Caroline M. Hay

Phosphole‐Containing π‐Conjugated Systems: From Model Molecules to Polymer Films on Electrodes

Two series of 2,5-dipyridyl- and 2,5-dithienylphosphole derivatives containing sigma3- or sigma4-P atoms were prepared, and their optical (UV/Vis absorption, fluorescence spectra) and electrochemical properties were systematically evaluated. These physical properties depend mainly on the natures of the 2,5-substituents and of the phosphorus moiety, and they revealed that these compounds contain extended pi-conjugated systems. Structure-property relationships were established on the basis of these experimental data and ab initio calculations on the parent molecules. The limited aromatic character and low-lying LUMO of the phosphole ring appear to be crucial for achieving a highly delocalised pi system. Electrooxidation of 2,5-dithienylphosphole derivatives affords electroactive films with low optical band gaps. As observed for the corresponding monomers, the optical and electrochemical properties of the polymers can be varied over a wide range by modifying the nature of the phosphorus moiety.

Preparation and characterisation of mixed bismuth and ruthenium clusters; X-ray crystal structures of [Ru3(µ-H)3(CO)9(µ3-Bi)], [Ru3(CO)9(µ3-Bi)2], and [Ru4(CO)12(µ4-Bi)2]

The inclusion of naked bismuth atoms into carbonyl cluster compounds of ruthenium has been achieved with the use of bismuth(III) nitrate pentahydrate, Bi(NO3)3·5H2O, as the bismuth containing reagent. We report the high-yield synthesis of [Ru3(µ-H)3(CO)9(µ3-Bi)](1) from the reaction of Bi(NO3)3·5H2O with [NBu4][Ru4H3(CO)12], the preparation of (1) and [Ru3(CO)9(µ3-Bi)2](2) from Bi(NO3)3·5H2O and Na[Ru3H(CO)11], and the preparation of [Ru4(CO)12(µ4-Bi)2](3) from Bi(NO3)3·5H2O and [Ru3(CO)12] in KOH–MeOH solution. The determination of the X-ray crystal structures of (1), (2), and (3) show that (1) has a slightly distorted tetrahedral heavy-metal framework with three hydrides, each bridging a Ru–Ru edge, that (2) has a trigonal-bipyramidal structure with the Ru3 ring capped above and below by µ3-Bi atoms, and that (3) has a square-bipyramidal metal framework with the Ru atoms defining the equatorial square plane and the Bi atoms symmetrically µ4-capping at the axial positions.

Preparation and characterisation of some mixed clusters of bismuth with osmium and ruthenium; crystal and molecular structures of Os3(μ-H)3(CO)9(μ3-Bi), Os4(CO)12(μ4-Bi)2, Ru3(μ-H)3(CO)9(μ3-Bi), and Ru4(CO)12(μ4-Bi)2

Abstract Reaction of NaBiO 3 with Os 3 (CO) 12 and a number of higher nuclearity osmium clusters affords a variety of bismuth-containing products, including Os 3 H 3 (CO) 9 Bi ( 1 ), Os 3 (CO) 9 Bi 2 ( 2 ), and Os 4 (CO) 12 Bi 2 ( 3 ). Under similar conditions, Ru 3 (CO) 12 affords only low yields of Ru 3 H 3 (CO) 9 Bi ( 5 ), but better yields of Ru 3 H 3 (CO) 9 Bi ( 5 ), Ru 3 (CO) 9 Bi 2 ( 6 ), Ru 4 (CO) 12 Bi 2 ( 7 ), and Ru 5 H(CO) 18 Bi ( 8 ), are obtained by reaction of Bi(NO 3 ) 3 · 5H 2 O with the [Ru 3 H(CO) 11 ] − anion. The structures of 1 , 3 , 5 , and 7 have been established by X-ray diffraction; 1 and 5 are isostructural with the known iron analogue, while the metal frameworks in 3 and 7 display different isomeric forms of the M 4 Bi 2 octahedron.

A bridging ligand featuring terminal 2-pyridylphosphole moieties: synthesis, optical properties and Ru(II)-complex

Abstract 2,2′-Di[2-(5-(2-pyridyl)phospholyl)]thiophene ( 2a ) has been obtained in 63% yield via the Fagan–Nugents route. Derivative 2a possesses an extended π-conjugated system and behaves as a bis( P , N -chelate) towards cationic ( p -cymene)RuCl fragments affording the air-stable complex 3a in 60% yield. A diastereoselective coordination was observed and the solid state structure of the model Ru-complex 2b featuring a related 2-(2-pyridyl)-5-(2-thienyl)phosphole ligand is presented.

2,5-Di(2-pyridyl)phospholes: model compounds for the engineering of π-conjugated donor–acceptor co-oligomers with a chemically tunable HOMO–LUMO gap

2,5-Di(2-pyridyl)phospholes possess an extended π-conjugated system with a charge transfer structure; high yielding chemical modifications involving the phosphorus atom allow fine tuning of the HOMO–LUMO gap.

Synthesis and X-ray crystal structure of two complexes of nickel(II) nitrate with pyridine-2-amidoxime (C6H7N3O): [Ni(C6H7N3O)2(NO3)2] and [Ni(C6H7N3O)3](NO3)2·H2O

Abstract The reaction between stoichiometric amounts of nickel(II) nitrate hexahydrate and pyridine-2-amidoxime in ethanol produces crystalline [Ni(C6H7N3O)2(NO3)2], but in water yields [Ni(C6H7N3O)3](NO3)2·H2O. Both complexes have been characterized by X-ray crystallography. The crystals of [Ni(C6H7N3O)2(NO3)2] are triclinic, space group P 1 (no. 2), with a = 8.544(1), b = 9.300(1), c = 12.790(1) A, α = 85.14(1), β = 77.81(1), γ = 63.26(1)° and Z = 2. The crystals of [Ni(C6H7N3O)3](NO3)2·H2O are monoclinic, space group P21/n, with a = 10.453(1), b = 13.261(2), c = 19.059(4) A, β = 98.19(1)° and Z = 4. Both complexes have a slightly distorted octahedral structure with the nitrate groups being coordinated ligands in the 1:2 complex and counter-ions in the 1:3 complex. The organic ligands coordinate through the heterocyclic and oxime nitrogens in both compounds.

