词条 | Low valent magnesium compounds |
释义 |
A number of stable low valent magnesium compounds containing a metal-metal, Mg-Mg, bond, where magnesium exhibits the formal oxidation state of +1 are known. These compounds generally have the formula L2Mg2, where L represents a bulky ligand.[1] The first examples of these stable magnesium(I) compounds were reported in 2007.[2] The chemistry of Mg is dominated by the +2 oxidation state and prior to 2007 only examples of crystalline compounds with short Mg-Mg distances that may indicate an Mg-Mg bond were known, such as the ternary metal hydrides Mg2RuH4, Mg3RuH3, and Mg4IrH5 and magnesium diboride,[3] Calculations had also indicated the stability of the Mg22+ cation[4] The preparation of the first compounds made involved the reduction of MgII iodine complexes with potassium metal and the bulky ligands were:[2]
Both examples have the formula L2Mg2, where L represents the bulky anionic bidentate ligand.[2] X-ray crystallographic studies showed an Mg-Mg bond length of 285.1 pm and 284.6 pm.[2] Theoretical studies indicate an essentially ionic formulation Mg22+(L−)2.[2] The Mg22+ ion is the group 2 analogue of the group 12 Hg22+ (present in e.g. mercury(I) chloride) and Cd22+ ions (present in cadmium(I) tetrachloroaluminate). Since then a variety of stable Mg(I) compounds have been prepared, some melting over 200 °C, some colorless, others colored, but all involving very bulky ligands.[1] Also complexes of the LMgMgL with monodentate ligands have been prepared and in these the coordination of the Mg atom increases from three to four.[1] The magnesium(I) dimers have proved to be useful reducing agents, for example in the preparation of tin(I) compounds.[5] References1. ^1 2 {{cite journal|authors= Stasch, Andreas and Jones, Cameron|year=2011|title= Stable dimeric magnesium(i) compounds: from chemical landmarks to versatile reagents|journal= Dalton Transactions|volume= 40|issue= 21|pages= 5659–5672|doi= 10.1039/C0DT01831G|pmid=21390353|accessdate=10 February 2015 |subscription=yes|url= http://pubs.rsc.org/en/content/articlelanding/2011/dt/c0dt01831g#!divAbstract}} 2. ^1 2 3 4 {{cite journal|last= Green|first= S. P.|authorlink= |author2=Jones C. |author3=Stasch A.|date=December 2007|title= Stable Magnesium(I) Compounds with Mg-Mg Bonds|journal= Science|volume= 318|issue= 5857|pages= 1754–1757|doi= 10.1126/science.1150856|id=|url=|accessdate=|quote=|pmid= 17991827 |bibcode = 2007Sci...318.1754G }} 3. ^{{cite journal|last= King|first= R. Bruce|authorlink=|date=October 2002|title= Chemical bonding topology of superconductors. 5. The similarities between magnesium diboride and cuprate superconductors and the role of subvalent magnesium|journal= Polyhedron|volume= 21 |issue= 23|pages= 2347–2350|doi= 10.1016/S0277-5387(02)01183-X|id=|url= http://www.sciencedirect.com/science/article/pii/S027753870201183X|accessdate=10 Feb 2015|quote= }}{{Subscription or libraries|sentence|via=ScienceDirect}} 4. ^.{{cite journal|last= Hogreve|first= H.|authorlink=|date=August 2004 |title= Mg22+: a long-lived metastable dication|journal= Chemical Physics Letters |volume= 394|issue= 1–3|pages= 32–36|doi= 10.1016/j.cplett.2004.06.099|id=|url=http://www.sciencedirect.com/science/article/pii/S0009261404009650|accessdate=10 February 2015|quote= |bibcode = 2004CPL...394...32H }}{{Subscription or libraries|sentence|via=ScienceDirect}} 5. ^{{cite journal|authors= Choong, Sam L. and Schenk, Christian and Stasch, Andreas and Dange, Deepak and Jones, Cameron|title= Contrasting reductions of group 14 metal(ii) chloride complexes: synthesis of a [small beta]-diketiminato tin(i) dimer|journal= Chemical Communications|year=2012|volume= 48|issue= 19|pages=2504–2506 |doi= 10.1039/C2CC18086C|pmid= 22281528|accessdate=10 February 2015 |subscription=yes|url= http://pubs.rsc.org/en/content/articlelanding/2012/cc/c2cc18086c#!divAbstract}} 1 : Magnesium compounds |
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