Metallacycloalkanes – Synthesis, Structure and Reactivity of Medium to Large Ring Compounds

Blom, Burgert; Clayton, Hadley S.; Kilkenny, M.L.; Moss, John R.

doi:10.1016/s0065-3055(05)54004-8

Cited by 33 publications

(20 citation statements)

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“…The 1 H NMR spectra of the bis(1-alkenyl) complexes, (1)(2)(3)(4), show characteristic signals for the protons in the terminal alkenes (see Section 4 for details). The products obtained from the RCM reaction showed broad alkene proton shifts in the region 5.3-5.6 ppm in 1 H NMR, similar to their platinum analogs, which are due to the E and Z isomers of the palladacycloalkenes and these isomers could not be isolated.…”

Section: Synthesis and Characterization Of Palladacyclesmentioning

confidence: 99%

“…In spite of this importance of medium to large metallacycloalkanes as intermediates, very little is known about such compounds. Noteworthy, up to now, no higher metallacycloalkanes containing more than 9-membered rings are known [3]. On decomposition, various metallacycloalkanes have shown an interesting organic product distribution, depending on several factors [4].…”

Section: Introductionmentioning

confidence: 99%

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New synthesis and thermal studies of palladacycloalkanes and their precursors

Mahamo

Zheng

Sivaramakrishna

et al. 2008

Journal of Organometallic Chemistry

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Section: Synthesis and Characterization Of Palladacyclesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

New synthesis and thermal studies of palladacycloalkanes and their precursors

Mahamo

Zheng

Sivaramakrishna

et al. 2008

Journal of Organometallic Chemistry

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“…Metal‐alkyls, alkenyls and metallacycloalkanes are very well documented species among the classical organometallic compounds, and they play a vital role in many synthetic and catalytic reactions . Ever since the preparation of the first metal‐alkenyl complex reported by Green and Smith, valuable insights into the mechanistic details of these reactions have been elucidated, including both thermodynamic and kinetic aspects .…”

Section: Introductionmentioning

confidence: 99%

“…Ever since the preparation of the first metal‐alkenyl complex reported by Green and Smith, valuable insights into the mechanistic details of these reactions have been elucidated, including both thermodynamic and kinetic aspects . The chemistry of metal‐alkenyls has experienced a notable development during the last few years, in part due to their involvement in different catalytic processes and their applications in organic synthesis, some of which can be found in the currently available literature . M‐alkenyl complexes have been postulated as key intermediates in the Fischer–Tropsch process and ethylene oligomerization reactions including the generation of thin platinum films for micro‐electronic and catalytic applications through the chemical vapor deposition (CVD) method .…”

Section: Introductionmentioning

confidence: 99%

“…Although it might be anticipated that metal‐alkenyls should display similar properties to open‐chain dialkyl transition metal complexes or metallacycles, they exhibit high reactivity due to the involvement of an olefinic double bond. The chemical properties are rather different from other known metal complexes of substituted alkyl or aryl complexes . Since then, the chemistry of metal‐alkenyls of platinum group metals (PGM) has been a current research topic in our laboratories, and a review on the exciting chemistry of metal‐alkenyls would be worthwhile.…”

Section: Introductionmentioning

confidence: 99%

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Alkenyl complexes of platinum group metals: a platform for diverse reactivity patterns

Sravani

Venkatesh

Vijayakrishna

et al. 2014

Applied Organom Chemis

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Intermediates for many catalysis reactions reported in the literature are metal‐alkyl and metal‐alkenyl, including metallacycloalkane species. Synthesis and reactions of metal‐alkyl, alkenyl and metallacyle complexes have shown a great deal of development during the past few decades. This review summarizes the significant contributions reported on metal‐alkenyl compounds, specifically those containing at least a carbon chain with pendant alkene group [M―CH2CH2CHCH2]. Although metal‐alkenyl complexes are stable with strong chelating diphosphines and with a decrease in the ligand donor strength, the complexes can decompose without any ambiguity. For example, platinum‐dialkenyl complexes react readily via β‐hydrogen elimination and reductive elimination promoted by the nature of the ligand, solvent and length of carbon chains. These complexes can also undergo intramolecular irreversible isomerization and this leads to the selective catalytic isomerization of 1‐alkenes to 2‐alkenes in the presence of platinum‐dialkenyl complexes as catalysts. Perhaps the most striking manifestations of flexibility are the facile and complete intramolecular and intermolecular alkene metathesis to yield the corresponding metallacycloalkenes in the presence of Grubbs’ catalysts. The diverse chemical reactivity of these complexes demonstrates both the scope and complexity of metal‐alkenyl chemistry depending on the nature of ligand and metal. Copyright © 2014 John Wiley & Sons, Ltd.

