Uptake of ethylene by sulfur-bridged cubane-type molybdenum/tungsten-nickel clusters [M3NiS4(H2O)10]4+ (M3 = Mo3, Mo2W, MoW2, W3): syntheses, structures and 1H NMR spectra

Shibahara, Takashi; Sakane, Genta; Maeyama, Masataka; Kobashi, Hiroyuki; Yamamoto, Takehiro; Watase, Takayoshi

crystal structure nickel metal sulfur cluster; mol structure nickel metal sulfur cluster; ethylene coordination nickel metal sulfur cluster; UV nickel metal sulfur cluster; NMR nickel metal sulfur cluster; cubane cluster nickel metal sulfur prepn; molybdenum nickel sulfur cluster prepn reaction; tungsten nickel sulfur cluster prepn reaction
The reaction of the incomplete cubane-type Mo/W clusters [M3S4(H2O)9]4+ (M3 = Mo2W, MoW2, W3) with Ni metal gave the corresponding single cubane-type Mo/W-Ni clusters [M3NiS4(H2O)10]4+, resp.  X-ray analyses of the clusters revealed that when pts- was used as the counteranion (Hpts = p-toluenesulfonic acid), the cluster [Mo2WNiS4(H2O)10]4+ (Mo2WNi) crystd. out as the single cubane-type [Mo2WNiS4(H2O)10](pts)4.7H2O (Mo2WNipts), and the clusters [MoW2NiS4(H2O)10]4+ (MoW2Ni) and [W3NiS4(H2O)10]4+ (W3Ni) crystd. out as the double cubane-type [{MoW2NiS4(H2O)9}2](pts)8.20H2O (MoW2Nipts) and [{W3NiS4(H2O)9}2](pts)8.20H2O (W3Nipts), resp.  The Mo/W-Ni cubane-type clusters [Mo3NiS4(H2O)10]4+ (Mo3Ni), Mo2WNi, MoW2Ni and W3Ni take up ethylene in aq. or org. solns. to give olefin p-complexes [Mo3NiS4(C2H4)(H2O)9]4+ (Mo3NiEt), [Mo2WNiS4(C2H4)(H2O)9]4+ (Mo2NiEt), [MoW2NiS4(C2H4)(H2O)9]4+ (MoW2NiEt) and [W3NiS4(C2H4)(H2O)9]4+ (W3NiEt), resp.  The reactivity of Mo3Ni with ethylene is not so high as the W contg. clusters, Mo2WNi, MoW2Ni and W3Ni, and the reaction does not complete in aq. soln.  However, in org. solns. such as CH2Cl2, the reaction was completed.  The following crystals were obtained and x-ray structures were detd.: [Mo2WNiS4(C2H4)(H2O)9](pts)4(Hpts)1/2.6H2O (Mo2WNiEtpts), [MoW2NiS4(C2H4)(H2O)9](pts)4(Hpts)1/2.6H2O (MoW2NiEtpts) and [W3NiS4(C2H4)(H2O)9](pts)4(Hpts)1/2.6H2O (W3NiEtpts).  The x-ray structure analyses revealed that the three clusters are isomorphous with each other and that ethylene coordinates to the Ni site in each cluster.  The ethylene mol. on the 3-fold axis is disordered, and Mo and W atoms in Mo2WNiEt and MoW2NiEt are statistically disordered.  1H NMR spectra of Mo3NiEt, Mo2WNiEt, MoW2NiEt and W3NiEt were obtained.  An increase in the no. of W atoms in the clusters resulted in an increase in the upfield chem. shift of the 1H NMR signal due to the coordinated ethylene: this tendency can be explained by the fact that W withdraws fewer electrons than Mo, which causes the higher electron d.
of the H atoms of ethylene in W-contg. clusters.  While the Ni complexes so far reported which are reactive toward ethylene contain zero-valent Ni, the formal oxidn. state of the Ni atoms in the clusters Mo3Ni, Mo2WNi, MoW2Ni and W3Ni is two, which is evident from the XPS data of Ni 2p3/2: Ni metal, 852.7; Mo3Ni, 854.7; Mo2WNi, 854.6; W3Ni, 854.5 eV.

Inorganica Chimica Acta

Elsevier B.V.

251

1-2

207

225