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The blue title compound, long assumed to be an olefin complex on the basis of an apparently single unresolved CN stretching band in the IR spectrum, has been identified by experiment and through DFT analysis as a σ complex with the tungsten atom coordinated to one of the nitrile N centers. The previously reported data are reinterpreted in light of the new structural assignment, and spectroelectrochemical results (UV–vis, IR, EPR) are presented.

The synthesis and characterization of [Pt{4′-(p-tolyl)trpy}Cl]SbF6 is described where trpy is 2,2′:6′,2″-terpyridine. A single crystal X-ray structure determination at 100 K shows that the cations are stacked in columns that comprise cations arranged in a staircase motif. Successive cations within a column are linked by π(trpy)–π(phenyl) stabilizing interactions; and each cation in one column is linked to a cation in an adjacent column by a weakly stabilizing Pt···Pt interaction. The Pt···Pt distance is 3.434(1) A. The metrics governing non-covalent interactions between [Pt{4′-(aryl)trpy}Cl]+ cations have been analyzed for the present structure and related structures in the CSD (Cambridge Structural Database). Cation dimers cluster into three distinct groups based on their lateral shifts and, to a lesser extent, the angular parameters governing their relative displacements; the dominant grouping exhibits Pt···Pt and π(trpy)–π(trpy) stabilizing interactions. An emission spectrum recorded at 77 K on a solid sample of the compound is best interpreted as arising from the decay of three photoexcited states: a 3MLCT (MLCT = metal-to-ligand charge transfer) state; a 3MMLCT (MMLCT = metal–metal-to-ligand charge transfer) state, and an excimeric 3π–π∗ state.

The synthesis and characterisation of the 4-(o-tolyl)-6-(3´´-isoquinolyl)-2,2´-bipyridyl [4-(otolyl) isqbipy] ligand is described. A single-crystal X-ray structure determination shows that it adopts a trans-trans conformation about the interannular bonds linking the central pyridine ring to the outer pyridine ring and the isoquinolyl moiety. The o-tolyl group is twisted by an angle of 51.7° out of the plane of the central pyridine ring. The synthesis and characterisation of the [Pt{4-(otolyl) isqbipy}Cl]SbF6 complex is described. The absorption spectrum of the complex measured in acetonitrile exhibits MLCT bands at 362 and 393 nm, as well as intraligand π-π* absorptions in the 200 - 350 nm range; the MLCT bands are shifted significantly to higher energy when compared to those recorded for the parent trpy complex, viz. [Pt{4´-(o-tolyl)trpy}Cl]SbF6, where trpy is 2,2´ : 6´,2´´-terpyridine. Similarly, the 3MLCT emission measured for the 4-(o-tolyl)isqbipy complex in a 1 : 1 CH2Cl2/CHCl3 solution is blue-shifted with respect to the emission spectrum recorded for the 4´-(o-tolyl)trpy complex. We attribute the higher energy MLCT absorption and emission for the 4-(o-tolyl)isqbipy complex to a significantly higher energy for its π*-LUMO than for that of the 4´-(o-tolyl)trpy complex. Emission spectra of the title compound have also been measured in a low-temperature 1 : 5 : 5 (v/v) DMF/methanol/ethanol (DME) glass as a function of concentration. These spectra show that aggregation of the complex occurs at rather low concentrations of 5 - 10 μM, probably to dimers. Variable-temperature emission spectra recorded on a solid sample of [Pt{4-(otolyl) isqbipy}Cl]SbF6 comprise relatively narrow asymmetric bands whose maxima are shifted to the red as the temperature is lowered: specifically λem(max) is 641 nm at r. t. (τ = 235 ns) and 676 nm at 77 K (τ = 1.36 μs). Temperature-dependent emission of this type is typical of a metal-metal-to-ligand charge transfer (MMLCT) excited state that has its origin in dz2 (Pt)-dz2 (Pt) orbital interactions in the crystal.

Treatment of [Pt(trpy)Cl]SbF(6) with AgSCN in a metathesis reaction affords after work-up yellow crystals of [Pt(trpy)(NCS)]SbF(6).CH(3)CN where trpy is 2,2':6',2''-terpyridine. A single crystal structure determination of the solvate shows that the SCN(-) ion is N-bound to the Pt atom, and that the planar cations stack as Pt(2) dimers with a PtPt separation of 3.293(1) A. The crystals rapidly de-solvate under ambient conditions to give a polycrystalline maroon material characterised as [Pt(trpy)(NCS)]SbF(6) (). A (15)N NMR spectroscopic study of a solution of isotopically labeled [Pt(trpy)((15)N(13)CS)]SbF(6) in CD(3)CN shows that both linkage isomers of the SCN(-) ion co-exist in solution with the N-bound isomer dominant, and the S-bound isomer present at a much lower concentration. Compound exhibits temperature dependent (3)MMLCT emission in the solid state; at 280 K the emission maximises at 692 nm, but red-shifts systematically on cooling to reach 762 nm at 80 K. Compound shows vapochromic behaviour that is selective and reversible for vapours of acetonitrile, DMF and pyridine. The colour change is from maroon for to yellow for all three solvates. The emission spectra recorded for the solvates maximise at wavelengths that are all significantly blue-shifted compared to lambda(em)(max) recorded for : the blue-shifts measured at 77 K are 90, 115 and 155 nm for the acetonitrile, DMF and pyridine solvates respectively. The origin of the vapochromic properties of compound is likely to do with the breaking and making of metallophilic PtPt interactions in the solid state.

The synthesis and characterisation of an orange polymorph of [Pt(trpy)(C CPh)]SbF6 is described where trpy = 2,2′:6′,2″-terpyridine. An X-ray crystal structure determination at 293 K reveals that the cations are planar and stacked head-to-tail with alternating Pt⋯Pt distances of 3.604(1) and 4.412(1) A. The perpendicular distances between successive cation planes are constant along the stack at a value of 3.33 A. Crystal structure determinations at 240 and 200 K show that reducing the temperature to 200 K has no significant effect on the cation arrangement. However, below 200 K there is a phase change that we have not been able to characterise, but which has an effect on the solid state photoluminescence exhibited by [Pt(trpy)(C CPh)]SbF6. Thus, whereas at temperatures of ⩾200 K, a broad peak with two components at ca. 566 and 597 nm is observed, below 200 K a longer wavelength peak develops that red-shifts as the temperature is lowered [λ(em)max = 637 nm at 80 K]. We assign the ⩾200 K emission as 3MLLCT in origin, since the X-ray data show that ligand–ligand (LL) and not metal–metal (MM) interactions are important at T ⩾ 200 K. On the other hand, the long wavelength emission observed below 200 K is typical of 3MMLCT emission, suggesting that the phase change leads to d z 2 ( Pt ) – d z 2 ( Pt ) orbital interactions. Of particular interest is that the cation exhibits 3MLCT emission in dichloromethane that maximizes at 619 nm, i.e., the high temperature solid state emission occurs at a shorter wavelength, an unexpected result since intermolecular interactions in the solid usually cause the emission to occur at longer wavelengths. A possible explanation for this unexpected result is given.

