Preparation of Photoreactive Oligomers by ADMET Polymerization of [(C₅H₄(CH₂)₈CH═CH₂)Mo(CO)₃]₂

Polymerization of the [(η 5 -C 5 H 4 (CH 2 ) 8 CH═CH 2 )Mo(CO) 3 ] 2 complex by acyclic diene metathesis polymerization (ADMET) is reported. The polymerization reactions were performed using Schrock’s catalyst, which resulted in formation of a polydisperse oligomer ( M n = 2300 and M w / M n = 4.3) with Mo−Mo bonds in the oligomer chain. Under dilute solvent conditions, the reaction was shown to favor the formation of the ring-closing metathesis (RCM) product. The ADMET oligomer was photochemically degradable, and irradiation with λ > 520 nm light in CCl 4 resulted in cleavage of the oligomer backbone and formation of the metal chloride complex [μ-C 5 H 4 (CH 2 ) 8 CH═CH(CH 2 ) 8 C 5 H 4 {Mo(CO) 3 Cl} 2 ]. The RCM product was also irradiated and the photochemical product is identical to that formed by irradiation of the oligomer. Copolymerization of [(η 5 -C 5 H 4 (CH 2 ) 8 CH═CH 2 )Mo(CO) 3 ] 2 with 1,9-decadiene using Grubbs’ second-generation catalyst resulted in a higher molecular weight oligomer ( M n = 3400, M w / M n = 3.9).