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A structural modification strategy to improve the photocatalytic performance of a series of cerium(iii) bis(guanidinate) mono(amide) molecular luminophores was demonstrated. Reducing the steric bulkiness of the amide ligand gave rise to two categories of complexes with distinct photophysical and photochemical properties. A structural parameter, the amide cone angle (ϑ), was applied to differentiate the two categories. Complexes with smaller cone angles (ϑ ＜ 156°, category B) exhibited more reducing potentials and faster electron-transfer rates than those of complexes with larger cone angles (ϑ ＞ 173°, category A). And only complexes in the category B could achieve the photocatalytic phenylation of an aryl bromide. These results demonstrated that reducing the steric bulkiness of the amide ligand improved the performance of cerium(iii) bis(guanidinate) mono(amide) photocatalysts in a systematic manner. [ABSTRACT FROM AUTHOR]

A methoxy-substituted tripodal hydroxylamine ligand, H3TriNOxOMe, was synthesized and coordinated to rare earth cations for separation purposes. Metrics of the resulting complexes were investigated and compared with their parent TriNOx3− counterparts for determination of the molecular basis for the described rare earth separation system. Addition of an electron donating group to the aryl backbone resulted in a more electron rich ligand that increased the equilbrium constant for complex dimerization five-fold. The new separation system yielded efficient Nd/Dy separations in toluene rather than benzene. [ABSTRACT FROM AUTHOR]

We report the synthesis and structure of a titanium(iv) benzophenone adduct bearing a terminal oxo ligand, (PNP)Ti = O(OTf)(OCPh2) (PNP− = N[2-PiPr2-4-methylphenyl]2) (2). Complex 2 is readily synthesized in 71% yield from the previously reported titanium alkylidene (PNP)Ti=CHtBu(OTf) (1) and two equivalents of benzophenone, by extruding the olefin Ph2C=CHtBu. Treatment of benzophenone adduct 2 with a bulky aryloxide salt results in formation of (PNP)Ti=O(OAr) (3) (OAr− = 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide), concurrent with salt elimination and displacement of the benzophenone. Complexes 2 and 3 were characterized by single-crystal X-ray diffraction and a variety of spectroscopic techniques, including NMR, UV-Vis-NIR spectroscopies, and TD-DFT calculations. [ABSTRACT FROM AUTHOR]

The first example of a structurally characterized titanium methylidene, (PN)2Ti=CH2, has been prepared via one-electron oxidation of (PN)2Ti(CH3) followed by deprotonation or by H-atom abstraction using an aryloxyl radical. The Ti=C distance was found to be 1.939(3) Å, and variable temperature, multinuclear, and multidimensional NMR spectroscopic experiments revealed the methylidene to engage in long range interactions with protons on the ligand framework. Computational studies showed that the Ti=C bond, which until now has eluded structural studies, displays all the hallmarks of a prototypical Schrock-carbene. [ABSTRACT FROM AUTHOR]

Correction for 'Synthesis of novel copper-rare earth BINOLate frameworks from a hydrogen bonding DBU-H rare earth BINOLate complex' by Grace B. Panetti, et al., Dalton Trans., 2018, 47, 14408–14410. [ABSTRACT FROM AUTHOR]

A series of cerium(iv) mixed-ligand guanidinate-amide complexes, {[(Me 3 Si) 2 NC(N i Pr) 2 ] x Ce IV [N(SiMe 3 ) 2 ] 3- x } + ( x = 0-3), was prepared by chemical oxidation of the corresponding cerium(iii) complexes, where x = 1 and 2 represent novel complexes. The Ce(iv) complexes exhibited a range of intense colors, including red, black, cyan, and green. Notably, increasing the number of the guanidinate ligands from zero to three resulted in significant redshift of the absorption bands from 503 nm (2.48 eV) to 785 nm (1.58 eV) in THF. X-ray absorption near edge structure (XANES) spectra indicated increasing f occupancy ( n f ) with more guanidinate ligands, and revealed the multiconfigurational ground states for all Ce(iv) complexes. Cyclic voltammetry experiments demonstrated less stabilization of the Ce(iv) oxidation state with more guanidinate ligands. Moreover, the Ce(iv) tris(guanidinate) complex exhibited temperature independent paramagnetism (TIP) arising from the small energy gap between the ground- and excited states with considerable magnetic moments. Computational analysis suggested that the origin of the low energy absorption bands was a charge transfer between guanidinate π orbitals that were close in energy to the unoccupied Ce 4f orbitals. However, the incorporation of sterically hindered guanidinate ligands inhibited optimal overlaps between Ce 5d and ligand N 2p orbitals. As a result, there was an overall decrease of ligand-to-metal donation and a less stabilized Ce(iv) oxidation state, while at the same time, more of the donated electron density ended up in the 4f shell. The results indicate that incorporating guanidinate ligands into Ce(iv) complexes gives rise to intense charge transfer bands and noteworthy electronic structures, providing insights into the stabilization of tetravalent lanthanide oxidation states., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

Correction for 'Synthesis of novel copper-rare earth BINOLate frameworks from a hydrogen bonding DBU-H rare earth BINOLate complex' by Grace B. Panetti, et al., Dalton Trans., 2018, 47, 14408-14410.

The preparation of a novel H-bonding DBU-H+ BINOLate Rare Earth Metal complex enabled the synthesis of the first copper-Rare Earth Metal BINOLate complex (CuDBU-REMB). CuDBU-REMB was compared to the analogous Li complex using X-ray crystallography and Exchange NMR spectroscopy (EXSY). The results provide insight into the role of the secondary metal cation in the framework's stabilization.

We report the synthesis and structure of a titanium(iv) benzophenone adduct bearing a terminal oxo ligand, (PNP)Ti = O(OTf)(OCPh 2 ) (PNP - = N[2-P i Pr 2 -4-methylphenyl] 2 ) (2). Complex 2 is readily synthesized in 71% yield from the previously reported titanium alkylidene (PNP)Ti[double bond, length as m-dash]CH t Bu(OTf) (1) and two equivalents of benzophenone, by extruding the olefin Ph 2 C[double bond, length as m-dash]CH t Bu. Treatment of benzophenone adduct 2 with a bulky aryloxide salt results in formation of (PNP)Ti[double bond, length as m-dash]O(OAr) (3) (OAr - = 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide), concurrent with salt elimination and displacement of the benzophenone. Complexes 2 and 3 were characterized by single-crystal X-ray diffraction and a variety of spectroscopic techniques, including NMR, UV-Vis-NIR spectroscopies, and TD-DFT calculations.