The synthesis and characterisation of the 4-(o-R-C6H4)pzbipy [R = H, CH3 or CF3; pzbipy = 6-(2″- pyrazinyl)-2,2′-bipyridyl] ligands are described. Reaction of the 4-(o-MeC6H4)pzbipy ligand with [Pt(PhCN)2Cl2] in the presence of AgSbF6 affords [Pt{4-(o-MeC6H4)pzbipy}Cl]SbF6 as a marooncoloured microcrystalline solid. The [Pt{4-(o-MeC6H4)pzbipy}Cl]+ cation exhibits low intensity photoluminescence in dichloromethane that maximises at 543 nm and which is assigned to a 3MLCT excited state (τ = 20 ns). The emission spectrum of the cation was also recorded in a frozen DME {1 : 5:5 (v/v) DMF / MeOH / EtOH} glass; a highly structured band is observed with vibrational spacings of ca. 1400 cm−1, indicating emission from an intraligand 3π-π∗ state (τ = 11 μs). Variable temperature solid emission spectra show maxima that occur at significantly lower energies than is observed in fluid solution and that shift to the red when the temperature is lowered; specifically, λ (em)max is 674 nm at 280 K (τ = 80 ns) and 723 nm at 80 K (τ = 1.3 μs). Emission behaviour of this type is typical of emission from a metal-metal-ligand charge transfer (MMLCT) excited state that has its origins in dz² (Pt)-dz² (Pt) orbital interactions in the crystal.

The synthesis and characterization of [Pt{4′-(R)trpy}(CN)]X (R = Ph, X = BF4 or SbF6; R = o-CH3C6H4, X = SbF6; R = o-ClC6H4, X = SbF6; or R = o-CF3C6H4, X = SbF6) are described where trpy = 2,2′:6′,2″-terpyridine. Single crystals of [Pt{4′-(Ph)trpy}(CN)]BF4·CH3CN were grown by vapour diffusion of diethyl ether into an acetonitrile solution of [Pt{4′-(Ph)trpy}(CN)]BF4. An X-ray crystal structure determination of the solvated complex confirms the near linear coordination of the cyanide ligand to the platinum centre. The cation is almost planar as evidenced by a twist of only 1.9° of the phenyl group out of the plane of the terpyridyl moiety. Cyclic voltammograms were recorded in DMF/0.1 M TBAH for the [Pt{4′-(R)trpy}(CN)]+ cations. Two quasi-reversible one-electron reduction (cathodic) waves are observed with E1/2 values that show the trend expected for an increasingly lower energy of the trpy-based LUMO of the complex i.e., [Pt{4′-(Ph)trpy}(CN)]+ ∼ [Pt{4′-(o-CH3C6H4)trpy}(CN)]+ < [Pt{4′-(o-ClC6H4)trpy}(CN)]+ < [Pt{4′-(o-CF3C6H4)trpy}(CN)]+. All the [Pt(4′-(R)trpy}(CN)]+ cations are photoluminescent in dichloromethane. Emission by [Pt{4′-(Ph)trpy}(CN)]+ is from an excited state with largely 3MLCT orbital parentage, but with some intraligand 3π–π* character mixed-in (τ = 0.1 µs). In contrast, the other three cations display emission that appears exclusively intraligand 3π–π* in origin (τ ∼ 0.8 µs). Emission spectra have been recorded in a low concentration frozen DME {1 : 5 : 5 (v/v) DMF–MeOH–EtOH} glass. For the R = o-CH3C6H4, o-ClC6H4 and o-CF3C6H4 cations the envelope of vibronic structure and energies of the vibrational components are essentially the same as that recorded in dichloromethane. However, for the [Pt{4′-(Ph)trpy}(CN)]+ cation, there is a blue-shift in the energies of the vibrational components as compared to that recorded in dichloromethane, as well as a change in the envelope of vibronic structure to a more “domed” pattern; this has been interpreted in terms of a higher percentage of intraligand 3π–π* character in the emitting state for the glass. Increasing the concentration of the glass invariably leads to aggregation of the cations and the consequent development of new low energy bands, such that at 0.200 mM broad peaks centred at ca. 650 and 700 nm dominate the spectrum; these bands are assigned to excimeric 3π–π* and 3MMLCT emission, respectively.

The synthesis and characterisation of [Pt{4′-(Np1)-trpy}(C CPh)]SbF 6 ( 1 ) and [Pt{4′-(Np1)-trpy}{C C(CH 2 ) 2 CH 3 }]SbF 6 ( 2 ) [4′-(Np1)-trpy = 4′-(1-naphthyl)-2,2:6′,2′-terpyridine] are described. Complexes 1 and 2 exhibit unimolecular 3 MLCT (MLCT = metal-to-ligand charge transfer) emission in acetonitrile and in a low concentration 77 K glass solution in butyronitrile. The high concentration glass emission as well as the emission in the solid state is from a 3 MMLCT (MMLCT, metal–metal-to-ligand charge transfer) excited state, reflecting the presence of d z 2 ( Pt ) – d z 2 ( Pt ) interactions in these media.

Reaction of [Pt(bipy)Cl2] (bipy = 2,2′-bipyridine) with an excess of silver triflate in refluxing acetonitrile readily affords [Pt(bipy)(MeCN)2](CF3SO3)2 as a yellow, crystalline solid. A single crystal X-ray diffraction study shows that the cations are arranged in a zig-zag manner in rows parallel to the b axis of the monoclinic unit cell. Consideration of the crystal structures of related bipyridyl ligand complexes of platinum(II), leads to the conclusion that a stacked structure with intermolecular Pt…Pt interactions for the title compound is prevented by the electrostatic repulsion between adjacent cations that are doubly charged.

The synthesis and characterisation of 4′-(2‴-chlorophenyl)-2,2′:6′,2″-terpyridine [4′-(o-ClC6H4)trpy] and [Pt{4′-(o-ClC6H4)trpy}Cl]SbF6 are described. An X-ray crystal structure determination of the salt reveals columns of cations and anions with the cations stacked parallel and head-to-tail. At 295 K the Pt⋯Pt distances alternate between 3.374(1) and 3.513(1) A while the perpendicular separation between the mean planes comprising the platinum and three bonded nitrogen atoms remains constant at 3.35 A. As evidenced by crystal structure determinations at 260, 240 and 180 K, the shorter Pt⋯Pt distances become systematically shorter and the longer Pt⋯Pt distances become systematically longer as the temperature of the crystal is lowered. Structural evidence is presented that shows that this trend is a consequence of the more closely separated platinum atoms slipping into line with respect to a perpendicular to the above planes; at the same time the more widely separated platinum atoms fall out-of-line as the temperature is lowered. Emission spectra measured on a polycrystalline sample of the salt at 40 K intervals from 280 to 80 K comprise a single, asymmetric and featureless band [λmaxem = 609 nm at 280 K] that systematically increases in intensity as the temperature is lowered. There is a slight blue shift in the wavelength of the emission maximum as the temperature is lowered to 240 K but, below this temperature, the emission maximum gradually and systematically shifts to the red [λmaxem = 642 nm at 80 K]. This behaviour is rationalised in terms of 3MMLCT emission, the energy of which being determined by subtle changes in the extent of dz2−dz2 orbital overlap between adjacent platinum atoms separated by the shorter distance on one hand, and between platinum atoms separated by the longer distance on the other.

