Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1961 Higher Oxidation States of Silver. Magdalena Usategui Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Usategui, Magdalena, "Higher Oxidation States of Silver." (1961). LSU Historical Dissertations and Theses. 658. https://digitalcommons.lsu.edu/gradschool_disstheses/658 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. I This dissertation has been Mic 61—2129 microfilmed exactly as received USATEGUI, Magdalena. HIGHER OXIDATION STATES OF SILVER. Louisiana State University, Ph.D., 1961 Chemistry, inorganic University Microfilms, Inc., Ann Arbor, Michigan HIGHER OXIDATION STATES OP SILVER A Dissertation Submitted to tbe Oraduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Chemistry by Magdalena Dsategui B.S., Louisiana State University, 1956 M.S., Louisiana State University, 1956 January, 1961 ACKNOWLEDGEMENT The author wishes to express her sincere gratitude for the advice and assistance of Dr. Joel Selbin under whose direction this work was conducted. Thanks are also due to Dr. M. C. Day for the use of his magnetic balance and to George Sexton for his help and assistance in working with the x-ray and infrared instruments. The author gives special thanks to Aurora F. de Castro for many stimulating discussions and for her constant encouragement throughout the course of this research. Special thanks are also eiven to Camille Delaquis for her help in the typing of this work. The author is also very grateful to the Research Corporation for their financial support. ii TABLE OF CONTENTS ACKNOWLEDGMENT ii LIST OF TABLES ▼ LIST OF FIGURES ▼i ABSTRACT vii INTRODUCTION 1 EXPERIMENTAL 1U A. Study of Higher Oxides of Silver lii 1. Reagents 11* 2. General Procedure 11* 3. Analyses 15 U. Physical Measurements 20 5. Analyses and Physical Measurements Results 2U B. Search for New Ligands to Stabilise Silver (II) 59 1. Preparation of Ligands 59 2. Preparation of Silver (I) Complex Salts 60 3. Preparation of Silver (II) Complex Salts 66 DISCUSSION A. Silver Fluoride and Silver Acetate 72 B. Silver Perchlorate 76 C. Silver Nitrate 81 D. Silver Sulfate 85 E. Replacement of Silver (II) 86 iii TABLE OF CONTENTS (Continued } Page F. pH Changes 87 Q. Silver (II) Stabilisation 88 H. The -HIC-CIN- Group as a Ligand for Silver (II) 92 I. Bis-(pyridlnaldazine) silver (I) nitrate 93 fill. SUGGESTIONS FOR FURTHER WORK 9$ IX. BIBLIOGRAPHY 97 X. VITA 103 LIST OF TAB LBS Paco I. AffOgNO, X-Ray Diffraction Data 28 II. Ag704N0) X-Ray Diffraction Data 30 III. Ag70aK0s X-Ray Diffraction Data 3$ IT. Ag704M0s X-Ray Diffraction Data 36 T. A(j04 .AgO X-Ray Diffraction Data liO TI. Ag»04.Ag0 X-Ray Diffraotion Data U2 VII. AgO X-Ray Diffraction Data U5 VIII. AgO X-Ray Diffraction Data ue IX.. Calibration Data U9 X. Calibration Data k9 XI. Magnetic Susceptibility Data 51 XII. Magnetic Susceptibility Data 51 XIII. Mixture of Ag70s504 and a Cd** Compound X-Ray Diffraction Data 5U XIV. Mixture of Ag70sS04 and a Cd*+ Coapound X-Ray Diffraction Data 56 XT. Mixture of Ag»04 .AgO and a Cd4"* Conpound 5? XTI. Ligands Deed 61 XVII. Effect of Oxidising Agent on tha Silver (I) Salts 69 XVIII. Suaaary of Data on Higher Oxides of Silrer 73 XIX. X-Ray Data on AgO 75 xx. X-Ray Data on Ag*0s.2Ag0 78 XXI. Suaaary of X-Ray Data on Hi (her Oxides of Silver 8U ▼ LIST or FIOURES Figura Paga 1 Magaatle Balanea 23 2 Graph of Volaaa Saaeaptlbilitlaa Varan* Araraga Dagraaa Turnad $0 ▼i ABSTRACT The use of ozone as an oxidising agent to obtain higher oxidation states of silver has been investigated. When ozone is bubbled through aqueous solutions of simple silver salts, black compounds of silver in higher oxidation states are formed. A study has been made to establish the composition, structure and stability of the black precipitates. All available soluble silver salts whose anions are not oxidized by ozones silver nitrate, silver sulfate, silver perchlorate, silver acetate and silver fluoride were reacted with ozone in aqueous solutions. The compositions of the precipitates formed were determined to be, respectively, Ag708N03, Ag70eS04 , Ag408, AgO and AgO. Chemical analysis, determination of oxidising power and infrared spectral data were used to establish their composition. X-ray powder diffraction studies were used to characterize the structure of the compounds. A spinel type of structure similar to magnetite, Fe304 , has been proposed for the products obtained which contain part of the silver in an oxidation state higher than two. An attempt was made to substitute other divalent cations for the silver (II) ion in the precipitates obtained from the nitrate, sulfate and perchlorate solutions. Precipitates were obtained containing some Cd++ but in amounts too small to make conclusive statements. vii Varying the time of ozonlzation