Ruthenium boryl systems

Fig. 25 Ruthenium boryl systems studied in the functionalization of alkanes (8.91-8.95)...

The first ruthenium dihaloboryl Cp/Ru(CO)2BCl2 (8.102) has recently been spectroscopically characterized, although no structural data were reported [60]. As with the related iron complex CpFe(CO)2BCl2 (8.35), 8.102 exhibits the relatively downfield-shifted 11B resonance (5b 81.0) and high frequency carbonyl stretching bands (2012, 1958 cm-1), expected for a boryl system featuring poorly 7r-donating substituents. The ferrocenyl(bromo)boryl complex Cp/Ru(CO)2B(Fc)Br (8.101) has also been synthesized recently and has spectroscopic properties similar to those of the closely related iron systems 8.63 and 8.64 [92]. 

A range of five- and six-coordinate osmium boryl complexes has been synthesized making use of similar approaches to those reported above for ruthenium. In particular, the reaction of phenylosmium(II) precursors with boranes, which proceed via elimination of benzene, has been shown to be a useful entry point into octahedral and square pyramidal osmium boryl complexes. Significant further chemistry has been reported on these systems, including substitution at both boron and metal centres, which has shed light on fundamental issues of structure/bonding and reactivity [12]. 

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