Halide and substituent dependent structural variation in copper(i) halide complexes of 1,5,9-triphosphacyclododecanes.

The reactions of 1,5,9-triethyl-1,5,9-triphosphacyclododecane, [12]-ane-P3Et3, and 1,5,9-tri(2-propyl)-1,5,9-triphosphacyclododecane, [12]-ane-P3iPr3 with copper(i)halides produce either bimetallic species of the type [([12]-ane-P3R3)Cu(CuX2)] (X = halide) or monomeric [([12]-ane-P3R3)CuX] depending on the nature of the halide and, to a lesser extent, the macrocycle. With CuCl only bimetallic complexes are formed with one copper centre bound to the macrocycle and a second attached through a Cu-Cu bond with a mono bridging chloride. CuBr affords monomeric [([12]-ane-P3R3)CuBr] complexes when performed in a 1 : 1 M : L ratio whereas the bimetallic compound [([12]-ane-P3Et3)(CuBr)2], resulted when a 2 : 1 ratio of M : L was employed.

Shaping and enforcing coordination spheres: probing the ability of tripodal ligands to favour trigonal prismatic geometry.

We report two tripodal frameworks, mono(2,2'-bipyrid-6-yl)bis(2-pyridyl)methanol () and bis(2,2'-bipyrid-6-yl)mono(2-pyridyl)methanol () which have one and two bipyridyl arms, respectively. Both ligands form complexes with the first row transition metals. Both ligands appear to overcome the steric strain involved in twisting the ligand to produce an octahedral complex and the solid state structures in general show more octahedral character than complexes of the related ligand, tris(2,2'-bipyrid-6-yl)methanol ().

Manganese(I) templates for the construction of benzannulated triphosphamacrocycles.

Nine-membered 1,4,7-triphosphamacrocycles with unsaturated benzo-backbones have been prepared using the [(CO)3Mn](+) unit as a template. Two synthetic methods have been employed for the macrocyclisation both of which involve the attack of a coordinated phosphide at an activated, electrophilic ortho-fluorophenyl substituent on a neighbouring pnictide donor. Addition of base to the precursor complex fac-[(CO)3Mn(dfppb)(PhPH2)](+), 1, where dfppb = 1,2-bis[di(2-fluorophenyl)phosphino]benzene, results in the direct formation of the macrocyclic compound fac-[Mn(CO)3(tribenzo-9aneP3-Ph,Ph(F)2)](+), 3.

Aspects of the coordination chemistry of rac-trans-1,2-diphosphinocyclohexane and the preparation of reinforced 9aneP₃ and 9anePN₂ macrocycles.

Racemic trans-1,2-diphosphinocyclohexane (t-chxnP2) has been synthesised and its coordination chemistry to Cu(I), Ag(I), Mn(I) and Fe(II) investigated. Compounds of empirical formula [Cu(t-chxnP2)2]BF4 and [Ag(t-chxnP2)2]BF4 have been prepared as isomeric mixtures and the solid-state structure of both complexes determined by single-crystal techniques. The Cu(I) complex is a monomeric species which crystallises with one ligand bearing the R,R configuration and the other being the S,S isomer whereas the Ag(I) complex crystallises as a polymer containing both chelating and bridging t-chxnP2 ligands with 3- and 4-coordinate Ag(I) centres and argentophilic bonds.

Evaluation of a fluorescent derivative of AMD3100 and its interaction with the CXCR4 chemokine receptor.

AMD3100 is a potent and selective antagonist of the CXCR4 receptor; it has been shown to block the route of entry of HIV into host T-cells. This compound and its analogues have since been found to act as haematopoietic stem cell mobilisation agents and, more recently, as anti-cancer agents. Here, we have examined a fluorescent derivative of AMD3100, L(1), which offered the potential to assess the behaviour of AMD3100 at the cell surface by using optical imaging modalities.

Iron(II) template synthesis of benzannulated triphospha- and triarsamacrocycles.

Nine-membered 1,4,7-triphospha- and triarsamacrocycles with unsaturated benzo-backbones have been prepared using the [Cp(R)Fe](+) unit as a template. The cyclisation involves the attack of a coordinated phosphide (or arsenide) nucleophile at an activated, electrophilic ortho-fluorophenyl substituent on a neighbouring pnictide donor. The macrocycle assembly is of the 2 + 1 type where two new chelate rings are formed from appropriately derivatised bidentate and monodentate phosphines/arsines.

