Randomized rounding: Difference between revisions
Jump to navigation
Jump to search
en>Helpful Pixie Bot m ISBNs (Build KE) |
en>Rjwilmsi m Citation parameter fixes, using AWB (9458) |
||
| Line 1: | Line 1: | ||
[[File:Cyclooctadiene-rhodium-chloride-dimer-2D-skeletal.png|thumb|Cyclooctadiene rhodium chloride dimer]]'''Organorhodium chemistry''' is the [[chemistry]] of [[organometallic compounds]] containing a [[rhodium]]-[[carbon]] [[chemical bond]], and the study of rhodium and rhodium compounds as [[catalyst]]s in [[organic reaction]]s.<ref>''Synthesis of Organometallic Compounds: A Practical Guide'' Sanshiro Komiya Ed. S. Komiya, M. Hurano 1997</ref> | |||
Stable organorhodium compounds and transient organorhodium intermediates are used as catalyst such as in olefin [[hydroformylation]], olefin [[hydrogenation]], olefin isomerization and the [[Monsanto process]]<ref name="Crabtree">{{cite book | last = Crabtree | first = Robert H. | title = The Organometallic Chemistry of the Transition Metals | edition = 4th | publisher = Wiley-Interscience | isbn = 0-471-66256-9 | date = 2005 | location = USA}}</ref> | |||
==Description== | |||
Organometallic rhodium compounds share many characteristics with those of cobalt (see [[organocobalt compound]]s), which is also in [[Group 9 element|group 9]]. Rhodium can exist in [[oxidation states]] of -III to +IV, but rhodium(I) and rhodium(III) are the most common. Rhodium(I) compounds (d<sup>8</sup> configuration) can occur with square planar or trigonal bipyramidal geometries, while rhodium (III) compounds (d<sup>6</sup> configuration) typically have an octahedral geometry.<ref name="Crabtree" /> | |||
==Examples== | |||
Important homoleptic rhodium compounds are [[tetrarhodium dodecacarbonyl]] Rh<sub>4</sub>(CO)<sub>10</sub> and [[hexadecacarbonylhexarhodium]] Rh<sub>6</sub>(CO)<sub>16</sub>. The hexarhodium compound is less preferred due to poor solubility. Both are important catalysts in [[hydroformylation]] of alkenes often accompanied by a phosphine ligand: | |||
:<math>\mathrm{RHC=CH_2\ +\ CO\ +\ H_2\ \xrightarrow {Rh_4(CO)_{10} / PPh_3}\ \ RCH_2CH_2CHO}</math> | |||
[[Nitrobenzene]] reduction is another reaction catalysed by this compound type: | |||
:<math>\mathrm{PhNO_2\ +\ C_6H_6\ +\ 3\ CO\ \xrightarrow {Rh_6(CO)_{16}}\ \ PhNHCOPh\ +\ 2\ CO_2}</math> | |||
[[Cyclooctadiene rhodium chloride dimer]] [RhCl(COD)]<sub>2</sub> is investigated for its use in [[C-H bond activation]]. [[Sandwich compound]]s of rhodium, such as [[rhodocene]], and [[Sandwich compound#Half sandwich compounds|half-sandwich compound]]s like [(η<sup>5</sup>-[[cyclopentadienyl|Cp]])Rh(CO)<sub>2</sub>] are well known. | |||
Another hexarhodium complex is (C<sub>60</sub>)Rh<sub>6</sub>(C<sub>60</sub>), where the rhodium center has two large [[Fullerene Ligands|fullerene ligands]] around it. | |||
{|class = "wikitable" | |||
|+ Other relevant organorhodium compounds used as catalysts | |||
!Name | |||
!Molecular formula | |||
!CAS | |||
|- | |||
|(Acetylacetonato)dicarbonylrhodium(I) || Rh(CO)<sub>2</sub>(C<sub>5</sub>H<sub>7</sub>O<sub>2</sub>) || 14874-82-9 | |||
|- | |||
|Bicyclo[2.2.1]hepta-2,5-diene-rhodium(I) chloride dimer | |||
|| C<sub>14</sub>H<sub>16</sub>Cl<sub>2</sub>Rh<sub>2</sub>|| 12257-42-0 | |||
|- | |||
|Chloro(1,5-cyclooctadiene)rhodium(I) dimer | |||
|| C<sub>16</sub>H<sub>24</sub>Cl<sub>2</sub>Rh<sub>2</sub> || 12092-47-6 | |||
|- | |||
|(Acetylacetonato)(norbornadiene)rhodium(I) | |||
|| C<sub>12</sub>H<sub>15</sub>O<sub>2</sub>2Rh || 32354-50-0 | |||
|- | |||
| Chloro(1,5-hexadiene)rhodium(I),dimer | |||
|| C<sub>12</sub>H<sub>24</sub>Rh<sub>2</sub>Cl<sub>2</sub> || 32965-49-4 | |||
|- | |||
| Acetylacetonatobis(ethylene)rhodium(I) | |||
