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词条 Germanate
释义

  1. Germanate oxy compounds

  2. Germanates in aqueous solutions

  3. Germanate zeolites

  4. See also

  5. References

In chemistry germanate is a compound containing an oxyanion of germanium. In the naming of inorganic compounds it is a suffix that indicates a polyatomic anion with a central germanium atom,[1] for example potassium hexafluorogermanate, K2GeF6.[2]

Germanate oxy compounds

Germanium is similar to silicon forming many compounds with tetrahedral {GeO4}[2] units although it can also exhibit 5[3] and 6[2] coordination. Analogues of all the major types of silicates and aluminosilicates have been prepared.[4] For example, the compounds Mg2GeO4 (olivine and spinel forms), CaGeO3(perovskite structure), Be2GeO4 (phenakite structure) show the resemblance to the silicates.[4][5] BaGe4O9 has a complex structure containing 4 and 6 coordinate germanium.[5] Germanates are important for geoscience as they possess similar structures to silicates and can be used as analogues for studying the behaviour of silicate minerals found in the Earth's mantle;[6] for example, MnGeO3 has a pyroxene type structure similar to that of MgSiO3 which is a significant mineral in the mantle.[7][8][9]

Germanates in aqueous solutions

The alkali metal orthogermanates, M4GeO4,containing discrete {{chem|GeO|4|4−}} ions, form acidic solutions containing {{chem|GeO(OH)|3|−}}, {{chem|GeO|2|(OH)|2|2−}} and [(Ge(OH)4)8(OH)3]3−.[2] Neutral solutions of germanium dioxide contain Ge(OH)4, but at high pH germanate ions such as {{chem|GeO(OH)|3|−}}, {{chem|GeO|2|(OH)|2|2−}} are present.[10]

Germanate zeolites

Microporous germanate zeolites were first prepared in the 1990s.[11][12]

A common method of preparation is hydrothermal synthesis using an organic amine as a template (structure determining agent).[13]

The frameworks are negatively charged due to extra oxide ions which leads to higher coordination numbers for germanium of 5 and 6. The negative charge is balanced by the positively charged amine molecules.

In addition to the ability of germanium to exhibit 4, 5 or 6 coordination, the greater length of the Ge–O bond in the {GeO4} tetrahedral unit compared to Si–O in {SiO4} and the narrower Ge–O–Ge angle (130°–140°) between corner shared tetrahedra allow for unusual framework structures.[14] A zeolite reported in 2005[15] has large pores – {{nowrap|18.6 × 26.2 Å}} interconnected by channels defined by 30-membered rings (the naturally occurring zeolite faujasite with channels defined by 12-membered rings[16]). Zeolites with frameworks containing silicon and germanium (silicogermanates), aluminium and germanium (aluminogermanates) and zirconium and germanium (zirconogermanates) are all known.[13][17]

