Valence and valence–core interactions in transition‐metal diatomic molecules

Boudreaux, Edward A.; Baxter, Eric

doi:10.1002/qua.20525

Cited by 6 publications

(3 citation statements)

References 3 publications

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“…As valence core electrons were shown previously to have a non‐insignificant effect on the bonding in these open shell diatomic molecules 4, the ground state Slater basis AOs include the 5s 2 5p 6 valence core, the 4f 4 6s 2 valence, and the 6p 0 virtual orbitals for each Nd atom. For each U atom the Slater basis is 6s 2 6p 6 valence core, 5f 3 6d 1 7s 2 valence, and the 7p 0 virtual orbitals.…”

Section: Procedures and Resultsmentioning

confidence: 99%

QR‐SCMEH‐MO calculations on inner‐transition metal diatomic molecules having 12 valence electrons‐Nd₂ and U₂

Boudreaux

Baxter

2010

Int J of Quantum Chemistry

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ABSTRACT:The QR-SCMEH-MO computational method has been developed and tested on a numerous variety of inorganic systems over some 45-plus years, with surprisingly good success. More recently this method has been applied to the transition metal molecules, Cr 2, Mo 2 , W 2 , and Sg 2 with 12 valence d/s electrons. The results were at least as good as those obtained from the most accurate ab initio and DFT methods currently available. An extension of the method has been made to the diatomic 12 valence electrons, f/s orbital systems, Nd 2 and U 2 , which is the topic of this presentation.

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Section: Procedures and Resultsmentioning

confidence: 99%

QR‐SCMEH‐MO calculations on inner‐transition metal diatomic molecules having 12 valence electrons‐Nd₂ and U₂

Boudreaux

Baxter

2010

Int J of Quantum Chemistry

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“…As we have recently noted [9], even though this bond is considered extremely short and has a formal bond order of six, its relevance was largely questioned [22] because of its significantly lower dissociation energy, as compared to analogous species involving atoms from the second or third row. Depending on the reported theoretical studies, the description of the bonding in Cr 2 has ranged from a sextuple bond [22][23][24][25][26], through a single bond [27], to an antiferromagnetically coupled diatomic bearing two chromium centers with opposite spins [22].…”

Section: The Chromium-chromium Multiple Bond -A Historical Overviewmentioning

confidence: 99%

Analysing the chromium–chromium multiple bonds using multiconfigurational quantum chemistry

Brynda

Gagliardi

Roos³

2009

Chemical Physics Letters

112

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a b s t r a c tThis Letter discusses the nature of the chemical bond between two chromium atoms in different di-chromium complexes with the metal atoms in different oxidation states. Starting with the Cr diatom, with its formally sextuple bond and oxidation number zero, we proceed to analyse the bonding in some Cr(I)-Cr(I) XCrCrX complexes with X varying from F, to Phenyl, and Aryl. The bond distance in these complexes varies over a large range: 1.65-1.83 Å and we suggest explanations for these variations. A number of dichromium complexes with bond distances around or shorter than 1.80 Å have recently been synthesized and we study one of these complexes, Cr 2 (diazadiene) 2 and show how the Cr-Cr bond order is related to the oxidation number and the ligand bonding, factors that are all involved in the determination of the short Cr-Cr bond length: 1.80 Å. The discussion is based on the use of multiconfigurational wave functions, which give a qualitatively correct description of the electronic structure in these multiply bonded systems.

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“…As revealed by numerous examinations of simple transition metal diatomics, − metal−metal bonded dimers have complicated electronic structures due to contributions from multiple, nearly degenerate configurations. Because M−M bonds are relatively weak and intraatomic exchange energies large, the overall electronic structure of the diamagnetic ground state represents a balance between extremes, consisting of one with normal shared electron pair bonds (i.e., closed-shell, maximally bonded limit) and one consisting of two antiferromagnetically coupled atoms, each having localized spin densities that maximize atomic exchange stabilization.…”

Section: D-block: Bonding In Rmmr Molecules (M = Cr Mo W) Of Groupmentioning

confidence: 99%

Origin of Trans-Bent Geometries in Maximally Bonded Transition Metal and Main Group Molecules

Landis

Weinhold

2006

J. Am. Chem. Soc.

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Recent crystallographic data unambiguously demonstrate that neither Ar'GeGeAr' nor Ar'CrCrAr' molecules adopt the expected linear (VSEPR-like) geometries. Does the adoption of trans-bent geometries indicate that Ar'MMAr' molecules are not "maximally bonded" (i.e., bond order of three for M = Ge and five for M = Cr)? We employ theoretical hybrid density functional (B3LYP/6-311++G) computations and natural bond orbital-based analysis to quantify molecular bond orders and to elucidate the electronic origin of such unintuitive structures. Resonance structures based on quintuple M-M bonding dominate for the transition metal compounds, especially for molybdenum and tungsten. For the main group, M-M bonding consists of three shared electron pairs, except for M = Pb. For both d- and p-block compounds, the M-M bond orders are reflected in torsional barriers, bond-antibond splittings, and heats of hydrogenation in a qualitatively intuitive way. Trans-bent structures arise primarily from hybridization tendencies that yield the strongest sigma-bonds. For transition metals, the strong tendency toward sd-hybridization in making covalent bonds naturally results in bent ligand arrangements about the metal. In the p-block, hybridization tendencies favor high p-character, with increasing avidity as one moves down the Group 14 column, and nonlinear structures result. In both the p-block and the d-block, bonding schemes have easily identifiable Lewis-like character but adopt somewhat unconventional orbital interactions. For more common metal-metal multiply bonded compounds such as [Re2Cl8]2-, the core Lewis-like fragment [Re2Cl4]2+ is modified by four hypervalent three-center/four-electron additions.

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Valence and valence–core interactions in transition‐metal diatomic molecules

Cited by 6 publications

References 3 publications

QR‐SCMEH‐MO calculations on inner‐transition metal diatomic molecules having 12 valence electrons‐Nd₂ and U₂

QR‐SCMEH‐MO calculations on inner‐transition metal diatomic molecules having 12 valence electrons‐Nd₂ and U₂

Analysing the chromium–chromium multiple bonds using multiconfigurational quantum chemistry

Origin of Trans-Bent Geometries in Maximally Bonded Transition Metal and Main Group Molecules

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Valence and valence–core interactions in transition‐metal diatomic molecules

Cited by 6 publications

References 3 publications

QR‐SCMEH‐MO calculations on inner‐transition metal diatomic molecules having 12 valence electrons‐Nd2 and U2

QR‐SCMEH‐MO calculations on inner‐transition metal diatomic molecules having 12 valence electrons‐Nd2 and U2

Analysing the chromium–chromium multiple bonds using multiconfigurational quantum chemistry

Origin of Trans-Bent Geometries in Maximally Bonded Transition Metal and Main Group Molecules

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Product

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QR‐SCMEH‐MO calculations on inner‐transition metal diatomic molecules having 12 valence electrons‐Nd₂ and U₂

QR‐SCMEH‐MO calculations on inner‐transition metal diatomic molecules having 12 valence electrons‐Nd₂ and U₂