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The Schiff-base compounds 2,4-di-tert-butyl-6-(((3,4,5-trimethoxyphenyl)imino)methyl)phenol (L1H), 2,4-di-tert-butyl-6-(((2,4,6-trimethoxyphenyl)imino)methyl)phenol (L2H), 2,4-di-tert-butyl-6-(((2,4-trimethoxyphenyl)imino)methyl)phenol) (L3H) derived from anilines bearing methoxy substituents have been employed in the preparation of alkylaluminum and zinc complexes. Molecular structure determinations reveal mono-chelate aluminum complexes of the type [Al(Ln)(Me)2] (L1, 1, L2, 2, L3, 3), and bis(chelate) complexes for zinc, namely [Zn(Ln)2] (L1, 5, L2, 6, L3, 7). All complexes have significant activity at 50 °C and higher activity at 100 °C for the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) with good control over the molar mass distribution (Mw/Mn &lt, 2) and molecular weight. Complex 1 was found to be the most active catalyst, achieving 99% conversion within 18 h at 50 °C and giving polycaprolactone with high molecular weight, results are compared against aniline-derived (i.e., non-methoxy containing) complexes (4 and 8). Aluminum or zinc complexes derived from L1 exhibit higher activity as compared with complexes derived from L2 and L3. Complex 1 was also tested as an initiator for the copolymerization of ε-CL and glycolide (GL). The CL-GL copolymers have various microstructures depending on the feed ratio. The crosslinker 4,4′-bioxepane-7,7′-dione was used in the polymerization with ε-CL using 1, and well-defined cross-linked PCL was afforded of high molecular weight.

Monophosphines prepared by iron catalysed hydrophosphination have been used as pro-ligands in iron catalysed Negishi cross-coupling of alkyl bromides and diphenyl zinc reagents. The cross-coupling has been investigated with monophosphines with varying electronic properties and we find the simplest, unsubstituted phosphine to offer the optimum reaction conditions (both in terms of yield of diarylmethane product and cost-effectiveness of the phosphine). In situ catalyst generation from monophosphine and FeCl2 was used in catalysis; however, preparation of a discrete homonuclear iron complex was also achieved and this four-coordinate iron-phosphine complex was isolated and used in catalysis.

Treatment of 1,3-bis(bromomethyl)benzene with two equivalents of the appropriate compound Li[N(H)C6H3R12-2,6] yielded the diamines 1,3-[CH2N(H)C6H3R12-2,6]2C6H41 [R1 = Me, abbreviated as H2(D)] or 2 [R = Pri, abbreviated as H2(D′)]. The crystalline complex [Li2(D′)]23 was obtained from 2 and 2 LiBun; the analogue from 1 and 2 LiBun was an incompletely characterised oil. The binuclear, crystalline zirconium(IV) amides [{Zr(NMe2)3}2(μ-D′)] 4, its D analogue 5 and [{Zr(NMe2)2}2(μ-D)2] 6 were prepared from [{Zr(NMe2)3(μ-NMe2)}2] and H2(D′) [or 2 H2(D′)], H2(D) and 2 H2(D), respectively. The single crystal X-ray molecular structures of complexes 3 and 4 have been elucidated. That of 3 comprises a sixteen-membered, twisted macrocyclic LiNC5NLiNC5N core with each of the two-coordinate lithium atoms part of the LiNLiN rhombus. The four-coordinate zirconium atoms in 4 are in an only slightly distorted tetrahedral environment, with the two Zr(NMe2)3 units arranged trans to one another across the central aromatic ring. None of 4–6, with MAO, showed catalytic activity for ethylene polymerisation under ambient conditions.

4‘-(Ferrocenyl)-2,2‘:6‘,2‘ ‘-terpyridine (Fctpy) and 4‘-(4-pyridyl)-2,2‘:6‘,2‘ ‘-terpyridine (pytpy) were prepared from the corresponding ferrocene- and pyridinecarboxaldehyle and 2-acetylpyridine using the Krohnke synthetic methodology. Metal complexes, [M(Fctpy)2](PF6)2 (M = Ru, Fe, Zn), [Ru(tpy)(Fctpy)](PF6)2 (tpy = 2,2‘:6‘,6‘ ‘-terpyridine), and [Ru(pytpy)2](PF6)2 were prepared and characterized. Cyclic voltammetric analysis indicated RuIII/II and ferrocenium/ferrocene redox couples near expected potentials (RuIII/II ∼1.3 V and ferrocenium/ferrocene ∼0.6 V vs Ag/AgCl). In addition to dominant πtpy → πtpy* UV absorptions near 240 and 280 nm and dπRu → πtpy* MLCT absorptions around 480 nm, the complexes [Ru(Fctpy)2](PF6)2 and [Ru(tpy)(Fctpy)](PF6)2 exhibit an unusual absorption band around 530 nm. Resonance Raman measurements indicate that this band is due to a 1[(d(π)Fc)6] → 1[(d(π)Fc)5(π*tpyRu)1] transition. For [Ru(Fctpy)2](PF6)2 and [Ru(tpy)(Fctpy)](PF6)2, excited-state emission and lifetime measure...

