Platinum-catalyzed double silylations of alkynes with bis(dichlorosilyl)methanes

Bis(dichlorosilyl)methanes 1 undergo the two kind reactions of a double hydrosilylation and a dehydrogenative double silylation with alkynes 2 such as acetylene and activated phenyl-substituted acetylenes in the presence of Speier’s catalyst to give 1,1,3,3-tetrachloro-1,3-disilacyclopentanes 3 and 1,1,3,3-tetrachloro-1,3-disilacyclopent-4-enes 4 as cyclic products, respectively, depending upon the molecular structures of both bis(dichlorosilyl)methanes (1) and alkynes (2). Simple bis(dichlorosilyl)methane (1a) reacted with alkynes [R¹-CC-R²: R¹ = H, R² = H (2a), Ph (2b); R¹ = R² = Ph (2c)] at 80 °C to afford 1,1,3,3-tetrachloro-1,3-disilacyclopentanes 3 as the double hydrosilylation products in fair to good yields (33-84%). Among these reactions, the reaction with 2c gave a trans-4,5-diphenyl-1,1,3,3-tetrachloro-1,3-disilacyclopentane 3ac in the highest yield (84%). When a variety of bis(dichlorosilyl)(silyl)methanes [(Me_nCl_3 − nSi)CH(SiHCl₂)₂: n = 0 (1b), 1 (1c), 2 (1d), 3 (1e)] were applied in the reaction with alkyne (2c) under the same reaction conditions. The double hydrosilylation products, 2-silyl-1,1,3,3-tetrachloro-1,3-disilacyclopentanes (3), were obtained in fair to excellent yields (38-98%). The yields of compound 3 deceased as follows: n = 1 > 2 > 3 > 0. The reaction of alkynes (2a-c) with 1c under the same conditions gave one of two type products of 1,1,3,3-tetrachloro-1,3-disilacyclopentanes 3 and 1,1,3,3-tetrachloro-1,3-disilacyclopent-4-enes (4): simple alkyne 2a and terminal 2b gave the latter products 4ca and 4cb in 91% and 57% yields, respectively, while internal alkyne 2c afforded the former cyclic products 3cc with trans form between two phenyl groups at the 3- and 4-carbon atoms in 98% yield, respectively. Among platinum compounds such as Speier’s catalyst, PtCl₂(PEt₃)₂, Pt(PPh₃)₂(C₂H₄), Pt(PPh₃)₄, Pt[ViMeSiO]₄, and Pt/C, Speier’s catalyst was the best catalyst for such silylation reactions.     

Tin(IV) and organotin(IV) derivatives of bis(pyrazolyl)acetate: Synthesis, spectroscopic characterization and behaviour in solution.: X-ray single crystal study of bis(pyrazol-1-yl)acetatotri-iodotin(IV) [SnI3(bdmpza)]

Novel heteroscorpionate-containing tin and organotin(IV) complexes, [SnR_nX_3 − n(L)], R = Me, Buⁿ, Ph, or cy; X = Cl, Br or I, n = 0, 1, 2 or 3; L = bis(pyrazol-1-yl)acetate (bpza) or bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza), have been synthesized and characterized by spectral (IR, ¹H, ¹³C and ¹¹⁹Sn NMR, ^119mSn Mössbauer) and analytical data. In [SnI₃(bdmpza)], the ligand is fac-N,N′,O-tridentate, the three iodine atoms thus also fac about the six-coordinate tin(IV) atom. Neutral bpzaH reacts with BuⁿSnCl₃, PhSnCl₃ and SnCl₄ in Et₂O in the absence of base, yielding 1:1 adducts [XSnCl₃(bpzaH)] (X = R or Cl).     

