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Three permethylindenyl zirconocenes have been supported on a hexane-insoluble form of polymethylaluminoxane modified with 40 wt % pentafluorophenol (sMAO(PFP)). The solid precatalysts were characterized by solid-state nuclear magnetic resonance spectroscopy, and their ethylene polymerization activity was studied. When supported on sMAO(PFP), Me2SB(Cp,I*)ZrX2 ({(η5-C9Me6)Me2Si(η5-C5H4)}ZrX2; X = Cl, CH2Ph, and Me) showed ethylene polymerization activities up to 25% higher than when supported on unmodified sMAO with the same [Al]0/[Zr]0 catalyst loading: activities of 6454 and 5144 kgPE molZr–1 h–1 bar–1 at 80 °C for Me2SB(Cp,I*)ZrCl2 supported on sMAO(PFP) and sMAO, respectively. The systems produced relatively low-molecular weight polyethylenes (Mw < 170 kg mol–1 at 80 °C) with minimal defects and branching. The polymers showed good flowability, although they displayed more aggregated morphologies than polyethylenes produced from unmodified sMAO. On increasing the solvent volume fivefold, the activity and polymer molecular weights approximately doubled.

Solid polymethylaluminoxane (sMAO) supported ansa-bridged permethylindenyl zirconocenes Me2SB(CpR,I*)ZrX2 ({(η5-C9Me6)Me2Si(η5-C5H3R)}ZrX2; R = H, Me, and nBu; X = Cl, Br, Me, and CH2Ph) have been investigated as catalysts for the slurry-phase polymerization of ethylene in the presence of H2. The catalysts demonstrated remarkable stability to H2 both in a high-throughput screening system and in a 2 L batch reactor, with an almost constant ethylene uptake maintained throughout the polymerization runs. The catalysts demonstrated very high ethylene polymerization activities, almost 3 times higher than sMAO-(CpnBu)2ZrCl2 (industrial standard zirconocene catalyst) under the same conditions. The presence of small quantities of H2 (

Rac- and meso-bis(1-hexamethylindenyl)phenylborane zirconium dichloride, {rac-, meso-( Ph BBI*)ZrCl 2 } has been synthesised and fully characterised. The slurry phase ethylene polymerisation performance of rac-( Ph BBI*)ZrCl 2 immobilised on a range of methylaluminoxane (MAO)-modified, solvent-dispersed, high surface area layered double hydroxides (AMO/AIM-Mg x Al-CO 3 LDHs) have been studied. The polymerisation activities show a strong dependence on the nature of the LDH. Rac-( Ph BBI*)ZrCl 2 supported on a MAO-modified 1-hexanol dispersed [Mg 0.73 Al 0.27 (OH) 2 ][CO 3 ] 0.135 LDH displayed a maximum ethylene polymerisation activity of 6641 kg PE mol Zr−1 h −1 bar −1 at 70 °C and 2 bar ethylene. Benchmarking studies reveal that some of the rac-( Ph BBI*)ZrCl 2 supported catalysts outperform a range of commonly used industrial metallocene PE catalysts.

A series of modified solid polymethylaluminoxane (sMAO) catalyst supports have been developed for slurry phase ethylene polymerisation, using aryl di-ol modifier groups. Characterisation using ICP-MS analysis, X-ray total scattering, SEM–EDX, diffuse FT-IR and solid state NMR spectroscopy shows that the organic linker groups are uniformly distributed in a proposed organic framework stucture we call a “sMAOF”. When used as a support for rac-ethylene{bis(1-indenyl)} zirconium dichloride, (EBI)ZrCl2, these linker modified sMAOF materials provide a 40% enhancement in polymerisation activity with respect to unmodified sMAO: activities of 163 × 103 and 116 × 103 kgPE molZr−1 h−1 at 80 °C for (EBI)ZrCl2 supported on sMAOF(1,4-HO(C6F4)OH) and sMAO, respectively. The observed activity increase is correlated with the higher BET surface area and increased porosity in the linker modified sMAOF activating support.

We report the synthesis and characterisation of eight constrained geometry complexes, with variation of the amido fragment, ansa-bridge, permethylindenyl group, metal centre and initiator groups from the parent complex Me2SB(tBuN,I*)TiCl2. These complexes have been shown to be highly active for slurry-phase ethylene polymerisation when supported on solid polymethylaluminoxane (sMAO), with activities up to 7048 kgPE/molTi/h/bar. Ethylene/1-hexene and ethylene/styrene copolymerisations have shown these complexes to be good incorporators of comonomers into the polymer chain.

