158789-96-9Relevant articles and documents
Chemistry of dinuclear fulvalene complexes. Dihydrides, Zwitterions, and ring-slippage complexes, derived from FvM2(CO)6 (M = Mo, W)
Tilset,Peter,Vollhardt,Boese
, p. 3146 - 3169 (2008/10/08)
Reduction of the metal - metal-bonded complex FvW2(CO)6 generated the dianion FvW2(CO)62-. An X-ray crystallographic analysis of [Et4N+]2[FvW2(CO)62- (monoclinic space group P21/c, a = 7.687(2) A, b = 13.752(4) A, c = 16.297(5) A, β = 94.80(2)°, V = 1716.8(8) A3, Z = 4) showed the dianion to contain a planar Fv ring system bonded to the two metal centers in an anti fashion. The diuanion reacted with a number of electrophiles to yield the neutral species FvW2(CO)6E2 (E = H, Me, Et, σ-C3H6. CH2Ph). The pKa values for the two consecutive deprotonations of FvW2(CO)6H2 were determined as 14.0 and 16.6 by equilibrium measurements in acetonitrile. Thermolysis and photolysis of FvW2(CO)6H2 yielded FvW2-(CO)6 and H2. Unlike Cp2W2(CO)6, FvW2(CO)6 underwent protonation at the W-W bond by HBF4·Et2O in acetonitrile. Reactions of FvW2(CO)6 and FvMo2(CO)6 with PMe3 and Me2-PCH2PMe2 (dmpm) resulted in generation of the dinuclear zwitterions FvM2(CO)5(PMe3)2 and FvM2(CO)5)(dmpm), respectively. An X-ray crystallographic analysis of FvMo2(CO)5 (orthorhombic space group P212121, a = 9.1049(8) A, b = 12.2598(14) A, c = 20.1606(18) A, V = 2250.4(7) A3, Z = 4) showed an anti coordination of the Mo(CO)3- and Mo(CO)2(dmpm)+ moieties at a planar Fv ligand. Electrophiles added at the anionic part of the zwitterions, whereas LiAlH4 effected reduction of coordinated CO to CH3 at the cationic center of FvMo2-(CO)5(PMe3)2. Excess PMe3 caused the conversion of FvMo2(CO)5(PMe3)2 and FvMo2(CO)5)-(dmpm) to Mo(CO)3(PMe3)3 along with FvMo(CO)2(PMe3)2 and FvMo(CO)2(dmpm), respectively. These reactions constitute the first ring-slippage reactions that have been observed in fulvalene metal complexes. When treated with Mo(CO)3(NCMe)3, FvMo(CO)2(PMe3)2 cleanly regenerated FvMo2(CO)5(PMe3)2.