We report the synthesis and characterisation of eight molecules that have in common a diphenylphosphino group bonded to an α-carbon atom of a thienyl or pyridyl ring: 5,5′-bis(diphenylphosphino)-2,2′-bithiophene 1; diphenyl(2,2′-bithienyl-5-yl)phosphine 2; 5,5″-bis(diphenylphosphino)-2,2′:5′,2″-terthiophene 3; diphenyl(2,2′:5′,2″-terthienyl-5-yl)phosphine 4; diphenyl[5-(2′-pyridyl)-2-thienyl]phosphine 5; diphenyl[6-(2′-thienyl)-2-pyridyl]phosphine 6; diphenyl{5-[6′-(diphenylphosphino)-2′-pyridyl]-2-thienyl}phosphine 7; and 2,6-bis[5′-(diphenylphosphino)-2′-thienyl]pyridine 8. Methods used for their synthesis range from lithiation of the parent heterocycle and subsequent reaction with PPh2Cl to the use of coupling reactions catalysed by metal complexes to assemble the molecule from its subunits. The crystal and molecular structures of 1, 7 and 8 have been determined and show that the 2,2′-bithienyl moiety in 1 adopts an s-trans-conformation, while the 2-(2′-thienyl)pyridyl moieties in 7 and 8 adopt s-cis-conformations in the solid state. These compounds represent a new series of ligands that are expected to bond to metals through the phosphorus and/or nitrogen atoms rather than a sulfur atom, in view of the poor donor ability of a thiophene sulfur towards metals.

The synthesis and structure of the Ru(I) dimer [Ru(bpy)(CO)2(CH3CN)]2(PF6)2 (1; bpy = 2,2‘-bipyridine) are described. The electrochemical properties of this complex have been examined. The irrevers...

The complexes [Pt(4′Ph-terpy)Cl]A (4′Ph-terpy = 4′-phenyl-2,2′:6′,2″-terpyridine; A = SbF6, CF3SO3, or BF4) have been prepared by reaction of [Pt(PhCN)2Cl2] with the appropriate silver salt followed by addition of the 4′-phenyl-2,2′:6′,2″-terpyridyl ligand. The hexafluoroantimonate salt is yellow but, depending on the method of crystallisation, the triflate and tetrafluoroborate salts can be isolated in two forms, one yellow and the other red, the red forms only being stable at low temperatures. The crystal structure of red [Pt(4′Ph-terpy)Cl]BF4·CH3CN has been determined at 153 K by X-ray diffraction methods. The [Pt(4′Ph-terpy)Cl]+ cations are stacked face-to-face in an extended chain of stepped tetramers, with essentially equal Pt· · ·Pt distances of ca. 3.3 A within a tetramer and a Pt· · ·Pt distance of 4.680 A between successive tetramers. The spectroscopic and solid state emission properties of the salts have been recorded. The yellow salts are characterised by emission from an isolated chromophore in an excited state that reflects the admixture of 3MLCT (MLCT = metal-to-ligand charge-transfer) and 3IL (IL = intraligand) character. This assignment is supported by the presence of vibrational structure in the emission band as well as by a lifetime of ca. 1 µs for the emission. The red [Pt(4′Ph-terpy)Cl]BF4·CH3CN salt, in contrast, exhibits emission from a 3MMLCT (MMLCT = metal–metal–ligand charge-transfer) state as a consequence of the strong platinum dz2–dz2 orbital interactions. This assignment is consistent with the observation of a narrow, structureless and asymmetric band as well as an emission lifetime of ca. 0.1 µs. There is a systematic and substantial red-shift of 75 nm in the emission maximum on cooling the red salt from 280 to 80 K, an unexpected result since bathochromic shifts of this kind are normally associated with stacked structures with a uniform Pt· · ·Pt separation. The above assignments are further supported by measurements of the emission spectra of solutions of varying concentrations of the tetrafluoroborate salt in a dimethylformamide–methanol–ethanol glass at 77 K and by lifetime measurements. Interestingly, pressure in the form of grinding the salts modifies their luminescent properties. Thus, crushed samples of the yellow hexafluoroantimonate salt exhibit multiple emission at 80 K from both the 3MMLCT and the mixed parentage 3MLCT/3IL excited states, whereas at room temperature the emission spectrum is dominated by a broad band centred at 644 nm associated entirely with the 3MMLCT emission.

An investigation of the effects of solvent, temperature and the bulk of the silyl and carbamate functionalities on the stereoselective synthesis of substituted vinyl carbamates from α-silyl benzyl carbamates is described.

Imidazolinylidene and thiazolinylidene complexes of gold in acetonitrile have been investigated by cyclic voltammetry. No Au(II) intermediate was observed during the redox reactions and Au(III) compounds form only by oxidative addition of halogens.

The crystal structure of [Pt(trpy)(MeCN)](SbF6)2, where trpy denotes 2,2‘:6‘,2‘‘-terpyridine, shows that the platinum complex packs as a monomer; however, the 3π−π* emission of the solid occurs at surprisingly long wavelengths at room temperature. At lower temperatures new, shorter-wavelength maxima appear. Of the known salts with the composition [Pt(trpy)Cl]A, the A = SbF6- system is the lone example that exhibits a temperature-independent emission maximum. In these platinum(II) terpyridines, energy migration to defects or trap sites is one of the phenomena responsible for the temperature dependence of the solid-state emission spectrum. If trap emission is evident, the low-temperature spectral data are most representative of the bulk material.

Treatment of [{Ru 2 [µ-η 2 -OC(R)O] 2 (CO) 4 } n ] or its acetonitrile adduct [Ru 2 {µ-η 2 -OC(R)O} 2 (CO) 4 (MeCN) 2 ] (R = H, Me or Et) with a two-fold molar equivalent of the phosphorus–nitrogen ligands 2-diphenylphosphinopyridine (dppy), 2-diphenylphosphinoquinoline (dpquin) and 6-diphenylphosphino-2,2′-bipyridine (dpbipy) in alcohol under reflux resulted in the formation of dinuclear products of the type [Ru 2 {µ-η 2 -OC(R)O} 2 (CO) 4 (PPh 2 R′) 2 ] (R′ = pyridyl, quinolyl or bipyridyl) in which the PPh 2 R′ ligands are monodentate, co-ordinating axially through the phosphorus donor atoms, as established X-ray crystallographically for [Ru 2 {µ-η 2 -OC(Me)O} 2 (CO) 4 (dppy) 2 ]. On the other hand reaction of [{Ru 2 [µ-η 2 -OC(R)O] 2 (CO) 4 } n ] with 2 molar equivalents of dppy or dpquin in toluene under reflux in the presence of NH 4 PF 6 and under a slight pressure of carbon monoxide afforded products of the type [Ru 2 {µ-η 2 -OC(R)O}(CO) 4 (µ-dppy) 2 ]PF 6 or [Ru 2 {µ-η 2 -OC(R)O}(CO) 4 (µ-dpquin) 2 ]PF 6 in which the dppy or dpquin ligands adopt the bridging co-ordination mode, this mode of co-ordination being confirmed through a crystal structure determination on [Ru 2 {µ-η 2 -OC(H)O}(CO) 4 (µ-dppy) 2 ]PF 6 . Reaction of [{Ru 2 [µ-η 2 -OC(R)O] 2 (CO) 4 } n ] with dpbipy in n-butanol under reflux likewise afforded products, isolated as their hexafluorophosphate salts, in which the phosphorus–nitrogen ligands are bridging, viz. [Ru 2 {µ-η 2 -OC(R)O}(CO) 2 (µ-dpbipy) 2 ]PF 6 , the structure of [Ru 2 {µ-η 2 -OC(Me)O}(CO) 2 (µ-dpbipy) 2 ]PF 6 being established X-ray crystallographically.