The structure of 4,4'-bipyridinium diiodide has been determined. The diprotonated cation possesses crystallographic inversion symmetry with the pyridyl rings coplanar. The crystal packing is dominated by weak but directional N-H···I (N···I distance of 3.47(2) A) and C-H···I (C···I distances of 3.74(3)3.77(3) A) interactions to give layers of ions. The layers stack parallel to the (101) direction and are linked together by an additional C-H···I interaction (C···I distance of 3.816(5) A). Crystal data: triclinic, P-1 (No. 2), a = 8.2940(13), b = 8.3842(11), c = 5.0978(8) A, a = 93.761(11)°, s = 112.281(12)°, ? = 106.887(11)°, V = 307.63(8) A3, Z = 1, Scalc = 2.22 g/cm3. Final residual values based on 997 observed (I > 2s(I)) reflections: R = 0.026, Rw = 0.034.

Deprotonation of [(2-C5H4N)CH2CMe2]C5H5 ( = HCppy) and CH3OCH2CH2C5H5 (= HCp§) with Ae[N(SiMe3)2]2 (Ae = Ca, Sr. Ba) in toluene produces the corresponding metallocenes, Cp'2Ae, in high yield. 1H NMR data reveal that the calcium complex (Cppy)2Ca does not bind tetrahydrofuran. The solid state structures of (Cppy)2Sr and (Cp§)2Ca were obtained by single crystal X-ray analysis, and found to be monomeric, with the Lewis base substituents on the cyclopentadienyl rings coordinated to the metal centers. Crystals of (Cppy)2Sr grown from toluene are orthorhombic, space group Pbcn, with a = 11.988(4) A, b = 16.141(4) A, 12.572(4) A, V = 2433(1) A3, Z = 4, R = 0.038, Rw = 0.043 based on 635 observed reflections. The complex possesses a bent metallocene geometry and contains a crystallographically imposed two-fold rotation axis passing through the strontium. The average Sr-C and Sr-N distances are 2.85(1) and 2.660(7) A respectively, and the ring centroid-Sr-ring centroid angle is 141.1°. Crystals of (Cp§)2Ca grown from toluene are monoclinic, space group P 21/n, with a = 6.912(4) A, b = 15.114(2) A, c = 15.435(3), s = l00.34(2)°, V = 1586.3(9) A3, Z = 4, R = 0.041, Rw = 0.048 based on 1318 observed reflections. The complex also has a bent metallocene geometry, with average Ca-C and Ca-O distances are 2.670(6) and 2.407(3) A respectively; the ring centroid-Ca-ring centroid angle is 136.6°.

The synthesis of a complete series of substituted 4,5,6,7-tetrahydroindenes (4,5,6,7-tetrahydroindene, 1; 1-methyl-, 1,3-dimethyl- and 1,2,3-trimethyl-4,5,6,7-tetrahydroindene, 2-4) is reported. The synthesis of ferrocenes (8-11) from these substituted cyclopentadienes is described. The electrochemistry of these ferrocenes indicates that these complexes are more readily oxidized than ferrocene and that the effect of methyl or alkyl substituents on the ease of oxidation is additive. A single crystal X-ray structure of two of the ferrocenes, bis(1,3-dimethyl-4,5,6,7-tetrahydroindenyl)iron(II), 10, and bis(1,2,3-trimethyl-4,5,6,7-tetrahy-droindenyl)iron(II), 11, indicates that steric hindrance causes the alkyl substituents to be bent away from the plane of the cyclopentadienyl ring. However, the structures differ in that the cyclopentadienyl rings in 10 are staggered wheras those in 11 are eclipsed. The synthesis of the cyclopentadienyltricarbonylmethyl compounds of molybdenum and tungsten from 3 and 4 is also described.

