Synthesis, spectroscopic and structural properties of Sn(ii) and Pb(ii) triflate complexes with soft phosphine and arsine coordination
Synthesis, spectroscopic and structural properties of Sn(ii) and Pb(ii) triflate complexes with soft phosphine and arsine coordination
Reaction of the divalent M(OTf)2 (M = Sn, Pb; OTf = CF3SO3) with soft phosphine and arsine ligands, L, where L = o-C6H4(ER2)2 (E = P, R = Me or Ph; E = As, R = Me), MeC(CH2ER2)3 (E = P, R = Ph; E = As, R = Me), PhP(CH2CH2PPh2)2 or P(CH2CH2PPh2)3, affords complexes of stoichiometry M(L)(OTf)2 as white powders, which have been characterised via elemental analysis, 1H, 19F{1H}, 31P{1H} and 119Sn NMR spectroscopy, with the expected 31P-119Sn and 31P-207Pb couplings clearly evident. The crystal structures of nine of these pnictine complexes are reported, in each case revealing retention of one or both OTf anions, which gives rise to a diverse range of coordination environments including monomers, as well as varying degrees of oligomerisation to form weakly associated (OTf-bridged) dimers, trimers and polymers. 19F{1H} NMR spectra indicate that the OTf is essentially anionic (dissociated) in solution. Anion metathesis of [M(OTf)2{MeC(CH2PPh2)3}] with Na[BArF] (BArF = B{3,5-(CF3)2C6H3}4) yields the corresponding [M{MeC(CH2PPh2)3}][BArF]2 salts, the crystal structures of all three (M = Ge, Sn, Pb) reveal pyramidal dications with discrete [BArF]− anions providing charge balance. Density functional theory (DFT) calculations on these [M{MeC(CH2PPh2)3}]2+ (M = Ge, Sn, Pb) dications using the B3LYP-D3 functional show the presence of a directional lone pair, which is a mixture of valence s and pz character, with the valence p-orbital character decreasing down group 14. Natural bond orbital (NBO) analysis also shows that the natural charge at the metal centre increases and the charge on the P centre decreases upon going down group 14.
2293-2308
Cairns, Kelsey R.
4d3b3ad3-d47a-4930-b55f-de1533c552a4
King, Rhys P.
2f9548b8-fc3b-447c-a5df-de5a3e513a39
Bannister, Robert D.
4dd3eb2a-5ba7-46de-9277-8dd7e8e39b74
Levason, William
e7f6d7c7-643c-49f5-8b57-0ebbe1bb52cd
Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037
23 January 2023
Cairns, Kelsey R.
4d3b3ad3-d47a-4930-b55f-de1533c552a4
King, Rhys P.
2f9548b8-fc3b-447c-a5df-de5a3e513a39
Bannister, Robert D.
4dd3eb2a-5ba7-46de-9277-8dd7e8e39b74
Levason, William
e7f6d7c7-643c-49f5-8b57-0ebbe1bb52cd
Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037
Cairns, Kelsey R., King, Rhys P., Bannister, Robert D., Levason, William and Reid, Gillian
(2023)
Synthesis, spectroscopic and structural properties of Sn(ii) and Pb(ii) triflate complexes with soft phosphine and arsine coordination.
Dalton Transactions, 52 (8), .
(doi:10.1039/d2dt03687h).
Abstract
Reaction of the divalent M(OTf)2 (M = Sn, Pb; OTf = CF3SO3) with soft phosphine and arsine ligands, L, where L = o-C6H4(ER2)2 (E = P, R = Me or Ph; E = As, R = Me), MeC(CH2ER2)3 (E = P, R = Ph; E = As, R = Me), PhP(CH2CH2PPh2)2 or P(CH2CH2PPh2)3, affords complexes of stoichiometry M(L)(OTf)2 as white powders, which have been characterised via elemental analysis, 1H, 19F{1H}, 31P{1H} and 119Sn NMR spectroscopy, with the expected 31P-119Sn and 31P-207Pb couplings clearly evident. The crystal structures of nine of these pnictine complexes are reported, in each case revealing retention of one or both OTf anions, which gives rise to a diverse range of coordination environments including monomers, as well as varying degrees of oligomerisation to form weakly associated (OTf-bridged) dimers, trimers and polymers. 19F{1H} NMR spectra indicate that the OTf is essentially anionic (dissociated) in solution. Anion metathesis of [M(OTf)2{MeC(CH2PPh2)3}] with Na[BArF] (BArF = B{3,5-(CF3)2C6H3}4) yields the corresponding [M{MeC(CH2PPh2)3}][BArF]2 salts, the crystal structures of all three (M = Ge, Sn, Pb) reveal pyramidal dications with discrete [BArF]− anions providing charge balance. Density functional theory (DFT) calculations on these [M{MeC(CH2PPh2)3}]2+ (M = Ge, Sn, Pb) dications using the B3LYP-D3 functional show the presence of a directional lone pair, which is a mixture of valence s and pz character, with the valence p-orbital character decreasing down group 14. Natural bond orbital (NBO) analysis also shows that the natural charge at the metal centre increases and the charge on the P centre decreases upon going down group 14.
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d2dt03687h
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Accepted/In Press date: 22 January 2023
Published date: 23 January 2023
Additional Information:
Funding Information:
We thank the EPSRC for support through the ADEPT Programme grant (EP/N035437/1) and through EP/R513325/1. We also thank the EPSRC National Crystallography Service for access to the X-ray diffraction facilities and Professor J. M. Dyke for helpful discussions regarding the DFT calculations.
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© 2023 The Royal Society of Chemistry.
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Local EPrints ID: 475526
URI: http://eprints.soton.ac.uk/id/eprint/475526
ISSN: 1477-9226
PURE UUID: 74d819d9-b890-46d1-bdcb-6892f8995aa4
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Date deposited: 21 Mar 2023 17:36
Last modified: 18 Mar 2024 02:39
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Author:
Kelsey R. Cairns
Author:
Rhys P. King
Author:
Robert D. Bannister
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