Tungsten complexes conformation

Schmidt reaction of ketones, 7, 530 from thienylnitrenes, 4, 820 tautomers, 7, 492 thermal reactions, 7, 503 transition metal complexes reactivity, 7, 28 tungsten complexes, 7, 523 UV spectra, 7, 501 X-ray analysis, 7, 494 1 H-Azepines conformation, 7, 492 cycloaddition reactions, 7, 520, 522 dimerization, 7, 508 H NMR, 7, 495 isomerization, 7, 519 metal complexes, 7, 512 photoaddition reactions with oxygen, 7, 523 protonation, 7, 509 ring contractions, 7, 506 sigmatropic rearrangements, 7, 506 stability, 7, 492 N-substituted mass spectra, 7, 501 rearrangements, 7, 504 synthesis, 7, 536-537... 

Further confirmation of the structure comes from the X-ray crystal structure analysis of the cyclopropylcarbinyl tungsten complex CpW(CO)3(C5FI9) which reveals a tetragonal bipyramidal geometry at the metal, and a typical bisected conformation of the cyclo-propylcarbinyl-M moiety. The sigma C—M bond distance of 234 pm is expectedly much longer than the W—CO bonds (115 pm). 

Fp C=CC2[Co2(CO)6]-moieties linked by a C-C single bond and is obtained from the reaction of the tetrayndiyl complex Fp i-(C=C)4 and Co2(CO)8.422 The two C2Co2 cores, which again involve the inner C=C triple bonds, induce a transoid conformation (S-shaped) in the carbon chain, analogous to that described above for the tungsten complexes. 

Study the conformations of adenosine monophosphates. Examples of through-space coupling are more common for fluorine than phosphorus, and a previously quoted example of through-space PH coupling in a tungsten complex was ruled out when the signs of the coupling constants of model compounds were taken into account. ... 

Tungsten(VI) complexes guanidine, 283 hydroxamic acids, 506 maleic acid, 475 conformation, 467 tartaric acid, 479 NMR, 468... 

Tungsten j4-diene cations in both s-trans and s-cis forms have been synthesized and the influence of the diene conformation on the regiochemistry of nucleophilic attack has been demonstrated488. Application of nucleophilic additions to Mo-complexed olefins in the construction of quaternary carbon centres has been summarized489. 

Methyl-3,5-diphenyl-l//-thiopyran 1-oxide forms red air-stable complexes with carbonyls of chromium, molybdenum and tungsten. (78CB1709). X-Ray diffraction measurements on these compounds confirm the non-planarity of the thiabenzene oxide nucleus and reinforce the evidence for high inversion barriers at sulfur. These complexes are found in isomeric forms with either the sulfur-oxygen bond axial to the half-chair conformation adopted by the ring, or the S- methyl group axial the complexes cannot be interconverted. 

The dimolybdates and ditungstates found with arabitol are closely related to the complex anions 14 and 21. Two dimolybdates are formed with D-arabitol ligands which adopt a sickle conformation with their eryf/tro-configured end as in 14 (O Fig. 2), this is the C4 chain from C2 to C5, in each case. The isomers differ in the coordination pattern one isomer has C2 and C4 in the /X2 mode, the other one C3 and C5 [25]. These isomers are the main species with tungsten(vi) as well, but a minor species is additionally formed in which the threo end of D-arabitol, this is Cl to C3, is used for complexation closely related to 21 [26,37]. 

Molybdenum and tungsten also use the central tetraol set of dulcitol, however, in a sickle conformation, to form dimolybdates respectively ditungstates with a coordination pattern similar to that found in the erythritol complex 14 (O Fig. 2) [25,26,27,43]. 

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