A new complex catalytic system CuX/bpy/Al(OR)3 for atom transfer radical polymerization

Synthesis and Characterization of MoOI2(PMe3)3 and Use of MoOX2(PMe3)3 (X = Cl, I) in Controlled Radical Polymerization

“…The various metals so far shown to be effective include Ti III , [4] Mo III , [5,6] Re V , [7] Fe II , [8,9] Ru II , [10] Ni II , [11] Ni 0 , [12] and Cu I . [13] Although no system currently appears to parallel the activities and practical advantages of certain Cu I complexes, the investigation of other metal systems is useful in order to shine additional light on the mechanistic details of the process. For instance, by using CpMoCl 2 L 2 complexes (L = tertiary phosphanes or L 2 = diene), we have demonstrated how the two trapping processes in Schemes 1 and 2 may simultaneously take place when the polymerization is carried out under ATRP conditions.…”

“…of this compound is used in conjunction with a variety of different catalysts based on Group 6-11 metals, including CpMoCl 2 (iPrN=CH-CH=NiPr), [6] MoX 3 (PMe 3 ) 3 , [14] ReIO 2 -(PPh 3 ) 2 , [7] CpFeX(CO) 2 (X = Br, I), [8] RuCl 2 (PPh 3 ) 3 , [10] NiBr 2 (PPh 3 ) 2 , [11] Ni(PPh 3 ) 4 , [12] and CuBr/bipy. [13] The proposed mode of action of this cocatalyst consists of a shift of the atom transfer equilibrium, caused by the stronger interaction of the Al Lewis acid with the halogen lone pairs in the more polarized Mo-X bond, relative to the C-X bond of the initiator/dormant species. [16] Table 3 shows that Al(OiPr) 3 is also effective in conjunction with the MoOX 2 (PMe 3 ) 3 catalysts, although by a smaller margin.…”

Attachment of a Hydrogen‐Bonding Carboxylate Side Chain to an [FeFe]‐Hydrogenase Model Complex: Influence on the Catalytic Mechanism

“…Of particular interest for the present study, the addition of certain Lewis acids, most notably Al(O i Pr) 3 , in conjunction with a number of catalysts has been shown to result in faster polymerization. This effect seems rather general, since it was shown for many different complexes based on a variety of different transition metals from Groups 6 to 11, including [Mo(Cp)Cl 2 ( i PrNCHCHN i Pr)],5 [MoX 3 (PMe 3 ) 3 ],6 [ReIO 2 (PPh 3 ) 2 ],7 [Fe(Cp)X(CO) 2 ] (X=Br, I),8 [RuCl 2 (PPh 3 ) 3 ],9 [NiBr 2 (PPh 3 ) 2 ],10 [Ni(PPh 3 ) 4 ],11 and [CuBr/bipy] 12. The detailed mechanism of action of this additive, however, is not completely understood.…”

How the interplay of different control mechanisms affects the initiator efficiency factor in controlled radical polymerization: An investigation using organometallic MoIII-based catalysts

“…The latter is thereby transformed into a halogen-terminated dormant chain, while the reduced metal complex (ML n ) acts as a catalyst since it is capable to reactivate the dormant chain (see Scheme 1). Systems based on a variety of transition metals, including Ti III [3], Mo III [4,5], Re V [6], Fe II [7,8], Ru II [9], Ni II [10], Ni 0 [11], and Cu I [12] have been shown effective.…”