Unique Axial Interacation of a Quadruply-Bonded Cr(II)-Cr(II) with Two Pt(II) Atoms in the Linearly Aligned Pt-Cr-Pt Supported by Four 6-Diphenylphosphino-2-pyridonate Ligands

摘要

Linearly aligned tetranuclear Pt(ll)-Cr(ll)-Cr(ll)-Pt(ll) complexes were prepared using a tridentate pyphos ligand (pyphos = 6-diphenylphosphino-2-pyridonate). The bonding between Cr(ll) and Pt(ll) was discussed on the basis ofmag- netic measurements. A dichromium complex, [Cr_2(PYphos)_4] (I), was prepared by the reaction of [Cr_2(OAc)_4] with the sodium salt of pyphos ligand. The complex I has four phosphorus atoms capable of holding transition metals at both of the axial positions of the Cr_2 moiety. Three tetranuclear Pt(ll)-Cr(ll)-Cr(ll)-Pt(ll) complexes, i.e., [Cr_2Pt_2Me_4(PYphos)_4] (2), [Cr_2Pt_2C_4(pyphos)4] (3), and [Cr_2Pt_2CI_2Me_2(PYphos)_4] (4), have been prepared by the addition of the respective plat- inum species, ptllMe_2, pt1lC1_2, and ptllMeCl, to the axial positions of the Cr_2 moiety of I. Magnetic measurements of 1-4 together with a crystallographic study for the complexes I and 2 revealed that the quadruply-bonded Cr-Cr distance was delicately altered by the nature of the Pt atoms, i.e., the kind of substituents (Cl and/or Me) on the Pt atoms.