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High‐Yield Synthesis of Medium and Large Platinacycloalkanes from Bis(alkenyl) Precursors

Sivaramakrishna

Moss

2007

Angewandte Chemie

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Metallacycloalkanes are an important class of compounds which have been known for many years to be key intermediates in useful catalytic reactions.[1] For example, metallacyclobutanes are known to be present in the alkene metathesis reaction.[2] More recently, metallacycloheptanes were first implicated, [3] then proven [4] to be involved in ethylene trimerization. There has been interesting discussion [5][6][7] and a belief that the formation of nine-membered and other larger metallacycloalkane rings is unlikely.In 2005, selective tetramerization of ethylene was discovered, which implicated metallacyclononanes as intermediates, [8] and Gibson and co-workers showed that larger metallacycloalkanes were involved in the catalytic formation of higher ethylene oligomers. [9] In spite of the demonstrated importance of medium to large metallacycloalkanes as intermediates, very little is known about such compounds.[10]The elegant synthesis of "molecular gyroscopes" through intramolecular alkene metathesis reactions using the Grubbs catalyst has been described by Gladysz and co-workers.[11]Recently, we introduced a new approach for the synthesis of small metallacycloalkane complexes using ring-closing metathesis (RCM) with the Grubbs catalyst.[12] Herein, we use this route to synthesize new medium to large ring metallacycloalkanes (Scheme 1), that is, exactly the ones that appear difficult to make by conventional methods.The bis(alkenyl)platinum(II) complexes 2 a-d were obtained by the transmetalation reaction of 1-alkenyl Grignard reagents with the corresponding dichloroplatinum(II) precursors 1. Complexes 2 were then readily converted into the platinacycloalkenes 3 using the RCM reaction with the Grubbs catalyst in CH 2 Cl 2 , and were obtained as colorless solids in high yield after recrystallization from CH 2 Cl 2 /diethyl ether. The hydrogenation of these compounds yielded the platinacycloalkanes 4 in high yield. The 31 P{ 1 H} NMR spectra of 4 in C 6 D 6 displayed a singlet at d = 3.4 ppm with Pt satellites ( 1 J Pt-P = 1620 Hz), which is quite similar to the precursor compounds 2 and 3.[13] These and all new compounds described in Scheme 1 were fully characterized. Crystals of 2 c and 3 d (L 2 = dppp = 1,3-bis(diphenylphosphino)propane) suitable for X-ray diffraction were obtained by recrystallization from CH 2 Cl 2 /hexane at T = 0 8C. To our knowledge, this is the first example of a structurally characterized larger metallacycloalkene compound reported in the literature.The molecular structures of 2 c and 3 d are illustrated in Figures 1 and 2, respectively. The structural analysis confirms that 3 d is the RCM product. The most striking structural features of complexes 2 c and 3 d are the differences in some of the bond angles and bond lengths. The PtÀC and PtÀP bond lengths in the two compounds are almost identical and comparable to the literature values [14] (2.118(3)-2.110(3) and 2.263(9)-2.293(7) , respectively), while the C = C distances range from 1.229(7) to 1.341(7) . The C = C distance in 3 d is comparati...

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Metallacycloalkanes – Synthesis, Structure and Reactivity of Medium to Large Ring Compounds

Cited by 33 publications

References 133 publications

New synthesis and thermal studies of palladacycloalkanes and their precursors

New synthesis and thermal studies of palladacycloalkanes and their precursors

Alkenyl complexes of platinum group metals: a platform for diverse reactivity patterns

High‐Yield Synthesis of Medium and Large Platinacycloalkanes from Bis(alkenyl) Precursors

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