Crystal structure of tricarbon-yl[η4-6-exo-(tri-phenyl-phosphino)cyclo-hepta-2,4-dien-1-one]iron(0) tetra-fluoro-borate.

The mol-ecular structure of tricarbon-yl[η4-6-exo-(tri-phenyl-phosphino)cyclo-hepta-2,4-dien-1-one]iron(0) tetra-fluoro-borate di-chloro-methane hemisolvate, [Fe(C28H22O4)(CO)3]BF4·0.5CH2Cl2, as determined by single-crystal X-ray diffraction is reported. The two independent tricarbon-yl[η4-6-exo-(tri-phenyl-phosphino)cyclo-hepta-2,4-dien-1-one] iron(0) cations and their corresponding anions form dimers, which constitute the asymmetric unit of the structure parallel to the (100) plane. Solid-state stability within that asymmetric unit as well as between neighboring dimeric units is afforded by C-H⋯O and C-H⋯F hydrogen bonds and C-H⋯π and Y-X⋯π (Y = B, C; X = F, O) inter-actions, which yield diperiodic sheets and a three-dimensional extended network.

Cleavage of [Pd2(PP)2(µ-Cl)2][BArF24]2 (PP = Bis(phosphino)ferrocene, BArF24 = Tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) with Monodentate Phosphines.

The addition of Na[BArF24] (BArF24 = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) to [Pd(PP)Cl2] (PP = 1,1'-bis(phosphino)ferrocene ligands) compounds results in the loss of a chloride ligand and the formation of the dimeric species [Pd2(PP)2(µ-Cl)2][BArF24]2. In most cases, the addition of a monodentate phosphine, PR3, to these dimeric species leads to cleaving of the dimer and formation of [Pd(PP)(PR3)Cl][BArF24]. While these reactions are readily observed via a significant color change, the 31P{1H} NMR spectra offer more significant support, as the singlet for the dimer is replaced with three doublets of doublets. The reaction seems to take place for a wide range of PR3 ligands, although there do appear to be steric limitations to the reaction. The compounds were thoroughly characterized by NMR, and X-ray crystal structures of several of the compounds were obtained. In addition, the ferrocenyl backbone of the 1,1'-bis(phosphino)ferrocene ligands provides an opportunity to examine the oxidative electrochemistry of these compounds. In general, the potential at which oxidations of these compounds occurs shows a dependence on the phosphine substituents.

Exploring opportunities for tuning phenyltris(pyrazol-1-yl)borate donation by varying the extent of phenyl substituent fluorination.

The importance of electron deficient Tp ligands motivates the introduction of electron-withdrawing substituents into the scorpionate framework. Since perfluorophenyltris(pyrazol-1-yl)borate affects significant anodic shifts in half-cell potentials in their metal complexes relative those of phenyltris(pyrazol-1-yl)borate analogues, the tuning opportunities achieved using 3,4,5-trifluorophenyl- and 3,5-bis(trifluoromethyl)phenyl(pyrazol-1-yl)borates were explored. Bis(amino)boranes ((3,4,5-F)C6H2)B(NMe2)2 and ((3,5-CF3)C6H3)B(NMe2)2 are precursors to fluorinated tris(pyrazol-1-yl)phenylborates. Thallium salts of these scorpionates exhibit bridging asymmetric κ3-N,N,N coordination modes consistent with the reduced π-basicity of the fluorinated phenyl substituents relative those of other structurally characterized tris(pyrazol-1-yl)phenylborates. While a comparative analysis of the spectral and X-ray crystallographic data for classical Mo(0), Mo(II), Mn(I), Fe(II) and Cu(II) complexes of [((3,4,5-F)C6H2)Bpz3]- and [((3,5-CF3)C6H3)Bpz3]- could not differentiate these ligands with respect to their metal-based electronic impacts, cyclic voltammetry suggests that 3,4,5-trifluorophenyl- and 3,5-bis(trifluoromethyl)phenyl(pyrazol-1-yl)borates affect similar anodic shifts within their metal complexes, with coordination of [((3,5-CF3)C6H3)Bpz3]- rendering metal centers more difficult to oxidize, and sometimes even more difficult to oxidize than their [C6F5Bpz3]- analogues. These data suggest that the extent of phenyl substituent fluorination necessary to minimize metal center electron-richness in phenyltris(pyrazol-1-yl)borate complexes cannot be confidently predicted.

Synthesis of disubstituted furans catalysed by [(AuCl)2(µ-bis(phosphino)metallocene)] and Na[BArF24].

The catalytic activity of a series of [(AuCl)2(µ-PP)] (PP = 1,1'-bis(phosphino)metallocene ligands) compounds in the presence of Na[BArF24] (BArF24 = tetrakis(3,5-bis(trifluoromethyl)phenyl borate)) was examined in the formation of disubstituted furans from pyridine-N-oxide and terminal alkynes. The products of these reactions were typically the 2,5-disubstituted furans, but in the case of using 2-ethynylpyridene, the 2,4-disubstituted furan formed. The catalytic efficiency was dependent upon both the nature of the terminal alkyne and the 1,1'-bis(phosphino)metallocene ligands. During the course of this study, two new compounds, [(AuCl)2(µ-dppr)] and [(AuCl)2(µ-dppo)] (dppr = 1,1'-bis(diphenylphosphino)ruthenocene; dppo = 1,1'-bis(diphenylphosphino)osmocene), were prepared and characterized by NMR. X-ray crystal structures of both compounds were determined and the oxidative electrochemistry of these new compounds was examined.

Teaching from the primary inorganic literature: lessons from Richard Andersen.

