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Bowles AWJ, Liu Y, Stevens MP, Vitorica‐Yrezabal IJ, McMullin CL, Ortu F. A Blueprint for the Stabilization of Sub-Valent Alkaline Earth Complexes. Chemistry 2023; 29:e202301850. [PMID: 37338225 PMCID: PMC10947258 DOI: 10.1002/chem.202301850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 06/19/2023] [Accepted: 06/20/2023] [Indexed: 06/21/2023]
Abstract
The study of sub-valent Group 2 chemistry is a relatively new research field, being established in 2007 with the report of the first Mg(I) dimers. These species are stabilized by the formation of a Mg-Mg covalent bond; however, the extension of this chemistry to heavier alkaline earth (AE) metals has been frustrated by significant synthetic challenges, primarily associated with the instability of heavy AE-AE interactions. Here we present a new blueprint for the stabilization of heavy AE(I) complexes, based upon the reduction of AE(II) precursors with planar coordination geometries. We report the synthesis and structural characterisation of homoleptic trigonal planar AE(II) complexes of the monodentate amides {N(SiMe3 )2 }- and {N(Mes)(SiMe3 )}- . DFT calculations showed that the LUMOs of these complexes all show some d-character for AE = Ca-Ba. DFT analysis of the square planar Sr(II) complex [Sr{N(SiMe3 )2 }(dioxane)2 ]∞ revealed analogous frontier orbital d-character. AE(I) complexes that could be accessed by reduction of these AE(II) precursors were modelled computationally, revealing exergonic formation in all cases. Crucially, NBO calculations show that some d-character is preserved in the SOMO of theoretical AE(I) products upon reduction, showing that d-orbitals could play a crucial role in achieving stable heavy AE(I) complexes.
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Affiliation(s)
- Alex W. J. Bowles
- School of ChemistryUniversity of LeicesterUniversity RoadLeicesterLE1 7RHUK
| | - Yu Liu
- School of ChemistryUniversity of LeicesterUniversity RoadLeicesterLE1 7RHUK
| | - Matthew P. Stevens
- School of ChemistryUniversity of LeicesterUniversity RoadLeicesterLE1 7RHUK
| | | | | | - Fabrizio Ortu
- School of ChemistryUniversity of LeicesterUniversity RoadLeicesterLE1 7RHUK
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2
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Stevens MP, Spray E, Vitorica-Yrezabal IJ, Singh K, Timmermann VM, Sotorrios L, Macgregor SA, Ortu F. Synthesis, characterisation and reactivity of group 2 complexes with a thiopyridyl scorpionate ligand. Dalton Trans 2022; 51:11922-11936. [PMID: 35876311 DOI: 10.1039/d2dt02012b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Herein we report the reactivity of the proligand tris(2-pyridylthio)methane (HTptm) with various Alkaline Earth (AE) reagents: (1) dialkylmagnesium reagents and (2) AE bis-amides (AE = Mg-Ba). Heteroleptic complexes of general formulae [Mg(Tptm)(R)] (R = Me, nBu; Tptm = {C(S-C5H4N)3}-) and [AE(Tptm)(N'')] (AE = Mg-Ba; N'' = {N(SiMe3)2}-) were targeted from the reaction of HTptm with R2Mg or [AE(N'')2]2. Reaction of the proligand with dialkylmagnesium reagents led to formation of [{Mg(κ3C,N,N-C{Bu}{S-C5H4N}2)(μ-S-C5H4N)}2] (1) and [{Mg(κ3C,N,N-C{Me}{S-C5H4N}2)(μ-OSiMe3)}2] (2) respectively, as a result of a novel transfer of an alkyl group onto the methanide carbon with concomitant C-S bond cleavage. However, reactivity of bis-amide precursors for Mg and Ca did afford the target species [AE(Tptm)(N'')] (3-AE; AE = Mg-Ca), although these proved susceptible to ligand degradation processes. DFT calculations show that alkyl transfer in the putative [Mg(Tptm)(nBu)] (1m') system and amide transfer in 3-Ca is a facile process that induces C-S bond cleavage in the Tptm ligand. 3-Mg and 3-Ca were also tested as catalysts for the hydrophosphination of selected alkenes and alkynes, including the first example of mono-hydrophosphination of 4-ethynylpyridine which was achieved with high conversions and excellent regio- and stereochemical control.
