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 [btmgbH2]Cl2 and the complexes [(btmgb)PtCl2], [(btmgb)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 eta2-coordinational mode. The hpp(-) anion, which usually prefers a bridging binding mode in dinuclear complexes, is eta2-coordinated in the Pt IV complex [(eta2-hpp)(hppH)PtCl2(N(H)C(O)CH3)], which is formed (in low yield) by reaction between cis-[(hppH)2PtCl2] and H2O2 in CH3CN.