Encapsulation CpRu

Recently, Bergman and Raymond reported on the stabilization of highly reactive organometallic species inside self-assembled [M4L6] coordination cages (120). The very reactive ion [CpRu(cis-l,3,7-octatriene)]BF4, for example, decomposes rapidly in aqueous solution (within minutes), but is stable for weeks in the same solvent when encapsulated in the tetrahedral [Ga4(L13)6]12- cage... 

Expanding on the encapsulation of organometallic guests, half-sandwich complexes of the form CpRu(q -diene)(H2O) were encapsulated in 1 [32]. When the diene portion of the half sandwich complex is unsymmetrically substituted, the ruthenium atom becomes a chiral center. Addition of CpRu(2-ethylbutadiene) (H2O) (4) to 1 revealed the existence of two diastereomers. Encapsulation of these racemic ruthenium complexes in racemic 1 leads to diastereomeric pairs of enantiomeric host-guest complexes (A/R, A/S, A/R, A/S) (Figure 7.3). However, chiral discrimination was not observed with the diastereomeric ratio (d.r.) being 50 50. 

Following the above procedure, a variety of organometallic guests such as Cp2pe, CpiCo, [CpRulp-cymene)], CpRu(diene)X, Cp Ru(diene)X, [Cp Ir(PMe3)(Me) (C2H4)] and other related systems were encapsulated in the tetrahedral assembly... 

Raymond et al. encapsulated two cationic mthenium sandwich complexes, [CpRuCtf-CeHs)]" and [CpRu(p-cymene)]+ (Cp = C5H5) in M4L5 assembly by guest exchange with NMeJ [14],... 

Encapsulation of the prochiral complex [CpRu(p-cymene)] by the chiral host renders enantiotopic protons diastereotopic, as evidenced by HNMR spectroscopy. 

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