Synthesis and characterization of N-methyliminodiacetato trans-R,R-, trans-S,S-, and cis-1,2-diaminocyclohexane platinum (IV) complexes: Crystal structure of chloro(trans-R,R-1,2-diaminocyclohexane) (N-methyliminodiacetato)platinum(IV) chloride

The compounds, chloro(trans-R,R-1,2-diaminocyclohexane)(N-methyliminodiacetato)platinum(IV) chloride, chloro(trans-S,S-1,2-diaminocyclohexane)(N-methyliminodiacetato)platinum(IV) chloride, and chloro(cis-1,2-diaminocyclohexane)(N-methyliminodiacetato)platinum(IV) chloride, were prepared and characterized by elemental analysis, IR, and ¹⁹⁵Pt NMR. The crystal structure of one of these three compounds, chloro(trans-R,R-1,2-diammocyclohexane)(N-methyliminodiacetato)platinum(IV) chloride, was determined by x-ray single crystal diffraction. This compound is particularly interesting because the 1,2-diaminocyclohexane (DACH) ring is in a twist-boat configuration rather than the chair configuration previously reported for other DACH platinum compounds. The crystal structure consists of two independent cations and anions, with all atoms between these two independent molecules (except those in the chiral DACH) related by a pseudo-inversion center. Both platinum atoms have slightly distorted octahedral coordination, with angles ranging from 81.8 to 100.8°. Crystallographic details: space group P2₁ (monoclinic); a = 19.864(5) Å, b = 7.026(2) Å, c = 12.446(3) Å, β = 106.62(2)°; Z = 4; R = 0.036 for 2333 reflections.