Graham N. Mott

Phosphorus-based 1,3-dipoles as three-electron one-carbon ligands: x-ray structure of μ-[phenyl(dicyclohexylphosphonio)ethenidyl]-μ-(diphenylphosphido)hexacarbonyldiiron, Fe2(CO)6[CC(PCy2H)Ph](PPh2)

Abstract The synthesis of μ-[phenyl(dicyclohexylphosphonio)ethenidyl]-μ-(diphenylphosphido)hexacarbonyldiiron, Fe2(CO)6[CC(PCy2H)Ph](PPh2) via nucleophilic attack by dicyclohexylphosphine at the β-carbon atom of the σπ-acetylide in Fe2(CO)6(CCPh)(PPh2) is described. This complex, which contains a one-carbon 3-electron bridging ligand has been characterised by microanalysis, infrared, mass, Mossbauer and 31P NMR spectroscopy and by a single crystal X-ray structure determination. Crystals are monoclinic, space group P21/c with a 10.932(3), b 8.983(2), c 38.644(6) A, β 94.48(2)°. With four molecules per unit cell and a formula weight of 764.4, the calculated density of 1.342 g cm−3 agrees with the measured value of 1.34 g cm−3. The structure was solved by heavy atom methods and refined by least squares techniques with iron and phosphorus atoms having anisotropic thermal parameters, to R and Rw values of 0.068 and 0.075 respectively. In the binuclear molecule an ironiron bond of length 2.550(2) A is bridged by a diphenylphosphido group and the carbon atom of an unusual dipolar ligand Cy2(H)P+C(Ph)C−. In the bridging one-carbon-3-electron ligand the coordinated carbon atom is trigonal and the atoms P(1), C(8), C(31), C(7) are virtually coplanar. Structural parameters are compared with those of other complexes containing bridging one-carbon, 3-electron and two-carbon, 3-electron ligands. Nucleophilic attack by phosphorus and nitrogen nucleophiles on σπ-acetylides appears to be a general route to these ligands.

Reduction of an acetylide CCr to an iminoethyl group CH2 C(R)NR′ in a binuclear iron complex via hydrogen migration from nitrogen to carbon: x-ray structure of Fe2(CO){6CH2C(Ph)NMe}(PPh2)

Abstract Primary amines RNH 2 effect reduction of the triple bond of the binuclear σπ-acetylide Fe 2 (CO) 6 (CCPh)(PPh 2 ) affording novel iminoethyl complexes Fe 2 (CO) 6 {CH 2 C(Ph)NR}(PPh 2 ) via hydrogen migration from nitrogen to carbon. An X-ray analysis of the iminoalkyl derivative Fe 2 (CO) 6 {CH 2 C(Ph)NMe}(PPh 2 ) shows the reduced ligand bonded as a bridging C(1e)N(2e) donor.

Carbon—carbon bond formation via coupling of isonitriles with μ2-η2-acetylides

Abstract The synthesis of carbon—carbon bonds via coupling of isonitriles RNC with the μ 2 -η 2 -acetylide in Fe 2 (CO) 6 (CCPh)(PPh 2 )via nucleophilic attack at carbocationic carbon is described.