Phosphines boron hydrides

A special kind of oxidative addition occurs between phosphine cobalt hydride complexes and boron halides ... 

The boron hydrides, silanes, phosphines, and most other covalent hydrides bum readily, some even being spontaneously flammable. 

Ammonia reacts with boron hydride to form a product with the empirical composition B2H6 2NH3 s2-is4) similarly, phosphine combines with diborane, in the gas phase above -30 °C and in the liquid phase in a sealed tube above -130 C, to give a white instable solid of constitution BH3PH3 (m.p. 32-35 °C) >is ). The dissociation pressure of BH3 PH3 is so large that the compound is already separated into its components at room temperature... 

A qualitatively similar dependence of ADh on boron orbital hybridization is noted in boron hydrides (104). -1bh = 81 cps for BHr where boron is tetrahedral while ABH = 136 cps for borazole where boron presumably is sp2. A ijh for BH3 adducts with ethers, amines, and phosphines range between 90 and 103 cps and for these compounds boron quadrupole coupling constants have been interpreted (22) in terms of a boron hybridization intermediate between sp2 and sp2. However, the simple dependence of... 

It should be clear from the discussion of Section 2 that all of these clusters can be unstable with respect to cluster degradation in the presence of Lewis bases with the formation of saturated fragment species (see Boron Hydrides and Polynuclear Organometallic Cluster Complexes). Thus, in the presence of an excess of phosphine, the reaction of [HFe3(CO)9(/u-H)2BH] changes from that shown in equation (10) to that shown in equation (12). The mononuclear boron and iron products demonstrate that both transition metal and main group element vertices are removed by base and the cluster is degraded. ... 

A comprehensive n.m.r. investigation of the boron hydride and halide addition compounds with a number of alkyl- and aryl-phosphines is reported by Rapp and Drake.220 The H data point to a relationship between... 

Bob authored more than 150 publications, not only on the boron hydrides but also on gallium, phosphines, and the thermodynamics of chelation. Long active in the ACS, he served as President (1982), member of the Council for more than 45 years and of the Board of Directors (1973-1983), and Associate Editor of the Journal of the American Chemical Society (1966-1968, 1971-1980), and a member of its Editorial Board (1969-1980). He was the founding editor of Inorganic Chemistry (1960-1964) and a member of its Editorial Board (1962-1979) and President of Inorganic Syntheses, Inc. (1969-1972). One of the early leaders of the Gordon Research Conferences, he was a member (1965-1972)... 

Very few phosphorus-acceptor atom coupling constants have been reported for complexes of non-transition elements (Table X) even the protonated phosphines appear to have received little attention. The absence of data may be partly explained by the prevalence of very rapid dissociation and recombination reactions for non-transition element compounds (see Section III.A.2), and at present results are available only for the very strong acceptors AlCl3, AlBr3, BH 3, some other boron hydrides and the proton. 1 1 ... 

Combination of phosphine with borane can give rise to a large variety of possible phosphorus-boron hydrides. The simplest of these, phosphinoborane, H2B-PH2, is a hypothetical compound, but a number of derivatives are known in which some or all of the H atoms are replaced by alkyl, aryl, halogen or other groups. 

Numerous reactions between phosphines and the boron hydrides are now known. Some of these reactions involve the breaking of B-H bonds with the elimination of hydrogen (9.85, 9.86), while others involve the break-up of the complex boron cage into smaller units (9.87-9.90). Non-phosphorus ligands of basic character also form complexes in this latter way [35]. 

Matsumi N, Chujo Y (1997) Synthesis of novel organoboron polymers by hydroboration polymerization of bisaUene compounds. 38. Polym BuU (Berl) 38(5) 531-536. doi 10.1007/s002890050083 Andreou A (2013) Synthesis tmd reactivity of boron hydrides for the preparation of chiral diboranes and bis-phosphines. University of Cambridge, Cambridge 39. 

Notable examples of general synthetic procedures in Volume 47 include the synthesis of aromatic aldehydes (from dichloro-methyl methyl ether), aliphatic aldehydes (from alkyl halides and trimethylamine oxide and by oxidation of alcohols using dimethyl sulfoxide, dicyclohexylcarbodiimide, and pyridinum trifluoro-acetate the latter method is particularly useful since the conditions are so mild), carbethoxycycloalkanones (from sodium hydride, diethyl carbonate, and the cycloalkanone), m-dialkylbenzenes (from the />-isomer by isomerization with hydrogen fluoride and boron trifluoride), and the deamination of amines (by conversion to the nitrosoamide and thermolysis to the ester). Other general methods are represented by the synthesis of 1 J-difluoroolefins (from sodium chlorodifluoroacetate, triphenyl phosphine, and an aldehyde or ketone), the nitration of aromatic rings (with ni-tronium tetrafluoroborate), the reductive methylation of aromatic nitro compounds (with formaldehyde and hydrogen), the synthesis of dialkyl ketones (from carboxylic acids and iron powder), and the preparation of 1-substituted cyclopropanols (from the condensation of a 1,3-dichloro-2-propanol derivative and ethyl-... 

Diisobutylaluminum hydride-Boron trifluoride etherate, 116 Diphenylsilane-Palladium(II) chlo-ride-Triphenylphosphine, 126 Diphenylsilane-Tetrakis(triphenyl-phosphine)palladium(0)-Zinc chloride, 126... 

Chiral addition of allyl metals to imines is one of the useful approaches toward the synthesis of homoallylic amines. These amines can be readily converted to a variety of biologically important molecules such as a-, / -, and y-amino acids. Itsuno and co-workers utilized the allylborane 174 derived from diisopropyl tartrate and cr-pinene for the enantioselective allylboration of imines. The corresponding iV-aluminoimines 173 are readily available from the nitriles via partial reduction using diisobutylaluminium hydride (DIBAL-H) <1999JOM103>. Recently, iV-benzyl-imines 176 have also been utilized for the asymmetric allylboration with allylpinacol boronate 177 in the presence of chiral phosphines as the chiral auxiliaries to obtain homoallylic A -benzylamines 178 in high yield and selectivity (Scheme 29) <2006JA7687>. 

Further surveys of the reactivity of HB(C6F5)2 with simple organometallic compounds have led to the discovery of more novel boron-based ligand systems. For example, reactions with Schrock s tungsten methylidyne family L4W(X)=CH63 (L = phosphine, X = Cl, OTf) result in electrophilic attack on the methylidyne ligand hydride abstraction... 

The phosphine 1-(1,2-C2BxoHii)P(CHs)2 was prepared and reacted with an iridium (I) complex, as shown in Fig. 27. Spectroscopic evidence strongly supported the view that the complexed Ir(I) had inserted into a B—H bond with the formation of an iridium-boron bond and an iridium-hydride link (58). Specific deuterium labels attached to the carborane moiety of the phosphine clearly proved this point. Thus, the B-H vertices of the icosahedral carborane group that are nearest the carbon atom bearing phosphorus were shown to be involved, although a distinction could not be made between the 3,6 or 4,5 sets of BH groups. 

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