Mono- and diprotonation of the superbasic bisguanidine 1,2-Bis(N,N,N',N'-tetramethylguanidino)benzene (btmgb) and Pt II and Pt IV complexes of chelating bisguanidines and guanidinates

New Pt complexes of chelating bisguanidines and guanidinate ligands were synthesized and characterized. 1,2-Bis(N,N,N',N'-tetramethylguanidino)benzene (btmgb) was used as a neutral chelating bisguanidine ligand, and 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinate (hpp(-)) as a guanidinate ligand. The salts [btmgbH](+)[HOB(C(6)F(5))(3)](-) and [btmgbH(2)]Cl(2) and the complexes [(btmgb)PtCl(2)], [(btmgb)PtCl(dmso)](+)[PtCl(3)(dmso)](-), and [(btmgb)PtCl(dmso)](+)[Cl(-)] were synthesized and characterized. In the [btmgbH](+) cation the proton is bound to only one N atom. In the other complexes, both imine N atoms are coordinated to the Pt(II), thus adopting a eta(2)-coordinational mode. The hpp(-) anion, which usually prefers a bridging binding mode in dinuclear complexes, is eta(2)-coordinated in the Pt(IV) complex [(eta(2)-hpp)(hppH)PtCl(2){N(H)C(O)CH(3)}], which is formed (in low yield) by reaction between cis-[(hppH)(2)PtCl(2)] and H(2)O(2) in CH(3)CN.