Fluxional rearrangements in molybdenum(>0>), tungsten(>0>) and rhenium(I) carbonyl complexes of 2,6-bis[(4S )-isopropyloxazolin-2-yl]pyridine (L). Crystal structure of [Mo(CO)4L] ‡

Abstract

Fluxional rearrangements in molybdenum(0), tungsten(0) and rhenium(I) carbonyl complexes of 2,6-bis[(4S)-isopropyloxazolin-2-yl]pyridine (L). Crystal structure of [Mo(CO) 4 L] ‡

Stereochemical rearrangements in tricarbonylrhenium(I) halide complexes of the nonracemic chiral ligand 2-[(4R,5R)-dimethyl-1,3-dioxan-2-yl]pyridine (L): a dynamic NMR study

“…The three complexes, [ReX(CO) 3 , as expected for a fac-octahedral tricarbonylrhenium(I) complex. 16 Analytically pure samples could not be obtained; consequently, elemental analyses (C, H and N) gave poor data.…”

“…We reported recently on the use of the C 2 -symmetric bis(oxazolines), 2,6-bis[(4S)-alkyloxazolin-2-yl]pyridine (alkyl = methyl or isopropyl), as a mechanistic probe for the dynamic stereochemical rearrangements in complexes of the type shown in Figure 1. 2,3 This paper describes the results of a detailed dynamic NMR study on the tricarbonylrhenium(I) halide complexes of the closely related acetal ligand, 2-[(4R),(5R)-dimethyl-1,3-dioxan-2-yl]pyridine (L), namely fac-[ReX(CO) 3 L] (X = Cl, Br or I).…”

“…The systematic study of fluxional processes provides a sensitive method for probing bonding interactions, particularly where multiple mechanistic pathways are competing. We have demonstrated recently that nonracemic chiral ligands can be used to elucidate dynamic processes that are otherwise unobservable, 2,3 providing detailed information on the bonding between the metal and the fluxional ligand. This paper illustrates the power of such an approach for the study of complex fluxional organometallic systems.…”

“…The three complexes, [ReX(CO) 3 L] (X = Cl, Br or I), were prepared similarly, as illustrated by procedure for the complex X = Br. …”

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].…”