Isocarbonyl complexes of divalent samarium and ytterbium. The molecular structures of [{Ln(TptBu,Me)(THF)(μ-CO)2Mo(η-C5H4Me)(CO)}2] (Ln = Sm, Yb)

The reaction of [Ln(TptBu,Me)I(THF)] (1a Ln = Sm, 1b Ln = Yb) with Na[Mo(η-C5H4Me)(CO)3] gives good yields of [{Ln(TptBu,Me)(THF)(µ-CO)2Mo(η-C5H4Me)(CO)3}2], 2a (Ln = Sm), 2b (Ln = Yb). The low temperature X-ray crystal structures of 2a and 2b have been determined. The structures contain a 12-membered ring of samarium/ytterbium and molybdenum atoms with isocarbonyl groups linking the metal centres. 2a represents the first example of an isocarbonyl bound to samarium(II). Addition of pyridine results in the breakup of the tetramer to give [{Ln(TptBu,Me)(py)n(µ-CO)Mo(η-C5H4Me)(CO)2}2].