4,4 -dimethyl-2,2 -bipyridine dmbpy

Materials. The ligand 4,4 -dimethyl-2,2 -bipyridine (dmbpy) and RuC13 3H20 are obtained from Fluka and Johnson Matthey, respectively. All reagents and solvents purchased are reagent grade and are used without further purification. 

In 2009, Roelfes and co-workers reported the catalytic AFC alkylation reaction with olefins in water mediated by a DNA-based catalyst. The DNA-based catalyst is self-assembled by combining a Cu" complex with salmon testes DNA (st-DNA), which is inexpensive and readily available. With 4,4 -dimethyl-2,2 -bipyridine (dmbpy) as the ligand, 30 mol% (0.3 mM) of [Cu(dmbpy)(N02)2] (Cu-dmbpy) and 1.4 mg mL of st-DNA (2 mM in base pairs) were found to be the optimal reaction conditions for the AFC reaction of indoles with o,p-unsaturated 2-acyl imidazoles 98. The AFC products 99 were obtained in good yields and enantioselectivity (Table 6.11). Particularly noteworthy was that with 0.15 mol% catalyst, good yields and high ee values (up to 93 /o) were also obtained for various a,p-unsaturated 2-acyl imidazoles 98 and indoles. 

Arakawa and coworkers [45] developed the on-line photoreaction cell depicted in Figure 5.3 and performed a series of studies on the detection of reaction intermediates in photosubstitution and photooxidation of Ru(II) complexes. The photosubstitution of Ru(bpy)2B [bpy = 2,2 -bipyridine B = 3,3 -dimethyl-2,2 -bipyridine (dmbpy) or 2-(aminomethyl)pyridine (ampy)] was studied in acetonitrile and pyridine. Irradiation of Ru(bpy)2B and related complexes yields a charge-transfer excited species with an oxidized Ru center and an electron localization on the bpy moiety. The excited-state complex underwent ligand substitution via a stepwise mechanism that includes ant] bidentate ligand (Scheme 5.6). Photoproducts such as Ru(bpy)2S2 (S = solvent molecule) and intermediates with a monodentate (mono-hapfo-coordination) B ligand, Ru(bpy)2BS, and Ru(bpy)2BSX+ (X=C10/, PF ) were detected. Other studies also identified photo-oxidized products of several mixed-valence Ru(II) complexes upon irradiation (7i> 420 nm) [31b, 46]. 

Re(bpy)(CO)3Cl-modified electrodes has not yet been explained. However, from the cyclic voltammograms of fac-Re(bpy)(CO)3Cl (Fig. 14) and from the intermediate complexes formed by electrolysis in acetonitrile in the presence and absence of C02, two different electrocatalytic pathways (Fig. 15) were suggested144 initial one-electron reduction of the catalyst at ca. -1.5 V versus SCE followed by the reduction of C02 to give CO and C03, and initial two-electron reduction of the catalyst at ca. -1.8 V to give CO with no C03. The electrochemistry of [Re(CO)3(dmbpy)Cl] (dmbpy = 4,4 -dimethyl-2,2 -bipyridine) was investigated145 to obtain mechanistic information on C02 reduction, and the catalytic reac-... 

In 1986, Breikss and Abruna reported electrochemical and mechanistic studies on a close analogue of the rhenium complex, (Dmbpy)Re[CO]3Cl, where Dmbpy = 4,4 dimethyl 2,2 bipyridine. The cyclic voltammogram of the complex at platinum in CH3CN/tetrabutylammonium perchlorate is shown in Figure 3.56 for simplicity we will consider only the electrochemistry taking place above c. —2.3V vs. SCE. 

Me4phen = 3,4,7,8-tetramethyl-l, 10-phenanthroline 4,4 -dmbpy = 4,4 -dimethyl-2,2 -bipyridine dbbpy = 4,4 -di- r/-butyl-2,2 -bipyridine dtfmbpy = 5,5 -ditrifluoromethyl-2,2 -bipyridine dppm = bis-(diphenylphosphino)methane dppf = l,l -bis(diphenylphosphino)ferrocene i -BINAP = l,l -binaphthaline-bis(a-diphenylphosphine) chiraphos = 2,3-bis(diphenylphosphino)butane... 

Finally, it is noted that an intriguing report suggests that the [Ru(L)(CO)2] polymers [L = bpy (2,2 -bipyridine) or dmbpy (4,4 -dimethyl-2,2 -bipyridine)] are reactive to light.61 Irradiation of an electrode on which one of these polymers has been deposited results in a marked increase in the current. When the light is switched off, the current returns to its original value. The implication is that the polymer can act as a conductive wire, but this phenomenon remains to be thoroughly investigated. 

Two tris(heteroleptic) Ru(II) complexes bearing styryl subunits, (4,4 -dimethyl-2,2 -bipyridine)(4,4 -di-tert-butyl-2,2 -bipyridine)(4,4 -bis[ -(p-methylcarboxy-styryl)]-2,2 -bipyridine)mthenium(II) hexafluorophosphate, [Ru(dmbpy)(dtbbpy)(p-COOMe-styryl-bpy)](PF6)2 and (4,4 -dimethyl-2,2 -bipyridine)(4,4 -di- nonyl-2,2 -bipyridine)(4,4 -bis[ -(p-methylcar-boxy-styryl)]-2,2 -bipyridine) ruthenium(II) hexafluorophosphate, [Ru(dmbpy)(dnbpy)(p-COOMe-styryl-bpy)](PF6)2 have been synthesized by Myahkostupov and Castellano, and characterized by the use of NMR /hh couplings including those across four bonds have been determined for the complexes and compared with those measured for the free ligands. 

In 2009, the general asymmetric coupling of substituted pyrroles (110) and indoles (208) with 2-acylimidazole substrate of type 200 was extended to other catalyst complexes such as 0.15-0.3 mol % of copper 4,4 -dimethyl-2,2 -bipyridine [Cu(dmbpy)]/DNA complexes [1.4—7 ug/niL DNA base pairs] in aqueous media. Good enantioselectivities (83-93%) of the corresponding adducts 202 and 209, respectively, were observed using sources of DNA such as st-DNA (salmon testes-DNA) and DNA-1 with the self-complimentary sequence of d(TCAGGGCCCTGA)2. A key limitation of this approach was the requirement of at least 5 1 ratio of arene to 200 to achieve good conversion to the adducts (no scheme provided) ... 

Much of the work in the Ru(II) polypyridine area has concentrated on Ru(bpy)3 and its derivatives. The electronic spectra are dominated by an intense charge-transfer band at -450 nm with e = 10" M cm" Ru(bpy)3 " shows modest photosubstitution activity with quantum yields <0.1. ° Photochemical methods have proven useful in the preparation of several derivatives, including the unusual isomer tran5-Ru(bpy)2(OH2)2 and Ru(bpy)2(dmbpy)(NCCH3) ", where dmbpy is the monodentate ligand 3,3 -dimethyl-2,2 -bipyridine. ... 

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