Preparation and characterization of [Hg{P(C6F5)2}2], [Hg{(μ-P(C6F5)2)W(CO)5}2], and [Hg{(μ-P(CF3)2)W(CO)5}2] and the X-ray crystal structure of [Hg{(μ-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{(mu-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)degrees. 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 pi back-bonding effect of the W-P bond in the order [W(CO)(5)PH(R-f)(2)], [Hg-{(mu-P(R-f)(2))W(CO)(5)}(2)], and [W{P(R-f)(2)}(CO)(5)](-) with R-f = C6F5 and CF3. The pi back-bonding effect of the W-C bonds increases vice versa.