Reaction of Spiro[2.4]hepta-4,6-diene with Molybdenum(II) Indenyl Compounds: Effects of Substitution in the Indenyl Ligand

Abstract

The series of molybdenum indenyl compounds [(Ind′)Mo(CO)2(NCMe)2][BF4] was prepared, and their reactivity toward spiro[2.4]hepta-4,6-diene was studied. It was observed that the spiro[2.4]hepta-4,6-diene ring opening could be blocked through substitution in the indenyl ring. Hence, the 2-substituted compound [(η5-C9H6Me)Mo(CO)2(NCMe)2][BF4] and 1,3-disubstituted compound [(η5-C9H5tBu2)Mo(CO)2(NCMe)2][BF4] do not produce the usual ansa-compounds but the compounds with η4-bonded spiro[2.4]hepta-4,6-diene [(Ind′)(η4-C5H4(CH2)2)Mo(CO)2][BF4]. The use of 1-substituted compounds [(η5-C9H6R)Mo(CO)2(NCMe)2][BF4] (R = Ph, tBu) or compounds with less sterically demanding substituents in the 1,3-positions [(η5-C9H5Ph2)Mo(CO)2(NCMe)2][BF4] does not block the ring-opening reaction. These compounds give ansa-molybdenocenes [(Ind′)(η5-C5H4CH2-η1-CH2)Mo(CO)][BF4] in a manner similar to that for the unsubstituted analogue. The reaction products were characterized by NMR and IR spectroscopy. Structures of [(η5-C9H5Ph2)Mo(η3...