Mono and dinuclear half-sandwich platinum group metal complexes bearing pyrazolyl-pyrimidine ligands: Syntheses and structural studies

Reactions of 0.5 eq. of the dinuclear complexes [(η6-arene)Ru(μ-Cl)Cl]2 (arene = η6-C6H6, η6-p-iPrC6H4Me) and [(Cp∗)M(μ-Cl)Cl]2 (M = Rh, Ir; Cp∗ = η5-C5Me5) with 4,6-disubstituted pyrazolyl-pyrimidine ligands (L) viz. 4,6-bis(pyrazolyl)pyrimidine (L1), 4,6-bis(3-methyl-pyrazolyl)pyrimidine (L2), 4,6-bis(3,5-dimethyl-pyrazolyl)pyrimidine (L3) lead to the formation of the cationic mononuclear complexes [(η6-C6H6)Ru(L)Cl]+ (L = L1, 1; L2, 2; L3, 3), [(η6-p-iPrC6H4Me)Ru(L)Cl]+ (L = L1, 4; L2, 5; L3, 6), [(Cp∗)Rh(L)Cl]+ (L = L1, 7; L2, 8; L3, 9) and [(Cp∗)Ir(L)Cl]+ (L = L1, 10; L2, 11; L3, 12), while reactions with 1.0 eq. of the dinuclear complexes [(η6-arene)Ru(μ-Cl)Cl]2 and [(Cp∗)M(μ-Cl)Cl]2 give rise to the dicationic dinuclear complexes [{(η6-C6H6)RuCl}2(L)]2+ (L = L1, 13; L2, 14; L3, 15), [{(η6-p-iPrC6H4Me)RuCl}2(L)]2+ (L = L1, 16; L2, 17; L3, 18), [{(Cp∗)RhCl}2(L)]2+ (L = L1, 19; L2, 20; L3, 21) and [{(Cp∗)IrCl}2(L)]2+ (L = L1 22; L2, 23; L3 24). The molecular structures of [3]PF6, [6]PF6, [7]PF6 and [18](PF6)2 have been established by single crystal X-ray structure analysis.