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Compounds of Li, Na, K and Ca of a tetradentate amino-bis(phenolato) ligand were prepared. Bimetallic compounds formulated as M2[L](THF)n (where M = Na, n = 1 (1·THF) or Li, n = 1 (2·THF)) were synthesized via the reaction of H2[L] (where [L] = 2-pyridylmethylamino-N,N-bis(2-methylene-4-methoxy-6-tert-butylphenolato) with sodium hydride or n-butyllithium, respectively, in THF. Monometallic complexes MH[L](THF)n (where M = Na, n = 1 (3·THF), Li, n = 0 (4) and K, n = 0 (5)) were obtained by reaction of H2[L] with MN(SiMe3)2 where M = Na, Li, or K. Calcium complex Ca[L](THF) (6·THF) was synthesized in two ways; reaction of Na2[L] with calcium iodide in THF, and reaction of Ca[N(SiMe3)2]2 with H2[L] in toluene. Compounds 1–6 exhibit activity for rac-lactide polymerization under melt and solution conditions. Moderate control of polymer molecular weights was achieved in toluene, whereas polydisperse polymer was obtained under solvent free conditions. MALDI-TOF MS analysis of the polymer end groups revealed a predominantly cyclic nature for the polylactides.

The affinity for nucleophile (azide, N3–, and chloride, Cl–) binding significantly influences the catalytic activity of chromium complexes for the copolymerization of cyclohexene oxide (CHO) and CO2. The binding of N3– and Cl– to two amino-bis(phenolate) Cr(III) chloride complexes [L1Cr(μ-Cl)]2 (1) and [L2CrCl(THF)] (2·THF), where L1 = methoxyethylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenolate) and L2 = dimethylaminoethylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenolate), were studied by both matrix assisted laser desorption/ionization time-of-flight and electrospray ionization mass spectrometry (MALDI-TOF-MS and ESI-MS, respectively). Upon reaction with [PPN][N3] ([PPN] = bis(triphenylphosphine)iminium), 1 exhibited greater ability to form six-coordinate bis-azide ions [L1Cr(N3)2]− and produced fewer five-coordinate species detected by MS than 2·THF. This corresponded to 2·THF having a significantly faster rate of polymerization with anionic nucleophile cocatalysts than 1. In the presence of 1 e...

Cobalt(II) and (III) complexes bearing tetradentate amino-bis(phenolate) ligands containing either pendent dimethylaminoethylene or pyridyl groups and phenolates bearing electron-donating alkyl or electron-withdrawing chloro substituents were synthesized. The compounds were characterized by mass spectrometry, elemental analysis and NMR for diamagnetic compounds. The influence of the electron donating ability and steric demand of the ligands on CO2/epoxide ring-opening copolymerization (ROCOP) and coupling reactions was investigated. Of the Co(II) systems studied, complex 3, which has an amino-bis(phenolate) ligand possessing chlorine-functionalized phenolates and a pyridyl pendent group, [L3] = 2-methylene-pyridyl-N,N-bis(2-methylene-2,4-dichlorophenolate), was active for poly(cyclohexene carbonate) formation. The complex showed up to 98% epoxide conversion, up to 98% polymer selectivity and up to 97% carbonate linkages. By comparison, Co(II) compounds 1 and 2 bearing alkyl groups on the phenolate donors were inactive for ROCOP. Structural characterization of 3 by X-ray diffraction (and supported by mass spectrometry and elemental analysis) showed the potassium acetate (KOAc), which formed as a synthetic by-product, remains coordinated to the Co[L3] unit through binding of the K+ ions to the chlorine substituents on the phenolate groups and acetate anions, resulting in a hexacobalt cluster in the solid state. Cobalt(III) compounds were prepared from the Co(II) complexes by aerobic oxidation in the presence of 2,4-dinitrophenol. The resulting 2,4-dinitrophenolate (2,4-DNP) complexes were diamagnetic species of which 7, possessing a dimethylamino-N,N-bis(2-methylene-2-tert-butyl-4-methyl-phenolate) ligand [L4], was characterized by single crystal X-ray diffraction. The Co(III) complexes 5–7 were inactive for ROCOP of cyclohexene oxide or propylene oxide but were active for cyclic carbonate formation for a variety of epoxides studied. A maximum turnover frequency of 20 h−1 was attained for conversion of epichlorohydrin to (chloromethyl)ethylene carbonate.