Synthesis and coordination chemistry of macrocyclic ligands featuring NHC donor groups.

Poly-NHC (NHC = N-heterocyclic carbene) ligands emerged almost immediately after the first stable NHCs had been described. Macrocyclic ligands, featuring NHC donor groups and their metal complexes, however, remained rare until recently. This perspective highlights modern developments in the fields of synthesis and coordination chemistry of macrocyclic poly-NHC ligands.

A facile one-pot synthesis of a new cryptand via a Pd(II)-catalysed carbonylation reaction.

We report the facile and efficient synthesis of a novel cryptand using a one-pot method involving a Pd(II)-catalysed carbonylation reaction. The crystal structure of the corresponding Cu(II) cryptate is also described.

The co-ordination chemistry of bis(2,2'-bipyrid-6'-yl)ketone with first row transition metals: the reversible interconversion of a mononuclear complex and a dinuclear hemiketal containing species.

Bis(2,2'-bipyrid-6'-yl)ketone has been shown to co-ordinate to Zn(II) to form either a dinuclear hemiketal complex in methanol solutions or mononuclear complexes in acetonitrile. The ligand readily complexes to the late transition metals in acetonitrile to yield mononuclear complexes (Mn(II), Co(II), Ni(II),Zn(II) and Cd(II)) however for Fe(II) only dinuclear complexes [Fe(2){(2-bipy)(2)C(OMe)O(-)}(2)][ClO(4)](2) could be isolated. The solid state structures of the mononuclear complexes exhibit varying degrees of distortion compared to an anticipated planar array of bipyridyl donors.

Functionalisation of terpyridine complexes containing the Re(CO)3(+) moiety.

The investigation into the substitution and addition chemistry of Re(sigma(2)-terpy)(CO)(3)Cl shows that the chloride in Re(sigma(2)-terpy)(CO)(3)Cl (1) may be substituted for acetonitrile to give [Re(sigma(2)-terpy)(CO)(3)(CH(3)CN)][PF(6)] (2), but in the cationic complex [Re(sigma(2)-terpyMe)(CO)(3)Cl][PF(6)] (4), where the pendant pyridine has been methylated, substitution of the chloride could not be achieved using standard conditions. However, use of [Re(sigma(2)-terpyMe)(CO)(3)I][PF(6)] (3) results in the formation of [Re(sigma(2)-terpyMe)(CO)(3)(CH(3)CN)][PF(6)](2) (5). The acetonitrile ligand in complex 2 was found to be labile and could be substituted by pyridine donors.

A novel bipyridine-based hexadentate tripodal framework with a strong preference for trigonal prismatic co-ordination geometries.

The synthesis of the novel ligand tris(2,2'-bipyrid-6-yl) methanol (L(1)) is described. Co-ordination of the ligand to the first row transition metals (Mn(2+)-Zn(2+)) as well as Cd(2+) showed that the ligand formed complexes close to trigonal prismatic in geometry in the solid state. Analysis of the geometry of the co-ordination spheres showed varying degrees of trigonal prismatic and octahedral character.

Synthesis of (1R,4S,6R)-5,5,6-trimethyl-2-phosphabicyclo[2.2.2]octane and derivatives.

The novel primary phosphine (1R,3S)-[1,2,2-trimethyl-3-(phosphinomethyl)cyclopentyl]methyl methanesulfonate 3a (or tosylate 3b) has been prepared in three steps from (1R,3S)-camphoric acid with a view to utilising it as a synthon for the preparation of polycyclic phosphines. Efforts to prepare a [3.2.

Coordination chemistry of cis,cis and trans,trans 1,1'-[1,2-phenylenebis(methylene)]bis(2,2,3,4,4-pentamethylphosphetane).

The cis,cis (5) and trans,trans (9) forms of the bidentate ligand 1,1'-[1,2-phenylenebis(methylene)]bis(2,2,3,4,4-pentamethylphosphetane) have been prepared from common precursors using two separate synthetic routes. The cis,cis isomer is attained selectively through the direct reaction of two mol equivalents of 2,2,3,4,4-pentamethylphosphetane with alpha,alpha'-dibromo-o-xylene in acetone. Protection of the 2,2,3,4,4-pentamethylphosphetane with BH(3) and conversion to the lithium phosphido-borane prior to adding the alpha,alpha'-dihalo-o-xylene leads to the isolation of the trans,trans isomer of 1,1'-[1,2-phenylenebis(methylene)]bis(2,2,3,4,4-pentamethylphosphetane).

