Synthesis and Reactivity of Mn–CF3 Complexes

Alex Daniels,Jason Da Gama,Bulat Gabidullin,R Baker,Racquel Edjoc

doi:10.3390/inorganics7010003

Abstract

The synthesis, characterization and reactivity of several bi- and tridentate, N-ligated manganese carbonyl trifluoromethyl complexes are presented. These complexes exhibit elongated Mn–CCF3 bonds (versus Mn(CF3)(CO)5), suggesting a lability that could be utilized for the transfer or insertion of the CF3 functional group into organic substrates. Unlike their Mn–X congeners (X = Cl, Br), these Mn–CF3 complexes exhibit a preference for hard donor ancillary ligands, thus enabling the synthesis of 4 N-ligated Mn–CF3 complexes including a mixed-donor tridentate complex using an NNS Schiff base ([2-(methylthio)-N-(1-(pyridin-2-yl)ethylidene)aniline]). Although we have not yet identified efficient CF3 transfer reactions, fluoride abstraction from the Mn–CF3 complexes using trimethylsilyl triflate affords the first stable Mn fluorocarbenes as evidenced by 19F NMR spectroscopy.

Highlights

Organometaalllliicc commppoouunnddss and especiallyy metal alkyls (M–R) are immensely important players in catalysis [[11,22]]..CCaatatalylysissisuutitlilziizninggmmeteatlaflluflourooraolkalyklyclocmopmlepxlexs,ehs,ohwoewverv,eirs,liessslecsosmcommomn donuedtuoethtoe tihneheirnehnetresntatbsitliatbyiloitfymoef tmaleptaelrfplueroflruoaolrkoyallkbyolnbdosn(dMs –(MRF–) R[3F–) 5[]3.–N5]o. nNetohneelethsse,letshse,stehecsoemcpoomupnodusnadres aurseefuusleftuol tthoethinecirnecarseiansginlygliymipmoprtoarntatnftiefildeldofoflfluuoororo-o-orgrgaannicicssyynnththeessisis[[66––1144]]
Synthesis of Mn(CO)5CF3, (1): Initial attempts at the formation of Mn–CF3 complexes began with reactions of MnX2 complexes (X = OAc, Br, Cl) with the Ruppert-Prakash reagent in an attempt to synthesize Mn–CF3 complexes directly. (Scheme 2, top) displacement of the X group by CF3 proved
Mn(CO)5CF3 and the NNS ligand were prepared following literature procedures [36,39]. 1H, 19F, and 31P{1H} NMR spectra were recorded on 300 MHz Bruker Avance or AvanceII instruments (Bruker, Billerica, MA, USA) at RT (21–23 ◦C). 1H NMR spectra were referenced to the residual proton peaks (C6D6: 7.16 ppm; CDCl3: 7.26 ppm). 19F NMR spectra were referenced to internal 1,3-bis(trifluoromethyl)-benzene (BTB) (Aldrich, 99%), set to −63.5 ppm. 19F NMR yields were calculated from product integration relative to a known quantity of BTB using 9 s delay times. 31P{1H} NMR data were referenced to external H3PO4, set to 0.0 ppm

Summary

Introduction

Organometaalllliicc commppoouunnddss and especiallyy metal alkyls (M–R) are immensely important players in catalysis [[11,,22]]..CCaatatalylysissisuutitlilziizninggmmeteatlaflluflourooraolkalyklyclocmopmlepxlexs,ehs,ohwoewverv,eirs,liessslecsosmcommomn donuedtuoethtoe tihneheirnehnetresntatbsitliatbyiloitfymoef tmaleptaelrfplueroflruoaolrkoyallkbyolnbdosn(dMs –(MRF–) R[3F–) 5[]3.–N5]o. nNetohneelethsse,letshse,stehecsoemcpoomupnodusnadres aurseefuusleftuol tthoethinecirnecarseiansginlygliymipmoprtoarntatnftiefildeldofoflfluuoororo-o-orgrgaannicicssyynnththeessisis[[66––1144]]. Prominenntt examples include [Cu]−−RRFFrreeaaggeennttssffoorrssttooiicchhiioommeettrriiccppeerrfflluuoorrooaallkkyyll ttrraannssffeerr ttoo organic substrates [15,16,17,18,19,20] and increasing numbers of ttrraannssiittiioonn mmeettaall ((ee..gg..,, CCuu,,NNii,,PPdd))ccaatatalylyzzeeddCC−−RFF (where RFF is usually CCFF33) bond-forming processes [21,22], which can be used to obtain high-value flfluorinated pharmaceuticals and agargorcohcehmeimcailcsa[l4s,6,[84],.6O,8n].e uOnsnoelveudncshoalvllednge,chaolwleenvgeer, inhvowlvevsemr,etailn-cvaotlavlyeszedmpeotlaylm-ceartiazlaytzioedn opfolflyumoerroiazlakteionnesovf ifalutohreoCaloksesneees–Aviralmthaen Cmoescsheea–nAisrmlmaasncmomecmhaonilsympraasctciocmedmwonitlhy mpreatcatlilcoecdenwe iothr Zmietgallelro–cNenaettoartyZpiegclaetra–lNysattsta(Stcyhpeemceat1a)l.ysts (Scheme 1). EEaarrllyy rreeppoorrttss bbyy ZZiieegglleerr aanndd ccoowwoorrkkeerrss ooff mmeettaall--ccaattaallyyzzeedd aallkkeennee ppoollyymmeerriizzaattiioonn pprroommootteedd bbyy EEtt22AAllCCll hhaavvee eevvoollvveedd 55 ddeeccaaddeess llaatteerr ttoo aa ttoouurr ddee ffoorrccee ooff oorrggaannoommeettaalllliicc cchheemmiissttrryy wwiitthh mmoolleeccuullaarr ccoonnttrrooll ooff ppoollyypprrooppyylleennee ttaaccttiicciittyy,, lliivviinngg ccaattaallyyssttss ffoorr bblloocckk ccoo--ppoollyymmeerr ffoorrmmaattiioonn,, aanndd llaattee mmeettaall cchhaaiinn--wwaallkkiinngg aass oonnllyy tthhrreeee ooff mmaannyy hhiigghhlliigghhttss [[2233––2255]]. IInn ccoonnttrraasstt,, ppoollyymmeerriizzaattiioonn ooff flfluuoorrooaallkkeenneess traditionally utilizes radical processes, either in the gas phase or in aqueous emulsions [26,27,28,29]. As a rIneosrugaltn,icws 2h0i1le, t6h, ex;pdrooi:pFeOrRtiPeEsEoRf RflEuVoIrEoWpolymers can be tuned by altering reawctwiown.mcdopnid.ciotmio/jnosuronralc/ihnaonrggainnicgs

Methods

Results

Conclusion