct 7;52(19):11544-50. doi: 10.1021/ic4018882. Epub 2013 Sep 19.

Authors

Sergio S Rozenel¹, Rosa Padilla, John Arnold

Affiliation

¹ Department of Chemistry, University of California , Berkeley, California 94720, United States.

PMID: 24050728
DOI: 10.1021/ic4018882

Abstract

The reduction chemistry of cobalt complexes with HPNP (HPNP = HN(CH2CH2P(i)Pr2)2) as a supporting ligand is described. Reaction of [(HPNP)CoCl2] (1) with n-BuLi generated both the deprotonated Co(II) species [(PNP)CoCl] (2) along with the Co(I) complex [(HPNP)CoCl] (3). Products resulting from reduction of 2 with KC8 vary depending upon the atmosphere under which the reduction is performed. Monomeric square planar [(PNP)CoN2] (4) is obtained under dinitrogen, whereas dimeric [(PNP)Co]2 (5) is formed under argon. Over time, 5 activates a C-H bond in the PNP ligand to form the species [Co(H)(μ-PNP)(μ-(i)Pr2PCH2CH2NCHCH2P(i)Pr2)Co] (6). We also observed the oxidative addition of H-Si bond to complex 3 to form [(HPNP)CoCl(H)SiH2Ph] (7). (1)H NMR studies showed that species 7 is in equilibrium with 3 and silane in solution. Complex 3 can be oxidized with AgBPh4 to generate {(HPNP)CoCl}BPh4 (8), a square planar species with a formal electron count of 15 electrons.