Three complexes were prepared using lithium, sodium and potassium reagents and an amine-(bis)phenol proligand. The proligand, benzylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenol) (abbreviated H2[L]), was reacted with n-butyllithium to give the lithium complex, Li2[L] (1), and NaH or KH to give the sodium, Na2[L] (2), and potassium, K2[L] (3), complexes, respectively. The compounds were also found to contain varying numbers of coordinated THF molecules. These complexes were characterized using 1H, 13C, and 7Li NMR (for the lithium complex), MALDI-TOF MS, elemental analysis and FT-IR. The potassium complex (3) was characterized in the solid state and exhibits η6 K-arene bonds as well as η1-bonding of the K ion to the ipso-carbons of the phenolate fragments. The reactivity of 1–3 towards the ring-opening polymerization of rac-lactide to form polylactide (PLA) was explored.

Reaction of benzylamino-N,N-bis(2-methylene-4,6-di-tert-amylphenol), H2L1, with anhydrous ferric chloride in the presence of a base yields FeCl(THF)L1 (1). In the solid state, complex 1 exists as a monomeric iron(III) species with a distorted trigonal bipyramidal geometry. Complex 1 is an air-stable, non-hygroscopic, single-component catalyst for C–C cross-coupling of aryl Grignard reagents with benzyl halides, including chlorides. Moderate to good yields of cross-coupled products can be obtained in diethyl ether at room temperature. Preliminary investigations include the screening of electron-donating and electron-withdrawing groups on both the benzylic substrate and the aryl Grignard reagent.

A series of cobalt(II), cobalt(III) and mixed valence cobalt(II/III) compounds has been prepared and characterized. The protonated tripodal tetradentate ligand precursors (dimethylaminoethylamino-N,N-bis(2-methylene-4-tert-butyl-6-methylphenol), H2[O2NN′]BuMeNMe2, dimethylaminoethylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H2[O2NN′]BuBuNMe2, and 2-pyridylamino-N,N-bis(2-methylene-4-tert-butyl-6-methylphenol), H2[O2NN′]BuMePy were reacted with cobaltous acetate tetrahydrate under varying conditions to afford a range of monometallic, bimetallic and trimetallic species. Monometallic compounds, 1 and 2, were obtained with pendant amine-containing ligands [O2NN′]BuMeNMe2 and [O2NN′]BuBuNMe2, respectively. Compound 1 is a trigonal bipyramidal CoII acetone adduct, CoII(OCMe2)[O2NN′]BuMeNMe2, and 2 is a distorted octahedral CoIII acetate complex, CoII(OAc)[O2NN′]BuBuNMe2. A dimethoxo-bridged dicobalt(III) complex, 3, was obtained using the pyridyl group-containing ligand, [O2NN′]BuMePy, after oxidation in air of a methanol solution of {Co[O2NN′]BuMePy}2. Two side-products, 4 and 5 were also obtained from this reaction. Complex 4 contains two octahedrally coordinated cobalt(III) atoms, each bonded to a tetradentate amine-bis(phenolate) ligand and bridged by one syn,syn η1:η1:μ2 acetate ligand, and one hydroxide ligand. Complex 5 is a heterotrimetallic compound and consists of two Co[O2NN′]BuMePy fragments, each bridged by a syn,anti η1:η1:μ2 acetate ligand to a central CaII(HOMe)4 fragment. Mixed valence CoIII–CoII–CoIII trimetallic complexes, 6 and 7, were obtained by reaction of H2[O2NN′]BuMePy or H2[O2NN′]BuBuPy ligands, respectively, with Co(OAc)2·4H2O in 2:3 molar ratios in methanol under nitrogen followed by aerobic oxidation. Diethylaminoethylamino-N,N-bis(2-methylene-4,6-di-tert-amylphenol), H2[O2NN′]AmAmNEt2 was reacted with cobaltous chloride hexahydrate under acidic conditions to give the ionic compound {H3[O2NN′]AmAmNEt2}+2[CoCl4]2−, 8.