Reaction of the electron-rich thiolate-bridged complex [Fe 2 (η-C 5 Me 5 ) 2 (µ- SEt) 2 (CO) 2 ] with 1 molar equivalent of the electron-acceptor compounds 7,7,8,8-tetracyanoquinodimethane (tcnq) and tetracyanoethylene (tcne) is accompanied by electron transfer and resulted in the formation of the dark green crystalline salts [Fe 2 (η-C 5 Me 5 ) 2 (µ- SEt) 2 (CO) 2 ] 2 [tcnq] 2 1 and [Fe 2 (η-C 5 Me 5 ) 2 (µ- SEt) 2 (CO) 2 ][tcne] 2 respectively. The crystal structures of these salts have been determined by X-ray diffraction methods and the cations thereof established to have very similar stereochemistries. The C 5 Me 5 ligands are cis disposed with respect to the Fe · · · Fe vector with the dihedral angles between their planes being 71 and 68° for 1 and 2 respectively. The Fe · · · Fe distances are respectively 3.077(2) and 3.069(2) A. Crystals of 1 consist of isolated units of composition D ˙+ (A) 2 2- D ˙ where D ˙+ denotes the cation and (A) 2 2- a (tcnq) 2 2- dimer, the planes of the tcnq moieties comprising the dimer and those of the adjacent C 5 Me 5 rings being virtually parallel. The compound is paramagnetic. Crystals of 2 consist of parallel rows of cations and tcne ˙- anions in the sequence · · · D ˙ A A ˙- D ˙+ A B ˙- D ˙+ A A ˙- D ˙+ A B ˙ - · · ·, where A A ˙- and A B ˙- label crystallographically independent anions. The two types of tcne ˙- anion are themselves approximately planar, but define different angles to the planes of the adjacent C 5 Me 5 rings of 4 and 72°. Magnetic susceptibility measurements for 2, in the range 5.0 to 310.0 K, suggest very little magnetic coupling between the unpaired spins on the cations and the tcne ˙- anions and thus this compound is also paramagnetic.

Treatment of [Cu(MeCN)4]PF6 in acetonitrile with 2,6-bis(diphenylphosphino)pyridine [(Ph2P)2py] afforded a colourless crystalline material characterised as [Cu2gm-(Ph2P)2PY3][PF612. An X-ray diffraction study confirmed that the three ligands bridge the two copper atoms bonding solely through the phosphorus atoms, each copper being trigonally coordinated; a cavity thus exists in the centre of the dinuclear dication bounded by the nitrogen donor atoms, the Cu… Cu distance and the diameter of the cavity being 4.744(2) and ca 4.9 A, respectively. Measurements of the solution emission spectra of [Cu2{μ-(Ph2P)2PY}3] [PF6]2 in the presence and absence of Cu+ and Ag+ ions suggest that these ions are trapped in the cavity on their addition to an acetonitrile solution of the complex. Addition of (Ph2P)2PY to [Cu(η2-bipy)(MeCN)2]PF6 (bipy = 2,2′-bipyridyl) in acetone afforded a yellow crystalline solid characterised as [Cu2{μ-(Ph2P)2py}2(η2-bipy)2][PF6]2. A crystal structure determination revealed that the two copper atoms are bridged by the two (Ph2P)2PY ligands bonding solely through the phosphorus atoms, with the irregular tetrahedral coordination at each copper being completed by the nitrogen atoms of the chelating bipyridyl ligands. The Cu… Cu distance is 6.806(2) A.

Protonation of the co-ordinatively unsaturated species [Ru2(µsb-CO)2(CO)2(µ-etipdp)2][sb = semi-bridging, etipdp =(PriO)2PNEtP(OPri)2] by acids of non-co-ordinating conjugate bases, e.g. HBF4·OEt2, produced [Ru2(µ-H)(µ-CO)(CO)3(µ-etipdp)2]+ which, as established X-ray crystallographically for the PF6– salt, contains both a bridging carbonyl and a bridging hydride ligand. This cationic species is very susceptible to attack by both neutral and anionic nucleophiles affording a range of product types. For instance, its reactions with anions X– which are capable of functioning as monodentate bridging ligands and which preferentially adopt the closed bridging co-ordination mode, e.g. halide and hydrogensulfide ions, afforded products of the type [Ru2(µ-X)H(µsb-CO)(CO)2(µ-etipdp)2](X = Cl, Br, I, SH, etc.), resulting from the substitution of a carbonyl group by the nucleophile. On the other hand, anionic nucleophiles such as H– and CN– gave addition products of the type [Ru2HX(CO)4(µ-etipdp)2](X = H, CN, etc.) in which the hydride and the X– ligand occupy equatorial sites trans disposed with respect to each other, as established in a separate study for [Ru2H2(CO)4(µ-etipdp)2]. Carbon monoxide also afforded a simple addition product, viz.[Ru2H(CO)5(µ-etipdp)2]+, but the majority of the other neutral nucleophiles studied, particularly the unsaturated systems, yielded products resulting from formal insertion of the nucleophile into the Ru–H bond. Thus sulfur produced [Ru2(µ-SH)(CO)4(µ-etipdp)2]+, while unsaturated nucleophiles of general formula X′Y′, e.g. PhCN and RCCH (R = H, Ph, etc.), gave products of the type [Ru2{µ-X′Y′(H)}(CO)4(µ-etipdp)2]+, e.g.[Ru2{µ-NC(H)Ph}(CO)4(µ-etipdp)2]+ or of the type [Ru2{µ-η2-X′Y′(H)}(CO)4(µ-etipdp)2]+, e.g.[Ru2(µ-η1 : η2-CHCHR)(CO)4(µ-etipdp)2]+. Heterocumulenes X″Y″Z″ such as CS2 and PhNCS behaved similarly affording products of general formula [Ru2{µ-η2-X″Y″(H)Z″}(CO)4(µ-etipdp)2]+ containing five-membered RuX″Y″Z″Ru rings. The co-ordinatively saturated pentacarbonyl [Ru2H(CO)5(µ-etipdp)2]PF6 gave products similar to those afforded by [Ru2(µ-H)(µ-CO)(CO)3(µ-etipdp)2]PF6 on reaction with systems of the type X′Y′ and X″Y″Z″ except that, for terminal alkynes such as PhCCH, alkenylcarbonyl-bridged products, e.g.[Ru2{µ-η2-OC(CHCHPh)}(CO)4(µ-etipdp)2]PF6, are produced. The crystal structures of the following compounds were determined : [Ru2(µ-H)(µ-CO)(CO)3(µ-etipdp)2]PF6, [Ru2(µ-I)H(µsb-CO)(CO)2(µ-etipdp)2], [Ru2{µ-N(CHPh)}(CO)4(µ-etipdp)2]PF6, [Ru2(µ-η1 : η2-CHCH2)(CO)4(µ-etipdp)2]PF6, [Ru2{µ-η2-OC(CHCHPh)}(CO)4(µ-etipdp)2]PF6 and [Ru2{µ-η2-SC(H)NPh}(CO)4(µ-etipdp)2]PF6.

