Ferrocenyl boryl complexes

The reaction of the T-shaped three coordinate platinum boryl complex trans-[ Cy3P)2Pt B(Br)Fc ] [BAr 4] (21) (Fc = ferrocenyl) with 4-methylpyri-dine leads to the formation of trans-[(Cy3P)2Pt(Br) B(Fc)(NC5H4Me-4) ]... 

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]. 

The resonance between 55 and 56 (R = H, alkyl, aryl, ferrocenyl) in ferrocenyl-methyl cations including the diferrocenylmethyl cation has been used by Cais to explain the similar bending of the exocyclic C,C bonds toward the iron atom (Scheme 10.20) [65].Thefieldhas recently been reviewedbyGleiteref a/. [62],who included related isoelectronic boryl substituted systems. Wagner et al. [66] have prepared compounds of this type, and the authors proposed attractive interactions between the iron and boron atoms, because the C-B bonds are bent toward the iron atom. The analogy does not only apply to ferrocenes but also to isoelectronic (cyclobutadiene)(cyclopentadienyl)cobalt complexes and other related compounds [62]. 

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