This Perspective article summarizes efforts paid in our group to develop efficient metal-based catalysts for the immortal ring-opening polymerization (iROP) of cyclic esters presence large amounts alcohols (ROH) as chain transfer agents. The catalyst systems reviewed include discrete organometallic complexes based on rare earths, magnesium, calcium and more specifically zinc, well simple employing metal triflate salts, notably Al(OTf)3, (stereo)controlled iROP lactide (LA), β-butyrolactone...

Abstract Metal‐based catalysts and initiators have played a pivotal role in the ring‐opening polymerization (ROP) of cyclic esters, thanks to their high activity remarkable ability control precisely architectures resulting polyesters terms molar mass, dispersity, microstructure, or tacticity. Today, after two decades extensive research, field is slowly reaching maturity. However, several challenges remain, while original concepts emerged around new types applications catalysis. This Review...

A new heteroleptic ethyl-zinc complex stabilized by a chelating bis(morpholinomethyl)phenoxy ligand has been synthesised and shown to be highly potent initiator for the immortal ring-opening polymerisation (ROP) of lactide β-butyrolactone, being able convert up 50 000 equiv. monomer in presence 1000 an alcohol as transfer agent. Two related complexes magnesium calcium have also prepared. These are stable solution, even large amounts alcohol, constitute effective catalysts ROP under mild conditions.

Efficient protocols for the syntheses of well-defined, solvent-free cations large alkaline-earth (Ae) metals (Ca, Sr, Ba) and their smaller Zn Mg analogues have been designed. The reaction 2,4-di-tert-butyl-6-(morpholinomethyl)phenol ({LO(1)}H), 2-{[bis(2-methoxyethyl)amino]methyl}-4,6-di-tert-butylphenol ({LO(2)}H), 2-[(1,4,7,10-tetraoxa-13-azacyclopentadecan-13-yl)methyl]-4,6-di-tert-butylphenol ({LO(3)}H),...

The reactions of the bulky amino-bis(phenol) ligand Me(2)NCH(2)CH(2)N[CH(2)-3,5-Bu(t)(2)-C(6)H(2)OH-2](2)(1-H(2)) with Zn[N(SiMe(3))(2)](2)(4), [Mg[N(SiMe(3))(2)](2)](2)(5) and Ca[N(SiMe(3))(2)](2)(THF)(2)(6) yield complexes 1-Zn, 1-Mg 1-Ca in good yields. X-ray structure showed complex to be dimeric, calcium a distorted octahedral coordination geometry. Five positions are occupied by an N(2)O(3) donor set, while sixth is taken up intramolecular close contact o-Bu(t) substituent, rare case...

New alkaline-earth amido complexes catalyze the regioselective intermolecular hydroamination (see scheme; Ae=alkaline earth) and hydrophosphination of styrene isoprene with unprecedented activities. The catalytic performances increased linearly size metal.

[{N^N}M(X)(thf)n] alkyl (X=CH(SiMe3)2) and amide (X=N(SiMe3)2) complexes of alkaline earths (M=Ca, Sr, Ba) divalent rare (Yb(II) Eu(II) ) bearing an iminoanilide ligand ({N^N}(-)) are presented. Remarkably, these proved to be kinetically stable in solution. X-ray diffraction studies allowed us establish size-structure trends. Except for one case oxidation with [{N^N}Yb(II){N(SiMe3)2}(thf)], all under the catalytic conditions constitute effective precatalysts cyclohydroamination terminal...

Aniline derivatives are frequently encountered in molecules of industrial relevance such as dyes or antioxidants, which make the development synthetic methods for functionalization these privileged structures highly sought-after. A general protocol hydroarylation electronically diverse alkenes with anilines would be ideal to provide densely functionalized compounds. However, this transformation has been underexplored compared more traditional unactivated because significant challenges...

The reaction of [H(OEt2)2][B(C6F5)4] with Zn[N(SiMe3)2]2, MgBu2, and {Mg[N(SiMe3)2]2}2 in diethyl ether proceeds very high yields to give the salts [(Et2O)3ZnN(SiMe3)2][B(C6F5)4] (2), [(Et2O)3MgnBu][B(C6F5)4] (3), [(Et2O)3MgN(SiMe3)2][B(C6F5)4] (4), respectively. structures 2 4 were determined by X-ray crystallography; compounds contain distorted-tetrahedral metal centers are isostructural. [(Et2O)3ZnCH2CH3][B(C6F5)4] (1) as well 2−4 catalyze ring-opening polymerization epoxides...

