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(C6F5)(3)](-) and [btmgbH(2)]Cl-2 and the complexes [(btmgb)PtCl2], [(btmngb)PtCl(dmso)](+)[PtCl3(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)PtCl2{N(H)C(O)CH3}], which is formed (in low yield) by reaction between cis-[(hppH)(2)PtCl2] and H2O2 in CH3CN.