Metallation of C5H5[C(Me)2CH2C5H4N-2] ( CppyH), C5H4(SiMe3)[{C(Me)2CH2 C5H4N-2}-3] ( Cp′pyH), C5H5-[C(Me)2C5H4N-2](Cppy(s)H, and C5H4[(SiMe3){C(Me)2C5H4N-2}-3] [Cp′py(s)H] with KH in THF yielded the potassium complexes KCppy (1), KCp′py (2), KCppy(s) (3), or KCp′ py(s) (4). Compounds 1–4 were readily converted into their homoleptic solvent-free ytterbium(II) complexes [Yb(Cppy)2] (5), [Yb(CP′py)2] (6), [Yb(Cppy(s)2 (7) and [Yb(Cp′py(s)2] (8). The crystal structures of5 and 8 show that both of the pyridyl groups in each complex are coordinated to the ytterbium. Some angles in 5 are Cp(1)-Yb-Cp(2) 137.7° and N(1)-Yb-N(2) 100.8(2)°, and the corresponding angles in 8 are Cp(1)-Yb-Cp(2) 136.9° and N(1)-Yb-N(2) 84.0(4)° (where Cp refers to the centroid of the cyclopentadienyl ring).

4'-Ferrocenyl-2,2' : 6',2"-terpyridine(Fctrpy) has been prepared from ferrocene carboxaldehyde and 2-acetylpyridine. A single crystal X-ray structure analysis indicates typical bond distances and angles with nearly coplanar aromatic rings. The angle between the cyclopentadienyl ring of the ferrocene moiety and the central pyridyl ring of the terpyridine is 19.2° Ruthenium complexes, Ru(Fctrpy) 2 2+ and Ru(trpy) (Fctrpy) 2+ (trpy = 2,2' : 6',2"-terpyridine) have been prepared and characterized electrochemically and spectrophotometrically.

The synthesis of 1,3-dialkyl substituted cyclopentadienes, C5H4RR', Cp'H (Va-g) (where R and R' are tert-butyl, isopropyl, neo-pentyl, cyclohexyl, or 1-methylcyclohexyl) is reported. These are synthesized by the nucleophilic addition of methyl or hydride anions to the corresponding 2-alkyl-6,6-dialkylfulvenes (IIIa-f) followed by hydrolysis. These substituted 1,3-cyclopentadienes have been converted to organometallic derivatives such as [Cp'Fe(CO)2]2, [Cp'M(CO)3Me] (M = Mo or W) and Cp'2Fe. The spectroscopic and electrochemical properties of selected complexes have been investigated to probe the steric and electronic properties of the substituted cyclopentadienyl ligands.

The synthesis of three vinylbenzyl complexes (n5-C5H5)-M(CO)n(CH2C6H4CH=CH2), [1), M=Mo, n=3; (2), M=W, n=3; (3), M=Fe, n=2] is reported. Complexes (1) and (2) have been copolymerized with monomers, such as styrene, methyl methacrylate, andN-vinyl-2-pyrrolidone, in benzene using azoisobutyronitrile as initiator. The rates of incorporation of (2) into copolymers with styrene and methyl methacrylate were the same as the rate of incorporation of the organic monomer. The homopolymerization of (2) was also carried out. Polymerizations occurred satisfactorily except for the copolymerization of (1) with styrene, where little incorporation of the organometallic monomer occurred.

2-Alkyl-6,6-dialkylfulvenes are synthesized by the condensation of monosubstituted 1,3-cyclopentadienes with carbonyl compounds in the presence of pyrrolidine and converted to the corresponding dialkyl-1,3-cyclopentadienes by the addition of nucleophilic reagents lithium aluminum hydride or methyllithium.

The room temperature hydrosilylation of linear 1,3-dienes and 1,3- or 1,4- cyclohexadienes using octacarbonyldicobalt(0) is described. Both cyclic dimers yield regiospecifically 2-cyclohexenylsilanes. The 2,3-dimethyl-1,3-butadiene (DMBD)/HSi(OSiMe3)2Me system has been investigated in particular detail, with variation of the concentrations of reactants or catalyst, temperature, solvent, or added ligands. The effect of these changes upon (a) total yield of silylated products and (b) relative proportions of the isomeric 1,2- or 1,4-adducts of silane to diene (diene/HSiX3) and of the bis-silylated adduct (diene/2 HSiX3), are assessed. p-Allylcobalt intermediates are suggested.

