Seven‐Coordination Chemistry

Drew, Michael G. B.

doi:10.1002/9780470166246.ch2

Cited by 127 publications

(6 citation statements)

References 552 publications

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“…Compound 2b shows a capped octahedral structure. The complex exhibits a major deviation from the ideal capped octahedral structure, but quite well reflects the angle proportions of the “conventional capped octahedron” as proposed by Drew. , The structure was already described in our preliminary communication . In 2b , the carbonyl group C(23)−O(1) occupies the capping position of a face of one phosphine and two CO ligands.…”

Section: Resultssupporting

confidence: 69%

Primary and Secondary Ferrocenylphosphine Complexes of Molybdenum(II) and Tungsten(II), [MI₂(CO)₃_-_n(PH₂R)₂₊_n] [M = Mo, W; R = Fc, FcCH₂; Fc = Fe(η⁵-C₅H₅)(η⁵-C₅H₄); n = 0, 1], [MI₂(CO)₃{PH(CH₂Fc)₂}₂], and [WI₂(CO)₃(NCMe){PH(CH₂Fc)₂}]: Pr

et al. 2005

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Reaction of [MI2(CO)3(NCMe)2] [M = Mo, W] with 2 or 3 equiv of PH2Fc or PH2CH2Fc [Fc = Fe(η5-C5H5)(η5-C5H4)] in CH2Cl2 or THF at various temperatures gave [MI2(CO)3L2] [M = Mo: L = PH2Fc (1a), PH2CH2Fc (2a), PH(CH2Fc)2 (5a); M = W: L = PH2Fc (1b), PH2CH2Fc (2b), PH(CH2Fc)2 (5b)] and [MI2(CO)2L3] [M = Mo: L = PH2Fc (3a), PH2CH2Fc (4a); M = W: L = PH2Fc (3b), PH2CH2Fc (4b)] in high yields. 2b and 4a were the first primary ferrocenylphosphine complexes of molybdenum(II) and tungsten(II) to be crystallographically characterized. Reaction of [WI2(CO)3(NCMe)2] with 1 equiv of PH(CH2Fc)2 in CH2Cl2 gave [WI2(CO)3(NCMe){PH(CH2Fc)2}] (6), the first structurally characterized tungsten(II) monophosphine complex with an acetonitrile ligand. All complexes show the structural motif of a capped octahedron. The formation of the bis-phosphine-substituted products is preferred when the reaction is carried out in a noncoordinating solvent at low temperatures, and with tungsten as the central atom, whereas coordinating solvents, higher temperatures, and molybdenum give rise to the formation of tris-phosphine-substituted products. VT 31P NMR studies of 1−5 show fluxional behavior in solution. Density functional theory (DFT) calculations give insight into the reasons for the structural characteristics and the dynamic behavior of the complexes. Complexes 1−4 show only very low activity in the polymerization of norbornadiene.

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Section: Resultssupporting

confidence: 69%

Primary and Secondary Ferrocenylphosphine Complexes of Molybdenum(II) and Tungsten(II), [MI₂(CO)₃_-_n(PH₂R)₂₊_n] [M = Mo, W; R = Fc, FcCH₂; Fc = Fe(η⁵-C₅H₅)(η⁵-C₅H₄); n = 0, 1], [MI₂(CO)₃{PH(CH₂Fc)₂}₂], and [WI₂(CO)₃(NCMe){PH(CH₂Fc)₂}]: Pr

et al. 2005

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“…As a mathematical problem, this is known as the Thomson problem . Identical monodentate ligands usually form complexes with structures that resemble the ideal polyhedra from the solution to the Thomson problem. − The electronic energy levels of lanthanides as free ions can accurately be described using the Russell–Saunders formulation, which takes the spin–orbit coupling into account . These Russell–Saunders states contain envelopes of electronic energy levels, which we refer to as microstates.…”

Section: Introductionmentioning

confidence: 99%

“…Such high-symmetry ligand fields are essentially impossible to achieve with the expected CNs of 7–9, and as such they are not relevant for this discussion. The solution for the Thomson problem for CNs 7, 8, and 9 are the pentagonal bipyramid (PBP), the square antiprism (SAP), and the tricapped trigonal prism (TTP), as shown in Figure . ,,− …”

