ORGANOMETALLIC CHEMISTRY: volume 41 978-1-78262-416-5, 1782624163, 978-1-78262-692-3, 978-1-78801-220-1

Table of contents :
Content: Recent Developments and Applications of Lewis Acidic Boron Reagents
Masked Low-Coordinate Main Group Species in Synthesis
The Diiron Centre: Fe2(CO)9 and friends
Taddol and Binol-derived Chiral Phosphonites in Asymmetric Catalysis
Gold-catalysed C-F Bond Activation
Silylamides: Towards a Half-century of Stabilising Remarkable f-Element Chemistry

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Published on 25 July 2017 on http://pubs.rsc.org | doi:10.1039/9781782626923-FP001

Organometallic Chemistry Volume 41

Published on 25 July 2017 on http://pubs.rsc.org | doi:10.1039/9781782626923-FP001

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A Specialist Periodical Report

Organometallic Chemistry Published on 25 July 2017 on http://pubs.rsc.org | doi:10.1039/9781782626923-FP001

Volume 41 Editors Paul Elliott, University of Huddersfield, UK Ian J. S. Fairlamb, University of York, UK Jason M. Lynam, University of York, UK Nathan J. Patmore, University of Huddersfield, UK Authors Graeme W. Bowling, Newcastle University, UK Arne Ficks, Newcastle University, UK James T. Fleming, Newcastle University, UK Conrad A. P. Goodwin, University of Manchester, UK Lee J. Higham, Newcastle University, UK Graeme Hogarth, King’s College London, UK Ji-Yun Hu, Peking University, China James R. Lawson, Cardiff University, UK David J. Liptrot, University of Bath, UK Rebecca L. Melen, Cardiff University, UK David P. Mills, University of Manchester, UK Jun-Long Zhang, Peking University, China

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Print ISBN: 978-1-78262-416-5 PDF eISBN: 978-1-78262-692-3 EPUB eISBN: 978-1-78801-220-1 ISSN: 0301-0074 DOI: 10.1039/9781782626923 A catalogue record for this book is available from the British Library r The Royal Society of Chemistry 2017 All rights reserved Apart from fair dealing for the purposes of research for non-commercial purposes or for private study, criticism or review, as permitted under the Copyright, Designs and Patents Act 1988 and the Copyright and Related Rights Regulations 2003, this publication may not be reproduced, stored or transmitted, in any form or by any means, without the prior permission in writing of The Royal Society of Chemistry or the copyright owner, or in the case of reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency in the UK, or in accordance with the terms of the licences issued by the appropriate Reproduction Rights Organization outside the UK. Enquiries concerning reproduction outside the terms stated here should be sent to The Royal Society of Chemistry at the address printed on this page. Whilst this material has been produced with all due care, The Royal Society of Chemistry cannot be held responsible or liable for its accuracy and completeness, nor for any consequences arising from any errors or the use of the information contained in this publication. The publication of advertisements does not constitute any endorsement by The Royal Society of Chemistry or Authors of any products advertised. The views and opinions advanced by contributors do not necessarily reflect those of The Royal Society of Chemistry which shall not be liable for any resulting loss or damage arising as a result of reliance upon this material. The Royal Society of Chemistry is a charity, registered in England and Wales, Number 207890, and a company incorporated in England by Royal Charter (Registered No. RC000524), registered office: Burlington House, Piccadilly, London W1J 0BA, UK, Telephone: þ 44 (0) 207 4378 6556. Visit our website at www.rsc.org/books Printed in the United Kingdom by CPI Group (UK) Ltd, Croydon, CR0 4YY, UK

Preface

Published on 25 July 2017 on http://pubs.rsc.org | doi:10.1039/9781782626923-FP005