A family of heteroleptic complexes zinc and magnesium supported by bulky multidentate amino-ether phenolate ligands has been developed; in combination with external chain transfer agents, they constitute efficient binary catalytic systems for the immortal ring-opening polymerisation cyclic esters.

The syntheses of the homoleptic compounds Ae[N(SiMe2H)2]2(THF)x (Ae = Ca, x 1, 2; Sr, 2/3, 3; Ba, 0, 4) are reported. They can be prepared by salt metathesis involving alkaline-earth metal iodides and KN(SiMe3)2 (1) or transamination between Ae[N(SiMe3)2]2(THF)2 HN(SiMe2H)2. These precursors constitute convenient starting materials for subsequent preparation {LnO}AeN(SiMe2H)2 heteroleptic complexes large metals, as exemplified {LO3}AeN(SiMe2H)2 ({LO3}−...

Abstract Well‐defined, base free cations of zinc and the alkaline‐earth metals (Mg, Ca, Sr, Ba) supported by a multidentate phenolate ligand stabilized perfluorinated weakly coordinating counterions are readily available simple procedures; solid‐state structures magnesium calcium derivatives were elucidated. Upon treatment with an excess i PrOH, these complexes generate highly efficient binary catalytic systems for immortal ring‐opening polymerization L ‐lactide, yielding poly( ‐lactide)s...

The synthesis of enantiomerically pure aluminium, gallium and indium complexes supported by chiral (R,R)-((HH)ONNO(HH)) (1), (R,R)-((MeH)ONNO(HMe)) (2), (R,R)-((tButBu)ONNO(tButBu)) (3), (R,R)-((MeNO2)ONNO(MeNO2)) (4), (R,R)-((HOMe)ONNO(HOMe)) (5) (R,R)-((ClCl)ONNO(ClCl)) (6) (1,2)-diphenylethylene-salen ligands is described. Several these have been crystallographically authenticated, which highlights a diversity coordination patterns. Whereas all Ga form [Ga2(CH2SiMe3)4(ONNO)] bimetallic...

Abstract The large alkaline earths (Ae), calcium, strontium and barium, have in the past 15 years yielded a brand new generation of heteroleptic molecular catalysts for production fine chemicals. However, integrity these complexes is often plagued by ligand redistribution equilibria solution. This personal account retraces paths followed our research group towards design stable alkalino‐earth complexes, including use intramolecular noncovalent Ae···H–Si Ae···F–C interactions. Their...

Abstract The factors governing the stability and reactivity towards cyclic esters of heteroleptic complexes large alkaline earth metals (Ae) have been probed. synthesis a family silylamido alkoxide calcium [{LO i }CaNu(thf) n ] supported by mono‐anionic amino ether phenolate ligands ( =1, {LO 1 } − =4‐( tert ‐butyl)‐2,6‐bis(morpholinomethyl)phenolate, Nu =N(SiMe 2 H) , =0, 4 ; =2, =2,4‐di‐ ‐butyl‐6‐{[2‐(methoxymethyl)pyrrolidin‐1‐yl]methyl}phenolate, 5 =4,...

Several new heteroleptic Sn(II) complexes supported by amino-ether phenolate ligands [Sn{LO(n)}(Nu)] (LO(1)=2-[(1,4,7,10-tetraoxa-13-azacyclopentadecan-13-yl)methyl]-4,6-di-tert-butylphenolate, Nu=NMe(2) (1), N(SiMe(3))(2) (3), OSiPh(3) (6); LO(2)=2,4-di-tert-butyl-6-(morpholinomethyl)phenolate, Nu=N(SiMe(3))(2) (7), (8)) and the homoleptic Sn{LO(1)}(2) (2) have been synthesized. The alkoxy derivatives [Sn{LO(1)}(OR)] (OR=OiPr (4), (S)-OCH(CH(3))CO(2)iPr (5)), which were generated...

Alkaline-earth (most prominently barium) complexes of the type [Ae{N(SiMe3 )2 }2 ⋅(THF)x ] and [{N^N}Ae{N(SiMe3 }⋅(THF)x are very active productive precatalysts (TON=396, TOF up to 3600 h(-1) ; Ca<Sr<Ba) for NH/HSi cross-dehydrocoupling, with excellent chemoselectivity in reaction (di)amines (di)hydrosilanes. Experimental DFT investigations revealed that reactions proceed by nucleophilic attack a metal amide at incoming silane subsequent turnover-limiting hydrogen transfer center.

