Cyclo -E 5 -bridged trinuclear triple-decker complexes (E = P, As) containing a triply-bonded Mo 2 unit and their isomerisation.

The reaction of the low-coordinate quadruply-bonded dimolybdenum complex Mo 2 [μ,κ 2 -PhB( N -2,6- i Pr 2 C 6 H 3 ) 2 ] 2 (1) with Cp*Fe(η 5 -E 5 ) (E = P, As) gives two trinuclear species Cp*Fe(μ 3 ,η 5:2:2 -E 5 )Mo 2 [μ,κ 2 -PhB( N -2,6- i Pr 2 C 6 H 3 ) 2 ] 2 (E = P (4) and As (5)). 4 undergoes facile isomerisation upon heating to give Cp*FeMo 2 [κ 2 -PhB( N -2,6- i Pr 2 C 6 H 3 ) 2 ](μ 3 ,κ:κ:η 2 -P 2 )[μ 3 ,κ:κ:η 3 κ-P 3 PhB( N -2,6- i Pr 2 C 6 H 3 ) 2 ] (6), where the FeMo 2 P 5 core motif displays a cubane-like structure.