Si–H Bond Activation and Dehydrogenative Coupling of Silanes across the Iron–Amide Bond of a Bis(amido)bis(phosphine) Iron(II) Complex

Abstract

Despite the utility of Si−Si bonds, there are relatively few examples of Si−Si bond formation by base metals. In this work, a four-coordinate iron complex, (PNNP)Fe II , is shown to strongly activate the Si−H bonds in primary silanes across the Fe− amide bonds in a metal−ligand cooperative fashion. Upon treatment with excess silane, Si−Si dehydrogenative homocoupling is shown to occur across the Fe−N amide bond without concomitant oxidation and spin state changes at the Fe center.

Modulation of Fe–Fe distance and spin in diiron complexes using tetradentate ligands with different flanking donors

“…Here we report the synthesis and properties of homoleptic Fe( ii ) complexes with L1 and L2 . Unlike previous examples with Ni and Ru, 13,14 and prior studies of square-planar Fe( ii ) complexes with stronger field PNNP ligands, 15 the aryl groups and donor atoms in L1 and L2 do not remain conjugated and coordinated in the same plane. Instead, they give rise to dinuclear Fe complexes with structures and spin configurations that are highly dependent on the identity of the flanking NMe 2 and SMe donor groups.…”

Z-selective dimerization of terminal alkynes by a (PNNP)FeII complex

“…This isomer shift compares favorably to related low-spin (PNNP)-ligated Fe II complexes. 25,26 Despite the activation of two C–H bonds, an overall four-electron process, these data support maintenance of the Fe II oxidation state via heterolytic cleavage of the alkyne C–H bonds across the Fe–amide bonds.…”

“…24 Our group has recently reported a square planar aryl-linked tetradentate bis(amido)bis(phosphine) Fe II complex, (PNNP)Fe (1), and its activation of B-H and Si-H bonds across the Fe-N amide bonds. 25,26 Positing that similar activity would be observed with acidic C-H bonds, we were inspired to treat 1 with terminal alkynes (pK a E 25). Herein, we report an Fe bis(phenylacetylide) complex resulting from the addition of 2 equiv.…”

Kappa what? Insights into the coordination modes of N2P2 ligands

“…82,83 The iron complex was able to activate Si-H bonds of primary silanes across the Fe-amide bonds in a metal-ligand cooperative fashion. 84 For the nickel complex, one or two phenyl groups from the triarylphosphine donors were eliminated by adding KH to yield 37, a squareplanar Ni(II) complex ligated by a tetraanionic bis(amido)/bis ( phosphido) ligand. 83 The sequential addition of various alkyl halides permitted the introduction of other substituents on the phosphine.…”