Five new group 4 ansa-bridged permethylindenyl complexes with either a dimethylsilane bridge or a tetramethyldisilane bridge have been synthesised and fully characterised. These complexes were supported on a hydrocarbon insoluble polymethylaluminoxane (sMAO) and their slurry-phase ethylene polymerisation performance was investigated. The highest activity was achieved using S B M e 2 (CpMe,I*)Zr(CH2SiMe3)2 (8042 kgPE molZr–1 h–1 bar–1 at 60 °C) but a decrease in activity was observed with an increase in the length of the bridge. DSC analysis of the polymers revealed the production of HDPE with minimal branching and defects, while SEM showed the production of polymer particles with commercially desirable uniform, ‘popcorn’, morphology. GPC analysis showed the production of polyethylenes with Mw S B M e 2 (Cp,I*)Zr(CH2SiMe3)2 was immobilised on MAO modified layered double hydroxide (LDHMAO). The slurry-phase polymerisation activity of S B M e 2 (Cp,I*)Zr(CH2SiMe3)2 on this support system was similar to the sMAO support; however, the polymer morphology was much less uniform.

Treatment of the bis(imino)pyridine molybdenum η6-benzene complex (iPrPDI)Mo(η6-C6H6) (iPrPDI, 2,6-(2,6-iPr2C6H3N═CMe)2C5H3N) with NH3 resulted in coordination induced haptotropic rearrangement of the arene to form (iPrPDI)Mo(NH3)2(η2-C6H6). Analogous η2-ethylene and η2-cyclohexene complexes were also synthesized, and the latter was crystallographically characterized. All three compounds undergo loss of the η2-coordinated ligand followed by N–H bond activation, bis(imino)pyridine modification, and H2 loss. A dual ammonia activation approach has been discovered whereby reversible M–L cooperativity and coordination induced bond weakening likely contribute to dihydrogen formation. Significantly, the weakened N–H bonds in (iPrPDI)Mo(NH3)2(η2-C2H4) enabled hydrogen atom abstraction and synthesis of a terminal nitride from coordinated ammonia, a key step in NH3 oxidation.

We report here the synthesis of two new ansa-bridged permethylindenyl zirconocenes, their reaction with solid polymethylaluminoxane (sMAO) and their use in slurry phase ethylene polymerisation. Meso-(EBI*)Zr(CH2Ph)2 and meso-(EBI*)Zr(CH2tBu)Cl, (EBI* = ethylenebis[1-(2,3,4,5,6,7-hexamethylindenyl)]) were synthesised from meso-(EBI*)ZrCl2 and KCH2Ph and LiCH2tBu respectively. The new zirconocenes were characterised by NMR spectroscopy and X-ray crystallography, and density functional theory calculations were carried out. Solid precatalysts were obtained when these compounds were reacted with the polymethylaluminoxane support. Ethylene polymerisation activities of up to 6000 kgPE/molZr/h/bar were obtained in the slurry polymerisation of ethylene. The polyethylenes showed molecular weights, Mw, above 200 000 kg/mol and low polydispersities, Mw/Mn

A family of group 15 MIII pyridine dipyrrolide complexes has been prepared and fully characterized; the reduction of these complexes was investigated with traditional strong metal reductants, which led either to over-reduction in the case of Mg and Zn or to ligand redistribution and "ate" complex formation when KC8 was used. However, by utilizing organosilanes as soluble reductants, the ring opening and two electron reduction of thf solvent was observed with concomitant formation of Bi-C and Si-O bonds; this is an example of a main group complex that is capable of ring opening a cyclic ether in the absence of additional metal reducing agents. The proposed BiII intermediate in this mechanism could be trapped using the stable organic radical TEMPO.

