title: Thermal and chemical decomposition of di(pyrazine)silver(II) peroxydisulfate and unusual crystal structure of a Ag(I) by-product.
abstract: High purity samples of a [Ag(pyrazine)(2)]S(2)O(8) complex were obtained using modified synthetic pathways. Di(pyrazine)silver(II) peroxydisulfate is sensitive to moisture forming [Ag(pyrazine)(2)](S(2)O(8))(H(2)O) hydrate which degrades over time yielding HSO(4)(-) derivatives and releasing oxygen. One polymorphic form of pyrazinium hydrogensulfate, β-(pyrazineH(+))(HSO(4)(-)), is found among the products of chemical decomposition together with unique [Ag(i)(pyrazine)](5)(H(2)O)(2)(HSO(4))(2)[H(SO(4))(2)]. Chemical degradation of [Ag(pyrazine)(2)]S(2)O(8) in the presence of trace amounts of moisture can explain the very low yield of wet synthesis (11-15%). Attempts have failed to obtain a mixed valence Ag(II)/Ag(I) pyrazine complex via partial chemical reduction of the [Ag(pyrazine)(2)]S(2)O(8) precursor with a variety of inorganic and organic reducing agents, or via controlled thermal decomposition. Thermal degradation of [Ag(pyrazine)(2)]S(2)O(8) containing occluded water proceeds at T > 90 °C via evolution of O(2); simultaneous release of pyrazine and SO(3) is observed during the next stages of thermal decomposition (120-285 °C), while Ag(2)SO(4) and Ag are obtained upon heating to 400-450 °C.
authors.affiliation: ICM, The University of Warsaw, Żwirki i Wigury 93, 02-089, Warsaw, Poland. pleszcz@icm.edu.pl
authors.forename: Piotr J
authors.initials: PJ
authors.lastname: Leszczyński
authors.forename: Armand
authors.initials: A
authors.lastname: Budzianowski
authors.forename: Lukasz
authors.initials: L
authors.lastname: Dobrzycki
authors.forename: Michał K
authors.initials: MK
authors.lastname: Cyrański
authors.forename: Mariana
authors.initials: M
authors.lastname: Derzsi
authors.forename: Wojciech
authors.initials: W
authors.lastname: Grochala