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

Abstract

Polymerization of the [(η5-C5H4(CH2)8CHCH2)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 CCl4 resulted in cleavage of the oligomer backbone and formation of the metal chloride complex [μ-C5H4(CH2)8CHCH(CH2)8C5H4{Mo(CO)3Cl}2]. The RCM product was also irradiated and the photochemical product is identical to that formed by irradiation of the oligomer. Copolymerization of [(η5-C5H4(CH2)8CHCH2)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).

Synthesis of Main‐Chain Metal Carbonyl Organometallic Macromolecules (MCMCOMs)

“…This inability of polymerization was probably attributed to the steric effect caused by the short alkyl chain connecting metal and C = C group . In the case of complex 5 in which the alkene substituents were located on the Cp ligand, ADMET under concentrated solution condition using Schrock's catalyst lead to the formation of oligomer 9 with a molecular weight of 2300 g mol −1 and a broad PDI of 4.3 (Figure ) . The molecular weight was slightly increased to 3400 g mol −1 when complex 5 was copolymerized with 1,9‐decadiene using Grubb's second generation catalyst, resulting in the formation of 10 (Figure ).…”

“…The molecular weight was slightly increased to 3400 g mol −1 when complex 5 was copolymerized with 1,9‐decadiene using Grubb's second generation catalyst, resulting in the formation of 10 (Figure ). In dilute solution, ring‐closing metathesis (RCM) was preferred, leading to cyclization product 11 (Figure ) …”

“…ADMET hompolymerization of complex 5 (a), copolymerization of complex 5 with 1,9‐decadiene (b), and ring‐closing metathesis of complex 5 (c). Adapted with permission . Copyright 2009, American Chemical Society.…”

“…[ 43 ] In the case of complex 5 in which the alkene substituents were located on the Cp ligand, ADMET under concentrated solution condition using Schrock's catalyst lead to the formation of oligomer 9 with a molecular weight of 2300 g mol −1 and a broad PDI of 4.3 ( Figure 6 ). [ 45 ] The molecular weight was slightly increased to 3400 g mol −1 when complex 5 was copolymerized with 1,9-decadiene using Grubb's second generation catalyst, resulting in the formation of 10 ( Figure 6 ). In dilute solution, ring-closing metathesis (RCM) was preferred, leading to cyclization product 11 ( Figure 6 ).…”

“…In dilute solution, ring-closing metathesis (RCM) was preferred, leading to cyclization product 11 ( Figure 6 ). [ 45 ]…”