ISSN:
1572-8862
Keywords:
Carboxylate
;
molybdenum
;
mixed valence
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Abstract From the reaction or Mo2Cl6(THF)3 with excess of NaO2CPh and PEt3 in THF three types of crystals have been obtained and recrystallized in CH2Cl2. They are brown compound Mo2(O2CPh)6(PEt3)2·2CH2Cl2 (1), yellowβ-Mo2(O2CPb)4 (2), and black Mo4O6(O2CPh)6(PEt3)2.CH2Cl2 (3). When a strict ratio of MO2Cl6(THF)3:NaO2CPh = 1:2 was applied, Mo2(O2CPh)4(THF)2, (4) was the only compound separated from the THF reaction mixture. Their structures have been determined by X-ray crystallography. There are three coordination modes of benzoate in 1: bridgingη 2-O2CPh, bridgingη 1-O2CPh and terminal O2CPh groups. Compound 2 is chemically well known, but was found to pack differently from the previously reported structure. Mo4O6(O2CPh)6(PEt3)2·CH2C12 (3) is a mixed-valence Mo (IV, V) tetranuclear compound in a butterfly arrangement. A molecule of 4 is actually a MO2(O2CPh)4 molecule with two THIF molecules axially coordinating to the molybdenum atoms. The crystallographic data for these compounds are as follows: 1, triclinicPl witha = 11.612(3) Å, b = 11.970(2) Å,c=12.135(3) Å,α=95.55(2)°,β=117.51(2)°,γ98.84(2)°,V=l450.8(7) Å3,Z=1,R=0.0673, and R w ,=0.0936; 2, monoclinicP21/n witha = 14,437(2) Å,b=5.6168(7) Å,c=15.979(3) Å,β=93,93(l)°,V=1292.7(4) Å3,Z=2,R=0.0217, and Rw=0.0352; 3, trigonal (hexagonal setting)R3¯ witha=28.83(4) Å,c=44.98(2) Å,V=323570(10) Å3,Z=18,R=0.067, andwR2=0203; 4 monoclinicP21/c witha=9.456(4) Å,b=17.757(8) Å,c=10.887(3) Å,β=109.63(2)°,V=1722(2)Å3 Z=2,R=0.0330, andR w = 0.0451.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01175835
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