Two methods for the synthesis of bis(imidazol-2-ylidene)pyridine iron dialkyl complexes, (CNC)Fe(CH(2)SiMe(3))(2), have been developed. The first route consists of addition of two equivalents of LiCH(2)SiMe(3) to the iron dihalide complex, (CNC)FeBr(2), while the second relies on addition of the free CNC ligand to readily-prepared (py)(2)Fe(CH(2)SiMe(3))(2) (py = pyridine). With aryl-substituted CNC ligands, octahedral complexes of the type ((Ar)CNC)Fe(CH(2)SiMe(3))(2)(N(2)) ((Ar)CNC = bis(arylimidazol-2-ylidene)pyridine) were isolated, where the dinitrogen ligand occupies the site trans to the pyridine of the CNC-chelate. In contrast, the alkyl-substituted variant, ((tBu)ACNC)Fe(CH(2)SiMe(3))(2) ((tBu)ACNC = 2,6-((t)Bu-imidazol-2-ylidene)(2)pyridine) was isolated as the five-coordinate compound lacking dinitrogen. Exposure of the ((Ar)CNC)Fe(CH(2)SiMe(3))(2)(N(2)) derivatives to an H(2) atmosphere resulted in formation of the corresponding iron hydride complexes ((Ar)CNC)FeH(4). These compounds catalyzed hydrogen isotope exchange between the deuterated benzene solvent and H(2), generating isotopologues and isotopomers of ((Ar)CNC)Fe(H(n))(D(4-n)) (n = 0–4). When (3,5-Me(2)(Mes)CNC)Fe(CH(2)SiMe(3))(2)(N(2)) (3,5-Me(2)(Mes)CNC = 2,6-(2,4,6-Me(3)-C6H2-imidazol-2-ylidene)(2)-3,5-Me(2)-pyridine) was treated successively with H(2) and then N(2), the corresponding reduced dinitrogen complex (3,5-Me(2)(Mes)CNC)Fe(N(2))(2) was isolated. The same product was also obtained following addition of pinacolborane to (3,5-Me(2)(Mes)CNC)Fe(CH(2)SiMe(3))(2)(N(2)).

A series of well-defined group 4 permethylindenyl complexes have been prepared and fully characterised by NMR spectroscopy and X-ray crystallography. Me2SB(Cp,I*)ZrCl2 ({(η5-C9Me6)Me2Si(η5-C5H4)}ZrCl2; 1), Me2SB(CpMe,I*)ZrCl2 ({(η5-C9Me6)Me2Si(η5-C5H3Me)}ZrCl2; 2), Me2SB(Cp,I*)HfCl2 (3) and Z-Me2SB(Cp,I*)ZrCl(O-2,6-Me-C6H3) (4) were investigated as initiators for the ring-opening polymerisation (ROP) of l-, d- and rac-lactide monomers in the presence of benzyl alcohol. 1-4 displayed second order dependence on monomer concentration and produced isotactic and heterotactic (Pr = 0.81) polylactides for the polymerisation of l-, d- and rac-lactide respectively. The effects of temperature, catalyst concentration, co-initiator concentration, solvent and scale were studied. At 80 °C, with two equivalents of benzyl alcohol, 4 was the most active initiator for the ROP of l-, d- and rac-lactide (kobs = 6.39, 6.38 and 5.89 M-1 h-1 respectively). The polylactides were characterised by NMR spectroscopy, GPC and MALDI-TOF mass spectrometry.

A series of ten well-defined group 4 ansa-bridged permethylindenyl complexes have been prepared, fully characterised and supported on inorganic solid supports. These catalysts were investigated in the slurry-phase polymerisation of ethylene. A range of inorganic solid supports have been utilised; solid polymethylaluminoxane (sMAO), MAO modified layered double hydroxide (LDHMAO) and MAO modified silica (SSMAO). The sMAO supported catalytic systems exhibit some of the highest slurry-phase polymerisation activities reported in literature with activities reaching 9509 kg PE mol M-1 h -1 bar -1 for Me2 SB(Cp Me ,I∗)ZrMe 2 at 80 °C after 5 minutes of polymerisation; 34% more active than an industrial standard under similar conditions. These systems produce polyethylenes with low molecular weights, M w , reaching as low as 46 kg mol -1 for E- Me2 SB(Cp nBu ,I∗)ZrCl 2 at 90 °C after 30 minutes of polymerisation with a uniform, mono-disperse "popcorn" morphology. The sMAO supported systems show much higher catalytic activities and much more industrially desirable polyethylene morphology than the same complexes supported on LDHMAO and SSMAO.

