Synthesis, characterization, and reactivity of a heterobimetallic organometallic complex with a trans bidentate ligand for catalytic carbon-hydrogen bond activation

Our group is interested in exploiting cis-alkynyl transition metals to form trans-bidentate ligands in order to explore C—H activation. The p-cymene-supported ruthenium(II) complex (p-cym)Ru(PMe3)(C22-py)2 (where C2-2-py = 2-ethynylpyridine) has been prepared and characterized by NMR spectroscopy. We are interested in the interaction of palladium(II) acetate utilizing the Ru(II) center as a hinge in order to force the pyridine ligands to act as a trans-bidentate ligand. The synthesis and characterization of (p-cym)Ru(PMe3)(C22-py)2, reactivity with Pd(OAc)2, and comparisons to the previously reported Cp*2Ti(C2-2-py)2

CCDC 2016835: Experimental Crystal Structure Determination

Related Article: Sarah L. McDarmont, Colin D. McMillen, Berhane Temelso, Jared A. Pienkos|2020|Z.Anorg.Allg.Chem.|646|1886|doi:10.1002/zaac.20200027

CCDC 2016834: Experimental Crystal Structure Determination

Related Article: Sarah L. McDarmont, Colin D. McMillen, Berhane Temelso, Jared A. Pienkos|2020|Z.Anorg.Allg.Chem.|646|1886|doi:10.1002/zaac.20200027

CCDC 2016836: Experimental Crystal Structure Determination

Related Article: Sarah L. McDarmont, Colin D. McMillen, Berhane Temelso, Jared A. Pienkos|2020|Z.Anorg.Allg.Chem.|646|1886|doi:10.1002/zaac.20200027

CCDC 2025817: Experimental Crystal Structure Determination

Related Article: J.S. McCarthy, C.D. McMillen, J.A. Pienkos, P.S. Wagenknecht|2020|Acta Crystallogr.,Sect.E:Cryst.Commun.|76|1562|doi:10.1107/S205698902001183

Synthesis and characterization of a \u3cem\u3e\u3c/em\u3e\u3cem\u3etert\u3c/em\u3e-butyl ester substituted titanocene dichloride: \u3cem\u3e\u3csup\u3et\u3c/sup\u3e\u3c/em\u3e\u3csup\u3e-BuOOC\u3c/sup\u3eCp\u3csub\u3e2\u3c/sub\u3eTiCl\u3csub\u3e2\u3c/sub\u3e

Bis[η5-(tert-butoxyca­rbonyl)­cyclo­penta­dien­yl]di­chlorido­titanium(IV), [Ti(C10H13O2)2Cl2], was synthesized from LiCpCOOt-Bu using TiCl4, and was characterized by single-crystal X-ray diffraction and 1H NMR spectroscopy. The distorted tetra­hedral geometry about the central titanium atom is relatively unchanged compared to Cp2TiCl2. The complex exhibits elongation of the titanium–cyclo­penta­dienyl centroid distances [2.074 (3) and 2.070 (3) Å] and a contraction of the titanium–chlorine bond lengths [2.3222 (10) Å and 2.3423 (10) Å] relative to Cp2TiCl2. The dihedral angle formed by the planes of the Cp rings [52.56 (13)°] is smaller than seen in Cp2TiCl2. Both ester groups extend from the same side of the Cp rings, and occur on the same side of the complex as the chlorido ligands. The complex may serve as a convenient synthon for titanocene complexes with carboxyl­ate anchoring groups for binding to metal oxide substrates

CCDC 2202472: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.,Related Article: M.R. Shevlin, E.E. Stumbo, C.D. McMillen, J.A. Pienkos|2022|IUCrData|7|x220830|doi:10.1107/S241431462200830

Is indenyl a stronger or weaker electron donor ligand than cyclopentadienyl? Opposing effects of indenyl electron density and ring slipping on electrochemical potentials

Complexes of the type RCp2Ti(C2Fc)2 (where RCp = cyclopentadienyl or a substituted cyclopentadienyl) have high molar absorptivity FeII to TiIV metal-to-metal charge transfer (MMCT) absorptions and have been investigated for possible use as photoredox catalysts. Relative to Cp2Ti(C2Fc)2, the MMCT shifts to higher or lower energy when RCp is either a stronger or weaker donor ligand than Cp, respectively. The indenyl ligand (Ind) has been described in the literature as both a stronger and weaker donor ligand than Cp. Herein, we report the preparation of Ind2Ti(C2Fc)2 and the complex with CuBr bound between the two alkynes, Ind2Ti(C2Fc)2CuBr, in order to determine the effect that replacing Cp with Ind has on the MMCT absorption energy. The complexes are characterized by NMR and UV–vis spectroscopy, cyclic voltammetry, and X-ray crystallography in the case of Ind2Ti(C2Fc)2CuBr. Relative to Cp2Ti(C2Fc)2, the FeIII/II potential of Ind2Ti(C2Fc)2 shifts cathodically and the TiIV/III potential shifts anodically, resulting in a lower energy MMCT absorption. The TiIV/III reduction wave is also chemically irreversible, with ipa/ipc approaching unity as the scan rate is increased from 10 to 500 mV/s. Examination of the literature reviewed in this report demonstrates that, in all cases, replacement of Cp with Ind leads to a cathodic shift of the potential for metal oxidation. However, replacement of Cp with Ind typically leads to an anodic shift of the reduction potential, leading some to suggest that Ind is a poorer e– donor than Cp. In the context of the literature, these results are interpreted as indicating that Ind is a better electron donor than Cp, but that reduction induces an η5 to η3 haptotropic shift that is rapid on the electrochemical time scale, stabilizing the reduction product, resulting in an anodic shift of the TiIV/III reduction. Furthermore, these opposing effects are not unique to this system

Titanocene as a New Acceptor (A) for Arylamine Donors (D) in D-π-A Chromophores

Charge transfer (CT) transitions are relevant in the fields of solar energy conversion and non-linear optical materials. Herein, a series of complexes with an alkynyl linkage between an aryl amine donor and a TiIV (titanocene) acceptoris reported. Each complex displays a strong (15,000 \u3c ε \u3c 24,000 M-1cm-1), low energy (520 \u3c l \u3c 560 nm) absorption ascribed to an amine to TiIV ligand-to-metal CT. This characterization is supported by UV-Vis spectroscopy, cyclic voltammetry, and TD-DFT calculations. These complexes are not photostable so an alternate architecture, wherein the amine donor is appended to the titanocene cyclopentadienyl ligand, has been designed. The molar absorptivity of the amine to TiIV CT in this latter architecture is lower (2100 M-1cm-1), indicating weaker donor-acceptor coupling. This architecture is indeed much more photostable