Pyramidal dicationic Ge(II) complexes with homoleptic neutral pnictine coordination: a combined experimental and density functional theory study
Pyramidal dicationic Ge(II) complexes with homoleptic neutral pnictine coordination: a combined experimental and density functional theory study
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 (Eelec) contributions, which favor a lower P–Ge–P angle, and nuclear–nuclear contributions (Enn), which favor a higher P–Ge–P angle, to the total energy (ETOT). An Atoms in Molecules (AIM) analysis reveals that one reason why Eelec 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.
12100–12108
King, Rhys, Paul
2f9548b8-fc3b-447c-a5df-de5a3e513a39
Greenacre, Victoria
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Levason, William
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Dyke, John
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Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037
16 August 2021
King, Rhys, Paul
2f9548b8-fc3b-447c-a5df-de5a3e513a39
Greenacre, Victoria
c665a38b-0b1a-4671-ac75-bf0679dd1c57
Levason, William
e7f6d7c7-643c-49f5-8b57-0ebbe1bb52cd
Dyke, John
46393b45-6694-46f3-af20-d7369d26199f
Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037
King, Rhys, Paul, Greenacre, Victoria, Levason, William, Dyke, John and Reid, Gillian
(2021)
Pyramidal dicationic Ge(II) complexes with homoleptic neutral pnictine coordination: a combined experimental and density functional theory study.
Inorganic Chemistry, 60 (16), .
(doi:10.1021/acs.inorgchem.1c01308).
Abstract
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 (Eelec) contributions, which favor a lower P–Ge–P angle, and nuclear–nuclear contributions (Enn), which favor a higher P–Ge–P angle, to the total energy (ETOT). An Atoms in Molecules (AIM) analysis reveals that one reason why Eelec 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.
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Germanium(II) dication - final accepted form
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Accepted/In Press date: 28 July 2021
Published date: 16 August 2021
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Funding Information:
We thank the EPSRC for funding via the ADEPT Programme Grant EP/N035437/1 and via Grant EP/P025137/1.
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© 2021 American Chemical Society.
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Copyright 2021 Elsevier B.V., All rights reserved.
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Local EPrints ID: 453501
URI: http://eprints.soton.ac.uk/id/eprint/453501
ISSN: 0020-1669
PURE UUID: 073144da-1220-48ef-9874-f6586db8cd72
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Date deposited: 18 Jan 2022 17:54
Last modified: 17 Mar 2024 06:48
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Author:
Rhys, Paul King
Author:
Victoria Greenacre
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