David G. Kelly

The structure of triphenylphosphorus–diiodine, Ph3PI2, the first crystallographically characterised dihalogen derivative of a tertiary phosphine

Triphenylphosphine reacts with diiodine in dry diethyl ether to produce Ph3PI2, shown by X-ray crystallography to be a molecular four-coordinate compound Ph3P–I–I, and not the five-coordinate Ph3PI2 or the ionic [Ph3PI]+I–, previously thought to be the only possible solid-state structures for such a compound.

Reactivity of BH3 and 9-BBN towards palladium(II) complexes of diphenylvinyl- and diphenylallyl-phosphine; X-ray structures of [PdCl2(PPh2CH2CH2CH3)]2 and [PdCl2(PPh2CH2CHCH2)]2

Abstract Palladium(II) chloride complexes PdCl 2 L 2 and [PdCl 2 L] 2 have been prepared with the phosphine ligands PPh 2 CHCH 2 and PPh 2 CH 2 CHCH 2 . The reactions of PdCl 2 L 2 complexes with thf·BH 3 afford equilibria in which the components may be identified by 31 P{ 1 H}-NMR spectroscopy. PdCl 2 L 2 and [PdCl 2 L] 2 complexes and phosphine–borane adducts are observed. In addition, analogues of the PdCl 2 L 2 and [PdCl 2 L] 2 complexes are present in which one or both phosphine ligands have undergone alkene hydroboration. The reaction of PdCl 2 (PhCN) 2 and the cyclic adduct formed between 9-BBN and PPh 2 CH 2 CHCH 2 [cyclo-(9-borabicyclo[3.3.1]nonanyl)-propyl(diphenyl)phosphine] has been studied. Opening of the P–B dative bond occurs with the formation of a [PdCl 2 L′] 2 complex in which the phosphine ligand contains a pendant borane moiety. Hydrolysis in air yields the crystallographically characterised dimer [PdCl 2 (PPh 2 CH 2 CH 2 CH 3 )] 2 . The X-ray structure of the unsaturated analogue, [PdCl 2 (PPh 2 CH 2 CHCH 2 )] 2 , has also been obtained. Both compounds exist as symmetrical dimeric structures with terminal and asymmetric bridging halides.

Reactivity of AlMe3 with titanium(IV) Schiff base complexes: X-ray structure of [Ti{(μ-Br)(AlMe2)}{(μ-Br)(AlMe2X)}(salen)] · C7H8 (X=Me or Br) and reactivity studies of mono-alkylated [Ti(Me)X(L)] complexes

Abstract [TiCl2(salen)] (1) reacts with AlMe3 (1:2) to give the heterometallic Ti(III) and Ti(IV) complexes [Ti{(μ-Cl)(AlMe2)}{(μ-Cl)(AlMe2X)}(salen)] (X=Me or Cl) (2) and [TiMe{(μ-Cl)(AlCl2Me)}(salen)] (3). Addition of diethyl ether to 3 affords [Ti(Me)Cl(salen)] (4). The analogous reaction of [TiBr2(salen)] (5) gives the crystallographically characterised [Ti{(μ-Br)(AlMe2)}{(μ-Br)(AlMe2X)}(salen)] (X=Me or Br) (6) and [Ti(Me)Br(salen)] (7) in a single step, whilst the comparable reaction of [TiCl2{(3-MeO)2salen}] (8) with AlMe3 yields [Ti(Me)Cl{(3-MeO)2salen}] (9) with no evidence of titanium(III) species. Reactivity of both halide and methyl groups of 4 has been probed using magnesium reduction, SbCl5 and AgBF4 halide abstraction and SO2 insertion reactions. Hydrolysis of [Ti(Me)X(L)] complexes affords μ-oxo species [TiX(L)]2(μ-O) [X=Cl, L=salen (13); X=Br, L=salen (14); X=Cl, L=(3-MeO)2salen (15)].

The reaction of coarse-grain metal powders with phosphoranes: a facile activation of metallic reagents and a novel route to metal–phosphine complexes. The X-ray crystal structures of Mnl2(PPhMe2) and FeBr3(PPhMe2)2

A route to new and existing transition metal phosphine complexes is provided by the reaction of coarse-grain metal powders and phosphoranes in diethyl ether, as exemplified here by Nil3(PMe3)2, FeBr3(PPhMe2)2 and Mnl2(PPhMe2).

Formation of titanium-aluminium Schiff base complexes: X-ray structure of [Ti(μ-Cl)(AlMe2) (μ-Cl)(AlMe2X)(salen)] (X = Me OR Cl)

Abstract Reaction of [TiCl 2 (salen)] [salen = N, N′-ethylene bis (salicylideneiminate)] and AlMe 3 in toluene/hexane afforded the hetero-bimetallic [Ti{(μ-Cl)(AlMe 2 )}{(μ-Cl)(AlMe 2 X)} (salen)] (X = Me or Cl), 1 and [TiMe{(μ-Cl)(AlCl 2 Me)} (salen)], 2 ; the crystal structure of the titanium(III) complex ( 1 ) has been determined. In tetrahydrofuran 2 forms the stable monoalkylated titanium(IV) complex [Ti(Me)Cl(salen)] ( 3 ).