Reaction of the electron-rich sulfido-bridged complex [Fe2(η-C5Me5)2(µ-SEt)2(CO)2] with electron-acceptor N,N′-dicyano-p-benzoquinone diimines resulted in electron transfer and formation of crystalline 1 : 1 salts of general formula [donor cation][acceptor anion]. The crystal structures of [Fe2(η-C5Me5)2(η-SEt)2(CO)2] and [Fe2(η-C5Me5)2(µ-SEt)2(CO)2][dmdcnqi](dmdcnqi =N,N′-dicyano-2,5-dimethyl-p-benzoquinone diimine) have been determined by X-ray diffraction methods. The neutral donor molecule possesses exact C2 symmetry, the molecules stacking in linear chains in the crystal with the C5Me5 rings of adjacent molecules parallel to each other. The donor cations in the electron-transfer salt also possess exact C2 symmetry and, moreover, are arranged similarly in the crystal, but with the planar acceptor anions sandwiched between the C5Me5 rings and at an angle of 11.4° to these rings. The sequence along the rows is thus one of alternating donor cations (D˙+) and acceptor anions (A˙–), i.e.⋯ D˙+A˙–D˙+A˙–D˙+A˙–⋯. Consistent with the formation of radical cations and anions is a decrease in the Fe ⋯ Fe distance from 3.445(1)A in the neutral donor molecule to 3.083(2)A in the donor cation. However, the temperature dependence of the magnetic susceptibility of this salt, when fitted by the Curie–Weiss law, affords a Weiss constant (θ) of only 0.414 K, which suggests that there is little ferromagnetic coupling between the unpaired spins on the radical cations and anions.

Treatment of the formally unsaturated species [Ru2(µsb-CO)2(CO)2(µ-etipdp)2][sb = semi-bridging, etipdp =(PriO)2PNEtP(OPri)2] with silver(I) salts such as AgSbF6 or AgBF4 in MeCN or PhCN led directly to the formation of the disolvated species [Ru2(CO)4(RCN)2(µ-etipdp)2]X2(R = Me or Ph; X = SbF6 or BF4), with no intermediates being detected. In contrast, as established spectroscopically, oxidation of this complex with silver(I) salts in very weakly co-ordinating solvents such as acetone or methanol afforded silver adducts of the parent species. Also, reaction with the electron acceptor tcnq (7,7,8,8-tetracyano-p-quinodimethane) in tetrahydrofuran (thf) gave the electron-transfer salt [Ru2(η1-tcnq)(CO)4(thf)(µ-etipdp)2][tcnq], while with p-chloranil(tetrachloro-1,4-benzoquinone) produced [Ru2(µ-Cl)(CO)4(µ-etipdp)2][p-OC6Cl4O]2 as a consequence of the benzoquinone functioning as a chlorinating agent as well as an electron acceptor. Cyclic voltammograms of [Ru2(µsb-CO)2(CO)2(µ-etipdp)2] and [Ru2(CO)4(RCN)2(µ-etipdp)2][SbF6]2(R = Me or Ph) have been measured in both aceto- and benzo-nitrile and are readily interpreted in terms of the redox process [Ru2(µsb-CO)2(CO)2(µ-etipdp)2]+ 2RCN [graphic omitted] [Ru2(CO)4(RCN)2(µ-etipdp)2]2+. The structure of the acetonitrile species [Ru2(CO)4(MeCN)2(µ-etipdp)2][BF4]2·CH2Cl2 has been determined X-ray crystallographically.

A new neolignan, which differs from ocobullenone at a single chiral centre, and a neolignan ketone, possibly a precursor of the ocobullenones, have been isolated from the stem bark of Ocotea bullata .

Methyl 2-bromomethylprop-2-enoate reacts with benzaldehyde and with salicylaldehyde via its Sn and Zn complexes under aqueous conditions to form α-methylene-γ-lactones in high yields. In the case of salicylaldehyde X-ray analysis proves conclusively formation of a five- rather than a seven-membered ring. Under the above conditions 2-bromomethyl-3-phenylprop-2-enoate does not afford any cyclic products.

Treatment of [Ru 2 (μ-CO)(CO) 4 (μ-etdp) 2 ] {etdp = (RO) 2 PN(Et)P(OR) 2 , R = Me or Pr i } with silver(I) carboxylates AgOC(O)R′ (R′ = Me, CF 3 or Ph) in acetone or tetrahydrofuran resulted in two electron oxidation and the formation of carboxylato species of the type [Ru 2 {μ-OC(R′)O}(CO) 4 (μ-etdp) 2 ] + for R′ = Me or Ph and [Ru 2 {η 1 -OC(O)R′}(CO) 5 (μ-etdp) 2 ] + for R′ = CF 3 . The acetate ligand in [Ru 2 {μ-OC(Me)O}(CO) 4 (μ-etdp) 2 ] + was displaced by other anionic ligands such as oxy-2-pyridinate or pyrazolate ions affording for these two ligands [Ru 2 (μ-NC 5 H 4 O)(CO) 4 (μ-etdp) 2 ] + and [Ru 2 (μ-N 2 C 3 H 3 )(η 1 -N 2 C 3 H 3 )(CO) 3 (μ-etdp) 2 ] respectively. The structures of [Ru 2 {μ-OC(Ph)O}(CO) 4 (μ-etipdp) 2 ]PF 6 {etipdp = (Pr i O) 2 PN(Et)P(OPr i ) 2 } and [Ru 2 (μ-NC 5 H 4 O)(CO) 4 (μ-etmdp) 2 ]PF 6 {etmdp = (MeO) 2 PN(Et)P(OMe) 2 } have been determined by X-ray crystallographically.

