Synthesis of Mo(CO)2(η3-PPh2(o-C6H4)C(O)H)2 and its reaction with C60

► Mo(CO)2(η3-PCHO)2 (1) has been prepared and reacted with C60. ► The structure of 1 shows the aldehyde groups are in a unique π-bonding fashion. ► Mo(CO)3(η3-(MeNCH2)3) and 1 show higher chemical reactivity than their tungsten analogues. ► The reaction of 1 and C60 leads to coupling of PCHO ligands is unique.