Synthesis, characterization and hydrolytic behavior of new bis(2-pyridylthio)acetate ligand and related organotin(IV) complexes

The new sodium bis(2-pyridylthio)acetate ligand, Na[(pyS)₂CHCO₂], has been prepared in ethanol solution using 2-mercaptopyridine, dibromoacetic acid and NaOH. New mono- and di-organotin(IV) derivatives containing the anionic bis(2-pyridylthio)acetate have been synthesized from reaction between SnR_nCl_4−n (R = Me, Ph and ⁿBu, n = 1-2) acceptors and Na[(pyS)₂CHCO₂]. Mono-nuclear complexes of the type {[(pyS)₂CHCO₂]R_nSnCl_4−n−1} have been obtained and characterized by elemental analyses, FT-IR, ESI-MS, multinuclear (¹H and ¹¹⁹Sn) NMR spectral data and X-ray crystallography. ESI-MS spectra of methanol solution of the complexes show the existence of hydrolysed species. Attempts to crystallize the dimethyltin(IV) derivative (3), from acetonitrile solution yield the dimeric dicarboxylatotetramethyldistannoxane (8), which was characterized by single crystal diffraction analysis.     

Synthesis and characterization of new organotin(IV) complexes with polyfunctional ligands

New mono-, di- and tri-organotin(IV) derivatives containing the neutral bis(2-pyridylthio)methane ligand, [(pyS)₂CH₂] and tris(2-pyridylthio)methane ligand, [(pyS)₃CH] have been synthesized from reaction with SnR_nCl_4−n (R = Me, ⁿBu, Ph and Cy, n = 1-3) acceptors. Mono-nuclear adducts of the type {[(pyS)₂CH₂]R_nSnCl_4−n} and {[(pyS)₃CH]R_nSnCl_4−n} have been obtained and characterized by elemental analyses, FT-IR, ESI-MS, multinuclear (¹H and ¹¹⁹Sn) NMR spectral data. The ¹H and ¹¹⁹Sn NMR and ESI-MS data suggest for the triorganotin(IV) derivatives a complete dissociation of the compounds in solution. The mono- and di-organotin(IV) derivatives show a greater stability in solution, and their spectroscopic data are in accordance with the existence of six-coordinated RSnCl₃N₂ or R₂SnCl₂N₂ species.     

Novel generation ponytails in fluorous chemistry: Syntheses of primary, secondary, and tertiary (nonafluoro-tert-butyloxy)ethyl amines

(Nonafluoro-tert-butyloxy)ethyl tosylate 4 was prepared in 65% yield from nonafluoro-tert-butanol 1 using commercially available reagents. Further reaction of 4 with HNR¹R² (R¹ = R² = H, CH₃; R¹ = H, R² = CH₃, (CH₂)₃C₈F₁₇, CH₂CH₂OC(CF₃)₃) affords the appropriate (CF₃)₃COCH₂CH₂NR¹R² amines in 20-69% yields. Improved overall yields of [(CF₃)₃COCH₂CH₂]_3−nNR_n to 1 were obtained by the reaction of (CF₃)₃CONa 2 and (XCH₂CH₂)_3−nNR_n (X = Cl, n = 0, 1, 2, R = CH₃; X = CH₃SO₂O, n = 1, R = CH₃SO₂) nitrogen mustards and a similar reactive β-substituted ethyl amine. The title amines are mobile colorless liquids and volatile with steam. The bulky fluorous ponytail (CF₃)₃CO(CH₂)₂ displays high acidic stability and increases fluorous character almost as much as the classical straight-chain C₈F₁₇(CH₂)₃ ponytail.     

Ligand substitution in the heterometallic cluster Cp*IrOs3(μ-H)2(CO)10

The reactions of the heterometallic cluster Cp*IrOs₃(μ-H)₂(CO)₁₀ with phosphines, isonitriles and pyridine under TMNO activation afforded the substitution products Cp*IrOs₃(μ-H)₂(CO)_10−nL_n (n = 1, 2; L = PPh₃, P(OMe)₃, ^tBuNC, CyNC or py) in good yields. For the monosubstituted derivatives, the substitution site was exclusively at an osmium atom in an axial position for L = phosphine or phosphite. Spectroscopic evidence suggested the presence of isomers in solution for the PPh₃ derivative. In contrast, for L = isonitrile, the ligand occupied an equatorial site. In the disubstituted derivatives, the group 15 ligands were coordinated to two different osmium atoms, one each at an axial and an equatorial site. The isomerism and fluxional behaviour of some of these clusters have also been examined.     

