Details

Autor(en) / Beteiligte

• King, Rhys P
• Greenacre, Victoria K
• Levason, William
• Dyke, John M
• Reid, Gillian

Titel

Pyramidal Dicationic Ge(II) Complexes with Homoleptic Neutral Pnictine Coordination: A Combined Experimental and Density Functional Theory Study

Ist Teil von

• Inorganic chemistry, 2021-08, Vol.60 (16), p.12100-12108

Ort / Verlag

American Chemical Society

Erscheinungsjahr

2021

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• An unusual series of Ge­(II) dicationic species with homoleptic phosphine and arsine coordination, [Ge­(L)]­[OTf]2, L = 3 × PMe3, triphos (MeC­(CH2PPh2)3), triars (MeC­(CH2AsMe2)3), or κ3-tetraphos (P­(CH2CH2PPh2)3) (OTf– = O3SCF3 –) have been prepared by reaction of [GeCl2(dioxane)] with L and 2 mol equiv of Me3SiOTf in anhydrous CH2Cl2 (or MeCN for L = triars, triphos). X-ray crystal structures are reported for [Ge­(PMe3)3]­[OTf]2, [Ge­(triars)]­[OTf]2, and [Ge­(κ3-tetraphos)]­[OTf]2, confirming homoleptic P3- or As3-coordination at Ge­(II) in each case and with the discrete OTf– anions providing a charge balance. The Ge–P/As bond lengths are significantly shorter than those in neutral germanium­(II) dihalide complexes with diphosphine or diarsine coordination. Solution NMR spectroscopic data indicate that the complexes are labile in solution. Using excess AsMe3 and [GeCl2(dioxane)] gives only the neutral product, [Ge­(AsMe2)2(OTf)2], the crystal structure of which shows four coordination at Ge­(II), via two As donor atoms and an O atom from two κ1-OTf– ligands; further weak, long-range intermolecular interactions give a chain polymer. The electronic structure of the [Ge­(PMe3)3]2+ dication has been investigated using density functional theory (DFT) calculations. The computed geometrical parameters for this dication are in good agreement with the experimental X-ray crystallographic values in [Ge­(PMe3)3]­[OTf]2. The results also indicate that the pyramidal arrangement of the [Ge­(PMe3)3]2+ (computed P–Ge–P angle 96.8° at the B3LYP-D3 level) arises from a balance between electronic energy (E elec) contributions, which favor a lower P–Ge–P angle, and nuclear–nuclear contributions (E nn), which favor a higher P–Ge–P angle, to the total energy (E TOT). An Atoms in Molecules (AIM) analysis reveals that one reason why E elec decreases as the P–Ge–P angle decreases is because of C···H and H···H interactions between atoms on different CH3 groups. The stability of the [Ge­(PMe3)3]2+ dication is enhanced by the distribution of a significant part of the positive charge on Ge2+ to the atomic centers of the PMe3 ligands. Similar results were obtained for [Ge­(AsMe3)3]­[OTf]2, showing the tris-AsMe3 complex to be less stable compared to the PMe3 analogue. Related calculations were also performed for the neutral [Ge­(PMe3)2(OTf)2] and [Ge­(AsMe3)2(OTf)2] complexes.