New heteroleptic Yb(II)-amide species supported by amidinate and 1,3,6,8-tetra-tert-butylcarbazol-9-yl ligands [2-MeOC6H4NC(tBu)N(C6H3-iPr2-2,6)]YbN(SiMe3)2(THF) (6) [1,3,6,8-tBu4C12H4N]Yb[N(SiMe3)2](THF)n (n = 1 (7), 2 (8)) were synthesized using the amine elimination approach. Complex 6 features an unusual κ(1)-N,κ(2)-O,η(6)-arene coordination mode of ligand onto Yb(II). Complexes 7 8 represent first examples lanthanide complexes with π-coordination carbazol-9-yl ligands. 7, as well...

Several monometallic {LO(i)}M complexes of lithium (M = Li; i 1 (1), 2 (2), 3 (3)) or potassium K, (4)) and the heteroleptic bimetallic complex {LO(3)}Li·LiN(SiMe2H)2 (5), all supported by monoanionic aminoether-phenolate {LO(i)}(-) (i 1-3) ligands, have been synthesized structurally characterized. A large range coordination motifs is represented in solid state, depending on chelating ability ligand, size metal number metallic centres found complex. Pulse-gradient spin-echo NMR showed that...

Abstract The first solvent‐free cationic complexes of the divalent rare‐earth metals, [{RO}RE II ] + [A] − (RE =Yb , 1 ; Eu 2 ) and [{LO}RE ([A] =[H N{B(C 6 F 5 3 } RE 4 ), have been prepared by using highly chelating monoanionic aminoether‐fluoroalkoxide ({RO} aminoether‐phenolate ({LO} ligands. Complexes are structurally related to their alkaline‐earth analogues [{RO}AE] (AE=Ca, Sr, ). Yet, two families behave very differently during catalysis ring‐opening polymerization (ROP) L ‐lactide (...

The new chiral Binap-based fluorinated dialcohol proteo-ligand {ONNO}H2 has been prepared under its enantiomerically pure and racemic forms following reaction of (R)- or (rac)-1,1′-binaphthyl-2,2′-diamine with 5,5,5-trifluoro-4-hydroxy-4-(trifluoromethyl)pentan-2-one. reacts the trivalent metallic precursors AlEt2Cl In(CH2SiMe3)3 to yield complexes (rac)-{ONNO}AlCl (1) (rac)-{ONNO}In(CH2SiMe3) (2), while (R)-{ONNO}H2 a 1:1 mixture Y(N(SiMe3)2)3 LiN(SiMe3)2 gives heterobimetallic...

The tin(II) complexes {LO(x)}Sn(X) ({LO(x)}(-) =aminophenolate ancillary) containing amido (1-4), chloro (5), or lactyl (6) coligands (X) promote the ring-opening polymerization (ROP) of cyclic esters. Complex 6, which models first insertion L-lactide, initiates living ROP L-LA on its own, but derivatives 1-4 require addition alcohol to do so. Upon one ten equivalents iPrOH, precatalysts trimethylene carbonate (TMC); yet, hardly any activity is observed if tert-butyl (R)-lactate used instead...

Abstract The behavior of the first aminophenolate catalysts large alkaline earth metals (Ae) [(LO i )AeN(SiMe 2 R) (thf) x ] ( =1–4; Ae=Ca, Sr, Ba; R=H, Me; =0–2) for cyclohydroamination terminal aminoalkenes is discussed. complexes [(BDI)AeN(SiMe H) (Ae=Ca, Ba, =1–2; (BDI)H=H C[C(Me)N‐2,6‐( Pr) C 6 H 3 )) and [(BDI)CaN(SiMe ) (thf)] supported by β‐diketiminate (BDI) − ligand have also been employed comparative mechanistic considerations. catalytic performances decrease in order Ca&gt;Sr≫Ba,...

The synthesis and characterization of a series new diamido-ether actinide(IV) alkoxide complexes are reported. Addition 2 equiv LiOiPr to [tBuNON]ThCl5Li3·DME ([tBuNON]2– = [(tBuNSiMe2)2O]2–) in toluene gives [tBuNON]Th(OiPr)3Li·DME (1-DME). Recrystallization 1-DME from diethyl ether [tBuNON]Th(OiPr)3Li·Et2O (1-Et2O). addition {[tBuNON]UCl2}2 {[tBuNON]U(OiPr)2}2 (2). If KOtBu is used instead, the product {[tBuNON]U(OtBu)}2 (3). reaction with [iPr2PhNCOCN]ThCl2·DME ([iPr2PhNCOCN]2–...