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Affiliation(s)
- Matthew P Stevens
- School of Chemistry, University of Leicester, University Road, LE1 7RH Leicester, UK.
| | - Emily Spray
- School of Chemistry, University of Leicester, University Road, LE1 7RH Leicester, UK.
| | | | - Kuldip Singh
- School of Chemistry, University of Leicester, University Road, LE1 7RH Leicester, UK.
| | - Vanessa M Timmermann
- School of Chemistry, University of Leicester, University Road, LE1 7RH Leicester, UK.
| | - Lia Sotorrios
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
| | - Stuart A Macgregor
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
| | - Fabrizio Ortu
- School of Chemistry, University of Leicester, University Road, LE1 7RH Leicester, UK.
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3
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Stevens MP, Spray E, Vitorica-Yrezabal IJ, Singh K, Timmermann VM, Sotorrios L, Ortu F. Structural Investigation of Magnesium Complexes Supported by a Thiopyridyl Scorpionate Ligand. Molecules 2022; 27:molecules27144564. [PMID: 35889437 PMCID: PMC9318590 DOI: 10.3390/molecules27144564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/12/2022] [Accepted: 07/14/2022] [Indexed: 12/03/2022] Open
Abstract
Herein, we report the synthesis of a series of heteroleptic magnesium complexes stabilized with the scorpionate ligand tris(2-pyridylthio)methanide (Tptm). The compounds of the general formula [Mg(Tptm)(X)] (1-X; X = Cl, Br, I) were obtained via protonolysis reaction between the proligand and selected Grignard reagents. Attempts to isolate the potassium derivative K(Tptm) lead to decomposition of Tptm and formation of the alkene (C5H4N-S)2C=C(C5H4N-S)2, and this degradation was also modelled using DFT methods. Compound 1-I was treated with K(CH2Ph), affording the degradation product [Mg(Bptm)2] (2; Bptm = {CH(S-C5NH3)2}−). We analyzed and quantified the steric properties of the Tptm ligand using the structural information of the compounds obtained in this study paired with buried volume calculations, also adding the structural data of HTptm and its CF3-substituted congener (HTptmCF3). These studies highlight the highly flexible nature of this ligand scaffold and its ability to stabilize various coordination motifs and geometries, which is a highly desirable feature in the design of novel organometallic reagents and catalysts.
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Affiliation(s)
- Matthew P. Stevens
- School of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK; (M.P.S.); (E.S.); (K.S.); (V.M.T.)
| | - Emily Spray
- School of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK; (M.P.S.); (E.S.); (K.S.); (V.M.T.)
| | | | - Kuldip Singh
- School of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK; (M.P.S.); (E.S.); (K.S.); (V.M.T.)
| | - Vanessa M. Timmermann
- School of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK; (M.P.S.); (E.S.); (K.S.); (V.M.T.)
| | - Lia Sotorrios
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
- Correspondence: (L.S.); (F.O.); Tel.: +44-(0)116-294-4670 (F.O.)
| | - Fabrizio Ortu
- School of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK; (M.P.S.); (E.S.); (K.S.); (V.M.T.)
- Correspondence: (L.S.); (F.O.); Tel.: +44-(0)116-294-4670 (F.O.)