DOI: 10.1039/9781782626923-FP005

Unusually for this volume, we have four editors. After many years at the helm of Organometallic Chemistry, Ian Fairlamb and Jason Lynam will be stepping down as editors after this issue, with Paul Elliott and Nathan Patmore taking over. Ian and Jason are thanked for their hard work and commitment to the series. The new editors will continue the successes of previous volumes, by continuing to bring together critical and comprehensive reviews in organometallic chemistry, defined in its broadest sense to give a diverse coverage of inorganic chemistry and including contributions at the interface with related fields. In this issue, we have two chapters on main group chemistry. James Lawson and Rebecca Melen discuss recent developments in Lewis acidic boron reagents, which have applications in diverse areas such as catalysis, borylation reactions and materials science. David Liptrot describes the chemistry of low coordinate main group molecules, highlighting their recent applications in synthetic chemistry. Moving to transition metal chemistry, Graeme Hogarth presents the recent advances in diiron carbonyl complexes which are of key importance to the biomimicry and understanding of bioinorganic chemistry. The use of Taddol and Binol-derived chiral phosphonites in asymmetric catalysis is reviewed by Lee Higham and coworkers. These ligands are effective for use in asymmetric transformation reactions, with particular attention given to palladium and rhodium-catalysed processes. Ji-Yun Hu and Jun-Long Zhang present the frontier developments in the challenging area of C–F bond activation through the use of gold-based catalysis. Finally, Conrad Goodwin and David Mills highlight some of the outstanding contributions silylamide ligands have been made to f-element chemistry over the last half-century. The review includes discussion of the remarkable bonding motifs that can be adopted, and synthetic utility of these species. It is clear from the range of articles in this volume that modern organometallic chemistry has a broad scope. It continues to play an important role in both established and emerging fields, ensuring the importance of this topic as it continues to expand continues in the years to come. Ian Fairlamb Jason Lynam Paul Elliott Nathan Patmore

Organomet. Chem., 2017, 41, v–v | v

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CONTENTS

Published on 25 July 2017 on http://pubs.rsc.org | doi:10.1039/9781782626923-FP007

Cover The cover image shows the organopalladium compound Pd2(dba)3. Image by Precision Graphic Services.

Preface Ian Fairlamb, Jason Lynam, Paul Elliott and Nathan Patmore

v

Recent developments and applications of Lewis acidic boron reagents

1

James R. Lawson and Rebecca L. Melen 1 Introduction to Lewis acidic boron compounds 2 Synthesis of Lewis acidic boron reagents 3 Applications of novel boranes and borocations 4 Advanced applications of Lewis acidic boron reagents 5 Main group catalysis using boron reagents 6 Conclusions References

Masked low-coordinate main group species in synthesis

1 3 7 12 17 23 24

28

David J. Liptrot 1 2 3 4 5 6 7

Scope Notes Introduction Masking strategies A diversion: group 12 Low-coordinate monomers of group 13 elements Low-coordinate dimers of group 13 elements

28 28 29 30 30 31 33

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8 Low-coordinate monomers of group 14 elements 9 Low-coordinate dimers of group 14 elements 10 Low-coordinate monomers of group 15 elements 11 Low-coordinate dimers of group 15 elements 12 Low-coordinate main group heterodimers 13 Conclusion References

The diiron centre: Fe2(CO)9 and friends

33 36 37 38 39 41 42

48

Graeme Hogarth 1 2 3 4 5 6 7 8

Introduction Fe2(CO)9: structure Fe2(CO)9: bonding and electron-counting Fe2(CO)9: in solution Unsaturated derivatives Fe2(CO)x [x ¼ 8–6] Isoelectronic derivatives [Fe2(CO)8]2 and [HFe2(CO)8] Radical anions [Fe2(CO)x] and cations [Fe2(CO)x]1 Derivatives of Fe2(CO)9 and [Fe2(CO)8]2: general comments 9 Replacement of bridging carbonyl(s): Fe2(CO)6(m-CO)3n(m-X2)n 10 Derivatives with bidentate ligands: Fe2(CO)6(m-CO)(m-L2) and Fe2(CO)5(k2-L2)(m-CO) 11 Derivatives of [Fe2(CO)8]2: Fe2(CO)8(k1-X)2 and Fe2(CO)6(k1-LX)2 12 Fe2(CO)6(m-S2) and related chalcogenide complexes 13 Diaazo-bridged complexes Fe2(CO)6(m-RNNR) and phosphorus analogues 14 Thionitroso Fe2(CO)6(m-RNS) and alkyne Fe2(CO)6(m-RCCR) complexes 15 [Fe2(CO)6(m-CO)(m-LX)] 16 Fe2(Z4-C4R4)2(m-CO)3 and related terminally substituted derivatives 17 Concluding remarks References

Taddol and Binol-derived chiral phosphonites in asymmetric catalysis Graeme W. Bowling, James T. Fleming, Arne Ficks and Lee J. Higham 1 Introduction 2 Stereoelectronic profile of phosphonites 3 Taddol-derived chiral phosphonites

viii | Organomet. Chem., 2017, 41, vii–ix

48 49 51 54 56 58 61 63 63 68 71 73 76 77 78 80 81 81

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4 Binol-derived chiral phosphonites 5 Conclusion Acknowledgements References

