Raman spectroscopy of nonbridged, dinuclear complexes

Schätzlein, Andreas G.; Schubart, Martin; Findeis, Bernd; Gade, Lutz H.; Fickert, C.; Pikl, R.; Kiefer, W.

doi:10.1016/s0022-2860(96)09733-5

Cited by 4 publications

(4 citation statements)

References 8 publications

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“…We would like to point out that the calculated harmonic IR and Raman spectra of 3x and 4x do not exhibit an isolated Co−Ti stretching vibration but instead exhibit several modes of low intensity that contain some amount of ν(Ti−Co). This is in accord with our inability to observe a metal−metal stretching mode in the Raman spectra of the heterobimetallic complexes reported in this study …”

Section: Calculationssupporting

confidence: 92%

Unsupported Ti−Co and Zr−Co Bonds in Heterobimetallic Complexes: A Theoretical Description of Metal−Metal Bond Polarity

et al. 1998

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The synthesis, structural, and theoretical characterization of heterobimetallic complexes [CH3Si{SiMe2N(4-CH3C6H4)}3M−Co(CO)3(L)] (M = Ti, Zr; L = CO, PPh3, PTol3) with unsupported metal−metal bonds between cobalt atoms and titanium or zirconium atoms is being reported. The synthesis of the dinuclear compounds was achieved by salt metathesis of the chlorotitanium and zirconium complexes and the alkalimetal carbonylates. X-ray crystal structure analyses of four of these heterobimetallic complexes established the unsupported metal−metal bonds [M = Ti, L = CO (3): 2.554(1) Å; M = Ti, L = PTol3 (4b): 2.473(4) Å; M = Zr, L = CO (5): 2.705(1) Å; M = Zr, L = PPh3 (6a): 2.617(1) Å] as well as the 3-fold molecular symmetries. Upon axial phosphine substitution, a metal−metal bond contraction of ca. 0.08 Å is observed, which also results in the quantum chemical structure optimizations performed on the model compounds [(H2N)3Ti−Co(CO)4] (3x) and [(H2N)3Ti−Co(CO)3(PH3)] (4x) using gradient-corrected and hybrid density functionals. A theoretical study of the homolytic dissociation of the metal−metal bonds focuses on the relaxation energies of the complex fragments and indicates that the geometrical constraints imposed by the tripod ligand lead to a major thermodynamic contribution to the stability of the experimentally investigated complexes. The central question of the polarity of the metal−metal bond is addressed by detailed analysis of the calculated electron charge distribution using natural population analysis (NPA), charge decomposition analysis (CDA), Bader's atoms in molecules (AIM) theory, and the electron localization function (ELF). Both the orbital-based NPA and CDA schemes and the essentially orbital-independent AIM and ELF analysis suggest a description of the Ti−Co bond as being a highly polar covalent single bond. The combination of AIM and ELF is employed for the first time to analyze metal−metal bond polarity and appears to be a powerful theoretical tool for the description of bond polarity in potentially ambiguous situations.

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Section: Calculationssupporting

confidence: 92%

Unsupported Ti−Co and Zr−Co Bonds in Heterobimetallic Complexes: A Theoretical Description of Metal−Metal Bond Polarity

et al. 1998

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“…Symmetric transitions are resonantly enhanced most strongly because the slope of the excited state potential energy surface is nonzero at the Franck–Condon region; the intensity of scattering scales with the square of the distortion. , The ability to amplify the intensity of vibrations when in resonance with an electronic transition enables resonance Raman spectroscopy to assist in the assignment of these specific electronic transitions . This technique, , as well as regular Raman spectroscopy, , has been used previously to establish electronic communication within bimetallic complexes. However, the present study represents the first instance when resonance Raman spectroscopy is used to investigate the nature of weak metal–metal interactions.…”

Section: Resultsmentioning

confidence: 99%

“…56,57 The ability to amplify the intensity of vibrations when in resonance with an electronic transition enables resonance Raman spectroscopy to assist in the assignment of these specific electronic transitions. 57 This technique, 58,59 as well as regular Raman spectroscopy, 60,61 has been used previously to establish electronic communication within bimetallic complexes. However, the present study represents the first instance when resonance Raman spectroscopy is used to investigate the nature of weak metal−metal interactions.…”

