Wasserlösliche Metallkomplexe und Katalysatoren, V. 2,2′‐Bipyridin‐5‐sulfonsäure und metallorganische Komplexe: Spektroskopie und Strukturchemie

Abstract

Water‐Soluble Metal Complexes and Catalysts, V. — 2,2′‐Bipyridine‐5‐sulfonic Acid and Organometallic Complexes: Spectroscopy and Structures Coplanar orientation of the pyridine rings in 2,2′‐bipyridine‐5‐sulfonic acid (1a) and in metal complexes of this ligand is evident from NMR studies. While the free acid 1a exists as a planar zwitter‐ion the rings of the salts 1b–d (Na+, [N(C4H9)4]+,[P(C6H5)4)]+) and sulfonamides 1f–h (tert‐butyl, benzyl, 2‐pyridylmethyl) are twisted. X‐ray crystal structures determined for four complexes 4e, h, 1, and 10b of the sulfonic acid and sulfonamide derivatives of 2,2′‐bipyridine show that there is no influence of the sulfonic acid and the sulfonamide groups (meta‐position) on the complex chemistry of the chelate ligand. Variation of solubility should, therefore, occur without principal changes of reactivity.

Microwave-Assisted Synthesis and Crystal Structure of Oxo(diperoxo)(4,4'-di-tert-butyl-2,2'-bipyridine)-molybdenum(VI)

“…The structure of 1 ( Figure 1 ) consists of a discrete neutral MoO(O 2 ) 2 (tbbpy) complex in which the organic ligand is N , N -chelated to the Mo VI centre. A search in the literature and in the Cambridge Structural Database (CSD, Version 5.30, November 2008 with 3 updates) for related oxodiperoxo molybdenum complexes revealed only a handful of structures having N , N -chelated moieties bound to molybdenum centres [ 10 , 12 , 13 , 14 , 15 , 17 , 26 ]. A considerable number of these concern derivatives of 4-(1H-pyrazol-4-yl)pyridine such as 3-(2-pyridyl)-1-pyrazolylacetic acid ethyl ester [ 13 ], 2-(1-allylpyrazol-3-yl)pyridine [ 14 ], (3-(2-pyridyl)-1-pyrazolyl)-cyclohexanol [ 15 ] and 2-(1-benzyl-1H-pyrazol-3-yl)pyridine [ 26 ].…”

“…In particular, oxodiperoxo molybdenum complexes bearing bidentate ligands, MoO(O 2 ) 2 (L-L), are known to be extremely useful catalysts in the epoxidation of olefins [ 7 , 8 , 9 ]. A variety of N , N -chelating ligands have been studied, including 2,2'-bipyridine (bpy) [ 10 ], sulfonated bipyridines [ 11 , 12 ], substituted pyrazolylpyridines [ 8 , 9 , 13 , 14 , 15 , 16 ], oxazolinylpyridines [ 17 ], and benzimidazolylpyridines [ 18 ]. The standard preparation of these complexes involves the treatment of the organic ligand with MoO 3 dissolved in H 2 O 2 (30%).…”

Microwave Assisted Synthesis of Molybdenum and Tungsten Tetracarbonyl Complexes with a Pyrazolylpyridine Ligand. Crystal structure of cis-[Mo(CO)4{ethyl[3-(2-pyridyl)-1-pyrazolyl]acetate}]

“…The IR spectra of 1 and 2 show four active ν(C≡O) normal modes in the 1810-2015 cm - [24,25], those containing organic ligands with N-aromatic donor atoms are far less common. Most of the reported structures belonging to this family contain either 2-pyridyl substituted ligands [26][27][28][29][30][31][32][33][34][35][36][37][38], 2,2'-bipyridine [39][40][41][42][43][44][45][46] or 1,10-phenanthroline [47,48] (and their derivatives). Thiel and co-workers described two structures for tetracarbonyl complexes of molybdenum chelated by 2-(3-pyrazolyl)pyridine residues [22,49].…”

New Insights into the Mechanism of Hydroperoxide Activation by Investigation of Dynamic Processes in the Coordination Sphere of Seven-Coordinated Molybdenum Peroxo Complexes

“…The complex geometries resulting from these calculations are in good agreement with the bond parameters obtained from X-ray structure analysis of analogous molybdenum peroxo complexes. [23,24,28,[40][41][42] Figure 1 shows a comparison between the calculated structural parameters and those of oxodiperoxo[3-(2-pyridyl)-1-pyrazolylacetic acid ethyl ester]molybdenum(VI). [23] All calculated bond lengths are found slightly too long, which is due to the applied method.…”