ROMP method

Just as single reference Cl can be extended to MRCI, it is also possible to use perturbation methods with a multi-detenninant reference wave function. Formulating MR-MBPT methods, however, is not straightforward. The main problem here is similar to that of ROMP methods, the choice of the unperturbed Hamilton operator. Several different choices are possible, which will give different answers when the tlieory is carried out only to low order. Nevertheless, there are now several different implementations of MP2 type expansions based on a CASSCF reference, denoted CASMP2 or CASPT2. Experience of their performance is still somewhat limited. 

The ROMP method was extended to synthesize cyclic polybutadiene using 1,5-cyclooctadiene (COD) or 1,5,9-frans-czs-frans-cyclododecatriene (CDT)... 

Week [203] developed a monomer salen complex linked to a norbomene via a stable phenylene-acetylene linker and its subsequent polymerization by means of the controlled ROMP method using 3 generation Grubb s catalyst (Scheme 137). This polymerization methodology led to fully functionalized immobilized metal-salen catalyst. By this way, the supported catalyst showed catalytic activities and stereoselectivities similar to the nonsupported Jacobsen catalyst. Moreover, activities and selectivities seemed to depend on the density of the catalytic moieties homopolymer 324 were less selective than their copolymer analogs 325. For example, AE of 1,2-dihydronaphtalene led in both cases to total conversion and 76% ee for the homopolymer 324 vs 81% ee for copolymer 325a. Recycle was possible and after 3 recyles a drastic decrease in ee was observed. AE of dihydronaphtalene led to 81% ee for the first cycle vs 6% ee for the third one. 

Scheme 11.31 Synthesis of block copolymers by combination of living anionic polymerization and ROMP methods.

Chien et al. have adopted the ROMP method for the synthesis of norbomene-acetylene diblock copolymers... 

The polydispersity index for precursor polymers prepared via the Durham route was only in the range of 1.8-2.8 [88]. Krouse and Schrock were able to improve on the metathesis ROMP method and prepared a series of acetylene block copolymers with success both in controlling the molecular weight and in achieving low polydispersity [82]. Compared to a living polymerization process, the well-controlled ROMP precursor polymers can be grown continuously... 

Figure 2.6. Synthesis of diblock and triblock copolymers of norborene and acetylene using the living ROMP method.

Because the conditions for final protecting-group removal can be harsh, eliminating this step allows for the synthesis of materials containing sensitive bioactive epitopes. Consequently, the ability to synthesize substituted polymers utilizing both defined initiators and unprotected monomers constituted a critical advance in the synthesis of bioactive substituted polymeric displays via ROMP. Methods that have been used successfully for the incorporation of polar bioactive ligands are highlighted. 

RMP2 method, 132 ROMP method, 132 Roothaan-Hall equations, 65 Rumer basis, spin functions, 199 Runge-Kutta (RK) integration method, 344... 

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