The synthesis and coordination chemistry of a tris-8-aminoquinoline tripodal ligand.

A tripodal tris-8-aminoquinoline ligand was synthesised in high yield via the Bucherer reaction. The septa-dentate ligand was found to give isolable complexes when coordinated with transition metals. Complexes of zinc(ii), cadmium(ii) and cobalt(iii) were isolated and their solid state structures were determined by single crystal X-ray diffraction.

Manganese complexes of phosphino-micro-phosphido ligands.

The reaction of the manganese precursors [MnOTf(CO)3{1,2-(PH2)2C6H4}], 5, or [MnOTf(CO)3{1,2-(PH2)2C2H4}], 6, with either the silver complex of 1,3-diallylbenzimidazol-2-ylidiene or the free carbene, resulted in the formation of the new, dimeric phosphino-micro-phosphido manganese species 7 and 8. Complex 7 crystallises in two isomeric forms (cis and trans), depending upon the choice of solvent. The structures of both isomers have been determined by single-crystal X-ray techniques.

Tungsten(0) and rhodium(I) complexes of a series of 2-(2'-halo)triarylphosphinines.

A series of halo substituted triarylphosphinines have been synthesised and coordinated to tungsten(0) and rhodium(I) to give [(2-(2'-halo)-triarylphosphinine)W(CO)(5)] and [(2-(2'-halo)-triarylphosphinine)Rh(COD)Cl] respectively. The complexes have been examined by NMR and IR spectroscopy in an effort to elucidate the nature of the bonding between the phosphinines and the respective metal centre. The W(CO)(5)(L) systems reveal restricted C-C bond rotation as evidenced by temperature-dependent (31)P{(1)H} NMR spectra.

Coordination chemistry of 2,6-dixylyl-4-phenylphosphabarrelene with selected transition metals.

The 2,6-dixylyl-4-phenylphosphabarrelene has been synthesised from the parent phosphinine and its properties as a ligand explored through the preparation and characterisation of the complexes W(CO)(5)(L), Re(CO)(4)(L)Cl, (eta(6)-cymene)RuCl(2)(L), [(eta(5)-Me(3)SiC(5)H(4))Fe(CO)(2)(L)]PF(6), Rh(1,5-COD)(L)Cl, Ir(1,5-COD)(L)Cl, and cis-Pt(L)(2)Cl(2), where L = 4-phenyl-2,10-bis-(2,4-dimethylphenyl)-4H-1,4-ethenophospholine ((x)PB), cymene = 4-isopropyltoluene, eta(5)-Me(3)SiC(5)H(4) = trimethylsilylcyclopentadienyl and 1,5-COD = 1,5-cyclooctadiene. The new complexes were characterised by spectroscopic and analytical techniques and, for [(eta(5)-Me(3)SiC(5)H(4))Fe(CO)(2)(L)]PF(6) and Ru(eta(6)-cymene)(L)Cl(2), by single-crystal X-ray structure determination. The coordination properties of the phosphabarrelene have been established and compared with analogous complexes of triarylphosphines and triarylphosphites.

Metal template controlled formation of [11]ane-P2C(NHC) macrocycles.

The synthesis of N-heterocyclic carbene-diphosphine macrocycles by metal template assisted cyclization reactions has been explored. Attempts to prepare the facial tungsten tricarbonyl precursor complex containing an NH,NH-functionalized carbene and a suitable diphosphine resulted in displacement of the coordinated carbene and the isolation of the corresponding diphosphine tungsten tetracarbonyl [3]. The Re(I) chloro tetracarbonyl complex bearing an NH,NH-functionalized carbene ligand [5] can be prepared and is a suitable precursor for the subsequent formation of the carbene-diphosphine tricarbonyl intermediate [H(2)-6]Cl bearing reactive 2-fluoro substituents at the phosphine-phenyl groups.

1-trimethylsilylphosphirane as a ligand and as a stable masked reagent for phosphirane.

1-Trimethylsilylphosphirane, C2H4PSiMe3, has been prepared on a multi gram scale from P(SiMe3)3 via CICH2CH2P(SiMe3)2. C2H4PSiMe3 is readily susceptible to protonolysis forming the thermally unstable parent phosphirane, C2H4PH, in good yields. Reaction of C2H4PSiMe3 with fac-M(CO)3(CH3CN)3 (M = Cr, Mo) or [Fe(eta5-C5H5)(eta6-C6H6)](PF6) give rise tofac-M(CO)3(C2H4PSiMe3)3 and [Fe(eta5-C5H5)(C2H4PSiMe3)3](PF6) respectively.