Synthesis and characterization of some organotin(IV) adducts containing a related series of pyridines: Crystal structure of [SnMe2Cl2(bu2bpy)]

Organotin(IV) complexes of [SnR_(4−n)Cl_n] (n = 2, R = Me, ⁿBu; n = 1, R = Ph) react with the bidentate pyridyl ligand 4,4′-di-tert-butyl-2,2′-bipyridine (bu₂bpy) to give hexa-coordinated adducts with the general formula [SnR_(4−n)Cl_n(bu₂bpy)]. However, the reaction of these organotin(IV) complexes with the corresponding monodentate ligand 4-tert-butylpyridine (bupy) resulted in the formation of the hexa-coordinated complex [SnMe₂Cl₂(bupy)₂] and the penta-coordinated complexes [SnR_(4−n)Cl_n(bupy)] (n = 2, R = ⁿBu; n = 1, R = Ph). Moreover, the reaction of the above organotin(IV) complexes with 4,4′-trimethylenedipyridine (tmdp) yields hexa-coordinated adducts with the general formula [SnR₂Cl₂(tmdp)] (R = Me, ⁿBu) and the penta-coordinated complex [ClPh₃Sn-μ-(tmdp)SnPh₃Cl] in the solid state. The resulting complexes have been characterized by multinuclear NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopy and elemental analysis. NMR data shows that the triphenyltin(IV) adducts are not stable in solution and dissociate to give tetra-coordinated tin(IV) complexes. The X-ray crystal structure determination of [SnMe₂Cl₂(bu₂bpy)] reveals that the tin atom is hexa-coordinated in an octahedral geometry with a trans-[SnMe₂] configuration.     

Arene-promoted lithiation of 1,n-dihaloalkanes (n=2-6): a comparative study

The reaction of 1,n-dichloroalkanes 3a (n=2-6) with an excess of lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB; 2.5 mol %) in the presence of different carbonyl compounds [Bu^tCHO, PhCHO, Et₂CO, (CH₂)₄CO, (CH₂)₅CO, (CH₂)₇CO, (−)-menthone], in THF at −78 °C leads, after hydrolysis with water, to the expected 1,(n+2)-diols 4, yields being <25% for n=2, 3 and in the range of 45-79% for n=4-6. When the same protocol is applied to 1,n-bromochloroalkanes 3b and 1,n-dibromoalkanes 3c (n=2-6), diols 4 are obtained in general with lower yields.     

The modification of bis(pyrazol-1-yl)methanes by chalcogen (S and Se) and their related reactions with organotin chloride and M(CO)5THF (M = Mo and W)

