Interest in the utility of polylactide as a commodity polymer has increased significantly recent years due to numerous environmental advantages over conventional petrochemically derived plastics. As such, development novel catalyst systems for ring opening polymerization lactide seen tremendous progress past decade. In particular, divalent metals (i.e. Mg, Ca and Zn) supported by monoanionic ancillary scaffolds are appealing because their low toxicity cost. A much less common approach...

A variety of transition-metal complexes with terminal silylene ligands have become available in recent years, because the discovery several preparative methods. In particular, three general synthetic routes to these emerged, on basis anionic group abstraction, coordination a free silylene, and alpha-hydrogen migration. The direct transformation organosilanes at metal center (silylene extrusion) has also been observed, this further spurred exploration silylenes as ligands. This Account...

Several diorganoscandium complexes stabilized by the β-diketiminato ligands (Ar)NC(R)CHC(R)N(Ar) (Ar = 2,6-iPr-C6H3; R CH3 (ligand a), tBu b)) have been synthesized. Reaction of lithium salts with ScCl3·3THF leads to LScCl2(THF)n, which may be readily alkylated form dialkyl derivatives. Most are isolated as base-free, four-coordinate complexes. characterized via X-ray crystallography, and a detailed discussion their structures is presented. Steric interactions between Ar Sc−alkyl groups...

The base-free dimethyl scandium complex supported by the bulky beta-diketiminato ligand ArNC((t)Bu)CHC((t)Bu)NAr (Ar = 2,6-(i)Pr(2)C(6)H(3), 1) reacts with various equivalencies of strong organometallic Lewis acid B(C(6)F(5))(3) to give alkyl cations. With 0.5 equiv, a monocationic mu-methyl dimer (2) was observed spectroscopically. Reaction further equiv borane gives monomeric methyl cation 3, which fully characterized, including via X-ray crystallography. This compound is fluxional on NMR...

The scandium-catalyzed intramolecular hydroamination of alkynes and alkenes is reported. Complex structure/catalyst activity investigations resulted in the identification a highly catalytically active cationic, β-diketiminato scandium complex.

A bulky anilido-imine donor that marries the attributes of β-diketiminato and salicylaldiminato ligand frameworks has been prepared used to stabilize bis-alkyl yttrium derivatives, which act as precursors cationic organoyttrium complexes.

Abstraction of methide from the beta-diketiminato supported organoscandium complex [L1ScMe2]2 using trityl borate activator [Ph3C][B(C6F5)4] in arene solvents gives solvent separated ion pairs which (C6H5Br, 1a; C6H6, 1b; C7H8, 1c; 1,3,5-Me3C6H3, 1d) is coordinated to cationic scandium center an eta6 bonding mode. L1 incorporates methyl groups 2,4 positions ligand backbone and bulky 2,6-diisopropylphenyl on nitrogen atoms. The relative binding strength arenes C6H5Br < C6H6 1,3,5-Me3C6H3...

Addition of bulky primary silanes to the osmium benzyl compound, Cp*(iPr3P)OsCH2Ph, afforded two neutral hydrogen-substituted silylene complexes via activation Si-H bonds. These species have been structurally characterized, and their reactivity has examined experimentally computationally. Comparison these with cationic analogue highlights dramatic influence charge distribution on reaction chemistry metal complexes.

Cationic zinc complexes of a bis(phosphinimine) pincer ligand have been prepared. Methylzinc and zinc–lactate structurally characterized, the latter is first cationic metal complex to promote coordination–insertion polymerization lactide at ambient temperature. This novel catalyst system remarkably active also exhibits living character. A detailed investigation kinetics mechanism process has undertaken.

A general approach for the synthesis of cationic zinc complexes supported by neutral ancillary ligands has been developed and exploited to prepare [LH][B(C6F5)4] (L = 4-(2,6-iPr2-C6H3NPPh2)dbf), 1a, [LH][SO3CF3], 1b) using [HNMe2Ph][B(C6F5)4] triflic acid, respectively. Reactions 1a 1b with diethylzinc afforded corresponding [LZnEt][B(C6F5)4], 2a, [LZnEt(OSO2CF3)], 2b. Both have exhibited notable activities catalytic polymerization l-lactide.