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4
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Woltornist RA, Collum DB. Sodium Hexamethyldisilazide: Using 15N- 29Si Scalar Coupling to Determine Aggregation and Solvation States. J Am Chem Soc 2020; 142:6852-6855. [PMID: 32233406 DOI: 10.1021/jacs.0c00331] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
29Si NMR spectroscopy, the method of continuous variations, and density functional theory computations show that sodium hexamethyldisilazide (NaHMDS) is a disolvated dimer in toluene, a mixture of disolvated dimer and tetrasolvated monomer in THF/toluene, and exclusively monomer in neat THF. The dioxane-solvated NaHMDS only partially deaggregates to monomer even in neat dioxane. 15N-29Si coupling constants and 29Si chemical shifts show a high and dependable correlation with the aggregation state. Monitoring either chemical shift or coupling constant versus THF concentration even in the high-temperature, rapid-exchange limit affords the solvation numbers consistent with DFT computations. The preparation of 15N-labeled NaHMDS has been improved.
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Affiliation(s)
- Ryan A Woltornist
- Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
| | - David B Collum
- Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
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5
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Quinlivan PJ, Shlian DG, Amemiya E, Parkin G. Reactivity of the carbodiphosphorane, (Ph 3P) 2C, towards main group metal alkyl compounds: coordination and cyclometalation. Dalton Trans 2019; 48:9139-9151. [PMID: 31145405 DOI: 10.1039/c9dt00678h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The carbodiphosphorane, (Ph3P)2C, reacts with Me3Al and Me3Ga to afford the adducts, [(Ph3P)2C]AlMe3 and [(Ph3P)2C]GaMe3, which have been structurally characterized by X-ray diffraction. (Ph3P)2C also reacts with Me2Zn and Me2Cd to generate an adduct but the formation is reversible on the NMR time scale. At elevated temperatures, however, elimination of methane and cyclometalation occurs to afford [κ2-Ph3PC{PPh2(C6H4)}]ZnMe and [κ2-Ph3PC{PPh2(C6H4)}]CdMe. Analogous cyclometalated products, [κ2-Ph3P{CPPh2(C6H4)}]ZnN(SiMe3)2 and [κ2-Ph3P{CPPh2(C6H4)}]CdN(SiMe3)2, are also obtained upon reaction of (Ph3P)2C with Zn[N(SiMe3)2]2 and Cd[N(SiMe3)2]2. The magnesium compounds, Me2Mg and {Mg[N(SiMe3)2]2}2, likewise react with (Ph3P)2C to afford cyclometalated derivatives, namely [κ2-Ph3PC{PPh2(C6H4)}]MgN(SiMe3)2 and {[κ2-Ph3PC{PPh2(C6H4)}]MgMe}2. While this reactivity is similar to the zinc system, the magnesium methyl complex is a dimer with bridging methyl groups, whereas the zinc complex is a monomer. The greater tendency of the methyl groups to bridge magnesium centers rather than zinc centers is supported by density functional theory calculations.
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Affiliation(s)
- Patrick J Quinlivan
- Department of Chemistry, Columbia University, New York, New York 10027, USA.
