Unusual Synthesis of Triosmium Carbene Clusters by Tandem Activation of Chlorohydrocarbons and Heterocyclic Amines

Reactions of the [Os3H2(CO)10] cluster complex (1) with six‐membered heterocyclic amines (morpholine, thiomorpholine, piperidine) and halohydrocarbons (CH2Cl2, ClHC=CHCl, CH2=CCl2) at ∼25 °C have been studied. Two main types of products are formed in all studied reactions. One product is carbene cluster [Os3(μ−H)(μ−Cl){η1−C(CH3)N(CH2CH2)2X}(CO)9] (X=O, S, CH2) (3, 3 a and 3 b). Second product is cluster containing enamine ligand [Os3(μ−H){μ‐CH=CHN(C2CH2)2Х)}2(CO)10] (X=O, S, CH2) (2, 2 a and 2 b). The carbene ligand is assembled on a cluster, from three organic molecules, thus representing the first example of carbene ligands formed in this way. Clusters with carbene ligand exist as two stable isomers (rotamers hindered towards the Os−C bond), as confirmed by NMR studies and conformational analysis. We have found that in reactions of cluster 1 with acyclic amines containing an oxygen atom in γ‐position (likely morpholine in CH2Cl2), only complexes with bridging enamine ligands are formed. Compounds 2 a, 2 b, 3 and 3 b are characterized by single‐crystal X‐ray diffraction. The carbene ligand is assembled on a cluster core of two dichloromethane and one morpholine at room temperature, which is the first example of carbene ligands formed in this way. Clusters with a carbene ligand exist as two stable isomers, as confirmed by NMR studies and conformational analysis. Possible mechanistic pathways for the formation of clusters with carbene and enamine ligands are proposed.