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Gold-catalysed C–F bond activation

100 107 107 108

110

Ji-Yun Hu and Jun-Long Zhang 1 Introduction 2 Gold catalyses C–F bond activation 3 Summary and outlook Acknowledgements References

Silylamides: towards a half-century of stabilising remarkable f-element chemistry

110 111 119 120 120

123

Conrad A. P. Goodwin and David P. Mills 1 Introduction and scope of the review 2 Low coordination number complexes 3 Reactivity 4 Multiple bonds 5 Conclusions References

123 124 134 145 147 148

Organomet. Chem., 2017, 41, vii–ix | ix

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Abbreviations Ac acac acacen Ad AIBN ampy Ar Ar* Ar 0 f arphos ATP Azb 9-BBN BHT Biim BINAP bipy Bis bma BNCT Bp bpcd bpk Bpz4 But2bpy t-bupy Bz Bzac cbd 1,5,9-cdt chd chpt CIDNP [Co] (Co) cod coe cot CP/MAS Cp CpR Cp* Cp 0 Cp00 CV CVD

acetate acetylacetonate N,N 0 -ethylenebis(acetylacetone iminate) adamantyl azoisobutyronitrile 2-amino-6-methylpyridine aryl 2,4,6-tri(tert-butyl)phenyl 3,5-bis(trifluoromethyl)phenyl 1-(diphenylphosphino)-2-(diphenylarsino)ethane adenosine triphosphate azobenzene 9-borabicyclo[3.3.1]nonane 2,6-dibutyl-4-methylphenyl biimidazole 2,2 0 -bis(diphenylphosphino)-1,1 0 -binaphthyl 2,2 0 -bipyridyl bis(trimethylsilyl)methyl 2,3-bis(diphenylphosphino)maleic anhydride boron neutron capture therapy biphenyl 4,5-bis(diphenylphosphino)cyclopent-4-ene-1,3-dione benzophenone ketyl (diphenylketyl) tetra(1-pyrazolyl)borate 4,4 0 -di-tert-butyl-2,2 0 -bipyridine tert-butylpyridine benzyl benzoylacetonate cyclobutadiene cyclododeca-1,5,9-triene cyclohexadiene cycloheptatriene chemically induced dynamic nuclear polarisation cobalamin cobaloxime [Co(dmg)2 derivative] cycloocta-1,5-diene cyclooctene cyclooctatriene cross polarisation/magnetic angle spinning Z5-cyclopentadienyl Z5-alkylcyclopentadienyl Z5-pentamethylcyclopentadienyl trimethylsilylcyclopentadienyl tetramethylethylcyclopentadienyl cyclic voltammetry(ogram) chemical vapour deposition

x | Organomet. Chem., 2017, 41, x–xiv  c

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Cy Cyclam Cym Cyttp dab dabco dba dbpe DBU DCA depe depm DFT diars diarsop dien diop DIPAMP diphos dipp dipyam DMAD DMAP dmbpy DME DMF dmg dmgH dmgH2 DMP dmpe dmpm dmpz DMSO dpae dpam dppa dppb dppbz dppe dppf dppm dppp DSD edt EDTA ee