The modification of bis(pyrazol-1-yl)methane by sulfur or selenium on the methine carbon has been successfully carried out by the reaction of the bis(pyrazol-1-yl)methide anion, prepared in situ by the reaction of bis(pyrazol-1-yl)methane with n-BuLi, with elemental sulfur or selenium. These bis(pyrazol-1-yl)methylthiolate or selenolate anions reacted with Ph₂SnCl₂ to form new organotin derivatives CH(3,5-Me₂Pz)₂ESnPh₂Cl (Pz = pyrazol-1-yl, E = S (1) or Se (2)), which have been characterized by NMR, IR and elemental analysis. The molecular structure of 2 determined by X-ray structure analysis indicates that bis(3,5-dimethylpyrazol-1-yl)methylselenolate is a bidentate monoanionic κ²-[N,Se] chelating ligand. The treatment of CH(3,5-Me₂Pz)₂ESnPh₂Cl with W(CO)₅THF resulted in the decomposition of ligands to yield pyrazole derivative of (3,5-Me₂PzH)W(CO)₅, while direct treatment of bis(pyrazol-1-yl)methylthiolate or selenolate anions with M(CO)₅THF (M = Mo or W) formed their tricarbonyl metal anions . Succedent reaction of these carbonyl metal anions with Ph₂SnCl₂ or Ph₃SnCl yielded heterobimetalic compounds CH(Pz)₂EM(CO)₃SnPh_nCl_3−n (n = 2 or 3), which have also been characterized by ¹H NMR, IR and elemental analysis. The structure of CH(3,4,5-Me₃Pz)₂SW(CO)₃SnPh₃ (8) has been confirmed by X-ray single crystal diffraction, showing that bis(3,4,5-trimethylpyrazol-1-yl)methylthiolate acts as a tridentate, monoanionic κ³-[N,S,N] chelating ligand.     

A novel pseudo-seven-component diastereoselective synthesis of λ-phosphanylidene bis(2,5-dioxotetrahydro-1H-pyrrole-3-carboxylates) via binucleophilic systems

The unusual 1:2 intermediate, generated by the addition of triphenylphosphine (TPP) to dialkyl acetylenedicarboxylates (DAAD) was trapped during the reaction of a Ph₃P/RN = C/DMAD binucleophilic system with TFA as an initial proton source in a pseudo-seven-component (7-CR) diastereoselective reaction to give λ⁵-phosphanylidene bis(2,5-dioxotetrahydro-1H-pyrrole-3-carboxylates) with three stereogenic centers and a phosphorane group in good yields.     

Synthesis and characterization of organophosphine/phosphite stabilized silver(I) methanesulfonates: Crystal structures of [Ph3PAgO3SCH3] and [(Ph3P)2AgO3SCH3]

Six organophosphine/phosphite stabilized silver(I) methanesulfonates of type [L_nAgO₃SCH₃] (L = Ph₃P, n = 1, 2a; n = 2, 2b; n = 3, 2c; L = (EtO)₃P; n = 1, 2d; n = 2, 2e; n = 3, 2f) were synthesized by the reaction of silver methanesulfonates with triphenylphosphine or triethylphosphite in dichloromethane under nitrogen atmosphere. These complexes were obtained in high yields and characterized by elemental analysis, ¹H-, ¹³C{H} NMR, IR spectroscopy and thermogravimetric analysis (TGA), respectively. X-ray single crystal analysis reveals that complex 2a is a tetramer [Ph₃PAgO₃SCH₃]₄ and complex 2b is a monomer. The thermal stability of 2a has been studied by applying thermogravimetric analysis. It starts to decompose between 50 and 440 °C in a three-step process. The final residue (Ag) is about 20.50%.     

Reactive extractive electrospray ionization tandem mass spectrometry for sensitive detection of tetrabromobisphenol A derivatives

Sensitive detection of tetrabromobisphenol A (TBBPA) and its derivatives, a group of emerging toxic contaminants, is highly necessitated in environmental investigation. Herein a novel analytical strategy based on reactive extractive electrospray ionization (EESI) tandem mass spectrometry for detection of tetrabromobisphenol A bis(2-hydroxyethyl ether) (TBBPA-BHEE), tetrabromobisphenol A bis(glycidyl ether) (TBBPA-BGE), tetrabromobisphenol A bis(allylether) (TBBPA-BAE), and tetrabromobisphenol S bis(allylether) (TBBPS-BAE) in industrial waste water samples was developed. Active silver cations (Ag⁺), generated by electrospraying a silver nitrate methanol solution (10 mg L⁻¹), collides the neutral TBBPA derivatives molecules in the EESI source to form [M + Ag]⁺ complexes of the analytes under the ambient conditions. Upon collision-induced dissociation (CID), characteristic fragments of the [M + Ag]⁺ complexes were identified for confident and sensitive detection of the four TBBPA derivatives. Under the optimized experimental conditions, the instrumental limits of detection (LODs) of TBBPA-BHEE, TBBPA-BGE, TBBPA-BAE and TBBPS-BAE were 0.37, 0.050, 0.76, and 4.6 μg L⁻¹, respectively. The linear ranges extended to 1000 μg L⁻¹ (R² ≥ 0.9919), and the relative standard deviations (RSDs), inter-day variation and intra-day variation were less than 7.8% (n = 9), 10.0% (n = 5), and 14.8% (n = 1 per day for 5 days) for all derivatives. TBBPA derivative manufacturing industrial waste water, river water and tap water samples were fast analyzed with the proposed method. The contents of TBBPA derivatives were various in the collected samples, with the highest 19.9 ± 0.3 μg L⁻¹ of TBBPA-BAE in the waste water samples.     

