Synthesis and crystal structure of platinum blue [(1,10-phen)Pt(μ-NHCOCH3)2Pt(1,10-phen)]2(NO3)4

The reaction of acetamide with PtphenCl(2) gave a mixed-valence black-brown-colored platinum complex Ptphen(NHCOCH3)NO3 (I), which was studied by X-ray diffraction. The monoclinic crystal (a = 16.389(6) angstrom, b = 19.664(6) angstrom, c = 11.049(4) angstrom; beta = 122.8(3)degrees, V = 2993(18) angstrom(3), space group C2/m, Z = 4, R = 0.0432) is built of dimeric [Pt(2)phen(2)(NHCOCH3)(2)](2+) cations and NO3- . anions. Each platinum atom in the dimer is linked to two nitrogen or oxygen atoms of the two bridging (NHCOCH3)(-) groups and two phenanthroline nitrogen atoms. The Pt-Pt distance in the dimer is 2.8891(19) angstrom. In the crystal, the dimers form pairs (tetramers), the interdimer Pt center dot center dot center dot Pt distance being 3.167(2) angstrom. Four platinum atoms are arranged nearly linearly (the Pt(2)Pt(1)Pt(1)* angle is 178.71(4)degrees). The UV-Vis spectrum of an aqueous solution of compound I exhibits bands at 360, 480, 630, 680, and 880 nm in the visible region. The diffuse reflectance spectrum of a polycrystalline sample of I (in the 300-900 nm range) contains bands at similar to 360, similar to 500, similar to 600, similar to 690, and similar to 890 nm.