A rare family of base-free organoscandium alkyl cations stabilized by β-diketiminato ligands (Ar)NC(R)CHC(R)N(Ar) (Ar = 2,6-iPr-C6H3; R CH3 (LMe), tBu (LtBu)) has been prepared reaction LScR2 with perfluorinated boranes B(C6F5)3 and (C12F8)B(C6F5). While the LMe ancillary lacked sufficient steric bulk to prevent C6F5 transfer metal center, LtBu derivatives were quite robust in solution. Although these species subject thermal decomposition via metalation an isopropyl group loss RH (ΔS⧧...

Species of the form [LH]+[BR4]− (R = pentafluorophenyl, phenyl, 1) were synthesized by reaction Brönsted acids with a novel bis-phosphinimine ligand (L 4,6-(MesN═PPh2)2dibenzofuran). Corresponding cationic complexes [LMgnBu]+[BR4]− (2) produced [MgnBu2] [LH]+[BR4]−. Organomagnesium species 2a and 2b exhibit extremely high activity as initiators for polymerization ε-caprolactone, yielding near-quantitative conversion monomer to molecular weight (>2.0 × 105 g/mol) polymer in 4 min at ambient...

Reaction of Cp*(iPr2MeP)RuCl (1) with 0.5 equiv Mg(CH2Ph)2(THF)2 afforded the benzyl complex Cp*(iPr2MeP)Ru(η3-CH2Ph) (2). Complex 2 readily reacted primary silanes H3SiR (R = trip, dmp, MesF; trip 2,4,6-iPr3-C6H2, dmp 2,6-Mes2-C6H3, MesF 2,4,6-(CF3)3-C6H2) to liberate toluene and afford hydrogen-substituted silylene complexes Cp*(iPr2MeP)(H)Ru═SiH(R) [R 3; 4; MesF, 5]. Complexes 3−5 exhibit characteristic SiH 1H NMR resonances downfield 8 ppm very small 2JSiH coupling constants (8−10 Hz)....

The first silylyne complex of a metal beyond group 6, [Cp*(iPr3P)(H)Os≡Si(Trip)][HB(C6F5)3], was prepared by new synthetic route involving hydride abstraction from silicon. NMR and DFT computations support the presence ligand, NBO ETS-NOCV analysis revealed nature this Os–Si interaction as triple bond consisting covalent σ two strong π back-donations. discovery allowed observations cycloadditions complex, terminal alkynes are shown to react via C–H additions across Os≡Si bond.

Base‐stabilized rhodium borylene complex κ2‐L(CO)Rh(BMes), 2; κ2‐L = κ2‐NN’‐Rh,κ1‐N‐B‐(2,5‐[iPr2P=N(4‐iPrC6H4)]2‐N’(C4H2)‐); Mes mesityl, reacts with a series of alkynes (PhC≡C—R; R Ph, Me, CO2Et, H) to yield unique structures whereby the alkyne has regioselectively added across boron and carbon atom CO ligand. The resulting complexes, LRh[C(O)C(Ph)C(R)B(Mes)], 3R, react additional afford cycle‐containing products, L(CO)Rh([[EQUATION]]), 5R, that ultimately release highly functionalized...

Base‐stabilized rhodium borylene complex κ2‐L(CO)Rh(BMes), 2; κ2‐L = κ2‐NN’‐Rh,κ1‐N‐B‐(2,5‐[iPr2P=N(4‐iPrC6H4)]2‐N’(C4H2)‐); Mes mesityl, reacts with a series of alkynes (PhC≡C—R; R Ph, Me, CO2Et, H) to yield unique structures whereby the alkyne has regioselectively added across boron and carbon atom CO ligand. The resulting complexes, LRh[C(O)C(Ph)C(R)B(Mes)], 3R, react additional afford cycle‐containing products, L(CO)Rh([[EQUATION]]), 5R, that ultimately release highly functionalized...

Mixed alkyl-amido lutetium complexes, L i Pr Lu(CH 2 SiMe 3 )(NHCPh ) ( 7 CPh3 and )(NHDipp) Dipp (L = 2,5-[ P=N(4- PrC 6 H 4 )] C N – ), were synthesized by addition of a bulky primary amine, NH R (R CPh , Dipp) (Dipp 2,6- to...