cyclohexyl 1,4,8,11-tetraazacyclotetradecane p-cymene PhP(CH2CH2CH2PCy2)2 1,4-diazabutadiene 1,4-diazabicyclo[2.2.2]octane dibenzylideneacetone 1,2-bis(dibutylphosphino)ethane 1,8-diazabicyclo[5.4.0]undec-7-ene 9,10-dicyanoanthracene 1,2-bis(diethylphosphino)ethane 1,2-bis(diethylphosphino)methane density functional theory o-phenylenebis(dimethyl)arsine {[(2,2-dimethyl-1,3-dioxolan-4,5-diyl)bis(methylene)]bis-[diphenylarsine]} diethylenetriamine {[(2,2-dimethyl-1,3-dioxolan-4,5-diyl)bis(methylene)]bis-1-[diphenylphosphine]} 1,2-bis(phenyl-o-anisoylphosphino)ethane 1,2-bis(diphenylphosphino)ethane 2,6-diisopropylphenyl di-(2-pyridyl)amine dimethyl acetylenedicarboxylate 2-dimethylaminopyridine dimethylbipyridine 1,2-dimethoxyethane N,N-dimethylformamide dimethylglyoximate monoanion of dimethylglyoxime dimethylglyoxime dimethylpiperazine 1,2-bis(dimethylphosphino)ethane bis(dimethylphosphino)methane 1,3-dimethylpyrazolyl dimethyl sulfoxide 1,2-bis(diphenylarsino)ethane bis(diphenylarsino)methane 1,2-bis(diphenylphosphino)ethyne 1,4-bis(diphenylphosphino)butane 1,2-bis(diphenylphosphino)benzene 1,2-bis(diphenylphosphino)ethane 1,1 0 -bis(diphenylphosphino)ferrocene bis(diphenylphosphino)methane 1,3-bis(diphenylphosphino)propane diamond–square–diamond ethane-1,2-dithiolate ethylenediaminetetraacetate enantiomeric excess Organomet. Chem., 2017, 41, x–xiv | xi

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EELS EH MO ELF en ES EXAFS F6acac Fc Fe* Fp Fp 0 FTIR FVP glyme GVB HBpz3 HBpz*3 H4cyclen HEDTA hfa hfacac hfb HMPA HNCC HOMO IGLO im Is* ISEELS KTp LDA LiDBB LMCT LNCC MAO Me2bpy Me6[14]dieneN4 Me6[14]N4 4,7-Me2phen 3,4,7,8-Me4phen Mes Mes* MeTHF mcpba MLCT MTO nap

electron energy loss spectroscopy ¨ckel molecular orbital extended Hu electron localisation function ethylene-1,2-diamine MS electrospray mass spectrometry extended X-ray absorption fine structure hexafluoroacetylacetonate ferrocenyl Fe(CO)2Cp* Fe(CO)2Cp Fe(CO)2Z5-(C5H4Me) Fourier transform infrared flash vacuum pyrolysis ethyleneglycol dimethyl ether generalised valence bond tris(pyrazolyl)borate tris(3,5-dimethylpyrazolyl)borate tetraaza-1,4,7,10-cyclododecane N-hydroxyethylethylenediaminetetraacetate hexafluoroacetone hexafluoroacetylacetonato hexafluorobutyne hexamethyl phosphoric triamide high nuclearity carbonyl cluster highest occupied molecular orbital individual gauge for localised orbitals imidazole 2,4,6-triisopropylphenyl inner shell electron energy loss spectroscopy potassium hydrotris(1-pyrazolyl)borate lithium diisopropylamide lithium di-tert-butylbiphenyl ligand to metal charge transfer low nuclearity carbonyl cluster methyl alumoxane 4,4 0 -dimethyl-2,2 0 -bypyridyl 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane 4,7-dimethyl-1,10-phenanthroline 3,4,7,8,-tetramethyl-1,10-phenanthroline mesityl 2,4,6-tributylphenyl methyltetrahydrofuran metachloroperbenzoic acid metal–ligand charge transfer methylrhenium trioxide 1-naphthyl

xii | Organomet. Chem., 2017, 41, x–xiv

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nb nbd NBS NCS NCT Neo Np np3 nta OEP OTf OTs Pc PES PMDT pd phen pic Pin Pmedta pp3 [PPN] þ py pydz pz R-PROPHOS R,R-SKEWPHOS RDF ROMP sal salen saloph SCF TCNE TCNQ terpy tetraphos TFA tfbb tfacac THF thsa tht TMBD TMEDA tmp TMS tol TP

norbornene norbornadiene N-bromosuccinimide N-chlorosuccinimide neutron capture theory neopentyl 1-naphthyl N(CH2CH2PPh2)3 nitrilotriacetate octaethylporphyrin trifluoromethanesulfonate (triflate) p-toluenesulfonate (tosylate) phthalocyanin photoelectron spectroscopy pentamethylenediethylenetetramine pentane-2,4-dionate 1,10-phenanthroline pyridine-2-carboxylic acid (þ)-pinanyl pentamethyldiethylenetriamine P(CH2CH2PPh2)3 [(Ph3P)2N] þ pyridine pyridazine pyrazolyl (R)-(þ)-1,2-bis(diphenylphosphino)propane (2R,4R)-bis(diphenylphosphino)pentane radial distribution function ring opening metathesis polymerisation salicylaldehyde N,N 0 -bis(salicylaldehydo)ethylenediamine N,N-bisalicylidene-o-phenylenediamine self consistent field tetracyanoethylene 7,7,8,8-tetracyanoquinodimethane 2,2 0 ,200 -terpyridyl 1,1,4,7,10,10-hexaphenyl-1,4,7,10-tetraphosphadecane trifluoroacetic acid tetrafluorobenzobarrelene trifluoroacetylacetonato tetrahydrofuran thiosalicylate (2-thiobenzoate) tetrahydrothiophen NNN 0 N00 -tetramethyl-2-butene-1,4-diamine (tmena) tetramethylethylenediamine 2,2,6-6-tetramethylpiperidino tetramethylsilane tolyl hydrotris(1-pyrazolyl)borate Organomet. Chem., 2017, 41, x–xiv | xiii

