Bis(1-methyluracilato-N3)-cis-diammineplatinum(II)-4-Water and Bis(μ-1-methyluracilato-N3,O4)-cis-diammineplatinum(II)diaquocopper(II) Sulfate-4.5-Water (Head-Head). Preparation, Crystal Structures, and Implications for the Formation of Heteronuclear Pt,M Complexes

Article abstract of DOI:10.1021/ja00388a020

The syntheses and crystal structures of two complexes of 1-methyluracil are reported. cis-Pt(NH3)2(1-MeU)2-4H2O (2) crystallizes in space group C2/c with cell parameters a = 26.822 (14) Angstroem, b = 7.030 (2) Angstroem, c = 20.044 (9) Angstroem, and β = 96.36 (4) deg and has eight formula units in the unit cell.The structure was refined on 2416 reflections to R₁ = 0.038 and R₂ = 0.044. 1-Methyluracil anion ligands, 1-MeU, exhibit N3 platinum binding and are arranged in head-tail fashion.With Cu(II), 2 forms heteronuclear complexes of Pt:Cu = 1:1 and 2:1 stoichiometries, depending upon the applied Pt:Cu ratio and the anions present.The crystal structure of one of these complexes has been determined. cis-SO4-4.5H2O (4) crystallizes in space group P1/ with cell parameters a = 10.398 (10) Angstroem, b = 10.773 (8) Angstroem, c = 11.772 (9) Angstroem, α = 102.88 (6) deg, β = 102.62 (7) deg, and γ = 105.05 (7) deg and has two formula units in the unit cell.The structure was refined on 3028 reflections to R₁ = 0.091 and R₂ = 0.096.Pt and Cu have square-planar coordination spheres and are linked through two 1-MeU ligands in a head-head arrangement, binding to Pt via N3 and to Cu via O4.The coordination spheres are completed by two NH3 ligands (Pt) and two H2O groups (Cu), each in cis arrangements.The Pt-Cu distance within the cation is 2.765 (3) Angstroem.Related heteronuclear Pt, Cu complexes of 2:1 stoichiometries and varying anions have been prepared and reasons for their formation are discussed.Possibilities for the formation of homonuclear Pt_x and heteronuclear Pt_x, M_y complexes with long metal chains are outlined.