Six new peralkylated bis(indenyl) zirconocene complexes have been synthesised and fully characterised; rac-­Me2SB(3-­EtI*)ZrX2 and meso-­Me2SB(3­-EtI*)ZrX2 (X = Cl, Br and CH2Ph). Solution-phase ethylene polymerisation using rac-Me2SB(3-­EtI*)ZrCl2/methylaluminoxane (MAO) and slurry-phase ethylene polymerisation using rac-Me2SB(3­-EtI*)ZrCl2 immobilised on solid polymethylaluminoxane (sMAO), MAO modified layered double hydroxide (LDHMAO) and MAO modified silica (SSMAO) were studied. Polymerisation conditions were optimised for sMAO-rac-Me2SB(3-­EtI*)ZrCl2 and applied to the other catalysts. A 75:25 mixture of rac-­ and meso-Me2SB(3­-EtI*)Zr(CH2Ph)2 supported on sMAO showed the highest polymerisation activities (4832 kgPEmolZr−1 h−1 bar−1 at 60 °C), producing high density polyethylenes (HDPE) with modest molecular weights (Mw of 336 kg mol−1 at 60 °C) and molecular weight distributions (Mw/Mn) less than 3.2. sMAO-rac-Me2SB(3-­EtI*)ZrCl2 was found to be responsive to H2 in a high-throughput screening system, producing polyethylenes with low molecular weights (Mw of 41 kg mol−1 with 1.6% H2). In the same high-throughput system, slurry-phase ethylene polymerisation in the presence of 1-hexene comonomer was shown to increase the polymerisation activity of sMAO-rac-Me2SB(3-­EtI*)ZrCl2) compared to polymerisation in the same system without 1-hexene.

A series of bis(peralkylindenyl)zirconocene and hafnocene complexes were synthesised and characterised by NMR spectroscopy, mass spectrometry and elemental analyses. 3-ethyl-2,4,5,6,7-pentamethylindanone, ( 3-Et Ind # [Formula presented] 3-ethyl-2,4,5,6,7-pentamethylindene, ( 3-Et Ind # )H, and rac-3-ethyl-2,4,5,6,7-pentamethylindenylhafnium dichloride, rac-( 3-Et Ind # ) 2 HfCl 2 , were also characterised by X-ray crystallography. rac- and meso-( 3-Et Ind # ) 2 MCl 2 (M = Zr or Hf) were obtained from the reaction of ( 3-Et Ind # )Li with ZrCl 4 or HfCl 4 . The group 4 metallocenes were then reacted with methylaluminoxane-functionalised silica (SSMAO) to afford silica supported catalysts. A mixture of rac- and meso-( 3-Et Ind # ) 2 ZrCl 2 supported on SSMAO demonstrated an initial polymerisation activity of 250 kg PE /mol M /h/bar. At 70 °C, using rac-( 3-Et Ind # ) 2 ZrCl 2 , solution phase polymerisation activities were twenty times faster than slurry phase polymerisation using SSMAO-rac-( 3-Et Ind # ) 2 ZrCl 2 (1243 and 75 kg PE /mol Zr /h/bar respectively).

A family of group 4 permethylpentalene complexes, Pn∗MCpRX (M = Ti, Zr; CpR = Cp, CpMe, CptBu, CpnBu, CpMe3, Ind; X = Cl, Me), has been synthesized and fully characterized by multinuclear NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction studies. These complexes were immobilized on an insoluble polymethylaluminoxane (sMAO), MAO-modified silica (ssMAO), and a MAO-modified layered double hydroxide (LDH-MAO). The effect of substitution around the Cp ligand was examined in relation to their performance (activity, Mw, PDI, polymer morphology) for ethylene polymerization measured both in solution and in slurry phase. Maximum solution-phase activities of 3585 kg/mol·h·bar were recorded at modest [Zr]:[Al] ratios of 1:250. These were compared to the activities recorded using the equivalent solid-supported complexes, and it was observed that sMAO was a superior support material with average increases in activity of 5.3 and 2.3 times relative to ssMAO and LDH-MAO, respectively. Most striking was the observation that slurry-phase ethylene polymerization activities using equivalent precatalysts supported on sMAO showed enhanced performance compared to the solution phase up to a maximum of 4486 kg/mol·h·bar.

Addition of H2 gas to the bis(arylimidazolin-2-ylidene)pyridine iron bis(dinitrogen) complex (H4-iPrCNC)Fe(N2)2 resulted in facile oxidative addition of the H–H bond to yield a mixture of (H4-iPrCNC)FeH4 and trans-(H4-iPrCNC)FeH2(N2), depending on the partial pressures of H2 and N2. Both iron hydride complexes were characterized by X-ray diffraction and proved relevant to the catalytic hydrogen isotope exchange of arene C(sp2)–H bonds. Activation of the benzene-d6 solvent at ambient temperature produced deuterated isotologues of both compounds that exhibit large isotopic perturbation of resonances in the hydride signals.