The catalytic activity of tris(pentanedionato)rhodium(III), (or rhodium(III) acetylacetonate) (I) has been investigated for the hydrosilylation of a variety of organic substrates: alkenes, terminal or internal acetylenes, conjugated dienes, or a,s-unsaturated carbonyls or nitriles. With PhCH=CH2 or PhCH2CH=CH2, ?-substitution was unexpectedly observed, as well as addition. Compound I is an active hydrosilylation catalyst in the absence of any added reducing agent, as is tetrakis(µ-acetato)dirhodium(II) (II) which does not, however, show any unusual catalytic activity due to the two metal atom cluster. Possible mechanisms are suggested.

The activity of rhodium phosphite complexes as catalyst precursors for hydrosilylation reactions has been investigated. These are found to be active for a wide variety of organic substrates. Both hydride clusters, [RhH[P(OR3)}2]n and chloride dimers, [RhCl{P(OR)3}2]2 (R = methyl or o-tolyl) were evaluated. The hydrosilylation of 1-hexyne by triethylsilane was investigated as a function of phosphite:rhodium ratio and also with various phosphites as ligand.

The catalytic activity of rhodium complexes for the hydrosilylation of substrates such as alkenes, 1,3-dienes, 1-alkynes, or ketones, is enhanced by the addition of organic oxidizing agents, such ast-butyl hydroperoxide, hydrogen peroxide, orm-chloroperbenzoic acid. Similar enhancement is found for the Group VIA hexacarbonyls in the hydrosilylation of 1,3-dienes.

The hydrosilylation of cyclohexadienes using Ni(acac)2 -Al(OEt)Et2 gives only the allylic cyclohexenylsilane with both 1,3- or 1,4-(in presence of a phosphine) cyclohexadienes. The reactions with the isomeric cis- or trans-1, 3-pentadienes (giving 1:1 adducts), using the Ni(acac)2 -AlEt3 catalyst, are compared. 2, 3-Dimethy1-1, 3-butadiene readily gives mainly the product of 1,4- rather than 1,2-addition, but the proportion of the latter is increased by incorporating PPh3 into the catalyst. Ni(acac)2 with other reducing agents as cocatalysts are also effective. Other less reactive catalysts for linear 1, 3-dienes include [NiCl2(PPh3)2]-BunMgBr, and [Ni(dipy) (PhCN)2] –AlEt3, and for crotonaldehyde [Ni(dipy)(PhCN)2].

The hydrosilylation of 1-pentyne by triethylsilane has been investigated using rhodium catalysts, formed by displacement of cyclooctene from dichlorotetrakis(cyclooctene)dirhodium(I) by various molar ratios of phosphines. The results are interpreted in terms of isomerization of an intermediate vinylrhodium complex.

The synthesis of a sterically hindered isocyanide, 2,6-di-isopropyl-phenylisocyanide, is described. The use of this isocyanide, together with 2,6-dimethylphenylisocyanide, as ligands for complexes of Group VIA metals and rhodium, which are catalysts for the hydrosilylation of a variety of unsaturated species, and for the metathesis of alkynes, is also reported.

Iridium complexes have been found to be active as catalysts for hydrosilylation reactions, especially for those involving 1,3-dienes and 1-alkynes. For ketones, iridium complexes show maximum activity if one molar equivalent (relative to iridium) of triphenylphosphine is added to the reaction mixture. Iridium complexes are also active catalysts for the hydrosilylation of a,s-unsaturated ketones, although the regioselectivity differs from that obtained with rhodium complexes. Attempts at asymmetric hydrosilylation of keto compounds using iridium complexes resulted in extremely low enantiomeric excesses.

Ziegler type systems, e.g., M(acac)n—AIEt3 (M = Ni, Co, or Fe) catalyse the hydrosilylation of 1,3-dienes or terminal acetylenes. With isoprene or 1,3-pentadiene the 1,4-adducts CH3 CH=C(CH3)CH2 SiX3 or CH3 CH2 CH=CHCH2- SiX3 are the major products, and Ni salts [NiCl2 or Ni(acac)2] provide the best catalysts. For 1,3-pentadiene and HSi(OR)3 a significant by-product is CH3 CH= CHCH(SiX3)CH3, the formation of which is suppressed by addition of phosphines. A chain-reaction mechanism consistent with these results involves the formation successively of a Ni0 complex, its oxidative adduct L(diene)Ni(H)- SiX3, a p-allyl complex L(p-allyl)NiSiX3, isomeric s-pentenyl derivatives, and (I)-(III) + the Ni0 complex. Terminal acetylenes RC CH yield the products in which linear dimerisation accompanies hydrosilylation. The head-to-head adduct H2 C=C(R)C(R)=CH(SiX3) preponderates over the head-to-tail isomer R(H)C= C(H)C(R)=CH(SiX3); structures of the former were established by IR and NMR studies and examination of the Diels—Alder adducts with tetracyanoethylene, including comparisons with results on RC CD. The catalytic cycle is believed to be similar to that proposed for 1,3-dienes; the linear dimerisation arising from successive insertion of RC CH into the Ni—H and Ni—C [in Ni—C(R)= CH2] bond. Competition experiments demonstrate that hydrosilylation is favoured by electronegative substituents X at Si, and that terminal acetylenes are more reactive than 1,3-dienes. Bis(p-1,5-cyclooctadiene)nickel(0) is also shown to be an effective hydrosilylation catalyst for 1,3-pentadiene.