Section: Introductionmentioning

confidence: 99%

Electronic Structure of Ytterbium(III) Solvates—a Combined Spectroscopic and Theoretical Study

et al. 2021

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The wide range of optical and magnetic properties of lanthanide(III) ions is associated with their intricate electronic structures which, in contrast to lighter elements, is characterized by strong relativistic effects and spin–orbit coupling. Nevertheless, computational methods are now capable of describing the ladder of electronic energy levels of the simpler trivalent lanthanide ions, as well as the lowest energy term of most of the series. The electronic energy levels result from electron configurations that are first split by spin–orbit coupling into groups of energy levels denoted by the corresponding Russell–Saunders terms. Each of these groups are then split by the ligand field into the actual electronic energy levels known as microstates or sometimes m J levels. The ligand-field splitting directly informs on the coordination geometry and is a valuable tool for determining the structure and thus correlating the structure and properties of metal complexes in solution. The issue with lanthanide complexes is that the determination of complex structures from ligand-field splitting remains a very challenging task. In this paper, the optical spectraabsorption, luminescence excitation, and luminescence emissionof ytterbium(III) solvates were recorded in water, methanol, dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF). The electronic energy levels, that is, the microstates, were resolved experimentally. Subsequently, density functional theory calculations were used to model the structures of the solvates, and ab initio relativistic complete active space self-consistent field calculations (CASSCF) were employed to obtain the microstates of the possible structures of each solvate. By comparing the experimental and theoretical data, it was possible to determine both the coordination number and solution structure of each solvate. In water, methanol, and N,N-dimethylformamide, the solvates were found to be eight-coordinated and have a square antiprismatic coordination geometry. In DMSO, the speciation was found to be more complicated. The robust methodology developed for comparing experimental spectra and computational results allows the solution structures of homoleptic lanthanide complexes to be determined.

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“…50 Identical mono-dentate ligands usually form complexes with structures that resemble the ideal polyhedra from the solution to the Thomson Problem. [51][52][53] The electronic energy levels of lanthanides as free ions can accurately be described using the Russel-Saunders formulation which takes the spin-orbit coupling into account. 54 These Russel-Saunders states contains envelopes of electronic energy levels, which we refer to as microstrates.…”

Section: Introductionmentioning

confidence: 99%

“…The solution for the Thomson Problem for coordination numbers 7, 8 and 9 are the pentagonal bipyramid (PBP), the square antiprism (SAP) and the tricapped trigonal prism (TTP), shown in Figure 1. 52,53,[58][59][60] Advances in instrumentation has led to a resolution in optical spectra that allows for the detection of individual ligand field levels. 27,[61][62][63] The ligand field splitting relates directly to the structure of the complex.…”

Section: Introductionmentioning

confidence: 99%

Electronic Structure of Ytterbium(III) Solvates – A Combined Spectro-scopic and Theoretical Study

Kofod¹,

Nawrocki²,

Platas‐Iglesias³

et al. 2021

Preprint

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The wide range of optical and magnetic properties of the lanthanide(III) ions is associated to their intricate electronic structures, which in contrast to lighter elements is characterized by strong relativistic effects and spin-orbit coupling. Nevertheless, computational methods are now capable of describing the ladder of electronic energy levels of the simpler trivalent lanthanide ions, as well as the lowest energy term of most of the series. The electronic energy levels result from electron configurations that are first split by spin-orbit coupling into groups of energy levels denoted by the corresponding Russel-Saunders terms. Each of these groups are then split by the ligand field into the actual electronic energy levels known as microstates or sometimes mJ levels. The ligand field splitting directly informs on coordination geometry, and is a valuable tool for determining structure and thus correlating the structure and properties of metal complexes in solution. The issue with lanthanide complexes is that the determination of complex structures from ligand field splitting remains a very challenging task. In this manuscript, the optical spectra – absorption, luminescence excitation and luminescence emission – of ytterbium(III) solvates were rec-orded in water, methanol, dimethyl sulfoxide and N,N-dimethylformamide. The electronic energy levels, that is the microstates, were resolved experimentally. Subsequently, density functional theory (DFT) calculations were used to model the structures of the solvates and ab initio relativistic complete active space self-consistent field (CASSCF) calculations were employed to obtain the microstates of the possible structures of each solvate. By comparing experimental and theoretical data, it was possible to determine both the coordination number and solution structure of each solvate. In water, methanol and N,N-dimethylformamide the solvates were found to be eight-coordinated and to have a square anti-prismatic coordination geometry. In DMSO the speciation was found to be more complicated. The robust methodology developed for comparing experimental spectra and computational results allows the solution structures of lanthanide complexes to be determined, paving the way for the design of complexes with predetermined properties. <br>

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Seven‐Coordination Chemistry

Cited by 127 publications

References 552 publications

Primary and Secondary Ferrocenylphosphine Complexes of Molybdenum(II) and Tungsten(II), [MI₂(CO)₃_-_n(PH₂R)₂₊_n] [M = Mo, W; R = Fc, FcCH₂; Fc = Fe(η⁵-C₅H₅)(η⁵-C₅H₄); n = 0, 1], [MI₂(CO)₃{PH(CH₂Fc)₂}₂], and [WI₂(CO)₃(NCMe){PH(CH₂Fc)₂}]: Pr

Primary and Secondary Ferrocenylphosphine Complexes of Molybdenum(II) and Tungsten(II), [MI₂(CO)₃_-_n(PH₂R)₂₊_n] [M = Mo, W; R = Fc, FcCH₂; Fc = Fe(η⁵-C₅H₅)(η⁵-C₅H₄); n = 0, 1], [MI₂(CO)₃{PH(CH₂Fc)₂}₂], and [WI₂(CO)₃(NCMe){PH(CH₂Fc)₂}]: Pr

Electronic Structure of Ytterbium(III) Solvates—a Combined Spectroscopic and Theoretical Study

Electronic Structure of Ytterbium(III) Solvates – A Combined Spectro-scopic and Theoretical Study

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Seven‐Coordination Chemistry

Cited by 127 publications

References 552 publications

Primary and Secondary Ferrocenylphosphine Complexes of Molybdenum(II) and Tungsten(II), [MI2(CO)3-n(PH2R)2+n] [M = Mo, W; R = Fc, FcCH2; Fc = Fe(η5-C5H5)(η5-C5H4); n = 0, 1], [MI2(CO)3{PH(CH2Fc)2}2], and [WI2(CO)3(NCMe){PH(CH2Fc)2}]: Pr

Primary and Secondary Ferrocenylphosphine Complexes of Molybdenum(II) and Tungsten(II), [MI2(CO)3-n(PH2R)2+n] [M = Mo, W; R = Fc, FcCH2; Fc = Fe(η5-C5H5)(η5-C5H4); n = 0, 1], [MI2(CO)3{PH(CH2Fc)2}2], and [WI2(CO)3(NCMe){PH(CH2Fc)2}]: Pr

Electronic Structure of Ytterbium(III) Solvates—a Combined Spectroscopic and Theoretical Study

Electronic Structure of Ytterbium(III) Solvates – A Combined Spectro-scopic and Theoretical Study

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Primary and Secondary Ferrocenylphosphine Complexes of Molybdenum(II) and Tungsten(II), [MI₂(CO)₃_-_n(PH₂R)₂₊_n] [M = Mo, W; R = Fc, FcCH₂; Fc = Fe(η⁵-C₅H₅)(η⁵-C₅H₄); n = 0, 1], [MI₂(CO)₃{PH(CH₂Fc)₂}₂], and [WI₂(CO)₃(NCMe){PH(CH₂Fc)₂}]: Pr

Primary and Secondary Ferrocenylphosphine Complexes of Molybdenum(II) and Tungsten(II), [MI₂(CO)₃_-_n(PH₂R)₂₊_n] [M = Mo, W; R = Fc, FcCH₂; Fc = Fe(η⁵-C₅H₅)(η⁵-C₅H₄); n = 0, 1], [MI₂(CO)₃{PH(CH₂Fc)₂}₂], and [WI₂(CO)₃(NCMe){PH(CH₂Fc)₂}]: Pr