N-Alkylation of carbamates and amides with alcohols catalyzed by a CpIr complex

New atom-economical catalytic systems consisting of [Cp^∗IrCl₂]₂/NaOAc (Cp^∗=pentamethylcyclopentadienyl) for the N-alkylation of carbamates and amides using alcohols as alkylating agents under solvent-free conditions have been developed. For example, the reaction of n-butyl carbamate with benzyl alcohol in the presence of [Cp^∗IrCl₂]₂ (5.0 mol % Ir) and NaOAc (5.0 mol %) at 130 °C under the absence of solvent gives n-butyl N-benzylcarbamate in the yield of 94%. The present catalytic system is applicable to not only carbamates but also amides, and only harmless water is produced as co-product.     

Triorganotin(IV) derivatives of umbelliferone (7-hydroxycoumarin) and their adducts with 1,10-phenanthroline: synthesis, structural and biological studies

New triorganotin(IV) derivatives of the general formula R₃Sn(Umb) (where, R = Me, n-Bu and Ph; Umb = umbelliferone anion) have been synthesized using sodium salt method. Further, the adducts of the general formula R₃Sn(Umb) · phen (where R = Me and Ph; phen = 1,10-phenanthroline) have also been synthesized by the interaction of the triorganotin(IV) derivatives of umbelliferone with 1,10-phenanthroline. The bonding and coordination behavior of these derivatives are discussed on the basis of IR, NMR (¹H, ¹³C and ¹¹⁹Sn), and ¹¹⁹Sn Mössbauer spectroscopic studies. These investigations indicate that umbelliferone acts as a monoanionic bidentate ligand in R₃Sn(Umb) coordinating through O(7) and O(1) in the solid-state. These polymeric R₃Sn(Umb) derivatives (where R = Me and n-Bu) have been proposed to have a trans-trigonal bipyramidal geometry with the three R groups in equatorial positions, while the axial positions are occupied by a phenolic oxygen and the O(1) atom from the adjacent molecule. A pseudotetrahedral geometry has been suggested for Ph₃Sn(Umb). A distorted octahedral geometry around tin has been proposed for R₃Sn(Umb) · phen, in which umbelliferone anion acts as a monodentate ligand coordinating through phenolic oxygen O(7). The newly synthesized derivatives have been assayed for their anti-inflammatory, cardiovascular and anti-microbial activities. The average LD₅₀ values >1000 mg kg⁻¹ of these derivatives indicate their safety margin. Among all the compounds tested, Ph₃Sn(Umb) · phen has been found to show potent anti-inflammatory activity with low mammalian toxicity and mild hypotensive activity.     

Chemo- and diastereoselective Bi(OTf)3-catalyzed benzylation of silyl nucleophiles

The direct alkylation of silyl enol ethers with para-methoxybenzylic alcohols or their corresponding acetates was efficiently catalyzed by Bi(OTf)₃ in CH₃NO₂ as the solvent. The reaction provided the α-benzylated carbonyl compounds in high yields after short reaction times using 1-2.5 mol % of the catalyst. Benzylic acetates other than para-methoxybenzylic acetates also underwent the reaction. High facial diastereoselectivities were observed with acetates derived from chiral α-branched para-methoxybenzylic alcohols. In addition, a catalytic reduction with Et₃SiH as the reducing agent is reported.     

