Calculated Structures of MO22+, MN2, and MP2 (M = Mo, W)

Pyykkö, Pekka; Tamm, Toomas

doi:10.1021/jp971537a

Cited by 29 publications

(43 citation statements)

References 29 publications

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“…Such cyclic molecules with strong metalnitrogen and long N-N bonds have been calculated for MoN 2 . 60,61 The calculated spectrum of the Ti͑N 2 ͒ species predicts the most intense infrared absorption at 1079 cm Ϫ1 , which is in reasonable agreement with the experimentally observed band at 1125.9 cm Ϫ1 . In addition, the BP86 calculation reproduces the unusual isotope shift to within 2 cm Ϫ1 , providing further support for the above assignment.…”

Section: Mn 2 Complexes In Solid Argon "M‫؍‬ti Zr and Hf…supporting

confidence: 82%

An infrared spectroscopic and density functional investigation of dinitrogen activation by group IV metal atoms

Kushto

Souter

Chertihin

et al. 1999

The Journal of Chemical Physics

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Section: Mn 2 Complexes In Solid Argon "M‫؍‬ti Zr and Hf…supporting

confidence: 82%

An infrared spectroscopic and density functional investigation of dinitrogen activation by group IV metal atoms

Kushto

Souter

Chertihin

et al. 1999

The Journal of Chemical Physics

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“…These orbitals and their influence on bonding have been discussed by various workers. [8,11] However, let us consider in somewhat more detail which changes in p bonding may be expected to happen upon bending such an MX 2 molecule. Starting from the linear structure (bending angle a 1808), we first loose any in-plane p bonding from the d yz (b 2 ) orbital, as the overlap with the ligand orbitals decreases rapidly (at the same time this d yz orbital starts to be involved more efficiently in s bonding, cf.…”

Section: Methodsmentioning

confidence: 99%

“…Thus, for example, O-Mo-O angles in MoO 2 2 fragments have angles in the 101 ± 1058 range for tetrahedral or octahedral complexes, [8,10,41,42] as well as in the free fragment ion. [11] However, this is expected to change in the presence of strong ancillary s-donor ligands like Y H, alkyl (see above).…”

Section: B Chromyl Fluoride and Related Complexesmentioning

confidence: 99%

“…ªmolybdenyl fragmentº, MoO 2 2 , which is present in many Mo VI dioxo complexes [8,9,10] but has also recently been considered computationally as an isolated species. [11] Here p bonding is thought to contribute to the small O-Mo-O bond angles (around 101 ± 1058). [8,11] Small O-M-O angles are also found for chromyl complexes, CrO 2 X 2 , and for a considerable number of related compounds.…”

Section: Introductionmentioning

confidence: 99%

“…[11] Here p bonding is thought to contribute to the small O-Mo-O bond angles (around 101 ± 1058). [8,11] Small O-M-O angles are also found for chromyl complexes, CrO 2 X 2 , and for a considerable number of related compounds. We will show here, by analyzing the results of density functional calculations, how these apparently contradictive views on the relation between p bonding and bond angles may be reconciled.…”

Section: Introductionmentioning

confidence: 99%

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On the Relation between π Bonding, Electronegativity, and Bond Angles in High-Valent Transition Metal Complexes

Kaupp

1999

Chem. Eur. J.

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Ligand-to-metal p bonding is important for the understanding of bond angles in d 0 transition metal complexes. This is demonstrated by density functional calculations on a number of model complexes, combined with natural bond orbital and natural localized molecular orbital analyses. Analyses of the simple model systems ScF 2 and ZrO 2 indicate a complicated dependence of p bonding on bond angle. In particular, in-plane p bonding exhibits a nonuniform dependence, whereas outof-plane p bonding shows a more regular behavior. This may be understood from the nodal properties of the relevant metal d orbitals. The net p bonding behavior then depends sensitively on the donor properties of the ligands. While p bonding appears to favor the bent equilibrium structure for the ªstrong pdonor caseº ZrO 2 , it is more efficient at a linear structure for the ªweak pdonor caseº ScF 2. Similar considerations come into play for more complicated species, exemplified by MX 2 Y 2 model complexes. Thus, the ªinverse Bents rule structuresº of TiCl 2 (CH 3 ) 2 and TiCl 2 H 2 are related to the improved in-plane p(Ti ± Cl) bonding at larger ClTi-Cl angles. In contrast, for CrO 2 F 2 or MoO 2 F 2 , the angular dependences of the strong in-plane and out-of-plane components of p(M ± O) bonding compensate each other partially, and the O-M-O angles appear to be dominated by the s-bonding framework. When introducing a strong s-bonding ancillary ligand, as in CrO 2 H 2 , the net p bonding does again seem to favor larger angles. Electronegativity effects on bond angles have been probed by studying heteroleptic complexes without significant p bonding. ªInverse structuresº are found for complexes like TiH 2 (CF 3 ) 2 or Ti-(SiH 3 ) 2 (CH 3 ) 2 , that is the smaller angles are those between the less electronegative ligands. Hybridization analyses indicate less d character for these bonds. The interpretation is complicated by the fact that even the structure for the silicon analogon of the latter complex violates Bents rule. In general, Bents rule appears to be less useful for d 0 transition metal complexes than for main group compounds, in part due to the much larger importance of p bonding for the former.

