Platinum Compounds of Cyclooctatetraene.

Jensen, Kai Arne; Nielsen, Erling Juhl; Reiter, Richard C.; Schønfeldt, E.; Steensgaard, Inger; Rosenberg, Th.

doi:10.3891/acta.chem.scand.07-0868

Cited by 31 publications

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“…While many COTs are relatively labile metal ligands (1,2,5,6-h 4 coordination), [17,19] structural modifications to the COT scaffold, such as benzannulation, often enhance their ability to bind to transition metals. [20,21] Members of the dibenzo[a,e]cyclooctatetraene (dbCOT) subfamily have been complexed with a variety of transition metals (e.g., Pd, Pt, Rh, Ir, Co, Mo, Cr, Cu).…”

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“…[30] Significantly, in several cases, the novel metal complex [Rh(dnCOT)(MeCN) 2 ]SbF 6 (7) was shown to enhance (entries 1, 4, 6, and 17) or even reverse (entry 8) the regioselectivity observed with [{RhCl(CO) 2 } 2 ] (20, Table 3). [31] It is noteworthy that in these representative reactions over a range of sterically and electronically diverse alkynes, [Rh(dnCOT)(MeCN) 2 ]SbF 6 (7) displays the best overall activity with respect to both reaction rate at room temperature and combined yields of 33 a/b (outperforming [Rh(C 10 H 8 )(COD)]SbF 6 (19) in some direct comparisons).…”

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Rhodium Dinaphthocyclooctatetraene Complexes: Synthesis, Characterization and Catalytic Activity in [5+2] Cycloadditions

2012

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New reactions provide new ways to think about bond construction and thus more, and often greener, options for achieving greater step, [1] atom [2] and time economical, [3] if not ideal, syntheses. [4] Guided by these considerations, we previously introduced a reaction for seven-membered ring synthesis involving metal-catalyzed [5+2] cycloadditions of vinylcyclopropanes (VCPs) and p systems. [5] While rhodium complexes have shown the greatest generality in catalyzing this process, working both intra-and intermolecularly and with absolute stereocontrol [6] and even in water, [7] ruthenium, [8] nickel, [9] and iron [10] catalysts have also been effective in many cases. We report herein the first studies of a new family of catalysts for [5+2] cycloadditions based on relatively little studied rhodium cyclooctatetraene (COT) complexes. We describe the synthesis and metal complexation of our dinaphtho[a,e]cyclooctatetraene (dnCOT) ligand 5 derived from a recently introduced [2+2+2+2] cycloaddition of diynes. [11] The resulting Rh-dnCOT catalyst provides [5+2] cycloadducts in high yields, often in minutes at room temperature, is compatible with a variety of functionalities, and exhibits enhanced or even reversed regiocontrol in selected cases, relative to known catalysts.The [2+2+2+2] cycloaddition of diynes has proven to be an excellent reaction for the synthesis of highly substituted COTs. [11] In addition to the value of such COTs as synthetic building blocks and components of novel materials and devices, [12][13][14][15][16] a further motivation for our interest in this process was the potential use of COTs as ligands for catalysis. Due to their tub-shaped conformation, certain COTs can coordinate transition metals in a 1,2,5,6-h 4 manner analogous to dienes such as cyclooctadienes (CODs). [17] Interestingly, the distance and bite angle between the binding alkene moieties in metal complexes of both COD and COT are the [*] Prof. .) for financial support. We also thank Allen Oliver at the University of Notre Dame for X-ray crystal structures. Justin P. Christy is acknowledged for his supporting work on the syntheses of COTs and for helpful discussions.Supporting information for this article (full experimental details, characterization of new compounds, preparation and characterization of dnCOT and its rhodium and iridium metal complexes, and procedures for [5+2] cycloadditions) is available on the WWW under http://dx.

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Rhodium Dinaphthocyclooctatetraene Complexes: Synthesis, Characterization and Catalytic Activity in [5+2] Cycloadditions

2012

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“…In 1953 Jensen (141) reported that the reaction between cyclo octatetraene and K2(PtCl4) produced the complex (C8H8)PtCl2. He like wise described the iodo derivative, (C8H8)PtI2.…”

Section: Organotransition Metalsmentioning

confidence: 99%

The History and Development of Organotransition Metal Chemistry

Rausch

1967

Werner Centennial

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Organotransition metal compounds have been known for over a century, but it has been only during the past 15 years that most of the major advances in this area have been made. Organotransition metal compounds consist of organic molecules or ligands coordinated to transition metals by one or more carbon atoms. In the present sur vey, the formation, properties, structure, and reactions of various classes of these substances are discussed. Empha sis has been placed on important discoveries and theories that have stimulated the rapid progress of organotransition metal chemistry. Pertinent reviews on various aspects of this subject have also been cited./^\rganometallic compounds containing neutral, unsaturated organic molecules coordinated to certain transition metals were known long before the advent of Werner's theories on coordination compounds. Until about 1950, however, this aspect of coordination chemistry remained fal low, and the structure and bonding of the compounds known at that time were quite perplexing. The discovery of ferrocene and the development of a rational theory of bonding in olefin-transition metal complexes in the early 1950's prompted a vigorous research effort around the world that has attracted the attention of organic chemists, inorganic chemists, crystallographers, and scientists of many allied disciplines. Research in organo transition metal chemistry presently is proceeding at a very rapid rate, and the synthesis and properties of seemingly unlimited new types of "organometallic, T complexes" represent an important frontier in coordina tion chemistry.The purpose of the present survey is twofold. Firstly, because the Werner Symposium is partly historical, some of the more important dis coveries and theories that have led to the present high level of interest in 486 Downloaded by UNIV OF NORTH CAROLINA on February 18, 2015 |

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“…In order to avoid this interference we selected the complex Pt II (C 8 H 8 )(CN) 2 for the present study. This compound was not known but expected to be accessible by procedures which have been employed for the preparation of Pt II (C 8 H 8 )X 2 with X = Cl, I and CH 3 [9,10]. For X = CN the LF states should be pushed up to very high energies owing to the large LF strength of cyanide [11].…”

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