Syntheses and structures of overcrowded silanedichalcogenols and their applications to the syntheses of silanedichalcogenolato complexes

Overcrowded silanedichalcogenols Tbt(Mes)Si(EH)(E′H), such as silanedithiol (E = E′ = S), hydroxysilanethiol (E = O, E′ = S) and hydroxysilaneselenol (E = O, E′ = Se), bearing an efficient combination of steric protection groups, Tbt and Mes (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl, Mes = 2,4,6-trimethylphenyl), were synthesized and isolated as air- and moisture-stable crystals, and their structures were fully characterized by spectroscopic and elemental analyses together with X-ray crystallographic analyses. The results of IR spectroscopy and the X-ray structural analyses suggested that these compounds exist as monomers without any intra- and intermolecular interactions such as hydrogen bonds even in the solid state and in solution. Novel four-membered-ring compounds, such as Tbt(Mes)Si(μ-S)₂PnBbt and [Tbt(Mes)Si(μ-E)(μ-E′)ML_n] [E, E′ = O, S, Se; Pn = Sb, Bi; Bbt = 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl; ML_n = Pd(PPh₃)₂, Pt(PPh₃)₂, Ru(η⁶-benzene)] were synthesized by utilizing the silanedichalcogenols as key building blocks. The molecular structures of these newly isolated compounds were determined by NMR spectroscopic data together with X-ray crystallographic analyses.     

Structural characterization and catalytic properties of bis(1,1,3,3-tetramethylguanidinium) dichromate

The structure of bis(1,1,3,3-tetramethylguanidinium) dichromate was determined from powder X-ray diffraction data. The compound crystallizes in the monoclinic system (space group P2₁/n) with a = 10.79714 (15) Å, b = 11.75844 (16) Å, c = 8.15097 (11) Å, β = 109.5248 (6)°. The structure consists of dichromate anions (Cr₂O₇²⁻) stabilized by tetramethylguanidinium cations ([H₂NC(N(CH₃)₂)₂]⁺ or [TMGH]⁺). Phase transitions of [TMGH]₂Cr₂O₇ were determined by differential scanning calorimetry, thermal gravimetric analysis and in situ Raman spectroscopy, where the decomposition of the matrix into CrO_x was found at 171-172 °C. Further heat treatment to above 400 °C resulted in formation of the thermodynamically stable Cr₂O₃, most likely with the [TMGH]⁺ cation as reductant. The catalytic activity of [TMGH]₂Cr₂O₇ supported on TiO₂ anatase in the selective catalytic reduction (SCR) of nitrogen oxide was also investigated, however only moderate activity was observed in the temperature range 100-400 °C compared to the activity of e.g., vanadia supported on titania.     

Preparation and protonation reactions of aryl complexes of manganese and rhenium

Aryl M(κ¹-Ar)(CO)_nP_5−n [M = Mn, Re; Ar = C₆H₅, 4-CH₃C₆H₄; n = 2, 3; P = P(OEt)₃, PPh(OEt)₂, PPh₂OEt] and Re(κ¹-C₆H₅)(CO)₃[Ph₂PO(CH₂)₃OPPh₂] complexes were prepared by allowing hydrides MH(CO)_nP_5−n to react first with triflic acid and then with the appropriate aryl lithium (LiAr) compounds. The complexes were characterized spectroscopically (IR and ¹H, ³¹P, ¹³C NMR) and by the X-ray crystal structure determination of Re(κ¹-C₆H₅)(CO)₃[Ph₂PO(CH₂)₃OPPh₂] derivative. Protonation reaction of the aryl complexes with HBF₄ · Et₂O lead to free hydrocarbons Ar-H and the unsaturated [M(CO)_nP_5−n]⁺ cations, separated as solids in the case of [Re(CO)₃P₂]BF₄ derivatives.     