A series of (amine)bis(phenolato)iron(III)acac complexes has been prepared and characterized. Reaction of Fe(acac)3 with the diprotonated linear tetradentate proligand N,N′-bis(4,6-di-tert-butyl-2-methylphenol)-N,N′-dimethyl-1,2-diaminoethane, H2[L1], and tripodal tetradentate ligand precursors dimethylaminoethylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H2[L2], dimethylaminoethylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenol), H2[L3], 2-methoxyethylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H2[L4], 2-methoxyethylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenol), H2[L5], and 2-methoxyethylamino-N,N-bis(2-methylene-4,6-dimethylphenol), H2[L6], produces the distorted octahedral FeIII complexes [L1]Fe(acac) (1), [L2]Fe(acac) (2), [L3]Fe(acac) (3), [L4]Fe(acac) (4), [L5]Fe(acac) (5), and [L6]Fe(acac) (6). In all of these complexes, the phenolato oxygen atoms are cis-oriented. The paramagnetic FeIII complexes 1–6 were also characterized by UV/Vis and IR spectroscopy, mass spectrometry, cyclic voltammetry, and magnetic measurements. Single crystal X-ray molecular structures have been determined for complexes 1, 2, 3, 5, and the proligand H2[L6]. Preliminary investigations of complexes 1–6 for catalytic cross-coupling reactions of aryl Grignard reagents with cyclic and acyclic secondary alkyl halides and benzyl halides were performed. While the activity for cyclohexyl chlorides and bromides was high, cross-coupling of benzyl halides was moderate and 2-bromo- and 2-chlorobutane gave poor yields of cross-coupled product.

Cross-coupling of Grignard reagents with dichloromethane is achieved using iron(III) catalysts. Aryl- and benzylmagnesium bromides show a range of activity toward double C―Cl bond activation resulting in the insertion of methylene fragments between two equivalents of the nucleophilic partner.

The preparation of tetradentate amine-bis(phenol) proligands with dichloro and difluoro substituted phenol groups and their reaction with FeX3 (X = Cl or Br) is described. The compounds, 2-pyridylamino-N,N-bis(2-methylene-4,6-dichlorophenol), H2[L1]; 2-pyridylamino-N,N-bis(2-methylene-4,6-difluorophenol), H2[L2]; dimethylaminoethylamino-N,N-bis(2-methylene-4,6-dichlorophenol), H2[L3]; 2-tetrahydrofurfuryl-N,N-bis(2-methylene-4,6-dichlorophenol), H2[L4]; and methoxyethylamino-N,N-bis(2-methylene-4,6-dichlorophenol), H2[L5] were prepared in aqueous medium and obtained as white powders in good to excellent yield. Ten new iron(III) halide complexes supported by these tetradentate ligands are reported. Representative single crystal X-ray diffraction structures were obtained for H2[L1] and a water adduct of the iron(III) complex, aquachloro{2-pyridylamino-N,N-bis(2-methylene-4,6-dichlorophenolato)}iron(III), 2·H2O. The structure of the proligand H2[L1] shows intramolecular hydrogen bonding. In the solid-state structure, the iron complex exhibits intermolecular hydrogen bonding between the water ligand and the phenolate oxygen of a neighbouring complex. The anhydrous complexes were studied for catalytic activity towards C–C cross-coupling of Grignard reagent nucleophiles with alkyl halide electrophiles.

