Formation, dynamic behavior, and chemical transformation of Pt complexes with a rotaxane-like structure

The reaction of [Pt(CH2COMe)(Ph)(cod)] (cod=1,5-eyclooctadiene) with (ArCH2NH2CH2C6H4COOH)+(PF6)(-) (Ar=4-tBuC(6)H(4) or 9-anthryl) in the presence of cyclic oligoethers such as dibenzo[24]crown -8 (DB24C8) and dicyclohexano[24]crown-8 (DC24C8) produces {(ce) [ArCH2NH2CH2C6H4COOPt(Ph)(cod)]}(+)(PF6)(-) (ce=DB24C8 or DC24C8, Ar=4-tBuC(6)H(4) or 9-anthryl) with interlocked structures. FABMS and NMR spectra of a solution of these compounds indicate that the Pt complexes with a secondary ammonium group and DB24C8 (or DC24C8) make up the axis and cyclic components, respectively. Temperature-dependent H-1 NMR spectra of a solution of {(DB24C8)[4-tBuC(6)H(4)CH(2)NH(2)CH(2)C(6)H(4)COOPt(Ph)(cod)]}(+)(PF6)(-) ({(DB24C8)[4-H])(+)(PF6)(-)) show equilibration with free DB24C8 and the axis component. The addition of DB24C8 to a solution of {(DC24C8)[4-H]}(+) (PF6)(-) causes partial exchange of the macrocyclic component of the interlocked molecules, giving a mixture of {(DC24C8)[4-H]}(+)(PF6)(-), ((DB24C8)[4-H]}(+)(PF6)(-), and free macrocyclic compounds. The reaction of 3,5-Me2C6H3COCl with {(DB24C8)[4-H]}(+) (PF6)(-) affords the organic rotaxane {(DB24C8)(4-tBuC(6)H(4)CH(2)NH(2)CH(2)C(6)H(4)COOCOC(6)H(3)Me(2)-3,5)}(+)(PF6)(-) through C-O bond formation between the aroyl group and the carboxylate ligand of the axis component. The addition of 2,2'-bipyridine (bpy) to a solution of ((DB24C8)[4-H])+(PF6)(-) induces the degradation of the interlocked structure to form a complex with trigonal bipyramidal coordination, [Pt(Ph)(bpy)(cod)](+)(PF6)(-), whereas the reaction of bpy with [Pt(OCOC6H4Me-4)(Ph)(cod)] produces the square-planar complex [Pt(OCOC6H4Me-4)(Ph)(bpy)].