Activation of C-H bonds in five-membered heterocycles by a half-sandwich yttrium alkyl complex

The highly labile half-sandwich alkyl complex [Y(eta (5):eta (C5Me4SiMe2NCM e3)-C-1)(CH2SiMe3)(THF)] smoothly undergoes a-bond metathesis with furan an d thiophene in pentane to give tetramethylsilane and the sparingly soluble complexes [Y(eta (5):eta (1)-C5Me4SiMe2NCMe3)(mu -2-C4H3X)](2) (X = O, S). They dissolve in THF to give the THF adducts [Y(eta (5):eta (1)-C5Me4Si- Me 2NCMe3) (2-C4H3X)(THF)(n)]. Pyrrole reacts with [Y(eta (5):eta (1)- C5Me4Si Me2NCMe3) (CH2SiMe3)(THF)] to give the Lewis base-free pyrrolide [Y(eta (5) :eta (1)-C5Me4SiMe2NCMe3)(NC4H4)](n).