A series of titanium complexes containing the permethylpentalene ligand (C8Me62−; Pn∗) – Pn∗Ti(O-2,6-Me-C6H3)Cl (1), Pn∗Ti(O-2,4-tBu-C6H3)Cl (2), Pn∗Ti(OtBu)Cl (3), Pn∗Ti(O-2,6-Me-C6H3)2 (4), Pn∗Ti(OtBu)2 (5) – or the (hydro)permethylpentalene ligand (C8Me6H−; Pn∗(H)) – Pn∗(H)Ti(O-2,6-Me-C6H3)Cl2 (6) and Pn∗(H)Ti(O-2,6-Me2-C6H3)3 (7) – were prepared by the reaction of [Pn∗TiCl(μ-Cl)]2 with the corresponding potassium salt or alcohol. All complexes have been characterized by single crystal X-ray diffraction studies and NMR spectroscopy. The (hydro)permethylpentalene complexes contain a stereocenter and planar chirality which can be described as R,RP or S,SP configurations.

Unsymmetrical permethylindenyl bent metallocene complexes have been synthesised and reacted with inorganic solid supports to afford catalysts for the slurry phase polymerisation of ethylene. Those supported on solid polymethylaluminoxane were both highly active catalysts and afforded polymers with a desirable, low aggregation, "popcorn" morphology.

A series of substituted phenyl mono-imido complexes of the type W(NR)Cl4(THF) (R = C6H5, 2,6-Me-C6H3, 3,5-Me-C6H3, 2,4,6-Me-C6H2, 4-OMe-C6H4, 2,6-F-C6H3 and 3,5-CF3-C6H3) have been synthesised and characterised. Reaction of these complexes with solid polymethylaluminoxane (sMAO) leads to immobilisation and in situ methylation of the chloride positions on the surface of the support. Reaction of W(NR)Cl4(THF) with trimethylaluminium (TMA) yields the trimethyl complexes W(NR)Me3Cl. Immobilisation of the isotopically labelled W{N(2,6-F-C6H3)}(13CH3)3Cl on sMAO furnished the supported complex with two identifiable methyl resonances in the 13C–{1H} solid state CPMAS spectrum (45 and 56 ppm), with the latter matching the unsupported complex, confirming retention of the structure on the surface. The sMAO-supported complexes (W : Al = 1 : 150) were tested for their propensity to dimerise ethylene (1 bar) in d6-benzene at 100 °C and compared with the previously reported sMAO-W{N(2,6-iPr-C6H3)}Cl4(THF) (sMAO-1.a). Complexes with electron deficient imido groups were shown to be the most active, and increased steric bulk in the ortho positions is also an important factor, with sMAO acting as a support, scavenger and activator. sMAO-W{N(3,5-CF3-C6H3)}Cl4(THF) was the most active, demonstrating a turnover frequency of 5.65 molC2H4 mol−1W h−1 and a selectivity towards 1-butene of 91% after 8 h.

A family of well-defined cyclopentadienyl and indenyl group 4 complexes has been prepared. The complexes Cp2ZrCl(O-2,6-Me-C6H3) (1), Cp2Zr(O-2,6-Me-C6H3)2 (2), Cp2ZrMe(O-2,6-Me-C6H3) (3), (Ind)2ZrCl(O-2,6-Me-C6H3) (4), (Ind)2ZrMe(O-2,6-Me-C6H3) (5), (Ind)2ZrMe(OtBu) (6), and rac-(EBI)ZrCl(O-2,6-Me-C6H3) (7) were investigated as catalysts for the polymerization of L- and rac-lactide. (Ind)2ZrMe(OtBu) was shown to be the fastest catalyst. At 100 °C, the rates of polymerization (kobs) for L- and rac-lactide were very similar (0.317 and 0.293 h−1 respectively). However, at 80 °C it was found that polymerization of L-LA (kobs = 0.217 h−1) was twice as fast as rac-LA (kobs = 0.120 h−1).

A tungsten imido complex W(NDipp)Me3Cl (Dipp = 2,6-(i)Pr-C6H3) is active for the selective dimerisation of ethylene to yield 1-butene under mild conditions. Immobilisation and activation of W(NDipp)Cl4(THF) on layered double hydroxides, silica or polymethylaluminoxane yields active solid state catalysts for the selective dimerisation of ethylene. The polymethylaluminoxane-based catalyst displays a turnover frequency (4.0 molC2H4 molW(-1) h(-1)) almost 7 times that of the homogeneous catalyst.