Arene complexes of lanthanoids

It seems to be rather strange that arene lanthanoid complexes remained unknown for a long time even so the energy of Ln-benzene bond is over 50 kcal/mol [57]. 

The first authentic zerovalent arenelanthanoid complexes [l,3,5-(t-Bu)3C6H3]2Ln (Ln-Y, Gd) have been obtained by Cloke and coworkers in die cocondensation of vaporized metal with an excess of l,3,5-tri-(t-butyl)benzene at 77 K [63]. The products are isolated after the recrystallisation from pentane as deep purple crystals highly soluble in hydrocarbon solvents. They are stable at room temperature, and may be sublimed at ca. lOOT/lO mbar with partial decomposition. Like all other arene derivatives of REM (Table IV.6 ) bis(arene) complexes are highly air and moisture sensitive. 

In accordance with Ln(0) state the yttrium and lutetium complexes are paramagnetic. However, the ESR signal at room temperature is observed only in the case of lutetium derivative (octet, g II =2.164, g L =2.05, A=9.5 mT). The yttrium compound displays an ESR spectrum at 77K (g II =2.085, gl =2.005, A=3.0 mT). 

Deep purple Green Dark Purple Blue Dark Blue Green Red Red Yellow Black Black Deep purple Purple 

Metal Atomic configuration Atom Ln liettOAB) Pred.I Pred.II Expt. 

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