Higher-Valent Derivatives of the d-Metal Acids, 13. — Homoscorpionates as Tripodal Anchoring Ligands of Chloro Functionalized Oxo and Imido Complexes of Elements of Group 5–7 Hydridotris(pyrazolyl)borate complexes of elements of group 5–7 have been prepared by reaction of d0-metalloyl chlorides [M(Y)nClm]x (Y = O, NR) with KTp* (Tp* = κ3-HB(3,5-Me2pz)3). Thus [NbOCl3]x and [TaOCl3]x are converted into monomeric and well-characterized oxo complexes [Tp* Nb(O)Cl2] (1) and [Tp*Ta(O)Cl2] (2). In a similar way [Tp* Mo(O)2Cl] (3) and [Tp*W(O)2Cl] (4) have been obtained from the oxo chlorides [MoO2Cl2]x and [WO2Cl2]x, respectively. tert-Butylamine reacts with NbCl5 and TaCl5 in the presence of pyridine to give the imido pyridine complexes [Nb(NtBu)Cl3(py)2] (5) and [Ta(NtBu)Cl3(py)2] (6) in excellent yield. Imido complexes [Tp*V(NtBu)Cl2] (7), [Tp* Nb(NtBu)Cl2] (8), and [Tp*Ta(NtBu)Cl2] (9) are formed by the reaction of KTp* with the precursers [V(NtBu)Cl3]x or 5 and 6, respectively. The corresponding imido complexes of group 6, namely [Tp*Cr(NtBu)2Cl] (10), [Tp*Mo(NtBu)2Cl] (11), and [Tp*W(NR)2Cl] (R = tBu 12a, 2,4,6-Mesityl 12b, SO2Ph 12c) are obtained directly from the imidoyl chlorides or their complexes with Lewis bases. 11 and 12 are prone to protonation at the imido ligand to yield cationic amido species [Tp*M(NtBu)(NHtBu)Cl]BF4 (M = Mo 13, W 14). Finally the preparation of cationic imido rhenium complex [Tp*Re(NtBu)2Cl]PF6 (15), isoelectronic with 10–12, is described. The molecular structure of 11 has been determined by X-ray diffraction. Despite of a maximum electron count of 20 valence electrons, all three pyrazolyl groups of the tripodal ligand are facially coordinated. In a way similar to the well-known ring slippage of analogous cyclopentadienyl complexes, the weakest bound pyrazolyl ligand is asymmetrically attached to molybdenum deviating from the positions expected for local C3v symmetry.

Reaction of [Ru2(µ-CO)(CO)4{µ-(RO)2PN(Et)P(OR)2}2](R = Me or Pri) with equimolar quantities of metal-containing electrophiles such as [AuCl(PPh3)], silver(I) salts, [Cu(MeCN)4]PF6 and HgCl2 has afforded cationic products in which the metal substrate are co-ordinated either terminally as in [Ru2(σ-HgCl)(CO)5{µ-(RO)2PN(Et)P(OR)2}2]+ or in the bridging mode as in [Ru2{µ-Au(PPh3)}(µ-CO)(CO)4{µ-(RO)2PN(Et)P(OR)2}2]+ and [Ru2(µ-AgLx)(µ-CO)(CO)4{µ-(RO)2PN(Et)P(OR)2}2]+(L = pyridine or MeCN, x= 1 or 2). The silver adducts readily rearrange in solution with the nature of the product(s) formed being dependent on the identity of the ligand L and/or the solvent employed For non-protic weakly co-ordinating ligands such as acetonitrile, the silver-bridged cations disproportionate in solution to the parent compound [Ru2(µ-CO)(CO)4{µ-(RO)2PN(Et)P(OR)2}2]and the solvento species [Ru2(CO)5(Solv){µ-(RO)2PN(Et)P(OR)2}2]2+ thereby establishing that the formation of [Ru2-(CO)5(Solv){µ-(RO)2PN(Et)P(OR)2}2]2+ by treatment of [Ru2(µ-CO)(CO)4{µ-(RO)2PN(Et)P(OR)2}2] with a two-fold molar amount of silver(I) ions in non-protic weakly co-ordinating solvents occurs via an inner-sphere mechanism. In the case of the aqua and acetone solvento species [Ru2(CO)5(solv)-{µ-(RO)2PN(Et)P(OR)2}2]2+(solv = H2O or Me2CO), both the solvent molecule and the carbonyl groups are labile with one or both being readily displaced by a wide range of neutral and ionic nucleophiles including carbon monoxide, isonitriles, nitriles, pyridine, 4,4′-bipyridine, dimethyl sulfide and tetra-hydrothiophene, and halide, thiocyanate, benzenethiolate, trifluoroacetate, acetate and hydride ions. The crystal structures of [Ru2{µ-Au(PPh3)}(µ-CO)(CO)4{µ-(MeO)2PN(Et)P(OMe)2}2]SbF6, [Ru2-(CO)5(PhCN){µ-(PriO)2PN(Et)P(OPri)2}2][SbF6]2 and [Ru2(CO)5(SC4H8){µ-(PriO)2PN(Et)P(OPri)2};2]-[SbF6]2 have been determined.

The acrylate ester of salicylaldehyde, in the presence of DABCO, affords a crystalline coumarin salt. Formation of this derivative confirms a vital intermediate in the mechanism of the reaction. Salicylaldehyde, suitably protected, reacts with methyl acrylate to afford a novel coumarin not unlike the vasodilator chromonar.

Reaction of 6-diphenylphosphino-2,2′-bipyridine (Ph2Pbipy) with copper(I) precursors such as [Cu(MeCN)4]+ and [Cu(2,2′-bipy)(MeCN)2]+ affords dinuclear phosphorusbipyridyl ligand-bridged dicopper products and in particular [Cu2(μ-Ph2Pbipy)2 (MeCN)2]2+ (1 and [Cu2(2,2′-bipy)(μ-Ph2Pbipy)2]2+ (2), respectively. The ligand coordinates head-to-tail in 1, and head-to-head in 2, as established by single crystal X-ray diffraction studies.

2,6-Dialkyl-5-methylene-1,3-dioxan-4-ones were prepared in good diastereomeric excess by treating pantolactone acrylate with a series of selected aldehydes in the Baylis-Hillman reaction. With benzaldehyde and trichloroacetaldehyde, non-cyclic products resulted. In the case of the latter aldehyde the α1-hydroxyalkyl acrylate 5b was isolated as a single diastereomer and its absolute configuration established by X-ray crystallography.

Reaction of the di-iron heptacarbonyl compounds [Fe2(μ-CO)(CO)6(μ-R2PCH2PR2)2] (R = Me or Ph) with a range of diphosphorus or diarsenic ligands under photochemical conditions affords the ligand-bridged pentacarbonyl derivatives [Fe2(μ-CO)(CO)4(μ-Me2PCH2PMe2)(μ-L-L)] [L-L = (MeO)2PN(Et)P(OMe)2 or (EtO)2PN(Me) P(OEt)2] and [Fe2(μ-CO)(CO)4(μ-Ph2PCH2PPh2)(μ-L-L)] [L-L = Me2PCH2PMe2, Ph2PN(Et)PPh2, Ph2AsCH2AsPh2, (MeO)2PN(Et)P(OMe)2 and (EtO)2PN(Me)P(OEt)2] in good yield. Treatment of these mixed ligand-bridged complexes with the protic acids HBF4 · Et2O or CF3COOH leads exclusively to the formation of the hydride-bridged species [Fe2(μ-H)(μ-CO)(CO)4(μ-R2PCH2PR2)(μ-L-L)]+ isolated as the tetrafluoroborate salts. Hydride-bridged products are also obtained by protonation of [Fe2(μ-CO)(CO)4{μ-(R′O)2PN(R″)P(OR′)2}2] (R″ = Me, R′ = Et; R″ = Et, R′ = Me, Pri or Ph) and [Fe2(μ-CO)(CO)4(μ-R2PCH2PR2)2] (R = Me or Ph), but whereas the diphosphazane-bridged species [Fe2(μ-H)(μ-CO)(CO)4{μ-(R′O)2PN(R″)P(OR′)2}2]+ are only stable to deprotonation in the presence of excess acid, the ditertiary phosphine-bridged species [Fe2(μ-H)(μ-CO)(CO)4(μ-R2PCH2PR2)2]+ can only be deprotonated by strong bases such as NaBH4. The structure of [Fe2(μ-CO)(CO)4(μ-Ph2PCH2PPh2)2] has been established X-ray crystallographically. The two iron atoms, which are bridged by a carbonyl group as well as by the two ditertiary phosphine ligands, are separated by a distance of 2.742(4) A, corresponding to a formal iron-iron bond.

Hexahydro-3a, 7a-dihydroxy-3,7,7-trimethyl-2-phenyl-4H-furo [3,2-c]pyran-4-one 6 has been obtained from the reaction between tetrahydro-4, 4-dimethyl-2-oxo-3-furanyl propanoate 4 , benzaldehyde and base. The product is the result of a modified benzilic acid rearrangement.

The reaction of ethyne with [Ru2(µ-CO)(CO)4{(RO)2PN(Et)P(OR)2}2] in toluene at 80 °C or with [Ru2(µsb-CO)2(CO)2{(RO)2PN(Et)P(OR)2}2](R = Me or Pri, sb = semi-bridging), in toluene at room temperature, affords almost exclusively the ethenediyl-bridged species [Ru2(µ-σ2-HCCH)(CO)4{(RO)2-PN(Et)P(OR)2}2] for R = Me and the vinylidene-bridged product [Ru2(µ-σ-CCH2)(CO)4{(RO)2-PN(Et)P(OR)2}2] for R = Pri; a second, minor product is also formed in each of these reactions and was identified as [Ru2(µ-σ-CCH2)(CO)4{(MeO)2PN(Et)P(OMe)2}2] and [Ru2(µ-σ2-HCCH)(CO)4-{(PriO)2PN(Et)P(OPri)2}2] respectively. The reactions of [Ru2(µ-CO)(CO)4{(RO)2PN(Et)P(OR)2}2] and [Ru2(µsb-CO)2(CO)2{(RO)2PN(Et)P(OR)2}2] with the terminal alkynes MeCCH, PhCCH and MeO2CCCH also afford mixtures of alkenediyl- and vinylidene-bridged products with the relative yields of these isomers being dependent on the identity of the alkyne and of the bridging diphosphazane ligand. On the other hand reaction with the internal alkyne MeO2CCCCO2Me gives solely the alkenediyl-bridged product [Ru2(µ-σ2-MeO2CCCCO2Me)(CO)4{(RO)2PN(Et)P(OR)2}2] irrespective of the diphosphazane ligand involved. Possible mechanisms for the formation of the two types of products are described. The crystal structure of [Ru2(µ-σ2-HCCH)(CO)4{(MeO)2PN(Et)P(OMe)2}2] is reported.

Thermolysis of [Ru2(µ-CO)(CO)4{µ-(RO)2PN(Et)P(OR)2}2], [Ru2H2(CO)4{µ-(RO)2PN(Et)P(OR)2}2] or [Ru2{µ-OC(O)}(CO)4{µ-(RO)2PN(Et)P(OR)2}2](R = Me or Pri) under appropriate reaction conditions affords the formally unsaturated species [Ru2(CO)4{µ-(RO)2PN(Et)P(OR)2}2], which have been established by X-ray crystallography for both R = Me and R = Pri to contain two complementary semi-bridging carbonyl groups as well as two terminal carbonyls. These compounds are highly labile and react under mild conditions with a range of small molecule nucleophiles and electrophiles including carbon monoxide, isonitriles, nitrosyl ions, alkynes, sulfur, hydrogen sulfide, dioxygen, sulfur dioxide, tin(II) chloride, dihydrogen, protons, halogens and carbon tetrachloride. The compound [Ru2H2(CO)4{µ-(PriO)2PN(Et)P(OPri)2}2], the product of the reaction involving dihydrogen and the tetraisopropoxy-diphosphazane derivative and in which, as determined by X-ray crystallography, the hydrogens are situated equatorially and trans to each other on different ruthenium atoms, is also highly reactive, typically reductively eliminating dihydrogen in its reactions with nucleophiles including alkynes.

Treatment of [Ru2(µ-CO)(CO)4{µ-(RO)2PN(Et)P(OR)2}2](R = Me or Pri) with AgSbF6 in methanol, ethanol or tetrahydrofuran–water resulted in the formation of the solvento species [Ru2(CO)5(R′OH){µ-(RO)2PN(Et)P(OR)2}2][SbF6]2 which is isolable for R′= H but which spontaneously deprotonates to the alkoxycarbonyl-bridged derivative [Ru2{µ-η2-OC(OR′)}(CO)4{µ-(RO)2PN(Et)P(OR)2}2]SbF6 for R′= Me or Et. The aqua species [Ru2(CO)5(H2O){µ-(RO)2PN(Et)P(OR)2}2][SbF6]2 was readily deprotonated in consecutive steps by appropriate bases to afford respectively the hydroxycarbonyl-bridged species [Ru2{µ-η2-OC(OH)}(CO)4{µ-(RO)2PN(Et)P(OR)2}2]SbF6 and the adduct [Ru2{µ-η2-OC(O)}(CO)4{µ-(RO)2PN(Et)P(OR)2}2] in which the carbon dioxide molecule adopts a novel bridging co-ordination mode; this deprotonation is reversible and treatment of the latter with HBF4·OEt2 leads to stepwise regeneration of the aqua species. The co-ordinated water molecule in [Ru2(CO)5(H2O){µ-(PriO)2PN(Et)P(OPri)2}2][SbF6]2 was readily displaced by acids HA derived from conjugate bases with potential co-ordinating properties such as thiolate ions R″S–(R″= H or Ph) or carboxylate ions R‴CO2–(R‴= H, Me, Ph or CF3), to produce monocationic pentacarbonyl species of the type [Ru2A(CO)5{µ-(PriO)2PN(Et)P(OPri)2}2]SbF6; detection of an intermediate, presumably [Ru2(CO)5(HA){µ-(PriO)2PN(Et)P(OPri)2}2][SbF6]2, was possible for HA = HCO2H and MeCO2H. The sulfido derivatives [Ru2(SR″)(CO)5{µ-(PriO)2PN(Et)P(OPri)2}2]SbF6(R″= H or Ph) rapidly decarbonylate in solution to afford the tetracarbonyl products [Ru2(µ-SR″)(CO)4{µ-(PriO)2PN(Et)P(OPri)2}2]SbF6 in which the sulfido group bridges the two ruthenium atoms. On the other hand the carboxylato derivatives [Ru2{OC(O)R‴}(CO)5{µ-(PriO)2PN(Et)P(OPri)2}2]SbF6(R‴= H, Me, Ph or CF3) are stable to decarbonylation in solution at room or elevated temperatures but can be decarbonylated to the carboxylato-bridged products [Ru2{µ-η2-OC(R‴)O}(CO)4{µ-(PriO)2PN(Et)P(OPri)2}2]SbF6 by irradiation with ultraviolet light. The water molecule in [Ru2(CO)5(H2O){µ-(PriO)2PN(Et)P(OPri)2}2][SbF6]2 was also readily displaced by the conjugate bases of the above acids HA, but in contrast to that observed for the carboxylic acids R‴CO2H (R‴= H, Me or Ph), reaction of the aqua species with the corresponding carboxylate ions R‴CO2– led to direct formation of the carboxylato-bridged species [Ru2{µ-η2-OC(R‴)O}(CO)4{µ-(PriO)2PN(Et)P(OPri)2}2]SbF6. Possible mechanisms for the formation of the various products are discussed as are the structures of [Ru2(CO)5(H2O){µ-(PriO)2PN(Et)P(OPri)2}2][SbF6]2·OCMe2, [Ru2{µ-η2-OC(OEt)}(CO)4{µ-(MeO)2PN(Et)P(OMe)2}2]SbF6, [Ru2{µ-η2-OC(Me)O}(CO)4{µ-(PriO)2PN(Et)P(OPri)2}2]PF6 and [Ru2{µ-η2-OC(O)}(CO)4{µ-(PriO)2PN(Et)P(OPri)2}2], established X-ray crystallographically.

