Diboron B

Miyaura and co-workers reported the reaction of bis(pinacolato)diboron (B—B bond) with one allylic carbonate under Pd(dba)2 in DMSO to afford the diaUyl dimer CH2=CPh—CH2—CH2—CPh=CH2. However, only one single case was reported, whereas acetates afford the normal coupling products. " ... 

C, b.p. 91 C, and has very similar properties to boron chloride but is a stronger Lewis acid. Diboron tetrabromide BjBr, is also known. 

Write the formulas of (a) cobalt(II) chloride hexahydrate (b) diboron trisulfide. STRATEGY... 

In contrast, reaction of ligand 72 with 4,4 -biphenyldiboronic acid has been successful and diboronate 73 is obtained in yields of 33%. This complex acts as a receptor for the paraquat dication forming a 1 1 complex with an association constant of 320 in acetone. The intermolecular forces responsible for the complexation are ion-dipole stabilization between the dative N B dipoles and the two cationic centers in paraquat, attractive tz-tz interactions between... 

Reductive methods form B—B bonds from B—X bonds. For B2X4 (X = Cl, Br, I) from BXj, an electric discharge is supplemented by the presence of a metal, or metal atoms, as halide scavenger. The passage of BX3 at low pressure through a rf discharge in the presence of Hg produces the diboron tetrahalides B2X4 at 300 mg h ... 

The metal catalysed hydroboration and diboration of alkenes and alkynes (addition of H-B and B-B bonds, respectively) gives rise to alkyl- or alkenyl-boronate or diboronate esters, which are important intermediates for further catalytic transformations, or can be converted to useful organic compounds by established stoichiometric methodologies. The iyn-diboration of alkynes catalysed by Pt phosphine complexes is well-established [58]. However, in alkene diborations, challenging problems of chemo- and stereo-selectivity control stiU need to be solved, with the most successful current systems being based on Pt, Rh and An complexes [59-61]. There have been some recent advances in the area by using NHC complexes of Ir, Pd, Pt, Cu, Ag and Au as catalysts under mild conditions, which present important advantages in terms of activity and selectivity over the established catalysts. 

Since boron trichloride reacts with many lubricants to form hydrogen chloride, the diboron tetrachloride synthesis is carried out in a grease-free system. A mercury float-valve vacuum system4 depicted in Fig. 15 is employed here. The U-traps have a capacity of 50 ml. without plugging and tubes A and B have... 

A stoichiometric reaction of tetrakis(triphenylphosphine)platinum(0) with bis(pinacolato)diboron gives cis-diborylplatinum(n) complex in high yield (Scheme 3).38 The diborylplatinum complex then reacts with an alkyne, giving m-diboration product.40,41 These results indicate that the diboration proceeds through the general mechanism shown in Scheme 1 (E1 = E2 = Bpin), which involves the formation of diborylplatinum(n), insertion of an alkyne into the B-Pt bond, and reductive elimination. 

A very efficient green-emitting fluorene copolymer 304 was synthesized by Shim and coworkers [390] via Suzuki coupling of dibromothieno[3,2-b]thiophene with dialkylfluorene-diboronic acid [390]. The authors compared the EL properties of this copolymer with PFO homopolymer 196 and PFO-bithiophene copolymer 295. Both the absorption and emission spectra of 304 are red-shifted compared with PFO 196 but slightly blue-shifted compared to bithiophene-based copolymer 295. PLEDs fabricated in the configuration ITO/ PEDOT/304/LiF/Al showed a pure green emission (CIE . v 0.29, r 0.63) close to the... 

Dibismuth ditellurium selenide, 4 25 Dibismuth ditellurium sulfide, 4 25 Dibismuthenes, 4 30-31 Dibismuthines, 4 29-30 Diblock copolymers, 7 646 23 367 Diborane, 13 619, 632, 634 Diborane(6), 4 141, 142, 184-185 bonding, 4 181 economic aspects, 4 228 physical properties of, 4 184t Diboron dioxide, 4 242t Diboron trioxide, 4 242t, 246 Dibromamine, 13 103 Dibromamine-B, 13 109 N, N-Dibromamines, 13 105 Dibromamine-T, 13 109 Dibromanine, 4 319 Dibromine oxide, 4 332... 

Miyaura and co-workers reported the platinum-catalyzed diboration of allenes with bis(pinacolato)diboron (Scheme 16.52) [57]. The catalytic cycle involves a sequence of oxidative addition of bis(pinacolato)diboron to Pt(0), insertion of an allene into the B-Pt bond and reductive elimination of an allylic boronate, re-producing the Pt(0) species. (Z)-Allylic boronates are formed stereoselectively in the reaction with monosubstituted allenes, which strongly suggests a pathway via a vinylplatinum species rather than a Jt-allylplatinum species. 

Fig. B10.4.1. Formation of non-cyclic and cyclic complexes of saccharides with the diboronic receptor S-la,b. ...

Bromodiborane, 0159 l-Bromopentaborane(9), 0186 Chlorodiborane, 0160 B-Ch lorodimcthy laminodiboranc, 0962 Diboron tetrachloride, 0161 Diboron tetrafluoride, 0162 l,2-Dibromopentaborane(9), 0187 Iododiborane, 0165 Tetraboron tetrachloride, 0179 See related non-metal halides, non-metal hydrides... 

B-Chlorodimethylaminodiborane, 0958 Diboron tetrachloride, 0161 Diboron tetrafluoride, 0162 l,2-Dibromopentaborane(9), 0187 Iododiborane, 0165... 

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