Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 5. Synthesis and crystal structure of [MnPt(µ-I)(COCH2CH2CH2)(CO)4(PBut2Me)]

Abstract

The mononuclear manganese–carbene complex [MnI([graphic omitted]H₂)(CO)₄] reacts with [Pt(C₂H₄)₂(PBu^t₂Me)] to afford a mixture of the triplatinum compounds [{Pt(µ-CO)(PBu^t₂Me)}₃] and a dimetalla-complex of composition [MnPtI(C₄H₆O)(CO)₄(PBu^t₂Me)]. A ¹³C n.m.r. study of the latter suggested that the 2-oxacyclopentylidene ligand was terminally bonded to the platinum and was not bridging the metal–bond. In order to establish the molecular structure, a single-crystal X-ray diffraction study was carried out. Crystals are orthorhombic, with space group Pbca and Z= 8 in a unit cell of dimensions a= 14.634(5), b= 19.546(18), and c= 16.325(5)Å. The structure has been determined by heavy-atom methods from automated diffractometer data collected at 200 K for 2.9 ⩽ 2θ⩽ 65° and refined to R 0.036 (R′ 0.036) for 3 197 reflections. A manganese–platinum bond is bridged by an iodo-ligand [Mn–Pt 2.603(1), Mn–I 2.689(2), Pt–I 2.662(1)Å]. The carbene ligand is terminally bonded to the platinum [C–Pt 1.889(8)Å] such that the [graphic omitted]H₂ group is essentially trans to the iodine atom, while the PBu^t₂Me group is trans to the metal–metal bond [P–Pt–Mn 167.8(1)°]. The CO ligands adopt four octahedral positions around the manganese atom. (Ethylene)bis(trimethylphosphine)platinum reacts with [MnI[graphic omitted]H₂)(CO)₄] to give [MnI(CO)₄(PMe₃)] and the previously reported complex [(OC)₄[graphic omitted]t(PMe₃)₂]. The latter species was also produced, together with [MnI(CO)₃(PMe₃)₂], by reacting [(OC)₄[graphic omitted]H₂)(PBu^t₂Me)] with an excess of trimethylphosphine.