title: Analysis of the bonding between two M(μ-NAr(#)) monomers in the dimeric metal(II) imido complexes {M(μ-NAr(#))}2 [M = Si, Ge, Sn, Pb; Ar(#) = C6H3-2,6-(C6H2-2,4,6-R3)2]. The stabilizing role played by R = Me and iPr.
abstract: The nature of the bonding between the two M(μ-NAr(#)) imido monomers [M = Si, Ge, Sn, Pb; Ar(#) = C6H3-2,6-(C6H2-2,4,6-R3)2; R = Me, iPr] in the {M(μ-NAr(#))}2 dimer is investigated with the help of a newly developed energy and density decomposition scheme as well as molecular dynamics. The approach combines the extended transition state energy decomposition method with the natural orbitals for chemical valence density decomposition scheme within the same theoretical framework. The dimers are kept together by two σ bonds and two π bonds. The σ bonding has two major contributions. The first is a dative transfer of charge from nitrogen to M. It amounts to -188 kcal/mol for {Si(μ-NAr(#))}2, -152 kcal/mol for {Ge(μ-NAr(#))}2 with -105 kcal/mol for {Sn(μ-NAr(#))}2, and -79 kcal/mol for {Pb(μ-NAr(#))}2. The second is a charge buildup within the ring made up of the two dimers. It amounts to -82 kcal/mol for M = Si with -61 kcal/mol for M = Ge and ∼-50 kcal/mol for M = Sn and Pb. We finally have π bonding with a donation of charge from M to nitrogen. It has a modest contribution of ∼-30 kcal/mol. The presence of isopropyl (iPr) groups is further shown to stabilize{M(μ-NAr(#))}2 [M = Si, Ge, Sn, Pb; Ar(#) = C6H3-2,6-(C6H2-2,4,6-iPr3)2] compared to the methylated derivatives (R = Me) through attractive van der Waals dispersion interactions.
authors: Department of Chemistry, University of Calgary , 2500 University Drive NW, T2N 1N4 Calgary, Alberta, Canada.
authors: Mateusz
authors: M
authors: Brela
authors: Artur
authors: A
authors: Michalak
authors: Philip P
authors: PP
authors: Power
authors: Tom
authors: T
authors: Ziegler