See also

  • Bismuth germanate (bismuth germanium oxide, BGO)
  • Sodium germanate

References

1. ^Nomenclature of Inorganic Chemistry IUPAC Recommendations 2005 – Full text (PDF)
2. ^1 2 3 Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier {{ISBN|0123526515}}
3. ^{{cite journal|last1=Nguyen|first1=Quang Bac|last2=Lii|first2=Kwang-Hwa|title=Cs4UGe8O20: A Tetravalent Uranium Germanate Containing Four- and Five-Coordinate Germanium|journal=Inorganic Chemistry|volume=50|issue=20|year=2011|pages=9936–9938|issn=0020-1669|doi=10.1021/ic201789f}}
4. ^1 {{Greenwood&Earnshaw}}
5. ^1 Encyclopedia of alkaline earth compounds R.C Ropp, Elsevier 2013 {{ISBN|978-0-444-59550-8}}
6. ^{{cite journal|last1=Ringwood|first1=A.E.|title=Phase transformations and the constitution of the mantle|journal=Physics of the Earth and Planetary Interiors|volume=3|year=1970|pages=109–155|issn=0031-9201|doi=10.1016/0031-9201(70)90047-6|bibcode=1970PEPI....3..109R}}
7. ^{{cite journal|last1=Ringwood|first1=A. E.|last2=Seabrook|first2=Merren|title=Some High-pressure Transformations in Pyroxenes|journal=Nature|volume=196|issue=4857|year=1962|pages=883–884|issn=0028-0836|doi=10.1038/196883a0|bibcode=1962Natur.196..883R}}
8. ^{{cite journal|last1=Hirose|first1=Kei|last2=Nagaya|first2=Yukio|last3=Merkel|first3=Sébastien|last4=Ohishi|first4=Yasuo|title=Deformation of MnGeO3 post-perovskite at lower mantle pressure and temperature|journal=Geophysical Research Letters|volume=37|issue=20|year=2010|issn=0094-8276|doi=10.1029/2010GL044977|bibcode=2010GeoRL..3720302H}}
9. ^{{cite journal|last1=Matsumura|first1=Hisashi|last2=Mamiya|first2=Mikito|last3=Takei|first3=Humihiko|title=Growth of pyroxene-type MnGeO3 and (Mn,Mg)GeO3 crystals by the floating-zone method|journal=Journal of Crystal Growth|volume=210|issue=4|year=2000|pages=783–787|issn=0022-0248|doi=10.1016/S0022-0248(99)00850-7|bibcode=2000JCrGr.210..783M}}
10. ^"Germanium: Inorganic Chemistry" F Glockling Encyclopedia of Inorganic Chemistry Editor R Bruce King (1994) John Wiley and Sons {{ISBN|0-471-93620-0}}
11. ^{{cite journal|last1=Cheng|first1=Jun|last2=Xu|first2=Ruren|last3=Yang|first3=Guangdi|title=Synthesis, structure and characterization of a novel germanium dioxide with occluded tetramethylammonium hydroxide|journal=Journal of the Chemical Society, Dalton Transactions|issue=6|year=1991|pages=1537|issn=0300-9246|doi=10.1039/dt9910001537}}
12. ^{{cite journal|last1=Li|first1=Hailian|last2=Yaghi|first2=O. M.|title=Transformation of Germanium Dioxide to Microporous Germanate 4-Connected Nets|journal=Journal of the American Chemical Society|volume=120|issue=40|year=1998|pages=10569–10570|issn=0002-7863|doi=10.1021/ja982384n}}
13. ^1 Zeolites and Related Materials: Trends Targets and Challenges(SET), 1st Edition, 4th International FEZA Conference, 2008, Paris, France; Eds. Gedeon, Massiani,Babonneau; Elsevier Science; {{ISBN|9780444532961}}
14. ^Introduction to Zeolite Molecular Sieves, Jiri Cejka, Herman van Bekkum, A. Corma, F. Schueth, Elsevier, 2007
15. ^{{cite journal|last1=Zou|first1=Xiaodong|last2=Conradsson|first2=Tony|last3=Klingstedt|first3=Miia|last4=Dadachov|first4=Mike S.|last5=O'Keeffe|first5=Michael|title=A mesoporous germanium oxide with crystalline pore walls and its chiral derivative|journal=Nature|volume=437|issue=7059|year=2005|pages=716–719|issn=0028-0836|doi=10.1038/nature04097|pmid=16193048|bibcode=2005Natur.437..716Z}}
16. ^Handbook Of Molecular Sieves: Structures, Rosemarie Szostak, 1992, Van Nostrand Reinhold, {{ISBN|0442318995}}, {{ISBN|978-0442318994}}
17. ^{{cite journal|last1=Plévert|first1=Jacques|last2=Sanchez-Smith|first2=Rebeca|last3=Gentz|first3=Travis M.|last4=Li|first4=Hailian|last5=Groy|first5=Thomas L.|last6=Yaghi|first6=Omar M.|last7=O'Keeffe|first7=Michael|title=Synthesis and Characterization of Zirconogermanates|journal=Inorganic Chemistry|volume=42|issue=19|year=2003|pages=5954–5959|issn=0020-1669|doi=10.1021/ic034298g}}

2 : Germanates|Oxyanions
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