An osmium complex bearing a terminal hydrogen-substituted stannylene ligand, Cp*(iPr3P)(H)Os═SnH(trip) (1) (trip = 2,4,6-triisopropylphenyl), has been prepared by extrusion, and the structurally characterized. Complex 1 coordinates Lewis bases activates O−H bonds of water methanol. Most interestingly, converts to metallostannylene Cp*(iPr3P)(H)2OsSn(trip) (2) thermally or photochemically what appears be radical process.

Cationic organozinc complexes of a neutral bis(phosphinimine) pincer ligand (L) have been prepared and structurally characterized. This recently introduced was constructed from dibenzofuran (dbf) framework with symmetric attachment phosphinimine groups at the 4 6 positions. Starting protonated derivatives [LH][B(C6F5)4] (1a), [LH][BPh4] (1b), or [LH2][BPh4]2 (1c), [LZnCH3][B(C6F5)4] (2a), [LZnCH3][BPh4] (2b), [LZnOAc][BPh4] (3), were via protonolysis an appropriate alkylzinc precursor. The...

The P-stereogenic phosphinimine ligands (dbf)MePhP═NAr (7: Ar = Dipp; 8: Mes; dbf dibenzofuran, Dipp 2,6-diisopropylphenyl, Mes 2,4,6-trimethylphenyl) were synthesized as racemates via reactions of the parent phosphines (rac)-(dbf)MePhP (6) with organoazides. 7 and 8 protonated by Brønsted acids to afford aminophosphonium borate salts [(7)-H][BAr4] (9: C6F5; 11: Ph) [(8)-H][BAr4] (10: 12: Ph). 9 10 active toward alkane elimination diethylzinc ethyl-[methyl-(S)-lactate]zinc give heteroleptic...

The synthesis of a novel bis(phosphinimine) ancillary ligand based on carbazole framework is described (HLPh, 4a; HLPipp, 4b; Ph = phenyl, Pipp para-isopropylphenyl). Protonolysis with Lu(CH2SiMe3)3(THF)2 afforded the corresponding lutetium dialkyl complexes (LuLPh(CH2SiMe3)2, 5a; LuLPipp(CH2SiMe3)2, 5b), which were thermally sensitive and rapidly underwent intramolecular metalative alkane elimination to generate LuLPh*(CH2SiMe3)(THF), 6a, LuLPipp*(CH2SiMe3)(THF), 6b, as highly reactive...

Cationic zinc complexes of a neutral pincer framework 4,6-(ArNPPh2)-dibenzofuran (L111: Ar = 2-iPrPh; L22: o-tolyl; L33: Ph), have been prepared and characterized. Crystallographic NMR studies the methylzinc [LZnCH3+][BAr4−] (4a–6a: m-(CF3)2–C6H3; 4b–6b: Ph) demonstrated that steric demands ligand dramatically affect solid-state geometry. The cationic zinc–lactate [LZnOR+][B(m-(CF3)2–C6H3)4−] (7: L L22; 8: L33; R CH(Me)CO2Me) were also studied, their efficacy as lactide polymerization...

A novel bis(phosphinimine)pyrrole based ligand (HL) and its synthesis are reported. Rare earth dialkyl complexes of the ligand, LLn(CH(2)SiMe(3))(2) (Ln = Er, Lu, Sc), have been prepared found to exhibit high thermal stability in solution. The protio-ligand lanthanide Lu) characterised by single crystal X-ray diffraction studies.

Two derivatives of a new bis(pyrazolyl)carbazole pincer ligand H(CzPzR), R = iPr and Me, their syntheses are reported. Lutetium dialkyl complexes the (CzPzR)Lu(CH2SiMe3)2, have been prepared found to exhibit high thermal stability in solution. These organolutetium compounds Lewis base free, solid-state structure (CzPziPr)Lu(CH2SiMe3)2 revealed that complex is monomeric with trigonal-bipyramidal geometry. Hydrogenolysis afforded trimetallic lutetium hydride possesses five bridging ligands....