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Nicht-VSEPR-Strukturen und chemische Bindung in d0-Systemen

Kaupp

2001

Angew. Chem.

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Martin Kaupp, geboren 1962 in Stuttgart, studierte dort sowie in Cincinnati Chemie. Nach der Diplomarbeit, die er 1989 in Stuttgart bei Hermann Stoll in theoretischer Chemie anfertigte, promovierte er 1992 in Erlangen mit einer quantenchemischen Arbeit bei Paul von RagueÂ Schleyer. Nach einem Aufenthalt am Max-Planck-Institut für Festkörperforschung in Stuttgart bei Hans-Georg von Schnering (1992Schnering ( /1993 setzte er seine Postdoc-Arbeiten 1993/1994 bei Dennis Salahub in MontreÂal fort. 1997 habilitierte er sich in theoretischer Chemie in Stuttgart, und seit 1999 ist er Professor an der Universität Würzburg. Seine Forschungsinteressen erstrecken sich über einen weiten Bereich der theoretischen Chemie und der Computerchemie. Das Thema der vorliegenden Arbeit spiegelt sein generelles Interesse an Strukturen und Bindungsverhältnissen von Verbindungen des gesamten Periodensystems wider. Ein weiteres, zentrales Forschungsthema ist die Entwicklung und Anwendung von Dichtefunktionalmethoden zur Berechnung und Interpretation von NMR-und EPR-Parametern, insbesondere die Erweiterung dieser Methoden auf Anwendungen mit schwereren Elementen. Diesbezüglich, aber auch hinsichtlich vieler anderer Bereiche der Chemie, ist er besonders am Einfluss relativistischer Effekte und an deren quantenchemischer Behandlung interessiert. AUFS¾TZE d 0 -Komplexe plexe, werden aber gelegentlich auch d 1 -oder d 2 -Beispiele erwähnen. AUFS¾TZE M. Kaupp Gasphasenelektronenbeugungs(GED)-Untersuchungen ergaben ebenfalls gewinkelte Strukturen. [26] Auf dem MP2-Niveau durchgeführten Ab-initio-Rechnungen an [MCp 2 ] [27] zufolge sind die energetisch günstigsten Isomere bei den Metallen Strontium, Barium, Samarium, Europium gewinkelt. Linear sind die Strukturen hingegen bei Calcium oder Ytterbium (für weitere Rechnungen siehe Lit. [26d, 28]). In allen Fällen war das Abwinkelungspotential extrem flach, sodass diese Komplexe am besten als quasilinear angesehen werden sollten. Infolgedessen werden verlässliche Strukturbestimmungen derartiger Verbindungen durch GED-Untersuchungen wegen des ¹Shrinkingª-Effektes schwierig. [10] Demgegenüber ergaben Rechnungen an den isoelektronischen, jedoch stärker kovalent gebundenen hypothetischen Kationen [MCp 2 ] (M Sc, La) [29] signifikant gewinkelte Strukturen mit groûen Linearisierungsbarrieren. Demnach nimmt die Tendenz zu gewinkelten Strukturen mit steigendem kovalentem Bindungsanteil zu (siehe auch Abschnitt 3.7). Gewinkelte Strukturen sind auch das Ergebnis von Rechnungen an den heteroleptischen Modellsystemen [CpM(NH)] (M Y, La), [30] und auch die Strukturen der Kationen [YH 2 ] , [31c] [ScF 2 ] [9f, 32] sowie [ScH 2 ] [32, 33] sind Rechnungen zufolge signifikant gewinkelt. Kleine Winkel und groûe Linearisierungsenergien wurden theoretisch und teilweise experimentell für [MO 2 ] (M Ti, Zr, Hf) gefunden. [34±36] Noch stärker gewinkelte Strukturen wurden für die Kationen [MO 2 ] (M Nb, Ta) [37] nachgewiesen sowie für die hypothetischen Ionen [MO 2 ] 2 (M Mo, W) vorausgesagt. [38] Auch für [CeO 2 ] lieferten...

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Calculated Structures of MO₂²⁺, MN₂, and MP₂ (M = Mo, W)

Cited by 29 publications

References 29 publications

An infrared spectroscopic and density functional investigation of dinitrogen activation by group IV metal atoms

An infrared spectroscopic and density functional investigation of dinitrogen activation by group IV metal atoms

On the Relation between π Bonding, Electronegativity, and Bond Angles in High-Valent Transition Metal Complexes

Nicht-VSEPR-Strukturen und chemische Bindung in d0-Systemen

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