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Nicholas HM, Goodwin CAP, Kragskow JGC, Lockyer SJ, Mills DP. Structural Characterization of Lithium and Sodium Bulky Bis(silyl)amide Complexes. Molecules 2018; 23:molecules23051138. [PMID: 29748490 PMCID: PMC6100173 DOI: 10.3390/molecules23051138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 05/03/2018] [Accepted: 05/04/2018] [Indexed: 11/16/2022] Open
Abstract
Alkali metal amides are vital reagents in synthetic chemistry and the bis(silyl)amide {N(SiMe₃)₂} (N′′) is one of the most widely-utilized examples. Given that N′′ has provided landmark complexes, we have investigated synthetic routes to lithium and sodium bis(silyl)amides with increased steric bulk to analyse the effects of R-group substitution on structural features. To perform this study, the bulky bis(silyl)amines {HN(SitBuMe₂)(SiMe₃)}, {HN(SiiPr₃)(SiMe₃)}, {HN(SitBuMe₂)₂}, {HN(SiiPr₃)(SitBuMe₂)} and {HN(SiiPr₃)₂} (1) were prepared by literature procedures as colourless oils; on one occasion crystals of 1 were obtained. These were treated separately with nBuLi to afford the respective lithium bis(silyl)amides [Li{μ-N(SitBuMe₂)(SiMe₃)}]₂ (2), [Li{μ-N(SiiPr₃)(SiMe₃)}]₂ (3), [Li{N(SitBuMe₂)₂}{μ-N(SitBuMe₂)₂}Li(THF)] (4), [Li{N(SiiPr₃)(SitBuMe₂)}(DME)] (6) and [Li{N(SiiPr₃)₂}(THF)] (7) following workup and recrystallization. On one occasion during the synthesis of 4 several crystals of the ‘ate’ complex [Li₂{μ-N(SitBuMe₂)₂}(μ-nBu)]₂ (5) formed and a trace amount of [Li{N(SiiPr₃)₂}(THF)₂] (8) was identified during the recrystallization of 7. The reaction of {HN(SitBuMe₂)₂} with NaH in the presence of 2 mol % of NaOtBu gave crystals of [Na{μ-N(SitBuMe₂)₂}(THF)]₂ (9-THF), whilst [Na{N(SiiPr₃)₂}(C₇H₈)] (10) was prepared by deprotonation of 1 with nBuNa. The solid-state structures of 1⁻10 were determined by single crystal X-ray crystallography, whilst 2⁻4, 7, 9 and 10 were additionally characterized by NMR and FTIR spectroscopy and elemental microanalysis.
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Affiliation(s)
- Hannah M Nicholas
- School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK.
| | - Conrad A P Goodwin
- School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK.
| | - Jon G C Kragskow
- School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK.
| | - Selena J Lockyer
- School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK.
| | - David P Mills
- School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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7
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Leng JD, Goodwin CAP, Vitorica-Yrezabal IJ, Mills DP. Salt metathesis routes to homoleptic near-linear Mg(ii) and Ca(ii) bulky bis(silyl)amide complexes. Dalton Trans 2018; 47:12526-12533. [DOI: 10.1039/c8dt00802g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
A series of bulky bis(silyl)amide ligands have been utilised to stabilise rare examples of formally 2-coordinate linear or near-linear Mg and Ca complexes.
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Affiliation(s)
- Ji-Dong Leng
- Guangzhou Key Laboratory for Environmentally Functional Materials and Technology
- School of Chemistry and Chemical Engineering
- Guangzhou University
- Guangzhou Higher Education Mega Center
- Guangzhou
| | | | | | - David P. Mills
- School of Chemistry
- The University of Manchester
- Manchester
- UK
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8
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de Bruin-Dickason CN, Boutland AJ, Dange D, Deacon GB, Jones C. Redox transmetallation approaches to the synthesis of extremely bulky amido-lanthanoid(ii) and -calcium(ii) complexes. Dalton Trans 2018; 47:9512-9520. [DOI: 10.1039/c8dt02138d] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Redox transmetallation protolysis and direct redox transmetallation reactions have been employed to access a variety of extremely bulky amido-lanthanoid(ii), and related calcium(ii) complexes which cannot be prepared using classical salt metathesis pathways.