had no influence on the composition of the products obtained* Studies of the room temperature stability of the oxidised products obtained from silver nitrate, silver sulfate and silver perchlorate solutions showed that the stability drops off in the order given with the last being very unstable* It is suggested that the presence of AgNOa and AgS04 , re­ spectively, in the first two confers added stability which is lacking in the third, which does not contain AgC104 . Magnetic susceptibility measurements have given variable results for the molar susceptibilities of these compounds. It is suggested that the phenomenon being observed Is not normal paramagnetism but rather ferrimagnetism or possibly antiferromagnetism. Chemical analyses and x-ray data es­ tablished the same composition and structure for compounds of variable molar magnetic susceptibilities. A search was made to find new ligands which would stabilise silver (II) but it was not successful. Osone and potassium peroxydisulfate were used as oxidizing agents. The preparation of four new silver (I) complexes is reported. They are* Bis-(bensalethylenedilmlne) silver (I) nitrate, Bis-(2 pyridinaldasine) silver (I) nitrate, tetrakis(triphenylphosphine) silver (I) perchlorate and tetrakis(triphenylarsine ) silver (I) perchlorate. viii INTRODUCTION Except for a few, not well characterised higher oxides of silver, there are no other reports in the literature of simple compounds containing trivalent silver. Reports on these conpounds are contradictory. Lately, there has been a renewed Interest in this field, undoubtedly caused by the confused state of the literature and the importance of stu­ dying higher oxidation states of such a common metal as silver. When an aoueous solution of silver nitrate is electrolysed under certain conditions, a black compound of silver is formed at the anode. This compound was first described as far back as 1801* (67). Many people since then have tried to establish its composition. Today, 156 years later, still little agreement can be found in the literature. Boee (10) determined the decomposition point for silver nitrate and silver sulfate solutions. Only one potential break was found for each solution and she concluded that only one compound is formed at the anode in each case. She made no analysis because she considered that it was impossible to get accurate results. Luther and Pokorny (3P) prepared the so-called peroxy- nltrates and peroxysulfates and reduced them at constant current in normal caustic soda. Three definite potentials were observed against the hydrogen electrode in normal caus­ tic soda, one at 1*57 volts, a second at 1.1*1 volts, and a third at 1.17 volts. The second and third correspond to the AgaOa-AgaO and AgaO-Ag stages respectively. Tha value of 1.57 volts must correspond to a higher oxide to which they assigned the formula AgaOa . Since the sane curves were obtained with the peroxynitrate and peroxysulfate, Luther and Pokorny, like Bose, concluded that neither silver sulfate nor silver nitrate is an Integral part of the compound, which was therefore concluded to be an impure oxide of silver. Other earlier investigators of the black product, however, have shown by chemical analysis of the orecipltate, that its composition may be expressed by the formula AFtOqROj (UUi 6U, 66, 67). Brown (12), in a very careful comparison of the copper-silver coulometers ratios, together with determinations of the composition of the crystals, decided upon the formula 2Aga04 .AgNOa. Weber (68), discussed the probable valence of silver in the oxide part of the formula 2Aga04 .AgNOa, writing it either AgaAg04 by analogy to the magnetic iron oxide. His various electrolytic experiments led him to conclude that the last formula, Ag(AgOa )a in whioh one third of the silver is cathodic and divalent and two thirds anodic and trivalent, is in harmony with his experimental results• Jlrsa (29)f subjected pulverised silver to the action of dry osone. The black material obtained from KOH solution gave 1.57 volts which dropped to 1,1*3 in 20 minutes. The potential remained constant at the value of lJi3 corresponding to AgaOa . The initial eaf.of 1.57 volts Indicated the presence of AgaOa. He considered the product of oxidation with osone of Ag or AgaO as a solid ■olmtion of the following composition, xAgaOa *yAgaO a*sAgaO, tho relative proportion* of x, y, k , doponding upon tko conditions of tho oxidation* Barblori (p), stndiod tho prodnot fornod by dissolving AgO in oonoontrated HMO, to dotornino tho ratio of AgtO (active). A ratio of 1*1.5-1.6 was fonnd in all cases, indicating tho oxistonoo of AgaOt* Tho roaotlon botvoon silver (I) salts and osono la nitric aold solutions, has boon stndiod in groat dotall by Voyos and his eoworkors (k8, k9, 50, 51, $2).