Synthesis of mono and doubly alkynyl substituted ferrocene and its crystal engineering using -C-H···O supramolecular synthon

Mono and doubly alkynyl substituted ferrocene complexes, [Fc(CH₂OCH₂CCH)_n], 2-3 (2: n = 1; 3: n = 2; Fc = ferrocene) have been synthesized from the room temperature reaction of mono and 1,1′-dihydroxymethyl ferrocene, Fc(CH₂OH)_n , 1a-b (1a: n = 1; 1b: n = 2) and propargyl bromide, in modest to good yields. These new ferrocene derivatives have been characterized by mass, IR, ¹H, ¹³C NMR spectroscopy, and molecular structures of compound 2 and 3 were unequivocally established by single crystal X-ray diffraction study. The crystal structure analysis revealed that 2 and 3 consist of infinite 1D zig-zag hydrogen bonded chains and 2D microporous hydrogen bonded network of molecules, linked by intermolecular C-H···O hydrogen bonding. The molecular structures of both 2 and 3 are further stabilized by C-H···π interactions.     

Reverse atom transfer radical polymerisation (RATRP) of methacrylates using copper(I)/pyridinimine catalysts in conjunction with AIBN

N-n-Propyl-2-pyridylmethanimine, 1, N-n-octyl-2-pyridylmethanimine, 2, N-n-lauryl-2-pyridylmethanimine, 3, and N-n-octadecyl-2-pyridylmethanimine, 4 have been used in conjunction with copper(II) bromide and azo initiators for the reverse atom transfer radical polymerisation of a range of methacrylates. AIBN to Cu^IIBr₂ ratios of 0.5:1, 0.75:1 and 1:1 give PMMA with M_n 11 500 g mol⁻¹ (PDi = 1.24) (at 22% conversion), 12 500 g mol⁻¹ (PDi = 1.06) (at 83% conversion) and 10 900 g mol⁻¹ (PDi = 1.11) (at 84% conversion), respectively. A Cu^IIBr₂ complex is demonstrated to be needed at the start of the reaction for good control over molecular weight and polydispersity as reactions using Cu(I)Br as catalyst yielded PMMA of M_n 31 000 g mol⁻¹ (PDi = 2.90), reactions with no copper yield PMMA of M_n 33 000 g mol⁻¹ (PDi = 2.95). The RATRP of styrene was carried out using Cu^IIBr₂ as catalyst. AIBN to Cu^IIBr₂ ratio of 0.5:1, 0.75:1 and 1:1 gave PS with M_n = 12 400 g mol⁻¹ (PDi = 1.27) at low conversion, M_n = 15 500 g mol⁻¹ (PDi = 1.11) and 12 400 g mol⁻¹ (PDi = 1.38), respectively at ∼85% conversion. A series of block copolymers of MMA with BMA, BzMA and DMEAMA (15 600 g mol⁻¹ (PDi = 1.18), 13 300 g mol⁻¹ (PDi = 1.14) 15 300 g mol⁻¹ (PDi) = 1.16), using a PMMA macroinitiator were prepared. Emulsion polymerisation of MMA using [initiator]:[Cu^(II)Br₂] ratio = 0.5:1 with Brij surfactant gave a linear increase of M_n with respect to conversion, final M_n = 112 800 g mol⁻¹ (PDi = 1.42). Further reactions were carried out with [initiator]:[Cu^(II)Br₂] ratio = 0.75:1 and 1:1. Both giving PMMA with M_n ∼ 32 000 g mol⁻¹ (PDi ∼ 2.4). These reactions exhibit no control, this is because the azo initiator is present in excess and all of the monomer is consumed by a free radical polymerisation as opposed to a controlled reaction. Particle size analysis (DLS) showed the particle size between 160 and170 nm in all cases.