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Affiliation(s)
| | | | - Deepak Dange
- School of Chemistry
- Monash University
- Melbourne
- Australia
| | | | - Cameron Jones
- School of Chemistry
- Monash University
- Melbourne
- Australia
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Ortu F, Gregson M, Wooles AJ, Mills DP, Liddle ST. Yttrium Methanide and Methanediide Bis(silyl)amide Complexes. Organometallics 2017. [DOI: 10.1021/acs.organomet.7b00394] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Fabrizio Ortu
- School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Matthew Gregson
- School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Ashley J. Wooles
- School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - David P. Mills
- School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Stephen T. Liddle
- School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
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10
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Goodwin CAP, Chilton NF, Natrajan LS, Boulon ME, Ziller JW, Evans WJ, Mills DP. Investigation into the Effects of a Trigonal-Planar Ligand Field on the Electronic Properties of Lanthanide(II) Tris(silylamide) Complexes (Ln = Sm, Eu, Tm, Yb). Inorg Chem 2017; 56:5959-5970. [DOI: 10.1021/acs.inorgchem.7b00664] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Conrad A. P. Goodwin
- School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Nicholas F. Chilton
- School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Louise S. Natrajan
- School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | | | - Joseph W. Ziller
- Department
of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - William J. Evans
- Department
of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - David P. Mills
- School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
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11
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Boutland AJ, Dange D, Stasch A, Maron L, Jones C. Two‐Coordinate Magnesium(I) Dimers Stabilized by Super Bulky Amido Ligands. Angew Chem Int Ed Engl 2016; 55:9239-43. [PMID: 27303934 DOI: 10.1002/anie.201604362] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Aaron J. Boutland
- School of Chemistry Monash University P.O. Box 23 Melbourne VIC 3800 Australia
| | - Deepak Dange
- School of Chemistry Monash University P.O. Box 23 Melbourne VIC 3800 Australia
| | - Andreas Stasch
- School of Chemistry Monash University P.O. Box 23 Melbourne VIC 3800 Australia
| | - Laurent Maron
- Université de Toulouse et CNRS, INSA, UPS, UMR 5215, LPCNO 135 Avenue de Rangueil 31077 Toulouse France
| | - Cameron Jones
- School of Chemistry Monash University P.O. Box 23 Melbourne VIC 3800 Australia
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12
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Boutland AJ, Dange D, Stasch A, Maron L, Jones C. Two‐Coordinate Magnesium(I) Dimers Stabilized by Super Bulky Amido Ligands. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201604362] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Aaron J. Boutland
- School of Chemistry Monash University P.O. Box 23 Melbourne VIC 3800 Australia
| | - Deepak Dange
- School of Chemistry Monash University P.O. Box 23 Melbourne VIC 3800 Australia
| | - Andreas Stasch
- School of Chemistry Monash University P.O. Box 23 Melbourne VIC 3800 Australia
| | - Laurent Maron
- Université de Toulouse et CNRS, INSA, UPS, UMR 5215, LPCNO 135 Avenue de Rangueil 31077 Toulouse France
| | - Cameron Jones
- School of Chemistry Monash University P.O. Box 23 Melbourne VIC 3800 Australia
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13
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Goodwin CAP, Chilton NF, Vettese GF, Moreno Pineda E, Crowe IF, Ziller JW, Winpenny REP, Evans WJ, Mills DP. Physicochemical Properties of Near-Linear Lanthanide(II) Bis(silylamide) Complexes (Ln = Sm, Eu, Tm, Yb). Inorg Chem 2016; 55:10057-10067. [DOI: 10.1021/acs.inorgchem.6b00808] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Conrad A. P. Goodwin
- School of Chemistry, The University of Manchester, Oxford
Road, Manchester M13 9PL, U.K
| | - Nicholas F. Chilton
- School of Chemistry, The University of Manchester, Oxford
Road, Manchester M13 9PL, U.K
| | - Gianni F. Vettese
- School of Chemistry, The University of Manchester, Oxford
Road, Manchester M13 9PL, U.K
| | - Eufemio Moreno Pineda
- School of Chemistry, The University of Manchester, Oxford
Road, Manchester M13 9PL, U.K
| | - Iain F. Crowe
- Photon Science Institute and School of
Electrical and Electronic Engineering, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Joseph W. Ziller
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | | | - William J. Evans
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - David P. Mills
- School of Chemistry, The University of Manchester, Oxford
Road, Manchester M13 9PL, U.K
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