Crystal and Molecular Structure of a Potential DNA Groove-Spanning Chelate:  [MV][Pt₂(hdta)Cl₂]·4H₂O (MV²⁺ = 1,1‘-Dimethyl-4,4‘-bipyridinium, hdta^4- = 1,6-Hexanediamine-N,N,N‘,N‘-tetraacetate)

Abstract

Light yellow crystals of [MV][Pt(2)(hdta)Cl(2)].4H(2)O (1) (MV(2+) = 1,1'-dimethyl-4,4'-bipyridinium, hdta(4)(-) = 1,6-hexanediamine-N,N,N',N'-tetraacetate) were examined by X-ray diffraction. A 0.08 x 0.24 x 0.24 nm crystal was shown to have space group C2/c, having unit cell dimensions of a = 22.757(5) Å, b = 13.566(3) Å, and c = 12.120(2) Å and unit cell angles of alpha = gamma = 90 degrees and beta = 109.07(3) degrees with Z = 4. A total of 3195 independent reflections were refined to R = 0.0454. Each Pt(II) site has the anticipated NO(2)Cl square-planar mer coordination. The Pt-N(1) distance (N(1) is the N donor of the hdta(4)(-) ligand) is 2.001(9) Å, only slightly shorter than typical Pt-N distances (2.04-2.09 Å) for sp(3) donors. The Pt-O distances to the coordinated glycinato donors in 1 are 2.012(7) and 2.000(8) Å, values very similar to those of trans-[Pt(gly)(2)] (gly = glycinate). The Pt-Cl distance of 2.310(3) Å is in the range of 2.27-2.32 Å observed for other Pt(II)-Cl(-) bonds. The bond angles are close to the ideal 90 degrees or 180 degrees value: angleN-Pt-O = 85.4(3) degrees and 83.2(4) degrees; angleN-Pt-Cl = 176.6(2) degrees. The [Pt(2)(hdta)Cl(2)](2)(-) units are packed in an end-to-end fashion such that the [Pt(II)(iminodiacetate)Cl] headgroups are overlapping. This provides square-planar to square-planar stacking of the headgroups. (1)H and (13)C NMR data are presented which show that the [Pt(2)(hdta)Cl(2)](2)(-) coordination of the solid state is maintained in solution. The coordinated glycinato arms of [Pt(2)(hdta)Cl(2)](2)(-) are equivalent, exhibiting only one AB pattern in the (1)H NMR (H(a), 4.31 ppm; H(b), 3.89 ppm; J(ab) = 16.1 Hz) and one type of coordinated carboxylate ((13)C NMR resonance at 189.7 ppm). Time-dependent (1)H and (13)C NMR spectra show that inosine first displaces only Cl(-) in [Pt(2)(hdta)Cl(2)](2)(-) in solutions up to one inosine per Pt(II) center. A higher concentration of inosines (Ino) results in the displacement of one of the glycinato arms, detectable at 175.0 ppm by (13)C NMR. The sequential nature and binding of two Ino ligands, necessarily cis in [Pt(2)(hdta)(Ino)(4)], mimics the steps necessary to allow major groove-spanning ligation of DNA in the manner of the Farrell-type binuclear platinum(II) amine complexes.

Interaction of N-acetylmethionine with a non-C2-symmetrical platinum diamine complex

“…X-ray structures of complexes containing either a carbonyl or carboxyl oxygen atom coordinated to platinum were examined [15][16][17][18][19]. From these, a typical Pt-O bond distance of 2.01 Å was observed.…”

Thermodynamic and kinetic study of the interaction between the Pt(ii) centres in [Pt2(N,N,N′,N′-tetrakis(2-pyridylmethyl)diamine)(H2O)2]4+. Influence of the bridging ligand

“…13,16 However, in other cases such an interaction of the two bridged Pt() centres has been observed. 11, 17 There is not enough data in the literature on this topic to formulate a relationship between the reactivity of the two platinum centres and the nature of the bridging ligand.…”

Solvothermal Preparation, Crystal Structure, and Photoluminescence of a Cadmium Compound With a Two-Dimensional Supramolecular Layer

“…The 4,4 0 -bipy are dimethylized on the two nitrogen atoms and, in order to meet the requirement of charge balance, each nitrogen atom must have one positive charge (as the cases documented before [16][17][18] ) and therefore yields a N,N 0 -dimethyl-4,4 0 -bipyridinium moiety. The pyridyl rings of the bipy are twisted with a dihedral angle being of 39.693 (7) .…”