Synthesis, characterization and x-ray crystal structure determination of platinum(II)-diaminoalkane complexes

Abstract

This study describes the synthesis and characterization of two new compounds, i.e. [Pt(en)(DMSO)Cl][Pt(DMSO)Cl 3] ( 2) and [Pt(bn) 2]Cl 2 ( 3), which were isolated from reactions of cis-[Pt(DMSO) 2Cl 2] ( 1) with 1,2-diaminethane (en) and 1,4-diaminobutane (bn), respectively. The complexes 2 and 3 were characterized by NMR, IR and elemental analysis, and their molecular structures have been determined by X-ray crystallographic analysis. Compound 2 crystallizes in the monoclinic space group P2 1/ n with a = 8.093(1), b = 7.599(2), c = 28.041(5) Å, β = 91.09(2)° and Z = 4 (dinuclear units. The structure consists of hydrogen bonded pairs of [Pt(en)(DMSO)Cl] + cations and [Pt(DMSO)Cl 3] − anions with the PtPt distance of 3.655(1) Å. The five-membered ring of the Pt-1,2-diaminoethane ligand has a C1-envelope conformation. Also observed is the normal trans influence of coordinated DMSO, as reflected in significantly longer Pt-ligand bonds trans to this ligand. Compound 3 crystallizes in the orthorhombic space group Pnma with a = 11.231(3), b = 8.045(2), c = 16.998(3) A ̊ and Z = 4 . The structure is composed of the bis(1,4-diaminobutane) platinum(II) cation and two uncoordinated chloride ions all located in special positions in the unit cell; the Pt and both chloride ions lie on the mirror plane perpendicular to the y-axis. Each of the two bn ligands is statistically disordered across a mirror plane over two conformations with 50% occupancy, while the seven-membered chelate ring of the Pt-bn adopts a twist-chair conformation. The cations with a unique ‘spider-like’ shape are hydrogen bonded to chloride ions in a three-dimensional network in the crystal lattice.