Reaction of n-propylamino-N,N-bis(2-methylene-4-tert-butyl-6-methylphenol), H(2)L1, n-propylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H(2)L2, and benzylamino-N,N-bis(2-methylene-4-tert-butyl-6-methylphenol), H(2)L3, with anhydrous ferric chloride in the presence of base yields the products, [FeL1(μ-Cl)](2) (1), [FeL2(μ-Cl)](2) (2) and [FeL3(μ-Cl)](2) (3). In the solid state, these complexes exist as chloride-bridged dimers giving distorted trigonal bipyramidal iron(III) ions. Reaction of H(2)L1 with FeBr(3), however, results in the formation of a tetrahedral iron(III) complex possessing two bromide ligands. The amine-bis(phenolate) ligand is bidentate in this complex and bonds to the iron(III) ion via the phenolate O-donors. The central amine donor is protonated, resulting in a quaternized ammonium fragment and the iron(III) centre possesses a negative formal charge. As a result, this complex is zwitterionic and formulated as FeBr(2)L1H (4). Complex 1 is an air-stable, non-hygroscopic, single-component catalyst for C-C cross-coupling of aryl Grignard reagents with primary and secondary alkyl halides, including chlorides. Good to excellent yields of cross-coupled products are obtained in diethyl ether at room temperature. In some cases where low yields are obtained under these conditions, the use of microwave-assisted heating of the reaction mixture can improve yields.

Two lithium amine-bis(phenolate) and four chromium(III) amine-bis(phenolate) complexes have been prepared. The diprotonated tripodal tetradentate ligand precursors 2-tetrahydrofurfuryl-N,N-bis(2-methylene-4-methyl-6-tert-butylphenol), H(2)[O(2)NO](BuMe); 2-tetrahydrofurfuryl-N,N-bis(2-methylene-4,6-tert-butylphenol), H(2)[O(2)NO](BuBu); 2-pyridylamino-N,N-bis(2-methylene-4,6-methylphenol), H(2)[O(2)NN'](MeMe); and 2-pyridylamino-N,N-bis(2-methylene-4,6-tert-butylphenol), H(2)[O(2)NN'](BuBu); can be lithiated using n-butyllithium. Isolation of the Li(2)[O(2)NO](RR') compounds generates dimeric {Li(2)[O(2)NO](RR')}(2) (R = t-Bu, R' = Me in 1 and R = R' = t-Bu in 2) in the solid state as shown by single-crystal X-ray diffraction. The lithiated ligands were used to prepare a series of Cr(III) complexes. Monometallic complexes are obtained when prepared and purified under strictly anhydrous conditions, giving CrCl(THF)[O(2)NO](RR') (R = t-Bu, R' = Me in 3 and R = R' = t-Bu in 4). However, bimetallic Cr complexes are obtained upon recrystallization in air, where adventitious water reacts with the complex resulting in protonation of one of the phenolate groups of the ligand and generating hydroxide, which bridges two Cr(III) centres. Solid-state single-crystal X-ray diffraction studies of {CrCl[O(2)NN'](MeMe)}(mu-HO){CrCl[HO(2)NN'](MeMe)}, 5, and {CrCl[O(2)NN'](BuBu)}(mu-HO){CrCl[HO(2)NN'](BuBu)}, 6, were performed. The paramagnetic Cr(III) complexes were also characterized by UV-vis spectroscopy, mass spectrometry and magnetic measurements.

The synthesis and structures of isomeric lithium diamine-bis(phenolate) complexes are reported. Deprotonation of the ligands, H2O2NN′tBu [Me2NCH2CH2N(CH2ArOH)2, Ar = 3,5-C6H2-tBu2] and H2O2N2tBu [HOArCH2NMeCH2CH2NMeCH2ArOH, Ar = 3,5-C6H2-tBu2], in diethyl ether affords base-free lithium complexes Li2O2NN′tBu (1) and Li2O2N2tBu (2) upon solvent removal. The dioxane adduct of (1) exhibits a polymeric structure in the solid-state, whereas the dioxane adduct of (2) possesses a dimeric structure. The syntheses of K2O2NN′tBu (3), K2O2N2tBu (4), Zr(O2NN′tBu)Cl2 (5) and Y(O2NN′tBu)Cl(THF), (6), are also reported. The transition metal complexes were isolated in good yields via salt metathesis reactions using 1 or 3.