A series of metal acetylacetonates [M(acacn] was characterized electrochemically using cyclic voltammetry and Differential Pulse Voltammetry. The Nicholson and Shain criteria [1, 2] was used to determine the electrochemical reduction mechanisms of these complexes. It was found that the reversibility of the electrochemical reduction is inversely proportional to the Ziegler—Natta catalytic activity of the metal acetylacetonate complex.

Two phosphine-rhodium(II) complexes, bis(tris-o-tolylphosphine)dichlororhodium(II) and bis(tricyclohexyl-phosphine)dichlororhodium(II), have been found to be active catalysts for the hydrosilylation of a variety of organic substrates, and, in conjunction with triethylaluminum, to be hydrogenation catalysts.

(+)- and (-)-2 ,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylarsino)butane, the arsenic analogs of (+)- and (-)-diop have been synthesized in good yields. These ligands give similar optical yields to diop in the asymmetric hydrosilylation of ketones, but lower optical yields for the asymmetric hydrogenation of a-acetamidocinnamic acid, but, in this case, yield the isomer having the opposite configuration to diop.

The catalytic activity of various rhodium carbene complexes has been investigated. These complexes are active for the hydrosilylation of a wide variety of unsaturated organic molecules such as olefins, acetylenes and dienes. Their activity is comparable to other rhodium(I) complexes previously used as hydrosilylation catalysts. The yield of products is found to vary with catalyst, silane and organic substrate.

The addition of trialkoxysilanes across the carbonyl bond in crotonaldehyde has been demonstrated for a variety of nickel(0) complexes. The carbon—carbon double bond is left intact. This differs from catalysts used previously, such as chloroplatinic acid or Wilkinson's compound, where 1,4-addition is reported for simple a, s-unsaturated aldehydes. The Ziegler system, Ni(acac)2-Et3Al, proved ineffective as a catalyst, due to competing polymerisation of the crotonaldehyde. The 1,4-addition of trialkoxysilanes to crotonaldehyde, catalysed by Wilkinson's compound, has been confirmed; the new cis- and trans-but-1-enoxytriethoxysilanes have been isolated and identified.

Many metal co-ordination complexes have been investigated as potential anti-cancer drugs with a rich diversity of effects and toxicity (1). One of the most successful is cis-diamminedichloroplatinum(II), which is an active anti-tumor agent at low concentration. Many complexes containing a variety of amines have been synthesized and tested, again with a wide range of effectiveness (1). We wish to report the synthesis of five new platinum complexes and the results of preliminary screening for potential anti-cancer activity.

Synthesis of two substituted cyclopentadienes, 1,3-bis(1-methylcyclohexyl) cyclopentadiene, Cp'H and [2-methyl-2-(2-pyridyl)ethyl]cyclopentadiene, Cp"H from fulvene intermediates is reported. These are readily converted to their early transition metal complexes Cp'W(CO)3Me, Cp"Mo(CO)3Me, Cp"W(CO)3Me and [Cp"Ti(O)Cl · CH2Cl2]2. The X-ray crystal structure of the titanium compound shows that the nitrogen of the pyridine cyclopentadienyl substituent is coordinated to the titanium.

The use of metal complexes on supports such as silica and alumina provides a method for heterogenizing homogeneous catalysts, allows easy recovery of catalysts from the product mixture, and also facilitates recovery of such systems in fixed bed reactors. Furthermore, novel enhanced catalytic activity is exhibited by these supported catalysts. Allyl-metals and benzyl-metals supported on silica and alumina are known to be active catalysts for carbonylation, hydrogenation and polymerization of a wide variety of substrates(1). We report our preliminary results using such systems as hydrosilylation catalysts.