Thiocyanate, Thiourea, and Dithiooxamide Complexes of Ruthenium Ruth Powers Yaffe Iowa State College
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Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1951 Thiocyanate, thiourea, and dithiooxamide complexes of ruthenium Ruth Powers Yaffe Iowa State College Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Physical Chemistry Commons Recommended Citation Yaffe, Ruth Powers, "Thiocyanate, thiourea, and dithiooxamide complexes of ruthenium " (1951). Retrospective Theses and Dissertations. 14185. https://lib.dr.iastate.edu/rtd/14185 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. 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ProQuest Information and Learning 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA 800-521-0000 NOTE TO USERS This reproduction is tlie best copy availabie. UMI* THIOCYANATE, THIOUREA, AND DITHIOOXAMIDE COMPLEXES OP RUTHENIUM by Ruth Pov;ers Yaffe A Dissertation Submitted to the Graduate Faculty in Partial Pulfillment of The Requirements for the Degree of DOCTOR OP PHILOSOPHY Major Subject: Physical Chemistry Approved: Signature was redacted for privacy. Signature was redacted for privacy. Head of Major Department Signature was redacted for privacy. Dean o^t Graduate College Iowa State College 1951 UMI Number: DP13067 UMI® UMI Microform DP13067 Copyright 2005 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ' ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 u / / 0 - ii - TABLE OP CONTENTS Page I. INTRODUCTION 1 II. REVIEW OP LITERATURE 2 A. Ruthenium Chemistry in General .... 2 B. Thiocyanate as a Complexlng Agent ... 6 C. Thiourea as a Complexlng Agent .... 10 D. Dithiooxamide as a Complexlng Agent . l4 III. INSTRUMENTS 1? IV. MATERIALS 19 A. Ruthenium rv Perchlorate 19 B. Ruthenium III Perchlorate 25 C. Sodium Thiocyanate 27 D. Thiourea 28 E. Dithiooxamide 30 P. Miscellaneous ...... 33 V. METHOD OP INTERPRETATION OP DATA 3^ VI. EXPERIMENTAL INVESTIGATIONS 47 A. Ruthenium-Thiocyanate System 47 B. Ruthenium-Thiourea System . 66 C. Ruthenium-Dithiooxamide System .... 103 VII. SUMMARY AND CONCLUSIONS 127 VIII. LITERATURE CITED . 132 IX. ACKNOWLEDGEMENTS 13T r/oiss - 1 - I. INTRODUCTION Ruthenium is one of the large group of elements present in the fission products. It is represented by several activities, among them Ru^^^ which has a 1.0 year half-life and, by reason of its 30 second daughter activity, has a fairly high energy of radiation. The specific interest in its active isotopes, together with the general lack of knowledge about its chemistry, has given strong impetus to the study of all aspects of the chemistry of ruthenium. As is to be expected of a transition element, ruthenium, in its +2, +3, and +4 oxidation states, forms numerous coordination compounds. Many of these coordination com pounds which have stable crystalline states have been studied, but virtually no Investigations have been carried out on the fundamental nature of ruthenium complexes stable only in solution. It is the purpose of this work to study, by means of spectrophotometry, three colored complexes of ruthenium which are stable only in solution. The investigation has as its immediate objective the determination of the formulae and the stability constants of these complexes. In this way, it is hoped that another small fragment will be added to our knowledge of the fundamental chemistry of ruthenium, and to the more general topic of the nature of complexes in solution. - 2 - II. REVIEW OP LITERATURE A. Ruthenium Chemistry In General The chemistry and literature of ruthenium, prior to 19^8, have been reviewed by Deford (1) In his thesis The Chemistry of Ruthenium. His bibliography, containing more than 250 entries. Is exceedingly useful since, previously, no complete and critical review of the chemistry of ruthe nium had ever been published. In his extensive review, Deford (1) surveyed the general chemistry of ruthenium. Then he discussed at length ruthenium metal, ruthenium oxides and hydroxides, ruthenates and perruthenates, halogenldes and halogen com plexes, ruthenium ammlnes, carbon