Publications by authors named "Maikel P. Wilms"

2 Publications

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Density Functional Study of the Primary Photoprocesses of Manganese Pentacarbonyl Chloride (MnCl(CO)(5)).

Inorg Chem 1997 Apr;36(8):1541-1551

Afdeling Theoretische Chemie, Vrije Universiteit, De Boelelaan 1083, 1081 HV, Amsterdam, The Netherlands, Dipartimento di Chimica, Universitá della Basilicata, Via N. Sauro, 85, 85100 Potenza, Italy, and Anorganisch Chemisch Laboratorium, J. H. van't Hoff Research Insitute, Universteit van Amsterdam, Nieuwe Achtergracht 166, 1018 WV, Amsterdam, The Netherlands.

Density functional calculations have been performed on the ground and excited states of MnCl(CO)(5) in order to explain the photochemistry of MX(CO)(5) complexes (M = Mn, Re; X = Cl, Br, I). As found earlier for Mn(2)(CO)(10) (Inorg. Chem. 1996, 35, 2886), the e(g)-type unoccupied 3d orbitals in the pseudooctahedral environment are located rather high in the virtual orbital spectrum, and the corresponding ligand-field (LF) excitations are more than 1 eV above the lowest excitations. Potential energy curves (PECs) nevertheless show that the lowest excited states, which involve transitions to the Mn-Cl sigma orbital at equilibrium geometry, are dissociative for axial and equatorial CO loss. The mechanism is again, as in Mn(2)(CO)(10), a strongly avoided crossing of the lowest excited state (a(1,3)E) with the higher dissociative LF states (different ones for CO(ax) and CO(eq) dissociation) which rapidly descend upon Mn-CO bond lengthening. In spite of the lowest excitation being to the Mn-Cl sigma-orbital, Mn-Cl homolysis cannot occur out of the lowest excited state. The photochemical behavior of Mn(2)(CO)(10), MnH(CO)(5), and MnCl(CO)(5) is compared. The mechanisms of CO loss are found to be very similar, but there is a large difference with respect to the breaking of the sigma bond (Mn-Mn, Mn-H, or Mn-Cl). Only in the case of Mn(2)(CO)(10), the lowest broad absorption band contains the sigma --> sigma excitation and leads to sigma bond breaking.
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April 1997

Bonding Properties of a Novel Inorganometallic Complex, Ru(SnPh(3))(2)(CO)(2)(iPr-DAB) (iPr-DAB = N,N'-Diisopropyl-1,4-diaza-1,3-butadiene), and its Stable Radical-Anion, Studied by UV-Vis, IR, and EPR Spectroscopy, (Spectro-) Electrochemistry, and Density Functional Calculations.

Inorg Chem 1996 Sep;35(19):5468-5477

Anorganisch Chemisch Laboratorium, J. H. van 't Hoff Research Institute, Universiteit van Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands, Amsterdam Institute for Molecular Studies, Universiteit van Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands, Afdeling Theoretische Chemie, Vrije Universiteit, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands, J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, 182 23 Prague, Czech Republic.

Ru(SnPh(3))(2)(CO)(2)(iPr-DAB) was synthesized and characterized by UV-vis, IR, (1)H NMR, (13)C NMR, (119)Sn NMR, and mass (FAB(+)) spectroscopies and by single-crystal X-ray diffraction, which proved the presence of a nearly linear Sn-Ru-Sn unit. Crystals of Ru(SnPh(3))(2)(CO)(2)(iPr-DAB).3.5C(6)H(6) form in the triclinic space group P&onemacr; in a unit cell of dimensions a = 11.662(6) Å, b = 13.902(3) Å, c = 19.643(2) Å, alpha = 71.24(2) degrees, beta = 86.91(4) degrees, gamma = 77.89(3) degrees, and V = 2946(3) Å(3). One-electron reduction of Ru(SnPh(3))(2)(CO)(2)(iPr-DAB) produces the stable radical-anion [Ru(SnPh(3))(2)(CO)(2)(iPr-DAB)](*-) that was characterized by IR, and UV-vis spectroelectrochemistry. Its EPR spectrum shows a signal at g = 1.9960 with well resolved Sn, Ru, and iPr-DAB (H, N) hyperfine couplings. DFT-MO calculations on the model compound Ru(SnH(3))(2)(CO)(2)(H-DAB) reveal that the HOMO is mainly of sigma(Sn-Ru-Sn) character mixed strongly with the lowest pi orbital of the H-DAB ligand. The LUMO (SOMO in the reduced complex) should be viewed as predominantly pi(H-DAB) with an admixture of the sigma(Sn-Ru-Sn) orbital. Accordingly, the lowest-energy absorption band of the neutral species will mainly belong to the sigma(Sn-Ru-Sn)-->pi(iPr-DAB) charge transfer transition. The intrinsic strength of the Ru-Sn bond and the delocalized character of the three-center four-electron Sn-Ru-Sn sigma-bond account for the inherent stability of the radical anion.
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September 1996