Synthesis and Reactivity of “Bismuthinidene” Compounds and the Formation of Bi1 Chelate Complexes

Abstract

Treatment of [Cp′Mn(CO)2THF] (Cp′C5H4Me) with BiCl3 at 20°C affords the “bismuthinidene” species [Cp′‐ (CO)2Mn]2BiCl (1b) and very small amounts of the “star‐type” compound [Cp′(CO)2Mn]3Bi2 (2). Higher yields of both compounds are obtained from the reaction of BiCl3 with [Na] [Cp′(CO)2MnSi(C6H5)3‐]. The molecular structure of 1b has been determined by an X‐ray diffraction study, which shows that the bismuth atom, having a trigonal‐planar coordination geometry, is bonded to two manganese atoms and one chlorine atom. There are weak interactions between the molecules of 1b in the solid state thus forming infinite spiral chains of “inidene” complexes. Compound 1b reacts with NaI to afford the iodine‐substituted species [Cp′(CO)2Mn]2BiI (3). Displacement of the chloride substituent from 1b by anionic chelating ligands AB− is also possible; 1b reacts with tropolonate, 8‐oxoquinolate, or 8‐mercaptoquinolate to form the bismuth(I) chelate compounds [CP′(CO)2Mn]Bi − AB (5a–c). The molecular structure of 5b has been determined by X‐ray crystallography which shows the bismuth atom in a pseudo trigonalbipyramidal geometry with the nitrogen atom lying above the plane defined by the two manganese and the oxygen atoms in an apical position. The molecular structure of 5c has also been determined, and although the numerical values are not very accurate, the coordination geometry of the bismuth atom is seen to be intermediate between pseudo trigonalbipyramidal and distorted tetrahedral. Abstraction of a chloride ligand from 1b by Me3SiOSO2CF3 affords the cationic cumulene‐type complex [Cp′(CO)2MnBiMn(CO)2Cp][CF3SO3] (6a). Dichloromethane solutions of 6a are not stable at room temperature but may be treated with 2,−2′‐bipyridine (bpy) to afford the stable adduct [{CP′(CO)2Mn}2Bi(bpy)][CF3SO3](7). The molecular structure of 7 has been determined by X‐ray analysis, and – similarly to 5c, although the numerical values are not very accurate – the overall geometry has been determined unequivocally. The bismuth atom is shown to have a distorted tetrahedral geometry, thus being ligated by two manganese atoms and the two nitrogen atoms of the bpy ligands.