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TP* TPP Trip Triph triphos TRIR Tsi TTF vi WGSR XPS Xyl

hydrotris(2,5-dimethylpyrazolyl)borate meso-tetraphenylporphyrin 2,4,6-triisopropylphenyl 2,4,6-(triphenyl)phenyl 1,1,1-tris(diphenylphosphinomethyl)ethane time resolved infrared (spectroscopy) tris(trimethylsilyl)methyl (Me3Si)3C tetrathiafulvalene vinyl water gas shift reaction X-ray photoelectron spectroscopy xylyl

xiv | Organomet. Chem., 2017, 41, x–xiv

Recent developments and applications of Lewis acidic boron reagents James R. Lawson and Rebecca L. Melen*

Published on 25 July 2017 on http://pubs.rsc.org | doi:10.1039/9781782626923-00001

DOI: 10.1039/9781782626923-00001

One field of organometallic chemistry that has seen great advancements over the last 20 years is that of main-group chemistry, in particular boron chemistry, that has led to a wealth of new discoveries. In this review, we will focus on modern advancements in this growing field, such as interesting uses of firmly established reagents, such as tris(pentafluorophenyl)borane, B(C6F5)3, which has demonstrated extensive applications in a wide variety of chemistry. In addition to this, a number of novel Lewis acidic boranes and borocations have been recently synthesised, which are often structurally tailored for a specific role such as borylation reactions or use in main-group catalysis. The reactions of these compounds are broad in scope, inclusive of borylation substitution reactions, addition of B–E across p-bonds and applications in pharmaceuticals and materials science. In addition, boron reagents often constitute the Lewis acid moiety of frustrated Lewis pairs (FLPs), an area of main-group chemistry that has also expanded rapidly, with numerous applications notably in main-group catalysis. Newly discovered Lewis acidic boron reagents and their implementations are proving to be an appealing and exciting applications-based field as more advances are discovered.

1

Introduction to Lewis acidic boron compounds

Boron reagents are often employed as Lewis acids due to their strongly electrophilic nature granted by a vacant p-orbital into which electrons can be received. Many neutral boranes have been synthesised and utilised, such as trialkyl-, triaryl- and trihalo-boranes, although as the field of boron chemistry has grown, more complex and structurally diverse boron reagents have been reported. One of the key features of neutral borane species is that the Lewis acidity can be attenuated by variation of the three substituents bound to boron. An example of this is tris(pentafluorophenyl)borane [B(C6F5)3], a powerful Lewis acid due to the electron withdrawing effects of the three perfluorinated aryl rings, which was first synthesised in the 1960s.1 Since this discovery, other strongly Lewis acidic boranes have been reported, select examples of which are included herein. A useful tool when considering Lewis acidic boranes is the ability to determine experimentally their Lewis acidity, allowing them to be placed on a scale, such as in Fig. 1.2 The most well-known procedures for this use NMR spectroscopic analysis. The Gutmann–Beckett method involves the coordination of triethylphosphine oxide (Et3PO) to a Lewis acid and recording the chemical shift in the 31P NMR spectrum.3 The Lewis basic oxygen atom of Et3PO can form an adduct with boron reagents, causing deshielding of the adjacent phosphorus atom, the degree of which can be

School of Chemistry, Cardiff University, Main Building, Cardiff CF10 3AT, Cymru/Wales, UK. E-mail: MelenR@cardiff.ac.uk Organomet. Chem., 2017, 41, 1–27 | 1  c

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F

Least Lewis acidic

F

B

C6 F 5 < F

F5C6

B

Br

Cl