Cyanide complexes boron

Beryllium, calcium, boron, and aluminum act in a similar manner. Malonic acid is made from monochloroacetic acid by reaction with potassium cyanide followed by hydrolysis. The acid and the intermediate cyanoacetic acid are used for the synthesis of polymethine dyes, synthetic caffeine, and for the manufacture of diethyl malonate, which is used in the synthesis of barbiturates. Most metals dissolve in aqueous potassium cyanide solutions in the presence of oxygen to form complex cyanides (see Coordination compounds). 

The complexes Fe(CNR)4(CN)2 (R = H, CH3, C2H5) are reported to form 1 2 complexes with boron trihalides (65). In these complexes the BX3 group coordinates to the cyanide nitrogen, giving the ligand group [CNBXj] . A mention of a similar complex was made earlier 161). 

Quite in contrast to, e.g., [CoCp2]+, borabenzene metal cations show a pronounced affinity toward hard nucleophiles such as amines, OH-, and to some extent even F- and H20. Qualitatively this affinity increases in the order CoCp2]+ 36 < 1 < 61 (69). [CoCp(C5H5BPh)]+ (1) adds tertiary amines at boron. With pyridine, the pyridinioboratacyclohexadienyl complex 70 is formed (K = 174 5 liters mol-1, in MeCN, 20°C), which can be isolated from CH2C12 as PF6- salt (69). The similar rhodium and iridium cations 36 and 37 form the stable cyanide adducts 71 and 72 (69). 

Often Lewis acids are added to the system as a cocatalyst. It could be envisaged that Lewis acids enhance the cationic nature of the nickel species and increase the rate of reductive elimination. Indeed, the Lewis acidity mainly determines the activity of the catalyst. It may influence the regioselectivity of the catalyst in such a way as to give more linear product, but this seems not to be the case. Lewis acids are particularly important in the addition of the second molecule of HCN to molecules 2 and 4. Stoichiometrically, Lewis acids (boron compounds, triethyl aluminium) accelerate reductive elimination of RCN (R=CH2Si(CH3)3) from palladium complexes P2Pd(R)(CN) (P2= e g. dppp) [7], This may involve complexation of the Lewis acid to the cyanide anion, thus decreasing the electron density at the metal and accelerating the reductive elimination. 

Photochemical deoxygenation of nitrobenzene to nitrosobenzene with cyanide ions 38,40) or by molecular complexation with boron trichloride have been reported. No experiments to elucidate the multiplicity of the reacting excited state have been described, however. 

Iron carbonyl complexes with As, Sb, Bi donor ligands, 6, 57 with boron, 6, 7 cyanides and isocyanides, 6, 15 Fe3(CO)i2, 6, 260... 

Diethyl phosphorocyanidate adds to a,/J-unsaturated aldehydes or ketones in the presence of lithium cyanide in a 1,2-fashion28. Boron trifluoride-diethyl ether complex catalyzed rearrangement of these allylic phosphates shows high E selectivity (>85 15) for the adducts derived from aldehydes and Z selectivity (>90 10) for ketone adducts. The selectivity of the rearrangement can be explained by assuming a chairlike transition state, in which the sterically more demanding x-substituent occupies the quasi-equatorial position. The steric requirement decreases in the order of R1 > CN > H. Thus, the cyano substituent occupies the quasi-equatorial position in the aldehyde-derived adduct (R1 = H), but the quasi-axial position in the ketone-derived adduct (R1 = CH3, C6H5). 

In contrast to the low yield when hydrogen chloride is employed, an 88% yield of 2,4,6-triphenyl- 1,3,5-triazine (7) is obtained when chlorosulfonic acid is used as catalyst in a molecular ratio of 3 1 (CiSOjH/PhCN) at 0-5 C C and a reaction time of 12 to 24 hours.174 Trifluo-romethanesulfonic acid as a catalyst and solvent trimerizes benzonitrile at 91 °C in a yield of 66%.175 Lewis acids alone, such as aluminum, zinc, iron or titanium chlorides, phosphorus pentachloride, and boron trifluoride, have a considerably lower catalytic activity than the corresponding mixtures of Lewis acid with various promotors, such as mineral acids, organic acids and water. These differences are attributed to a change in the structure of the active complexes with the aryl cyanides. 

Trialkyl- and triarylboranes react with various sodium compounds, e.g., the hydride, cyanide, hydroxide, and amide as well as the allfyls, aryls, alcoholates, and phenolates, under mild conditions to form stable complex salts (borates) which contain four-coordinate boron as the central atom in the anion 1-4... 

The treatment of one equivalent of 5-lithio-2,3-dihydro-1,4-dioxin with 0.5 equivalent of copper(I) cyanide solubilized as its lithium chloride (0.5 equiv.) complex at — 15°C affords the corresponding cyanocuprate. The reactivity of this cuprate was assessed by its conjugate addition to cyclic enones, and by nucleophilic epoxide opening the presence of boron trifluoride etherate led to enhancement... 

AMIDES Boron tribromide. Boron trifluoride etherate. 6-Chloro-l-p-chlorobenzene-sulfonyloxybenzotriazole. Diethylphosphoryl cyanide. Dihalobis(triphenylphosphine)-palladium(H). Dihalobis(triphenylphosphine)paUadium(ll) complexes. Palla-dium(II) chloride. Sodium amide. Trimethylsilyl isocyanate. Triphenylphosphine ditriflate. 

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