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Title: New pathways to tungsten and molybdenum oxides, nitrides and azides

Abstract

This research effort focused on the use of both inorganic solution synthesis of molecular precursors and solid state reactions involving molecular compounds to yield desired condensed materials. Two types of molecular compounds have been investigated. First, trichloronitridotungsten(VI) ([WNCl[sub 3]][sub 4]) has been prepared using an improved synthetic approach and characterized structurally by single crystal X-ray diffraction techniques. [WNCl[sub 3]][sub 4] crystallizes in the space group P1 as planar 8- membered W-N rings interconnected through chloride bridges. The inter-tetramer linkage is weak and broken easily to accommodate basic ligands in the site trans to the W-N triple bond. The reactivity of WNCl[sub 3], with nitriding agents, such as ammonia, ytrimethylsilylazide and lithium nitride, has been investigated, which resulted in the preparation and spectroscopic identification of new tungsten azido and nitrido compounds. Second, the reactivity of the metal dimers Mo[sub 2] (O[sub 2]CCH[sub 3])[sub 4] and Mo[sub 2]Cl[sub 4]py[sub 4] with trimethylsilylazide has been explored, and the reactions in pyridine were found to yield a material corresponding to the formulation MoN (N[sub 3])py. Thermolytic decomposition of this azide at 280[degrees]C was performed under argon, dynamic vacuum or ammonia. The thermal decomposition in ammonia was found to produce a molybdenum nitride relatively freemore » of carbon (5%, compared to 24% in materials decomposed in inert environments) with a Mo:N ratio of 1:1.8. Through the use of solid state reactions, WNCl[sub 3] was converted into a hexagonal ammonium tungsten bronze, (NH[sub 4])[sub 0.28]WO[sub 3[minus]y] (NH)[sub y]. Relative to conventional preparations, this new ammonium bronze synthesis increased the probability of isoelectronic imido substitution for oxide in the bronze framework.« less

Authors:
Publication Date:
Research Org.:
Iowa State Univ. of Science and Technology, Ames, IA (United States)
OSTI Identifier:
6973748
Resource Type:
Miscellaneous
Resource Relation:
Other Information: Thesis (Ph.D.)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; AZIDES; CHEMICAL PREPARATION; MOLYBDENUM NITRIDES; MOLYBDENUM OXIDES; TUNGSTEN NITRIDES; TUNGSTEN OXIDES; CHEMICAL REACTION KINETICS; SEMICONDUCTOR MATERIALS; CHALCOGENIDES; KINETICS; MATERIALS; MOLYBDENUM COMPOUNDS; NITRIDES; NITROGEN COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; PNICTIDES; REACTION KINETICS; REFRACTORY METAL COMPOUNDS; SYNTHESIS; TRANSITION ELEMENT COMPOUNDS; TUNGSTEN COMPOUNDS; 400201* - Chemical & Physicochemical Properties; 360201 - Ceramics, Cermets, & Refractories- Preparation & Fabrication

Citation Formats

Close, M R. New pathways to tungsten and molybdenum oxides, nitrides and azides. United States: N. p., 1992. Web.
Close, M R. New pathways to tungsten and molybdenum oxides, nitrides and azides. United States.
Close, M R. Wed . "New pathways to tungsten and molybdenum oxides, nitrides and azides". United States.
@article{osti_6973748,
title = {New pathways to tungsten and molybdenum oxides, nitrides and azides},
author = {Close, M R},
abstractNote = {This research effort focused on the use of both inorganic solution synthesis of molecular precursors and solid state reactions involving molecular compounds to yield desired condensed materials. Two types of molecular compounds have been investigated. First, trichloronitridotungsten(VI) ([WNCl[sub 3]][sub 4]) has been prepared using an improved synthetic approach and characterized structurally by single crystal X-ray diffraction techniques. [WNCl[sub 3]][sub 4] crystallizes in the space group P1 as planar 8- membered W-N rings interconnected through chloride bridges. The inter-tetramer linkage is weak and broken easily to accommodate basic ligands in the site trans to the W-N triple bond. The reactivity of WNCl[sub 3], with nitriding agents, such as ammonia, ytrimethylsilylazide and lithium nitride, has been investigated, which resulted in the preparation and spectroscopic identification of new tungsten azido and nitrido compounds. Second, the reactivity of the metal dimers Mo[sub 2] (O[sub 2]CCH[sub 3])[sub 4] and Mo[sub 2]Cl[sub 4]py[sub 4] with trimethylsilylazide has been explored, and the reactions in pyridine were found to yield a material corresponding to the formulation MoN (N[sub 3])py. Thermolytic decomposition of this azide at 280[degrees]C was performed under argon, dynamic vacuum or ammonia. The thermal decomposition in ammonia was found to produce a molybdenum nitride relatively free of carbon (5%, compared to 24% in materials decomposed in inert environments) with a Mo:N ratio of 1:1.8. Through the use of solid state reactions, WNCl[sub 3] was converted into a hexagonal ammonium tungsten bronze, (NH[sub 4])[sub 0.28]WO[sub 3[minus]y] (NH)[sub y]. Relative to conventional preparations, this new ammonium bronze synthesis increased the probability of isoelectronic imido substitution for oxide in the bronze framework.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1992},
month = {1}
}

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