2.6- Bis pyridin

Likewise, quantum mechanical calculation succeeds in giving a theoretical explanation of some facts that the resonance theory could not explain, for example, why bis(pyridine-2)monomethine cyanine and bis(pyridine-4)monomethine cyanine possess the same lowest energy transition contrary to the 2,2 - and 2,4 -quinoline monomethine dyes, together with a molecular coefficient extinction lower than that of the 4,4 -quinoline dye (11). Calculation shows also that there is no theoretical reason for observing a relationship between and pK in a large series of dyes with different nuclei as it has been postulated, even if limited observations and calculations in short homogeneous series could lead to this conclusion (105). 

Bis-fsopropylidene or benzylidene derivatives of 2,2 dioxo-A-3,3 biselena-zoi-5,5 inylidene bis hydrazones, table of products. 253 Bis(pyridine-2)monomethine cyanine. 

Methoxyquinoxaline (10, R = H) gave 6-methoxy-5-nitroquinoxaline (10, R = N02) (95% H2SO4, KN03i slowly, 20°C, 2 h 79%) ° a similar procedure was used to make 6-methoxy-3-morpholino-5-nitroquinoxalme (11) (90%) but more vigorous conditions were used to afford 6-meth-oxy-5-nitro-2,3-bis(pyridin-2-yl)quinoxalme (12) (95% H2SO4, KNO3I slowly, 20°C 70°C, 3 h 96%). ... 

Methyl-5-nitro-2,3-bis(pyridin-2-yl)quinoxaline (32, R = N02) gave 6-methyl-... 

Titanium imido complexes supported by amidinate ligands form an interesting and well-investigated class of early transition metal amidinato complexes. Metathetical reactions between the readily accessible titanium imide precursors Ti( = NR)Cl2(py)3 with lithium amidinates according to Scheme 84 afforded either terminal or bridging imido complexes depending on the steiic bulk of the amidinate anion. In solution, the mononuclear bis(pyridine) adducts exist in temperature-dependent, dynamic equilibrium with their mono(pyiidine) homologs and free pyridine. 

Treatment of bis(pyridine) complexes of molybdenum and tungsten, M(f/ -allyl)Cl(CO)2(py)2 (M = Mo, W) with equimolar amounts of lithium amidinates Li[RC(NPh)2] (R = H, Me) afforded amidinato complexes of the type M(r -allyl)[RC(NPh)2](CO)2(py) (M = Mo, W). Reactions of the latter with acetonitrile, PEts, and P(OMe)3 have been investigated Free amidines react with M(r -allyl)Cl(CO)2(NCMe)2 according to Scheme 124 to give the corresponding bis(amidine) complexes. ... 

The mass spectral behavior of several nuclear and extranuclear nitroquinoxalines has been investigated in some detail.290,763 The X-ray analysis of 5-nitro-2,3-bis(pyridin-2-yl)quinoxaline1115 and its bisperchlorate salt1113 have been reported. Reduction to quinoxalinamines is the main transformation of nitroquinoxalines, but they also undergo useful displacement reactions. 

The bis pyridine complex [Ir(cod)py2][PF6], (314), is prepared by the reaction of [IrCl(cod)]2 with pyridine in the presence of NH4PF6.508 Best yields were achieved from a water/acetone (1 1) solvent system. Reaction of (314) with equimolar amounts of P(C6Hn)3 affords the substituted, air-stable species [Ir(cod) P(C6Hii)3 py][PF6]. 

Figure 9 Retention of metal-induced conformation of a bis(pyridine) ligand by heating in the presence of...

The structure of a non-hydrolyzed dimer, cA-[(2,2 -bipyridine)palladium(II)]2(/i-l,3-N03)2 2+ is shown in Figure 45.521 The dimerized m-( 2.2-bi pyridine) Pd11 units aggregate into a dimer-to-dimer linear conformation through direct metal—metal interaction522 and tt-tt stacking.523 Notably, the dimer was first reported to be linked by double nitrato-bridges (/x-l,3-N03)2 in a cofacial... 

A dinuclear complex of Pd11 was obtained by the reactions of Pd(bpm)(H20)2]2+ (bpm = bis (pyridine-2-yl)methane) with model nucleobases as constituents of DNA.534... 

The structure of coordination polymers formed with 3,6-bis(pyridin-3-yl)-l,2,4,5-tetrazine and zinc salts can be controlled by the choice of alcoholic solvents. Infinite lattice compounds of the form [Zn2L2(N03)4(Me0H)2(//-L)] and [Zn2(/U-L)3(N03)4](CH2C12)2) have been structurally characterized. The former structure shows an alternating single- and double-bridged species whereas the latter exists as a non-interpenetrated ladder complex.273... 

Amongst the synthetic magnesium(II) complexes, a comparison of bis(pyridine)magnesium(II)-tetrabenzoporphyrin (26) with bis(pyridine)magnesium(II)-octamethyltetrabenzoporphyrin (10) in vitro (HeLa cells), and in vivo using liposomal delivery, showed that while (26) was more effective than (10) in cell kill, (10) had the greater tumor selectivity ([tumor]/[muscle] = 36.0 after 24 h). Zinc(II) tetrabenzoporphyrin also showed promising activity nickel(II) tetrabenzoporphyrin derivatives were inactive.117... 

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