|| C<sub>9</sub>H<sub>15</sub>O<sub>2</sub>Rh || 12082-47-2 | |||
|- | |||
| [1,4-Bis(diphenylphosphino)butane](1,5-cyclooctadiene)rhodium(I) tetrafluoroborate | |||
|| C<sub>36</sub>H<sub>40</sub>BF<sub>4</sub>P<sub>2</sub>Rh || 79255-71-3 | |||
|} | |||
==Cyclometallation== | |||
[[Metallacycle|Cyclometalated]] [[rhodium]] compounds constitute an important class of [[organometallic]] chemistry. Although such compounds are well documented in the literature rhodium(III) cyclometalates with [[azo compound|azo]] function are spare. A typical example of this category viz. novel hexacoordinated [[orthometalated]] rhodium(III) thiolato complex trans-[Rh(C<sup>∧</sup>N<sup>∧</sup>S)Cl(PPh<sub>3</sub>)<sub>2</sub>] was synthesized from benzyl 2-(phenylazo)phenyl thioether and RhCl<sub>3</sub>·3H<sub>2</sub>O in the presence of excess PPh<sub>3</sub> via in situ C(sp<sup>2</sup>)−H and C(sp<sup>3</sup>)−S bond scissions. This is the first example for a coordination compound of (phenylazo)thiolate ligand. The mechanism of formation of orthometalated [[azobenzene]] derivative was described to proceed via initial coordination of azo-nitrogen followed by [[electrophilic]] substitution at the pendant phenyl ring. PPh<sub>3</sub> plays a crucial role in the C(sp<sup>3</sup>)−S cleavage process. Reductive cleavage by [[single electron transfer]] (SET) mechanism is likely to be operative for the C−S bond cleavage. Unlike analogous (phenylazo)phenolato compound the orthometalated thiolato complex exhibits a fully reversible oxidative wave at 0.82 V vs Ag/AgCl and this response is supposed to be primarily centered on the thiolato sulfur atom.<ref>{{cite journal | author = K. Pramanik, U. Das, B. Adhikari, D. Chopra, H. Stoeckli-Evans | title = RhCl<sub>3</sub>-Assisted C-H and C-S Bond Scissions: Isomeric Self-Association of Organorhodium(III) Thiolato Complex. Synthesis, Structure, and Electrochemistry | journal = [[Inorg. Chem.]] | year = 2008 | volume = 47 | pages = 429–438 | doi = 10.1021/ic7016006 | pmid=18161963 | issue = 2}}</ref> | |||
==See also== | |||
* Chemical bonds of carbon with other elements in the periodic table: | |||
{{ChemicalBondsToCarbon}} | |||
==References== | |||
{{Reflist}} | |||
[[Category:Organorhodium compounds| ]] | |||
Revision as of 19:07, 1 September 2013
Organorhodium chemistry is the chemistry of organometallic compounds containing a rhodium-carbon chemical bond, and the study of rhodium and rhodium compounds as catalysts in organic reactions.[1]
Stable organorhodium compounds and transient organorhodium intermediates are used as catalyst such as in olefin hydroformylation, olefin hydrogenation, olefin isomerization and the Monsanto process[2]
Description
Organometallic rhodium compounds share many characteristics with those of cobalt (see organocobalt compounds), which is also in group 9. Rhodium can exist in oxidation states of -III to +IV, but rhodium(I) and rhodium(III) are the most common. Rhodium(I) compounds (d8 configuration) can occur with square planar or trigonal bipyramidal geometries, while rhodium (III) compounds (d6 configuration) typically have an octahedral geometry.[2]
Examples
Important homoleptic rhodium compounds are tetrarhodium dodecacarbonyl Rh4(CO)10 and hexadecacarbonylhexarhodium Rh6(CO)16. The hexarhodium compound is less preferred due to poor solubility. Both are important catalysts in hydroformylation of alkenes often accompanied by a phosphine ligand:
Nitrobenzene reduction is another reaction catalysed by this compound type:
Cyclooctadiene rhodium chloride dimer [RhCl(COD)]2 is investigated for its use in C-H bond activation. Sandwich compounds of rhodium, such as rhodocene, and half-sandwich compounds like [(η5-Cp)Rh(CO)2] are well known.