For many who passed through his classroom, Richard Andersen demonstrated how inorganic chemistry can be taught by incorporating the research literature. The Interactive Online Network of Inorganic Chemists (IONiC) through its website and summer workshops for faculty has supported the development and sharing of more than a hundred exercises or "learning objects" derived from articles highlighting research across the inorganic field. Faculty can adapt and implement these learning objects in their own classrooms to achieve goals such as demonstrating historical context, teaching course material via current research, and elaborating on the scientific process. Literature discussion learning objects highlight current and past research in inorganic chemistry and teach students both chemistry content and how the body of inorganic knowledge is constructed.

Spectroscopic, structural and computational analysis of [Re(CO)3(dippM)Br](n+) (dippM = 1,1'-bis(diiso-propylphosphino)metallocene, M = Fe, n = 0 or 1; M = Co, n = 1).

While the redox active backbone of bis(phosphino)ferrocene ligands is often cited as an important feature of these ligands in catalytic studies, the structural parameters of oxidized bis(phosphino)ferrocene ligands have not been thoroughly studied. The reaction of [Re(CO)3(dippf)Br] (dippf = 1,1'-bis(diiso-propylphosphino)ferrocene) and [NO][BF4] in methylene chloride yields the oxidized compound, [Re(CO)3(dippf)Br][BF4]. The oxidized species, [Re(CO)3(dippf)Br][BF4], and the neutral species, [Re(CO)3(dippf)Br], are compared using X-ray crystallography, cyclic voltammetry, visible spectroscopy, IR spectroscopy and zero-field (57)Fe Mössbauer spectroscopy. In addition, the magnetic moment of the paramagnetic [Re(CO)3(dippf)Br][BF4] was measured in the solid state using SQUID magnetometry and in solution by the Evans method. The electron transfer reaction of [Re(CO)3(dippf)Br][BF4] with acetylferrocene was also examined. For additional comparison, the cationic compound, [Re(CO)3(dippc)Br][PF6] (dippc = 1,1'-bis(diiso-propylphosphino)cobaltocenium), was prepared and characterized by cyclic voltammetry, X-ray crystallography, and NMR, IR and visible spectroscopies. Finally, DFT was employed to examine the oxidized dippf ligand and the oxidized rhenium complex, [Re(CO)3(dippf)Br](+).

Electrochemistry of 1,1'-bis(2,4-dialkylphosphetanyl)ferrocene and 1,1'-bis(2,5-dialkylphospholanyl)ferrocene ligands: free phosphines, metal complexes, and chalcogenides.

The oxidative electrochemistries of a series of chiral bisphosphinoferrocene ligands, 1,1'-bis(2,4-dialkylphosphetanyl)ferrocene (FerroTANE) and 1,1'-bis(2,5-dialkylphospholanyl)ferrocene (FerroLANE), were examined. The reversibility of the oxidation is sensitive to the steric bulk of the alkyl groups. New transition metal compounds and phosphine chalcogenides of these ligands were prepared and characterized. X-ray crystal structures of 10 of these compounds are reported. The percent buried volume (%V(bur)) is a recently developed measurement based on crystallographic data that examines the steric bulk of N-heterocyclic carbene and phosphine ligands. The %V(bur) for the FerroTANE and FerroLANE structures with methyl or ethyl substituents suggests these ligands are similar in steric properties to 1,1'-bis(diphenylphosphino)ferrocene (dppf). In addition the %V(bur) has been found to correlate well with the Tolman cone angle for phosphine chalcogenides. The oxidative electrochemistries of the transition metal complexes occur at more positive potentials than the free ligands. While a similar positive shift is seen for the oxidative electrochemistries of the phosphine chalcogenides, the oxidation of the phosphine selenides does not occur at the iron center, but rather oxidation occurs at the selenium atoms.

Cyclopentadienyl Ligand Effects on Enthalpies of Protonation of the Ru-Ru Bond in Cp'(2)Ru(2)(CO)(4) Complexes.

Basicities of a series of Cp'(2)Ru(2)(CO)(4) complexes were established by measuring the heats evolved (DeltaH(MHM)) when the complexes were protonated by CF(3)SO(3)H in 1,2-dichloroethane at 25.0 degrees C. Spectroscopic studies show that the protonation occurs at the metal-metal bond to form [Cp'(2)Ru(2)(CO)(4)(&mgr;-H)](+)CF(3)SO(3)(-), in which all of the CO ligands are terminal. The basicities (-DeltaH(MHM)) increase with the Cp'(2) ligands in the following order: (C(5)Me(4)CF(3))(2) < (C(9)H(7))(2) < C(5)H(4)C(5)H(4) < C(5)H(4)CH(2)CH(2)C(5)H(4) < (C(5)H(5))(2) < (C(5)Me(5))(2) < C(5)H(4)CH(2)C(5)H(4). This trend can be understood in part by considering that more strongly donating Cp' ligands increase the basicity of the Ru-Ru bond. Another important factor is the CO-bridging or nonbridging form of each Cp'(2)Ru(2)(CO)(4) complex. A dimer with bridging CO groups is significantly less basic than another dimer with only terminal CO groups although the donor abilities of their Cp' ligands are nearly equal. The Ru-Ru bond in Cp(2)Ru(2)(CO)(4) is substantially more basic than the Ru in the related mononuclear CpRu(CO)(2)H. Molecular structures of [Cp(2)Ru(2)(CO)(4)(&mgr;-H)](+)CF(3)SO(3)(-), [(C(5)H(4)CH(2)C(5)H(4))Ru(2)(CO)(4)(&mgr;-H)](+)CF(3)SO(3)(-), and (C(5)H(4)CH(2)CH(2)C(5)H(4))Ru(2)(CO)(4) as determined by X-ray diffraction studies are also presented.