A Coordination Compound of Ge⁰ Stabilized by a Diiminopyridine Ligand

Abstract

Reduction of the cationic Ge(II) complex [dimpyrGeCl][GeCl3] (dimpyr=2,6-(ArN=CMe)2NC5H3, Ar=2,6-iPr2C6H3) with potassium graphite in benzene affords an air sensitive, dark green compound of Ge(0), [dimpyrGe], which is stabilized by a bis(imino)pyridine platform. This compound is the first example of a complex of a zero-valent Group 14 element that does not contain a carbene or carbenoid ligand. This species has a singlet ground state. DFT studies revealed partial delocalization of one of the Ge lone pairs over the π*(C=N) orbitals of the imines. This delocalization results in a partial multiple-bond character between the Ge atom and imine nitrogen atoms, a fact supported by the X-ray crystallography and IR spectroscopy data.

Tetrylones: An Intriguing Class of Monoatomic Zero‐valent Group 14 Compounds

“…The molecular structure of 25 (Figure ) revealed a N‐Ge‐N bond angle of 152.76(8)° and that the Ge−N bond length (2.047(7) Å) is shorter than that of the Ge−N* bond (2.306(7) Å). Moreover, the N−C bond length was elongated to 1.320(2) Å, which supports the decreasing multiple‐bond character that was observed by IR spectroscopy …”

“…The frontier molecular orbitals of 25 (Figure ) show that the HOMO of the singlet state corresponds to a diffuse π‐type orbital positioned at the germanium atom. This orbital spans the two bridging imine nitrogen atoms and includes back‐bonding interactions between the 4p orbital of the germanium atom and the 2p orbital of the pyridine nitrogen atom . In addition, the HOMO exhibits a contribution from an antibonding interaction across the iminoacyl (N=C) bond, which is consistent with the elongation of the C=N bond observed by X‐ray crystallography and the redshift of the imine (C=N) stretching vibration in the IR spectrum.…”

“…The ability of bis(imino)pyridine ligands to stabilize transition metals in low oxidation states is well‐documented . Nikonov and co‐workers have reported a germanium(0) compound that is stabilized by such a bis(imino)pyridine ligand . Treatment of bis(imino)pyridine 23 with two molar equivalents of GeCl 2 ⋅dioxane cleanly generated salt 24 (Scheme ), which was reduced with two molar equivalents of KC 8 in benzene to afford germylone 25 as a dark green solid (Scheme ) .…”

“… Plots of the HOMO (a) and HOMO−1 (b) of 25 , calculated at the B3PW91/3–21G (6–311G(3d) for Ge) level of theory.…”

Stabilization of Heterodiatomic SiC Through Ligand Donation: Theoretical Investigation of SiC(L)2 (L=NHCMe, CAACMe, PMe3)

“…[1] Thevariety of ligands available nowadays and their tunable chemical features,such as s-donor and p-acceptor character and singlet-triplet gap,h ave proven to be tremendously useful to achieve synthetic accomplishments. L(n = 1, 2), where E n is C 1 , [2] Si 1 , [3] Ge 1 , [4] B 2 , [5] C 2 , [6] Si 2 , [7] Ge 2 , [8] Sn 2 , [9] P 2 , [10] and As 2 . L(n = 1, 2), where E n is C 1 , [2] Si 1 , [3] Ge 1 , [4] B 2 , [5] C 2 , [6] Si 2 , [7] Ge 2 , [8] Sn 2 , [9] P 2 , [10] and As 2 .…”