Template controlled synthesis of a coordinated [11]ane-P2C NHC macrocycle.

Rhenium complex []Cl with the coordinated [11]ane-P(2)C(NHC) macrocycle was obtained by a metal template controlled ring formation reaction; in this reaction a coordinated NH,NH-stabilised imidazolidin-2-ylidene ligand was connected via the nitrogen atoms to two phenyl substituents of a 2-fluorophenyl substituted diphosphine ligand.

Template synthesis of benzannulated triphosphacyclononanes--a new class of phosphacrowns via template assisted nucleophilic P-C bond formation.

A 9-membered triphosphorus macrocycle with o-phenylene backbone functions has been stereoselectively prepared on a CpFe(+) template by two successive nucleophilic attacks of coordinated phosphide on a coordinated o-fluorophenylbiphosphine.

Template synthesis of 1,4,7-triphosphacyclononanes.

Iron(II) templates based on a [(eta(5)-Cp(R))Fe]+ core have been employed for the successful synthesis of 1,4,7-triphosphacyclononane derivatives (9-aneP3R'3) from a range of appropriately functionalized coordinated diphosphines and monophosphines. 1,2-Diphosphinoethane (1,2-dpe) or (2-phosphinoethyl)phenylphosphine (Phdpe) undergo a base-catalyzed Michael-type addition to trivinylphosphine, divinyl(benzyl)phosphine, or divinyl(phenyl)phosphine in [(eta(5)-Cp(R))Fe(diphosphine)(monophosphine)]+ complexes (2a-j) to give [(eta(5)-Cp(R))Fe(9aneP3R'3)]+ derivatives (4a-j) containing coordinated triphosphacyclononanes bearing one (with Phdpe) or two (with 1,2-dpe) secondary phosphine donors. The rates of macrocyclization show a dependence on the nature of the substituent(s) R on the cyclopentadienyl ligand with increased rates being observed along the series R = H5 < (Me3Si)H4 < 1,3-(Me3Si)2H3 approximately = Me5.

Template synthesis of 9-membered triphospha-macrocycles with rigid o-phenylene backbone functions.

[eta(5)-Cp(R)Fe(CH3CN)(1,2-diphosphinobenzene)]+ complexes are readily formed from [eta(5)-Cp(R)FeL3]+ salts and act as template precursors for the intramolecular hydrophosphination of co-ordinated trivinylphosphine with 1,2-diphosphinobenzenes. This sequence constitutes a versatile synthetic route to a new class of co-ordinated triphosphacyclononanes bearing a rigid o-phenylene backbone link. The efficiency of the synthesis depends markedly upon the nature of the Cp(R) ligand.

Iron complexes of facially capping triphosphorus macrocycles.

Primary and secondary phosphine piano-stool complexes of the type [eta(5)-CpFeL3]+ (L = phenylphosphine, 3, (alpha-methyl)vinylphosphine, 4, allylphosphine, 5, (2-methylpropenyl)phosphine, 5b, allyl(phenyl)phosphine, 6) are described. The alkenyl phosphine complexes, 5 and 6, react by intramolecular hydrophosphination to give the corresponding [eta(5)-CpFe]+ complexes of 1,5,9-triphosphacyclododecane (12-aneP3R3, 2, R = H), 9 and 10 respectively. Alkylation of the secondary phosphines in 9 is achieved by hydrophosphinations with ethene to give the 12-aneP3R3 (R = Et) derivative 11.

Palladium(II) complexes of new OPN phosphine ligands and their application in homogeneously catalysed reactions of CO with alkenes or alkynes.

Palladium complexes of a series of functionalised phosphines bearing the OPN donor set [2-pyCH(2)P(Ph)CH(2)(CHOCH(2)CH(2)CH(2)), 1; 2-py CH(2)P(Ph)-CH(2)CH(2)(CHOCH(2)CH(2)O), 2; 2-pyCH(2)P(Ph)CH(2)CH(2)CO(2)Me, 3; 2-pyP(Ph)CH(2)(CHOCH(2)CH(2)CH(2)), 4; 2-py = 2-pyridyl] have been prepared and characterised. Ligands 1-3 form five membered P-N chelates which is confirmed for PdCl(2) complexes of and by X-ray crystallography. O-coordination appears to be generally disfavoured although there is evidence of transient O-coordination for selected Pd complexes of 4.