The niobium(III) chloride precursors R[P2N2]NbCl stabilized by the bis-(amidophosphine) macrocycle (where R[P2N2]=RP(CH2SiMe2NSiMe2CH2)2PR, R=phenyl, Ph, or cyclohexyl, Cy), react with MeMgCl under argon to form the paramagnetic R[P2N2]NbMe (R=Ph, 1; R=Cy, 2) complexes. The methyl complexes 1 and 2 can be stabilized by the donor solvent pyridine to form the paramagnetic adducts R[P2N2]NbMe(py) (R=Ph, 3; R=Cy, 4). Methyl complexes 1 and 2 readily react with N2 to form the diamagnetic dinuclear dinitrogen compounds, (R[P2N2]NbMe)2(μ-N2) (R=Ph, 5; R=Cy, 6), which have been characterized crystallographically. Dinitrogen complex 5 is fluxional and undergoes enantiomeric inversion of the six-coordinate niobium centres via axial rotation about the NbN2Nb axis. Complex 6 shows no enantiomeric inversion, likely due to the steric effects of the cyclohexyl substituents. The dinitrogen ligand itself is labile at elevated temperatures and undergoes reversible dissociation; the dinitrogen complexes are reformed upon cooling to room temperature. Reaction of 5 and 6 with CO displaces the N2 fragment forming the bridging acyl complexes (R[P2N2]Nb)2(μ-COCH3)2 (R=Ph, 7; R=Cy, 8) where the carbonyl fragments bond to the metal centres in a η2 fashion. Addition of H2 to 5 and 6 results in the formation of the previously reported paramagnetic dinuclear dinitrogen complex, (R[P2N2]Nb)2(μ-N2).

Hydrogenolysis of R[P2N2]NbCH2SiMe3 (where R[P2N2] = RP(CH2SiMe2NSiMe2CH2)2PR; R = cyclohexyl, Cy, or phenyl, Ph) in benzene or toluene causes hydride addition to the aromatic solvent resulting in ...

The coordination chemistry of the two mixed donor macrocyclic ligands R[P2N2] (where R[P2N2] = RP(CH2SiMe2NSiMe2CH2)2PR, R = cyclohexyl (Cy) or phenyl (Ph)) with niobium(III) is presented. The reaction of the dilithio precursors R[P2N2]Li2(S) (R = Cy, S = THF; R = Ph, S = 1,4-dioxane) with NbCl3(DME) (DME = 1,2-dimethoxyethane) generates the complexes R[P2N2]NbCl (R = Cy, 1; R = Ph, 2). For R = Cy, single-crystal X-ray diffraction studies and variable-temperature magnetic susceptibility measurements indicate that 1 is mononuclear in the solid state; however, analogous variable-temperature magnetic data suggest that 2 is dinuclear in the solid state due to the observation of antiferromagnetic exchange. In solution, 2 is apparently monomeric similar to 1. Adduct formation between these mononuclear complexes is also evident; reaction of 2 with neutral donors and coordinating solvents produces the mononuclear derivatives Ph[P2N2]NbCl(L) (L = py, CO, PMe3, THF, MeCN), of which the pyridine adduct, 3e, has been...

The title reaction affords diarylmethanes (III) in highly variable yields and significant amounts of homo-coupled by-products.

Catalytic cross-coupling of aryl Grignard reagents with primary and secondary alkyl halides bearing β-hydrogens is achieved using Fe(III) amine-bis(phenolate) halide complexes.

Catalytic cross-coupling of aryl Grignard reagents with primary and secondary alkyl halides bearing beta-hydrogens is achieved using Fe(III) amine-bis(phenolate) halide complexes.

In the title complex, [Mn(C(36)H(50)N(2)O(2))(CH(3)COO)(H(2)O)]·CH(3)CH(2)OH, the Mn(III) atom is in an octa-hedral environment and is coordinated by the tetra-dentate amine-bis-(phenolate) ligand, a monodentate acetate anion and a water mol-ecule. An ethanol solvent mol-ecule is also found in the asymmetric unit. The structure displays O-H⋯O and C-H⋯O hydrogen bonding.