Complexes biphenyl

Biphenylbis(tricarbonyt)chromium (l).1 Lithium anthracenide converts biphenyl complexed by two Cr(CO), groups into a fairly stable dianion of structure 2, in which two V-cyclohexadienyl anions are coordinated with Cr(CO)3. This dianion is alkylated by an alkyl halide to form 3, in which one benzene ring is... 

Changing the arene can also have a significant effect on the rate and extent of hydrolysis. For example, there is a 2-fold difference in the hydrolysis rate between the biphenyl complex [Ru(ri6-biphenyl)Cl(en)]PF6, and the tetrahydroanthracene complex [Ru(ri6-5,8,9,10-tetrahydroanthracene)Cl(en)]PF6 or the dihydroanthracene complex [Ru(ri6-9,10-dihydroanthracene)Cl(en)]PF6, demonstrating that variations in the steric and electronic effects of arene ligands can modulate the aquation rate [68]. 

Metallacycles (see Metallacycle) are readily prepared via C-C bond activation, particularly in a strained ring. Insertion of Pt(0) into biphenylene leads to the formation of biphenyl complex. Following this strategy, the reaction of semibuckminsterfullerene (C30H12) with Pt(0) yields a buckybowl complex (Scheme 21). Similar ring expansion... 

The electrochemical behavior of two types of linked half-sandwich complexes appears to be influenced by structural changes which accompany the electron-transfer steps. The biphenyl complex (Cr2(CO)ft( 17, 17 -C12H10)] (11) is reduced in a reversible two-electron process at -1.61 V [versus Ag/AgCl, in tetrahydrofuran (THF) at 0°C] to a persistent dianion (28). The cyclic voltammetric peak separation of —35 mV argues against an interpretation involving two one-electron reductions to isolated redox sites (which would give a 60 mV peak separation) [vide ante (75)]. Rather, for the second electron transfer must be more positive than for the first, and the second reduction is, therefore, more facile than the first. 

Alkynylation. Addition of 1-alkynes to a-keto esters is catalyzed by (acac)Rh(CO)2 in the presence of a hindered phosphine ligand [e.g., 2-(di-t-butylphosphino)biphenyl]. Complexes containing more electron-rich analogues of the acetylaetonato ligand favor the reaction. 

In the isomorphous structure of benzophenone and biphenyl complexes, the 3 cyd molecules are associated in head to head dimers all secondary hydroxyl ends of the two partners are connected by hydrogen bonds. These dimers are stacked along the c axis to produce channels... 

The guest molecules are disordered as they usually are in clathrates, and we could not provide a conformation model of the guest molecules. However, the contents of the channels appeared different in the two structures. In the benzophenone complex, the analysis of the electron density revealed that the guest is completely included in the B Cyd torus and that the carbonyl occupies two positions near the level of the 04 a-toms of the glucose rings. In the biphenyl complex on the other hand, this fact cannot be ascertained. 

Polychlorinated biphenyls (PCBs) are organic compounds that contain chlorine atoms in a biphenyl complex. Some of the 209 PCBs are known under different commercial names. These compounds are chemically and thermally stable with... 

The soluble and homogeneous forms [2] of highly reactive metals such as Rieke calcium, barium, or strontium are effective reagents for this type of polymerization. The polymerization failed when insoluble highly reactive metal powders such as Rieke magnesium [31] were used (Equation 9.2). The soluble biphenyl complexes M(biphenyl)2 (M = Ca, Sr, or Ba) were sufficiently active to facilitate polymerization. In contrast only oxidative addition of Mg into the carbon-chlorine bond occurred, and upon workup only a-chlorotolu-ene and a,a-dichlorotoluene were recovered quantitatively as products after 24 h of reflux. No coupling reaction or polymerization occurred. 

Synthesis and Characterization of Rare Earth Biphenyl Complexes 6C, lOTT-Electron Aromatic Systems... 

SYNTHESIS AND CHARACTERIZATION OF RARE EARTH BIPHENYL COMPLEXES 6C, IOtt-ELECTRON AROMATIC SYSTEMS... 

Table 3.5. Absorption and Emission Spectra of Platinum Biphenyl Complexes...

Chromium - Three arene biphenyl complexes have been reported and the mixed valmce interactions of Cr Cr" have been electrochemically and spectrochemically studied. Cross coupling [(Ti -2,6-disubstituted-l-bromobenzene)CrC03] with 2-substituted boronic acids... 

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