1.4- pyrazine ligands

The late transition metals, either Co or Ni, bond to four apical oxygen atoms of two vertex-shared 5 units (Fig. 17.9a), two each to layers both above and below, and also bond to two bridging pyrazine ligands in a trans fashion. The al-... 

The binding of the diuretic amiloride 95 to DNA has been studied <06CC1185>. The chiral camphor-derived pyrazine ligand 96 showed monomeric coordination to Cu and Zn, in contrast to the bidentate polymeric behaviour of related earlier compounds <06ARK218>. 

When the donor atoms in the Lewis bases are in diagonally opposite positions, polymeric arrays are possible and can demonstrate reversible inclusion chemistry. There are three nickel xanthate adducts containing such ligands capable of forming bridges. The first of these contains pyrazine ligands as... 

Figure 55. The structure of polymeric [Ni(S2CO—i-Pr)2(pyr)]oo showing (a) the linear polymeric chain aligned along the b axis, and (b) highlighting the orthogonal relationship between the xanthate and pyrazine ligands. The structure has symmetry in that the nickel atom is located on a center of inversion and the pyrazine ligand is disposed about a center of inversion.

The lone set of dimers in Table II, [M(C5Me5)2]2(M Pyraz ne) (Fig. 20 M = Ba), were synthesized from the base-free metallocenes by addition of pyrazine to MCp (1 2), analogous to the dioxane reaction for the amide compounds (Fig. 8).103 The pyrazine compounds are intensely colored owing to both charge transfer and intraligand electronic transitions. The pyrazine ligand has been shown to be labile by uv-vis spectroscopy. 

Fig. 20. ORTEP drawing of [BaCpj fjU-l,4-pyrazine) showing the pyramidal geometry around each barium atom. Each barium atom lies 0.65 A out of the plane defined by the two ring centroids and the nitrogen atom of the pyrazine ligand. (Redrawn from Ref. 103.)...

PTV PU PVA PVAC PVAL PVC PVDC PVDF PVE PVF PXRD py Py PY Py-GC-MS pyr pyrr pz programmed-temperature vaporizer polyurethane poly (vinyl alcohol) poly(vinyl acetate) poly (vinyl alcohol) poly (vinyl chloride) poly(vinylidene dichloride) poly(vinylidene difluoride) poly (vinyl ether) poly(vinyl fluoride) powder X-ray diffraction pyridine (ligand) pyridine pyramidal (coordination compounds) pyrolysis-gas chromatography-mass spectrometry pyrazine (ligand) pyrrolidine (ligand) pyrazole (ligand)... 

Pyrazine, piperazine, and pyrazole are, like 4,4 -bipyridyl, suitable ligands for bridging pairs of Zn + ions to give a variety of polynuclear species, while multifunctional (bi)pyridine-pyrazine ligands give scope for the assembly... 

The bimetallic species bis(dichloromethylstannyl)methane coordinates one equivalent of bipy to form the asymmetric (45) with both four- and six-coordinate tin centers (Scheme 15). Bis(chloro-dimethylstannyl)methane has been used to explore the bridging capability of pyrazine ligands (Scheme 16). ... 

TR3 spectra were used to obtain data on the ligand modes of both high- and low-spin isomers of [Fe(L)]2+, where L = /V,/V,/V, /V -tetrakis(2-pyridylmethyl)-6,6,-bis(aminomethyl)-2,2 -bipyridine or V,V -bis(benzyl)-7V,7V -bis(2-pyridyl-methyl)-6,6,-bis(aminomethyl)-2,2 -bipyridine.193 Resonance Raman and TR3 data were used to obtain detailed ligand mode information for Ru(bi-py)2(dpp)2+ and (bipy)2Ru(dpp)Ru(bipy)24+, where dpp = 2,3-bis(2-pyridyl)-pyazine, and their bipy-d8 analogues.194 A resonance Raman study has been carried out on electronic communication and delocalisation in complexes involving two Ru3 clusters linked by a pyrazine ligand.195... 

PXRD py py PY Py-GC-MS pvr pyrr Pz a powder X-ray diffraction pyridine (ligand) pyridine pyramidal (coordination compounds) pyrolysis—gas chromatography—mass spectrometry pyrazine (ligand) pyrrolidine (ligand) pyrazole (ligand)... 

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