Preparation and Characterization of [Hg{P(C6F5)2}2], [Hg{((mu)-P(C6F5)2)W(CO)5}2], and [Hg{((mu)-P(CF3)2)W(CO)5}2] and the X-ray Crystal Structure of [Hg{((mu)-P(C6F5)2)W(CO)5}2]·2DMF

The thermally unstable compound [Hg{P(C6F5)2}2] was obtained from the reaction of mercury cyanide and bis(pentafluorophenyl) phosphane in DMF solution and characterized by multinuclear NMR spectroscopy. The thermally stable trinuclear compounds [Hg{((mu) -P(CF3)2)W(CO)5}2] and [Hg{((mu)-P(C6F5)2)W(CO)5}2] are isolated and completely characterized. The higher order NMR spectra exhibiting multinuclear satellite systems have been sufficiently analyzed. [Hg{(-P(CF3)2)W(CO)5}2]·2DMF crystallizes in the monoclinic space group C2/c with a = 2366.2(3) pm, b = 1046.9(1) pm, c = 104.0(1) pm, and(beta)= 104.01(1). Structural, NMR spectroscopic, and vibrational data prove a weak coordination of the two DMF molecules. Structural, vibrational, and NMR spectroscopic evidence is given for a successive weakening of the back-bonding effect of the W-P bond in the order [W(CO)5PH(Rf)2], [Hg{((mu)-P(Rf)2)W(CO) 5}2], and [W{P(Rf)2}(CO)5]^- with Rf = C6F5 and CF3. The(pi)back-bonding effect of the W-C bonds increases vice versa.