Bis bidentate

A number of zinc-bound bidentate bis(thioether) donor ligands were characterized as distorted tetrahedral complexes of zinc dichloride. The complexes 2,3-bis(methylthio)hexane,l,2-bis (methylthio) cyclohexane, and m-[5,6-bis(methylthio)-l,3-cycloheptadiene showed a variation in S—Zn—S angles.539... 

Evans group has demonstrated that bidentate bis(oxazolinyl)-Cu(II) (86 and 87) and tridentate bis(oxazolinyl)pyridine-Cu(II) (88 and 89) can be used... 

Some bidentate bis(imidazolin-2-ylidene)s 18 have been used for the preparation of complexes with chelating dicarbene ligands [75-80]. The synthesis, properties, and coordination chemistry of tripodal tris(imidazolin-2-ylidene) ligands like 19... 

Finally, bidentate bis(guanidinium) hosts like 26 reported by Anslyn et al. have recently been shown to bind phenyl phosphate anions in a bis(bidentate) fashion. Hydrogen-bonding N(H) -0 distances are in the range 2.658(7)-2.868(6) A, while solution studies in 15% HjO/DMSO give binding constants of ca. 500 M" with dibenzyl phosphate. ... 

The bidentate bis(diphenylphosphino) alkane ligands (entries 8 and 42) are not capable of forcing the porphyrin ligand to leave the equatorial position of noble metal porphyrins. Either two bidentates are bound in a monodentate fashion, or a bidentate bridges two metalloporphyrin entities. 

This chapter is an update and, as such, will not cover the Nobel Prize winning discovery of crown ethers. It is worth briefly noting, however, that the class of compounds now known generally as crown ethers were discovered by Pedersen in the 1960s <1967JA7017>. At the time, his goal was to prepare bidentate, bis(phenol) compounds that... 

A variety of other bidentate bis(phosphole) complexes have been prepared over the last decade, with the majority incorporating elements of chirality. These are discussed in the section on chiral bidentate ligands (Section 3.15.12.2.3). 

The parent ligand has played an important part in the history of coordination chemistry, as the stereochemical arrangement of bidentate bis or tris (en) complexes lead to the concept of... 

Ruthenium(II) complexes may also be used to oxidize N-Boc hydroxylamine in the presence of tert-butylhydroperoxide (TBHP) to the corresponding nitroso dieno-phile, which is subsequently trapped by cyclohexa-1,3-diene to give the hetero Diels-Alder adduct (Entry 1, Scheme 10.26) [51]. A triphenylphosphine oxide-stabilized ruthenium(IV) oxo-complex was found to be the catalytically active species. Use of a chiral bidentate bis-phosphine-derived ruthenium ligand (BINAP or PROPHOS) result in very low asymmetric induction (8 and 11%) (Entry 2, Scheme 10.26). The low level of asymmetric induction is explained by the reaction conditions (in-situ oxidation) that failed to produce discrete, stable diastereomerically pure mthenium complexes. It is shown that ruthenium(II) salen complexes also catalyze the oxidation of N-Boc-hydroxylamine in the presence of TBHP, to give the N-Boc-nitroso compound which can be efficiently trapped with a range of dienes from cyclohepta-1,3-diene (1 h, r.t., CH2CI2, 71%) to 9,10-dimethylanthracene (96 h, r.t., CH2CI2,... 

Bis(allyldibutylstannyl)naphthalene is highly effective for the selective allylation of aldehydes and ketones under neutral conditions (Eq. 112) [151]. Such a transformation is not realized with monostannane. The former reaction proceeds without any catalyst by taking advantage of the chelation-induced Lewis acidity of bidentate bis(stannyl) compounds. 

The absolute configurations of some octahedral complexes can be described using either the skew-line reference system (Section IR-9.3.4.11) or the C/A system. The first is used more commonly, but the C/A system is more general and may be used for most complexes. The skew-line reference system is only applicable to tris(bidentate), bis(bidentate) and closely related systems. 

N-5 Silver(I) salts form solid coordination networks with bidentate bis(3-cyanophenyl)acetylene... 

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