Allyl and μ-allyl complexes from reactions of a hydrido-bridged molybdenum-manganese complex with dienes: crystal structures of (η-C5H5)(CO)2Mo(μ-PPh2)Mn(η3-C3H5)(CO)3 and (η-C5H5)(CO)Mo(μ-σ:η4-C5H9)(μ-PPh2)Mn(CO)3

Abstract The complex (η-C5H5)(CO)2Mo(μ-H)(μ-PPh2)Mn(CO)4 reacts under photolysis with the dienes allene, 1,1-dimethylallene, 1,3-butadiene and 2-methyl- 1,3-butadiene to give heterodimetallic allyl complexes in which the allyl ligand is bonded to either the Mn atom, the Mo atom or, alternatively, to both metal atoms. The crystal structure of two of these complexes, (η-C5H5)(CO)2Mo(μ-PPh2)Mn(η3-C3H5)(CO)3 and (η-C5H5)(CO)Mo(μ-σ: η4-C5H9)(μ-PPh2)Mn(CO)3, have been determined by X-ray diffraction. In the former the allyl ligand is η3bonded to the manganese atom, which is also coordinated by three CO groups, the bridging PPh2 group and the Mo atom [MoMn = 3.038(1) A]. In the latter complex the syn-CH3CHC(CH3)CH2 allyl ligand is η3bonded to the Mo atom and also via coordination of one CH bond of the CH2 group to the Mn atom. The Mo atom is additionally coordinated by an η-C5H5 ligand, a CO group, the PPh2 group and the Mn atom [MoMn = 2.800(1) A]. In the presence of CO, the μ-allyl complexes are in equilibrium in solution with complexes of proposed formula (η-C5H5)(CO)(η3-allyl)Mo(μ-PPh2)Mn(CO)4, containing the allyl ligand bonded exclusively to the Mo atom, but these latter complexes lose CO and revert to the μ-allyl complexes readily on attempted isolation. The μ-allyl complex (η-C5H5)(CO)Mo(μ-σ: η4-C4H7)Mn(CO)3 gives a 1:1 adduct with P(OMe)3 in which the coordination of the allyl CH bond to the Mn atom is replaced by bonding of the P(OMe)3 group. The μ-allyl complexes can be deprotonated with LIBun giving anionic species which are postulated to contain μ-allylidene ligands. One such species, [(η-C5H5)(CO)Mo(μ-σ:η3-CH3CHCHCH)(η-PPh2)Mn(CO)3]−, has been reacted with CD3COOD to regenerate the corresponding allyl complex; the added deuterium atom is located exclusively at the site involved in the interaction with the Mn atom.

Photochemistry of Os3(CO)12 with AuPPh3Cl: synthesis and structural characterisation of (µ-AuPPh3)(µ-Cl)Os3(CO)10

Studies showing the potential of photochemistry for the preparation of mixed-metal clusters are presented, the synthesis and molecular structure of (µ-AuPPh3)(µ-Cl)Os3(CO)10 being reported.

Synthesis and characterisation of phosphido-bridged hexaosmium “raft” clusters; crystal structure of OS6H2(CO)18(μ3-PPh)

Treatment of the activated “raft” cluster Os6(CO)20(NCMe) with PR1R2H (R1R2Ph; R1Ph, R2H) at room temperature affords the phosphine-substituted cluster Os6(CO)20(PR1R2H) (R1R2Ph (1); R1Ph, R2H (1)) in quantitative yield. Thermolysis of 1 in toluene gives a single orange-brown product characterised as Os6(CO)16(μ-PPhO2) (3). This complex is also obtained from the thermolysis of Os6(CO)17(PPh2H), which has the bicapped tetrahedral metal framework. Thermolysis of 2 gives two products, characterised as Os6H2(CO)18(μ3-PPh) (4) and the known complex Os5(CO)15(μ4-PPh) (5). The structure of 4 has been established by a single-crystal X-ray diffraction study. The metal framework consists of a central Os3 triangle each side of which is bridged by another Os atom to give an arrangement of four triangles sharing three common edges. Three of these triangles are approximately coplanar, but the fourth, which is asymmetrically capped by the phosphorus atom of the μ3-PPh group, is tilted by 72.4° from the Os5 plane. Complex 4 crystallises in space group P1− with a 9.733(2), b 10.555(1), c 17.585(2) A, α 95.87(1), β 94.47(2), γ 105.60(1)°, Z = 2; 4591 observed data with F > 4σ(F) were refined by blocked full-matrix least squares to R = 0.080, Rw = 0.079.

Isolation, characterisation, and crystal and molecular structure of [Os6AuC(CO)20(μ-OMe)]

Abstract Treatment of [Os 3 (CO) 10 (μ-AuPEt 3 )(μ-COMe)] with [Os 3 (CO) 10 (NCMe) 2 ] in refluxing toluene affords the new carbido compound [Os 6 AuC(CO) 20 (μ-OMe)] ( 1 ). A single-crystal X-ray structure analysis of 1 shows that an Os 2 fragment and an Os 4 carbido fragment are linked together by a gold atom.