Phosphane complex bonding

This mechanism, involving sequential hydronation of N2 initially at the nitrogen atom remote from the metal(s), followed by cleavage of the N—N bond, then hydronation of the resulting nitride, is, in essence, the same mechanism that has been developed on electron-rich, low-oxidation-state Mo phosphane complexes (Section III). The only real difference is that in this case the N2 is bound to four Fe sites in a cluster. 

The two coordinated COD molecules in Am[Co(COD)2] (27b) and the four bonded ethylenes in Am[Co(C2H4)4] (27a) are readily displaced by CO or butadiene at low temperatures as in Eq. (32) (42, 43). The diphos-phane (CH2)2[P(C6HU)2]2 displaces only two ethylene molecules from 27a at 0°C giving 30. These latter compounds (Am = Li, K) react with hydrogen to yield novel alkali metal-containing hydridocobalt-phosphane complexes (31) which have 2H2 per AmCo (47). 

Ditertiary phosphane complexes of nickel were found to be effective in the formation of pyrone 108 by cyclocotrimerization of alkynes with carbon dioxide. The formation of the nickelacyclopentadiene 105 from two moles of alkyne and a nickel complex is followed by CO2 insertion into a nickel-carbon bond to give the oxanickelacycloheptadienone 106, which then eliminates 108 with intramolecular C—O coupling. Another route involving [4 + 2] cycloadditions of 105 with CO2 in a Diels - Alder reaction to give 107 cannot be ruled out but is less probable because CO2 does not undergo [4 + 2] cycloaddition with dienes. Addition of another alkyne to 105 results in the formation of a benzene derivative (Scheme 38). ... 

In summary, prominent features of ylide nickel complexes versus phosphane complexes have been identified an electron-rich nickel center, energetically destabilized nickel-localized occupied orbitals, a significant weakening of the Ni-O bond, the phosphoms moiety being located outside the nickel coordination plane, thus opening one axial position in the nickel coordination sphere for easy monomer landing . 

With Iridium In 2008, Tsuchikama etal. [89] reported the use of the cationic Ir—hidentate phosphane complex formed from [Ir(COD)2]BF, and BINAP (2,2 -Bis(diphenylphosphino)-l,l -binaphthyl) for the catalytic addition of ortho-C-U. bonds of aryl ketones to 2dkynes and alkenes, which gave alkeny-lated products in good to high yield (Scheme 4.14). 

VT-multinuclear NMR studies have allowed one to establish unequivocally whether the M-coordinated-C02 framework is a rigid structure or not To this end, it is necessary that other nuclei (such as the P-donor atoms of phosphanes) are bonded to the metal centre so that, when the metal favours the coupling, it is possible to observe whether the solid state stmcture is maintained in solution or the framework exhibits some fluxionality. Complex 1 has been extensively investigated and the fluxional behaviour has been well explained by coupling IR and NMR studies [6, 40],... 

Aqueous HCI solutions hydrolyze the P-N bond to give the amine hydrochloride and R2P-OH, which then disproportionates and is oxidized to diphenylphosphinic acid. A free phosphinous amide anion, with the countercation complexed by a crown ether, has been shown to be hydrolyzed and oxidized to the corresponding phosphinite with unusual ease [119]. Formic acid in toluene can be utilized for converting P,P-disubstituted phosphinous amides into their respective phosphane oxides [30]. 

The rather complicated indium-phosphorus cluster framework 24 was obtained by the reaction of indium(III) chloride with PhP(SiMe3)2 in the presence of triethyl-phosphane [Eq. (12)] [29]. Apparently, a complex redox process occurred, in the course of which phosphorus atoms were oxidized by the formation of three P-P bonds, while six indium atoms were reduced from +3 to +2 accompanied by the formation of three In-In bonds. The In-In (average 274 pm) and P-P bond lengths (average 222 pm) represent localized single bonds. Other strategies for the... 

---