Richard L. Keiter

On the synthesis and 31P{1H} NMR spectrum of (CO) 5W(μ-PPh2CH2PPh2) W(CO)5

The dimetallic complex, (CO)5W(μ-PPh2CH2PPh2)W(CO)5, is synthesized from either a 2:1 mixture of (CO)5W(NCMe) and (CO)5W(η1-PPh2CH2PPh2) or a 3:1 mixture of (CO)5W(NCMe) and PPh2CH2PPh2 in toluene at 60°C. The coupling constants, 2Jpp′ = 22.9 Hz, 1JWP = 246.9 Hz and3JWP′ = 4.5Hz are consistent with those reported in the literature for similar complexes. The complex (CO)5W(η1-PPh2CH2PPh2) is stable with respect to chelation at room temperature.

Tetracarbonyl group 6 complexes containing secondary and tertiary phosphines

Abstract The mixed ligand tetracarbonyl derivatives, cis -M(CO) 4 (PPh 2 H)(PPh 3 ) (M  Cr, Mo, W) and cis -W(CO) 4 (PPh 2 H)(L) (L  PEt 3 , PEt 2 Ph, PEtPh 2 ) have been prepared from the reaction of M(CO) 5 PPh 2 H with L in THF in the presence of potassium t-butoxide. These reactions are accompanied in most instances by the formation of [W(CO) 5 PPh 2 ] − , [(OC) 5 M(μ-PPh 2 )M(CO) 5 ] − , [(OC) 5 M(μ-PPh 2 )-M(CO) 4 (PPh 2 H)] − , [(OC) 4 M(μ-PPh 2 ) 2 M(CO) 4 ] 2− , (OC) 4 M(μ-PPh 2 ) 2 M(CO) 4 , and cis -M(CO) 4 (PPh 2 H) 2 .

The Synthesis of BIS(Phosphine)Tricarbonyliron(O) Complexes

Abstract The high-yield synthesis of trans-Fe(CO)3L2 (L = PPh3, PPh2 H, P(n-Bu)3, PPh2 CH=CH, PPh2Me) can be acheived in one step by the reaction of Fe(CO), with L and NaOH in refluxing n-butanol. The reaction is selective for trans disubstitued complexes and is complete in 2 h.

Crystal structure of trans-W2(CO)6(PPh2H)2(μ2-PPh2)2

The molecular structure of trans-W2(CO)6(PPh2H)2(μ2-PPh2)2 was determined by X-ray diffraction analysis. The two tungsten centers, bridged by two diphenylphosphido ligands, are separated by 3.0667(6) Å with W–P–W angles of 77.10(5) and 77.08(5)○. Average tungsten–phosphorus bond distances are 2.461(17) and 2.4576(21) Å for bridging and terminal phosphorus groups, respectively, with a range of 0.037 Å for the former and 0.001 Å for the latter. The complex crystallizes in the monoclinic space group P21/c with a = 19.282(4) Å, b = 12.158(2) Å, c = 21.294(9) Å, β = 92.821(4)○, and Z = 4.

Nuclear magnetic resonance studies of chelate-ring effects in tungsten(0) carbonyl complexes of poly(tertiary phosphines)

Magnetic multiple-resonance experiments have been used to determine the absolute signs of the various 31P–31P spin-coupling constants in tungsten carbonyl complexes of the ligand Ph2PCH(CH2PPh2)CH2CH2PPh2. Apparently anomalous values of these coupling constants may thereby be accounted for in simple terms and shown to be consistent with earlier ideas on the effects of chelate-ring formation on n.m.r. parameters.