Titanium(IV) complexes of the crystallographically characterised fluorene-Schiff base N-2-fluorenyl(salicylideneimine) and related bi- and tetradentate ligands

Schiff base ligands have been prepared by the condensation of 2-aminofluorene with salicylaldehyde (1, flusalH) or 3-methoxy-2hydroxybenzaldehyde (2, MeOflusalH). Compound 1 reacts with TiCl4 in a 1:1 stoichiometry to afford [TiCl3(flusal)] (3) and in a 2:1 ratio to yield [TiCl4(flusalH)(2)] (4). The reaction of excess TiBz(4) with compound 1 results in the isolation of the octahedral Ti(IV) complex [Ti(flusal)(2)(flusalaBz)(2)] (5). Crystallographic and spectroscopic data for the latter indicate a complex containing two Schiff base ligands present as conventional N,O chelates and a further two ligands in which the C=N function is reduced by the addition of benzyl and hydrogen moieties producing an O-bound species with pendant amine. The single crystal X-ray diffraction structure of compound 1 has been obtained and compared with the published data for compound 5. Similar ligand alkylation to that observed in compound 5 is also achieved by the reaction of organolithium reagents with compounds 1 and 2; the reaction of PhLi and compound 2 followed by aqueous hydrolysis affords MeOflusalaPhH (6). Although reactivity does occur between TiCl4 and compound 6, the products could not be fully characterised. Thus tetradentate reduced Schiff base ligands were synthesised by the reaction of salenH, with MeLi or PhLi, giving salenaMe(2)H(2) (7) and salenaPh(2)H(2) (8), respectively. Reaction of compound 8 and TiCl4 affords the quadruply deprotonated amido complex [Ti(salenamidoPh(2))] (9), which hydrolyses in air to the mu-oxo amine complex [Ti(salenaPh(2))O] (10).

Lanthanide complexes of new ditopic, tripodal macrocycles: synthetic, structural, stability and luminescence studies

Abstract Mannich reactions of salicylaldehyde with 1,4,7-triazacyclononane afford new ditopic, tripodal macrocycles that contain adjacent proton-binding and lanthanide-binding compartments; structural and stability studies illustrate the O6-pendant compartments as metal-binding and the N3-capping macrocyclic compartment as proton-binding while pH-modulated stabilities span the range Log 17–35. Luminescence of the Eu(III) and Tb(III) complexes is weak, as expected for complexes that include coordinated water.

Synthesis and reactivity of copper(I) phosphine–alkene complexes: X-ray crystal structure of CuCl(Ph2PCPhCH2)2

Copper(I) chloride complexes containing bifunctional phosphine/alkene ligands of the form CuCl(Ph2PCH=CH2)(n) (n = 1, 3) and CuCl( Ph2PCPh=CH2)(2) have been synthesized, with the latter being characterized by single crystal X-ray diffraction. Complexes decompose rapidly on reaction with hydroborating agents NaBH4 and Na[B(OMe)(3)H], although the thermally unstable Cu(BH4) (Ph2PCPh=CH2)(2) may be observed by NMR spectroscopy. The complexes show considerable resistance to thermally initiated alkene polymerization, the only significant reactivity for diphenylvinylphosphine complexes being trace ligand dissociation and subsequent aerobic oxidation to Ph2P(O)CH=CH2. Similar dissociation/oxidation is not observed for CuCl(Ph2PCPh=CH2)(2). Lewis acid initiated polymerization, using Et2O . BF3, results in the facile formation of copper(I) coordinated polymeric phosphine ligands for diphenylvinylphosphine complexes, but again no reactivity is induced in the more sterically hindered alpha-styrenyl analogue.

Modifications of commercial pressurized solvent extraction (PSE) systems for the analysis of polychlorinated biphenyls in avian whole blood and serum

The present study considers simple and cost-effective modifications to commercial pressurised solvent extraction cells to extract polychlorinated biphenyls (PCBs) from avian blood and serum. Blood ...

Tertiary phosphine complexes of nickel (II) thiocyanate: an evaluation of the photostabilisation of polystyrene.

Polystyrene films have been prepared incorporating zinc stearate and nickel(II) thiocyanate complexes of methyldiphenyl- and alkenyldiphenyl-phosphines (alkenyl=vinyl, allyl, but-3-enyl, pent-4-enyl). Investigation of the thermal and fluorescence properties of the nickel complexes indicates high thermal stability and minimal photochemical activity. Polymer films containing the zinc and nickel complexes were photodegraded under artificial conditions and referenced to a similarly exposed nickel-free standard. The degradation of films containing nickel additives and the nickel-free standard was assessed using diffuse reflectance IR spectroscopy, CIELab colour space and 31P{1H} NMR. Within the polymer films nickel complexes do not degrade at a significantly greater rate than the polymer matrix, and whilst those containing vinyl, but-3-enyl and pent-4-enyl functions appear passive (displaying neither photosensitisation nor photostabilisation), methyl and allyl substituted complexes do offer significant stabilisation. Phosphine oxide species are identified by 31P{1H} NMR as the principal decomposition products, suggesting that peroxide oxidation of co-ordinated phosphines may represent the principal mode of photostabilisation. Assessments of colour space fastness on exposure to aqueous, acidic and alkaline media were made. These indicate comparable decomposition of nickel(II) thiocyanate and zinc stearate complexes in all three environments, suggesting that hydrolytic processes predominate in complex decomposition.