New Trinuclear Complexes of Group 6, 8, and 9 Metals with a Triply Bridging Borylene Ligand

• Published in: Chemistry : a European journal Vol. 22; no. 26; pp. 8889 - 8896
• Main Authors: Yuvaraj, K., Bhattacharyya, Moulika, Prakash, Rini, Ramkumar, V., Ghosh, Sundargopal
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 20.06.2016
• Subjects: boron; borylenes; metallaboranes; rhodium; ruthenium; metallaboranes; borylenes; ruthenium; boron; rhodium
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201600637

Trinuclear complexes of group 6, 8, and 9 transition metals with a (μ3‐BH) ligand [(μ3‐BH)(Cp*Rh)2(μ‐CO)M′(CO)5], 3 and 4 (3: M′=Mo; 4: M′=W) and 5–8, [(Cp*Ru)3(μ3‐CO)2(μ3‐BH)(μ3‐E)(μ‐H){M′(CO)3}] (5: M′=Cr, E=CO; 6: M′=Mo, E=CO; 7: M′=Mo, E=BH; 8: M′=W, E=CO), have been synthesized from the reaction between nido‐[(Cp*M)2B3H7] (nido‐1: M=Rh; nido‐2: M=RuH, Cp*=η5‐C5Me5) and [M′(CO)5⋅thf] (M′=Mo and W). Compounds 3 and 4 are isoelectronic and isostructural with [(μ3‐BH)(Cp*Co)2(μ‐CO)M′(CO)5], (M′=Cr, Mo and W) and [(μ3‐BH)(Cp*Co)2(μ‐CO)(μ‐H)2M′′H(CO)3], (M′′=Mn and Re). All compounds are composed of a bridging borylene ligand (B−H) that is effectively stabilized by a trinuclear framework. In contrast, the reaction of nido‐1 with [Cr(CO)5⋅thf] gave [(Cp*Rh)2Cr(CO)3(μ‐CO)(μ3‐BH)(B2H4)] (9). The geometry of 9 can be viewed as a condensed polyhedron composed of [Rh2Cr(μ3‐BH)] and [Rh2CrB2], a tetrahedral and a square pyramidal geometry, respectively. The bonding of 9 can be considered by using the polyhedral fusion formalism of Mingos. All compounds have been characterized by using different spectroscopic studies and the molecular structures were determined by using single‐crystal X‐ray diffraction analysis. Building boron bridges: The thermolysis of half‐sandwich complexes of nido‐[(Cp*M)2B3H7] (M=Rh, RuH; Cp*=η5‐C5Me5) with a group 6 metal carbonyl [M(CO)5⋅thf] (M=Cr, Mo, W) led to the formation of a heterotrimetallic complexes with a triply bridging borylene ligand (see figure).