Another hexarhodium complex is (C60)Rh6(C60), where the rhodium center has two large fullerene ligands around it.
| Name | Molecular formula | CAS |
|---|---|---|
| (Acetylacetonato)dicarbonylrhodium(I) | Rh(CO)2(C5H7O2) | 14874-82-9 |
| Bicyclo[2.2.1]hepta-2,5-diene-rhodium(I) chloride dimer | C14H16Cl2Rh2 | 12257-42-0 |
| Chloro(1,5-cyclooctadiene)rhodium(I) dimer | C16H24Cl2Rh2 | 12092-47-6 |
| (Acetylacetonato)(norbornadiene)rhodium(I) | C12H15O22Rh | 32354-50-0 |
| Chloro(1,5-hexadiene)rhodium(I),dimer | C12H24Rh2Cl2 | 32965-49-4 |
| Acetylacetonatobis(ethylene)rhodium(I) | C9H15O2Rh | 12082-47-2 |
| [1,4-Bis(diphenylphosphino)butane](1,5-cyclooctadiene)rhodium(I) tetrafluoroborate | C36H40BF4P2Rh | 79255-71-3 |
Cyclometallation
Cyclometalated rhodium compounds constitute an important class of organometallic chemistry. Although such compounds are well documented in the literature rhodium(III) cyclometalates with azo function are spare. A typical example of this category viz. novel hexacoordinated orthometalated rhodium(III) thiolato complex trans-[Rh(C∧N∧S)Cl(PPh3)2] was synthesized from benzyl 2-(phenylazo)phenyl thioether and RhCl3·3H2O in the presence of excess PPh3 via in situ C(sp2)−H and C(sp3)−S bond scissions. This is the first example for a coordination compound of (phenylazo)thiolate ligand. The mechanism of formation of orthometalated azobenzene derivative was described to proceed via initial coordination of azo-nitrogen followed by electrophilic substitution at the pendant phenyl ring. PPh3 plays a crucial role in the C(sp3)−S cleavage process. Reductive cleavage by single electron transfer (SET) mechanism is likely to be operative for the C−S bond cleavage. Unlike analogous (phenylazo)phenolato compound the orthometalated thiolato complex exhibits a fully reversible oxidative wave at 0.82 V vs Ag/AgCl and this response is supposed to be primarily centered on the thiolato sulfur atom.[3]
See also
- Chemical bonds of carbon with other elements in the periodic table:
Template:ChemicalBondsToCarbon
References
43 year old Petroleum Engineer Harry from Deep River, usually spends time with hobbies and interests like renting movies, property developers in singapore new condominium and vehicle racing. Constantly enjoys going to destinations like Camino Real de Tierra Adentro.
- ↑ Synthesis of Organometallic Compounds: A Practical Guide Sanshiro Komiya Ed. S. Komiya, M. Hurano 1997
- ↑ 2.0 2.1 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.
My blog: http://www.primaboinca.com/view_profile.php?userid=5889534 - ↑ One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting
In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang
Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules
Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.
A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running
The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more
There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang