Cycloheptatriene and -enyl Complexes of the Early Transition Metals

Green, Malcolm L. H.; Ng, Dennis K. P.

doi:10.1021/cr00034a006

Cited by 145 publications

(128 citation statements)

References 76 publications

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“…3− charge description inappropriate [133]. Such difficulties with OS assignment and subsequent ambiguities in classification of covalent organometallic compounds led Green [27] to devise the CBC.…”

Section: Seven-membered Ringsmentioning

confidence: 99%

Toward a comprehensive definition of oxidation state (IUPAC Technical Report)

Karen

McArdle

Takats

2014

Pure and Applied Chemistry

111

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A generic definition of oxidation state (OS) is formulated: "The OS of a bonded atom equals its charge after ionic approximation". In the ionic approximation, the atom that contributes more to the bonding molecular orbital (MO) becomes negative. This sign can also be estimated by comparing Allen electronegativities of the two bonded atoms, but this simplification carries an exception when the more electronegative atom is bonded as a Lewis acid. Two principal algorithms are outlined for OS determination of an atom in a compound; one based on composition, the other on topology. Both provide the same generic OS because both the ionic approximation and structural formula obey rules of stable electron configurations. A sufficiently simple empirical formula yields OS via the algorithm of direct ionic approximation (DIA) by these rules. The topological algorithm works on a Lewis formula (for a molecule) or a bond graph (for an extended solid) and has two variants. One assigns bonding electrons to more electronegative bond partners, the other sums an atom's formal charge with bond orders (or bond valences) of sign defined by the ionic approximation of each particular bond at the atom. A glossary of terms and auxiliary rules needed for determination of OS are provided, illustrated with examples, and the origins of ambiguous OS values are pointed out. An electrochemical OS is suggested with a nominal value equal to the average OS for atoms of the same element in a moiety that is charged or otherwise electrochemically relevant.

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Section: Seven-membered Ringsmentioning

confidence: 99%

Toward a comprehensive definition of oxidation state (IUPAC Technical Report)

Karen

McArdle

Takats

2014

Pure and Applied Chemistry

111

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“…Transition metal complexes with these ligands have been studied extensively and many of which have contributed to the development of areas such as homogenous catalyst, organic synthesis, new materials and biological and medical sciences [95]. …”

Section: Substitution Reactions Of Cyclopentadienyl and Cyclohepatriementioning

confidence: 99%

The chemistry of group-VIb metal carbonyls

Kaushik¹,

Singh²,

Kumar³

2012

Eur. J. Chem.

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KEYWORDSThe special interest attached to the chemistry of metal carbonyls arises from several causes. While quite distinct from the metal carbonyls in the organometallic compounds, they differ in physical properties (e.g., their volatility) from all other compounds of the transition metals. Chemically, they constitute a group of compounds in which the formal valency of the metal atoms is zero, and in this respect (apart, perhaps, from the ammoniates of the alkali metals) they are comparable only with the recently discovered compounds. As a class, the carbonyls are reactive compounds, and a number of new types of inorganic compounds have been discovered. In the concepts for new products, performance, product safety, and product economy criteria are equally important. They are taken into account already when the raw material base for a new industrial product development is defined. Since the discovery of nickel carbonyl by Mond and Langer in 1888, the carbonyls of the iron group and of chromium, molybdenum and tungsten have found important technical applications, e.g., in the Mond nickel process, and for the preparation of the metals in a state of subdivision and of purity suitable for powder metallurgy, for catalysts, etc. The reaction mechanism of the processes developed for producing the carbonyls technically has only recently received its interpretations. Within the space of review it is necessary to limit discussion to a few topics. Particular stress has accordingly laid upon (a) the chemical bonding in metal carbonyls, (b) importance of IR and NMR spectroscopy in characterization of metal carbonyls, (c) substitution reactions of G-VIb metal carbonyls, (d) kinetics and mechanism of substitution reactions in metal carbonyls, (e) substituted complexes of G-VIb metal carbonyl, (f) chelate complexes of G-VIb metal carbonyls, (g) uses of G-VIb metal carbonyl complexes and (h) studies done on G-VIb metal carbonyls.

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“…[172] Tamm and co-workers reported the synthesis and full characterization of sila [1] [168b] in 2007. For both compounds experimental and theoretical investigations revealed strong structural distortion in particular at the {Si-C 7 H 6 } site, and unusually high values for b angles (see Table 7) were observed, suggesting highly strained molecules ( Figure 12 and Figure 13).…”

Section: Metallocenophanes Of Cobaltmentioning

confidence: 99%

Strained Metallocenophanes and Related Organometallic Rings Containing π‐Hydrocarbon Ligands and Transition‐Metal Centers

2007

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The structures, bonding, and ring-opening reactions of strained cyclic carbon-based molecules form a key component of standard textbooks. In contrast, the study of strained organometallic molecules containing transition metals is a much more recent development. A wealth of recent research has revealed fascinating nuances in terms of structure, bonding, and reactivity. Building on initial work on strained ferrocenophanes, a broad range of strained organometallic rings composed of a variety of different metals, pi-hydrocarbon ligands, and bridging elements has now been developed. Such strained species can potentially undergo ring-opening reactions to functionalize surfaces and ring-opening polymerization to form easily processed metallopolymers with properties determined by the presence of the metal and spacer. This Review summarizes the current state of knowledge on the preparation, structural characterization, electronic structure, and reactivity of strained organometallic rings with pi-hydrocarbon ligands and d-block metals.

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Cycloheptatriene and -enyl Complexes of the Early Transition Metals

Cited by 145 publications

References 76 publications

Toward a comprehensive definition of oxidation state (IUPAC Technical Report)

Toward a comprehensive definition of oxidation state (IUPAC Technical Report)

The chemistry of group-VIb metal carbonyls

Strained Metallocenophanes and Related Organometallic Rings Containing π‐Hydrocarbon Ligands and Transition‐Metal Centers

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