compounds, sulfur com pounds, nitrogen compounds, and cyanide complexes. To supplement this survey, Deford performed many experiments in order to corroborate the findings reported in the litera ture or to serve as a basis for deciding between conflicting reports. The discovery of ruthenium is generally credited to C. Claus who extracted the pure metal from platinum residues in 1844. The name ruthenium, derived from Ruthenia, meaning Russia, was given to the element by G. W. Osann in I827. The compounds that Osann obtained were very impure and did not establish the existence of the element with certainty. - 3 - Ruthenium Is found In platinum ores to the extent of a few per cent. The metal Is very resistant to attack by acids. Including aqua regia, but it is quite rapidly attacked by molten hydroxides. The atomic weight for ruthenium accepted in 19^9 by the International Union for Chemistry is 101.7. This is based on the ratio of ruthenium to oxygen in ruthenium dioxide, and is probably high since the dioxide is usually contaminated by traces of metallic ruthenium. The atomic weight found from analysis of highly purified chloro- pentammlneruthenlum III chloride is 101,1. Ruthenium is unique among elements in that it exhibits all possible oxidation states from 0 to +8. The zero state is considered to exist in such com pounds as the carbonyls. The existence of monovalent ruthenium has been estab lished from the carbonyl halogenldes, such as Ru(C0)Br. The bivalent state is well established. With very strong reducing agents, the deep-blue ruthenium II chloride may be obtained. Although ruthenium II is very unstable, many stable complex compounds of bivalent ruthenium such as trlsdipyridylruthenium II chloride have been prepared. The trlvalent state is probably the most typical of ruthenium. Ruthenium III forms complex salts with many acid radicals including chloride, sulfate, nitrate, nitrite. _ 4 _ and oxalate. Both the simple and complex salts are exten sively hydrolyzed In solution. Trivalent ruthenium in solu tion is easily oxidized to the tetravalent state. Hydrous ruthenium III oxide is slowly precipitated from solutions of ruthenium salts by the addition of alkaline hydroxides. It is readily oxidized to ruthenium dioxide. Of the lower valence states, the most stable in solu tion is ruthenium IV. Like trivalent ruthenium, tetra valent ruthenium forms numerous complex compounds. Both the simple and complex salts are extensively hydrolyzed in solution. Ruthenium in these compounds is easily re duced to the trivalent state. When solutions of the salts of tetravalent ruthenium are treated with alkaline hydrox ides, hydrous ruthenium dioxide is slowly precipitated. The dioxide shows no acidic properties and does not form ruthenites. If any generalities may be drawn about the relative stabilities of the trivalent and tetravalent states, it may be said that ruthenium III is the more stable in solid phase, whereas ruthenium IV is the more stable in solution. However ruthenium III is greatly stabilized by complex formation. The only known compound of pentavalent ruthenium is the very unstable fluoride, RuP^, formed by the action of fluorine on ruthenium at elevated temperatures. - 5 - The most Important compounds of hexavalent ruthenium are the ruthenates, M2RuOj^, formed when ruthenium tetroxlde Is absorbed in solutions of metal hydroxides. The alkali ruthenates readily dissolve in water to give orange-colored solutions which are unstable, decomposing slowly to give the hydrous dioxide and oxygen. The only known compounds of heptavalent ruthenium are the perruthenates which are prepared by absorbing ruthenium tetroxlde in solutions of ruthenates. Although the solid perruthenates are relatively stable, the aqueous solutions rapidly decompose to ruthenates, ruthenium dioxide, and oxygen. Octavalent ruthenium is known only as the tetroxlde, RuO]|., which is formed when acid solutions of ruthenium salts are acted upon by very strong oxidizing agents. The com pound is quite volatile, and has a characteristic unpleasant odor resembling ozone. The dry compound is stable