Matthew D. Francis

Synthesis and structural characterisation of the 3,5-di-tert-butyl-1,2,4-triphospholyl complexes of monovalent gallium and thallium, [M(η5-P3C2Bu2t)], M=Ga, Tl

Abstract Treatment of a metastable toluene–THF solution of GaBr with KP 3 C 2 Bu 2 t led to the monomeric triphospholyl gallium(I) complex [Ga(η 5 -P 3 C 2 Bu 2 t )] ( 3 ). The corresponding thallium complex [Tl(η 5 -P 3 C 2 Bu 2 t )] ( 4 ) was prepared in a similar manner by treatment of TlCl with [Li(tmeda) 2 ][(P 3 C 2 Bu 2 t )]. Both complexes, which are monomeric in solution and in the gas phase, were characterised by mass spectrometry and multinuclear NMR spectroscopy. X-ray structure analyses of both complexes showed them to consist of weakly interacting monomeric half sandwich units in the solid state.

Synthesis and structural characterisation of the first uncoordinated phosphorus-substituted stibolyl anion

Abstract The synthesis, crystal and molecular structures of the 2,4-diphosphastibolyl ring anion, [C 2 1 Bu 2 P 2 Sb] − , are described.

Evidence for η6 Coordination to a Fullerene

Abstract Evidence for the first η6 derivative of a fullerene, [MoC60F18(CO)3] has been obtained from reaction between [Mo(CH3CN)3(CO)3] and C60F18.

A novel synthetic route to chalcogen substituted diphospholes

Abstract The reaction of [Li(TMEDA) 2 ][1,2,4-SbP 2 C 2 Bu t 2 ] 1 with E(S 2 CNEt 2 ) 2 (E = Se or Te) leads to the chalcogen substituted diphospholes [1,2,4-EP 2 C 2 Bu t 2 ] (E = Se 2 , E = Te 3 ). Compound 3 represents the first example of a tellurium substituted diphosphole.

Synthesis, crystal and molecular structures of pyridine adducts of the zinc and cadmium bis-1,2,4-triphospholyl complexes [M(η1-P3C2tBu2)2(NC5H5)n] (M=Zn, n=2; M=Cd, n=3)

Abstract The reaction between zinc or cadmium dichloride and the triphospholyl anion P3C2tBu2− in each case leads to highly insoluble orange compounds, the structures of which are believed to be polymeric. Subsequent treatment with pyridine leads to the monomeric complexes [M(η1-P3C2tBu2)2(NC5H5)n] (M=Zn, n=2; M=Cd, n=3). Both complexes, which are fluxional in solution even at low temperature, have been fully characterised by multinuclear NMR spectroscopy and single crystal X-ray diffraction studies.

The first diphosphastibolyl complexes: synthesis and characterisation of [Ru(η5-C5R5)(η5-C2But2P2Sb)]; R = H or Me

Treatment of the novel ring anion [C2But2P2Sb]– 4 with [Ru(ηC5R5)(MeCN)3]PF6, (R = H, Me), affords the compounds [Ru(η5-C5R5)(η5-C2But2P2Sb)](R = H 6, Me 7), which represent the first examples of complexes derived from a diphosphastioblyl ring; the X-ray crystal structure of 7 is described.

The molecular structure of [In(P3C2Bu2t)] using gas-phase electron diffraction and ab initio and DFT calculations

The molecular structure of [In(P 3 C 2 Bu t 2 )] has been determined by gas-phase electron diffraction using the SARACEN method. The experimental geometric parameters showed good correlation with those obtained from quantum chemical calculations and from a previous X-ray diffraction study. Calculations were performed using various DFT methods and also MP2 theory to identify the most suitable method for calculating structures of this type. The accuracy of the calculations was gauged by reference to experimentally determined parameters. The use of small-core and large-core pseudopotentials on the indium atom was also tested, showing that the lack of electrons explicitly considered in the calculation when a large-core pseudopotential was used affected the accuracy of the calculation. Similar calculations have been performed for the less symmetrical [In(P 2 C 3 BU t 3 )], but electron diffraction data of adequate quality could not be obtained.

Synthesis, crystal and molecular structure of [Sn(η4-P2C2But2)]: the first non transition metal 1,3-diphosphacyclobutadienyl compound

Treatment of [Zr(eta 5-C5H5)2(PCBut)2] with SnCl2 led to the novel monomeric (1,3-diphosphacyclobutadienyl)tin(II) half sandwich complex [Sn(eta 4-P2C2But2)] which has been characterised by multinuclear NMR spectroscopy and in the solid state by a single crystal X-ray diffraction study.

1,2-ADDITIONS OF PHENYLSELENENYL HALIDES TO PHOSPHAALKYNES

Abstract The preparation of a variety of selenophosphaalkenes by addition of phenylseleneyl halides to phosphaalkynes is described. The process is stereoselective and largely regioselective. The stereoselectivity is explained by postulating the presence of a cyclic selenophosphirenylium cation. The reaction of one of the prepared selenophosphaalkenes with tBuLi is discussed.

A study of the molecular and electronic structures of the indium(I) phospholyls [In(η5-P2C3But3)] and [In(η5-P3C2But2)] by X-ray diffraction, photoelectron spectroscopy and density functional theory

The crystal and molecular structures of [In(η5-P2C3But3)] are reported. He I and He II photoelectron (PE) spectra of [In(η5-P3C2But2)] and of [In(η5-P2C3But3)] are assigned by comparison with related systems and with the aid of density functional calculations of the ionisation energies (IE). In both cases the first PE band comprises ionisation from the ring π levels together with an ionisation from a Pσ orbital. The second band is due to ionisation from an In-ring antibonding orbital with In s character. Other Pσ ionisation bands lie at higher IE. Substitution of CBut by P within the five membered aromatic ring increases the IE of related bands. Geometry optimisation of the parent complexes [In(η5-P3C2H2)] and [In(η5-P2C3H3)] gave structural parameters in good agreement with the X-ray data. Attempts to find an energy minimum corresponding to η1-coordination were unsuccessful, the structures reverting to the η5-coordination mode. Bonding of the ring is principally due to overlap of the two upper occupied π orbitals with the In 5p orbitals. Some rehybridisation at the P atoms assists this overlap. Mulliken population analysis shows the In 5p occupation to be ca. half an electron in both cases.