Section: Resultsmentioning

confidence: 99%

Characterization of an Iron–Ruthenium Interaction in a Ferrocene Diamide Complex

et al. 2013

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Reaction of [fc(NH2)2]RuCl2(PPh3)2 (fc = 1,1'-ferrocenylene) with 2 equiv of KO(t)Bu led to the formation of a diamido ruthenium complex, [fc(NH)2]Ru(PPh3)2, whose solid-state molecular structure revealed a short Fe-Ru distance. A metal-to-metal charge transfer band was observed in the electronic absorption spectrum of [fc(NH)2]Ru(PPh3)2. The Fe-Ru interaction was characterized by resonance Raman spectroscopy for the first time and also by (1)H NMR, UV-vis, NIR, Mössbauer spectroscopy, and X-ray crystallography. Density functional theory (DFT) calculations including natural bond order analysis, Bader's atom in molecules method, and time-dependent DFT (TDDFT) provided further support that the iron-ruthenium bond is a weak donor-acceptor interaction with iron acting as the Lewis base.

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“…Previously, Raman spectroscopy was used to study the heterobimetallic compounds MeSi[SiMe 2 N(tol)] 3 Ti-M¢(CO) 2 Cp (M¢ = Fe, Co) and MeSi[SiMe 2 N(tol)] 3 M¢-Co(CO) 3 PPh 3 (M¢ = Ti, Zr), however the metal-metal stretching mode overlapped with the lattice modes. 51 Our method relies on the fact that by only changing the group 4 element, all of the Raman bands are expected to shift in a predictable way, and the greatest shift ought to be due to a predominantly metal-metal stretching mode. A similar procedure has been used to identify Mo and W with nitrogen, phosphorus, and arsenic.…”

Section: Vibrational Spectroscopymentioning

confidence: 99%

Preparation and physical properties of early-late heterobimetallic compounds featuring Ir–M bonds (M = Ti, Zr, Hf)

2012

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Treatment of Cp*Ir N(t)Bu (1) with the appropriate metallocene equivalent is an effective route for the preparation of the heterobimetallic complexes Cp*Ir(μ-N(t)Bu)MCp(2) (2-M, M = Ti, Zr, Hf). The electronic structures of the isostructural series of compounds, 2-M, are described with reference to single-crystal X-ray, Raman, UV-vis, and cyclic voltammetry data. Density functional theory (DFT) calculations were used to aid in the interpretation of this experimental work. Treatment of the zirconium or hafnium congeners with 2,6-lutidinium triflate leads to protonation of the Ir-M bond, to afford Cp*Ir(μ-N(t)Bu)(μ-H)MCp(2)OTf (3-M, M = Zr, Hf). Compound 3-Zr was characterized by single-crystal X-ray diffraction and independently prepared by the reaction of 1 and Cp(2)Zr(H)Cl in the presence of Me(3)SiOTf. In reactions analogous to those for 2-Zr, 2-Hf reacts with S(8) and aryl azides to insert an S-atom or aryl azide fragment into the metal-metal bond, yielding Cp*Ir(μ-N(t)Bu)(μ-S)HfCp(2) (6-Hf) and Cp*Ir(μ-N(t)Bu)(N(3)Ph)HfCp(2) (4-Hf), respectively. Heating 4-Hf results in N(2) extrusion to form Cp*Ir(μ-N(t)Bu)(NPh)HfCp(2) (5-Hf). The kinetics of the latter reaction were studied to obtain activation parameters and a Hammett trend; these data are compared to those for the analogous reaction involving Ir-Zr heterobimetallics.

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Raman spectroscopy of nonbridged, dinuclear complexes

Cited by 4 publications

References 8 publications

Unsupported Ti−Co and Zr−Co Bonds in Heterobimetallic Complexes: A Theoretical Description of Metal−Metal Bond Polarity

Unsupported Ti−Co and Zr−Co Bonds in Heterobimetallic Complexes: A Theoretical Description of Metal−Metal Bond Polarity

Characterization of an Iron–Ruthenium Interaction in a Ferrocene Diamide Complex

Preparation and physical properties of early-late heterobimetallic compounds featuring Ir–M bonds (M = Ti, Zr, Hf)

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