ORGANOMETALLIC COMPLEXES WITH METAL-METAL BONDS XVI. SYNTHESIS OF NEW TRI- AND TETRAMETALLIC PLATINUM-MANGANESE COMPLEXES. CRYSTAL STRUCTURES OF

Article abstract of DOI:10.1016/S0022-328X(00)93952-4

Reaction of cis-PtCl2(PPh2Cl)2 with NaMn(CO)5 in tetrahydrofuran yields new tri- and tetrametallic platinum-manganese complexes.The substitution of the Pt-Cl and P-Cl bonds is accompanied by a redox reaction, a labilization of the Pt-P bonds as exemplified by the isolation of complexes in which such bonds have been broken or created, and the rupture of one Mn-CO bond.The various complexes were separeted by column chromatography and the following tri- and tetrametallic complexes were characterized: Pt(CO)22, I, which is most likely to possess a linear Mn-Pt-Mn arrangement; , II, which was shown by X-ray diffraction to have a chiral PtMn2P2 framework with two Pt-Mn bonds (average 2.744(1) Angstroem forming an angle of 159.54(6) deg, and two PPh2 groups spanning these bonds; , III, which possesses one Pt-Mn bond (2.847(2) Angstroem) spanned by a PPh2 ligand, whereas the other Pt-Mn separation (3.618(2) Angstroem) does not correspond to a metal-metal bond, the metal being only connected by two PPh2 ligands; , IV, which is a centrosymmetric molecule characterized by the first planar heterotetrametallic chain (with Pt(1)Pt(1)'=2.669(1) Angstroem and Pt(1)Mn(1)=2.717(2) Angstroem and Mn(1)Pt(1)Pt(1)'=146.11(8) deg), and by one bridging PPh2 group on each Pt-Mn bond and two PPh2 bridges on the Pt-Pt bond.Almost planar pentacoordination is found for platinum in II and IV, and is most likely for III, but the hydrogen atom in the latter was not located by X-ray diffraction.The synthetic method used in this work appears promising for the preparation of novel heteropolymetallic complexes, although a detailed reaction mechanism cannot be proposed.