Dinuclear diphosphinecopper(I) complexes of the bis(chelating)‘S-frame’ ligand di-tert-butyl azodiformate exhibit a remarkable kinetic and thermodynamic stability of the deep blue o-semiquinonoid intermediate as evident from its facile formation, stability towards air and protic media, and from the electrochemical potential range. The comproportionation constant of [CuI2{µ-N2[CO(OBut)]2}{µ-Ph2P(CH2)6PPh2}2]+ was established at 1019·7. The crystal structure of the tetraphenylborate salt has been determined. It shows an ‘inverse cryptate’ structure; two bridging diphosphine ligands span the two bridgehead copper(I) centres which are fixed at 4.82 A apart by the bis(chelating) azodicarboxylate anion radical. In contrast to the neutral (reduced) form of the complex, the dicationic oxidised state could only be spectroelectrochemically.

Hexahydro-3a, 7a-dihydroxy-3,7,7-trimethyl-2-phenyl-4H-furo [3,2-c]pyran-4-one 6 has been obtained from the reaction between tetrahydro-4, 4-dimethyl-2-oxo-3-furanyl propanoate 4 , benzaldehyde and base. The product is the result of a modified benzilic acid rearrangement.

The acrylate ester of salicylaldehyde, in the presence of DABCO, affords a crystalline coumarin salt. Formation of this derivative confirms a vital intermediate in the mechanism of the reaction. Salicylaldehyde, suitably protected, reacts with methyl acrylate to afford a novel coumarin not unlike the vasodilator chromonar.

We report the synthesis and characterisation of eight molecules that have in common a diphenylphosphino group bonded to an α-carbon atom of a thienyl or pyridyl ring: 5,5′-bis(diphenylphosphino)-2,2′-bithiophene 1; diphenyl(2,2′-bithienyl-5-yl)phosphine 2; 5,5″-bis(diphenylphosphino)-2,2′:5′,2″-terthiophene 3; diphenyl(2,2′:5′,2″-terthienyl-5-yl)phosphine 4; diphenyl[5-(2′-pyridyl)-2-thienyl]phosphine 5; diphenyl[6-(2′-thienyl)-2-pyridyl]phosphine 6; diphenyl{5-[6′-(diphenylphosphino)-2′-pyridyl]-2-thienyl}phosphine 7; and 2,6-bis[5′-(diphenylphosphino)-2′-thienyl]pyridine 8. Methods used for their synthesis range from lithiation of the parent heterocycle and subsequent reaction with PPh2Cl to the use of coupling reactions catalysed by metal complexes to assemble the molecule from its subunits. The crystal and molecular structures of 1, 7 and 8 have been determined and show that the 2,2′-bithienyl moiety in 1 adopts an s-trans-conformation, while the 2-(2′-thienyl)pyridyl moieties in 7 and 8 adopt s-cis-conformations in the solid state. These compounds represent a new series of ligands that are expected to bond to metals through the phosphorus and/or nitrogen atoms rather than a sulfur atom, in view of the poor donor ability of a thiophene sulfur towards metals.

The purple, phosphinidene-capped, phosphido-bridged triruthenium cluster [Ru 3 (μ 3 -PPh)(μ 2 -PPh 2 ) 2 (CO) 7 ] reacts readily with carbon monoxide, trimethylphosphite, sodium borohydride and diphenylacetylene under mild conditions to afford product mixtures from which [Ru 3 (μ-PPh)(μ 2 -PPh 2 ) 2 (CO) 7+ n ] ( n = 1, 2 or 3), [Ru 3 (μ 3 -PPh)(μ 2 -PPh 2 ) 2 (CO) 6 {P(OMe) 3 }], [Ru 3 (μ 3 -η 3 -PhPCPhCPh)(μ 2 -PPh 2 ) 2 (CO) 6 ], respectively, can be isolated. The structure of [Ru 3 (μ 3 -PPh)(μ 2 -PPh 2 ) 2 (CO) 6 {P(OMe) 3 }] has been established X-ray crystallographically.

Reaction of the diphosphazane-bridged diruthenium derivatives Ru 2 (μ-CO)(CO) 4 [μ-(RO) 2 PN(Et)P(OR) 2 ] 2 (R=Me, i Pr) with the electron acceptors TCNX (X=Q, E) affords products of the type {Ru 2 (CO) 5 [μ-(RO) 2 PN-(Et)P(OR) 2 ] 2 (η 1 -TCNX)}(TCNX) containing a TCNX radical anion in both the inner and outer coordination sphere of the cation

Reaction of the electron-rich diphosphazane-bridged diruthenium complexes [Ru 2 (μ-(CO)(CO) 4 {μ-(RO) 2 PN(Et)P(OR) 2 } 2 ] (R = Me or i Pr) with the electron-acceptor ligands 7,7,8,8-tetracyano- p -quinodimethane, TCNQ, and tetracyanoethylene, TCNE, results in electron transfer and the formation of the charge transfer salts [Ru 2 (CO) 5 (TCNX) {μ-(RO) 2 PN(Et)P(OR) 2 } 2 ]TCNX (X  Q or E) containing the radical anion of the electron-acceptor ligand in both the inner and the outer coordination spheres.

(−)(R,R)-2-Amino-1-(4-nitrophenyl)propan-1,3-diol 3 has been used to resolve racemic 3-hydroxy-2-methylene-3-phenylpropanoic acid 1a. Conversion of the laevorotatory enantiomer into anti and syn methyl 3-hydroxy-2-methyl-3-phenylpropanoate, 2a and 2b respectively, was achieved with Pd/H2. Correlation of the specific rotations of 2a and 2b with isomers of known configuration established the absolute configuration of 4a as R. This was confirmed independently by X-ray crystallography.

This paper lays out the research agenda of the Thorn project, a collaboration between IBM Research and Purdue University with the goal of exploring how to incrementally transition rapid prototypes into robust programs. The project is in its early stages and we have more questions than answers.Out of 518 enterprises, 11% reported using server scripting languages, which was higher than C/C++.---The Forrester Wave: Dynamic Programming LanguagesAny doubt that a Perl-based application would be robust enough to handle a large, mission-critical, financial-batch system has been dispelled by Pluto's performance with the Swedish national pension since its launch in the fall of 2000. More than 5 million customers take part... accounts exceed 6 billion dollars.---Perl Runs Sweden's Pension System