| Abstract
| - The first examples of mixed halide−chalcogenidehexatungsten clusters as the molecular complexes,[W6Se8-xClx(PEt3)6]+,were prepared via the reaction of W6Cl12with Na2Se and PEt3 in refluxing toluene.Singlecrystals of the mixed chloride−selenide cluster cationic complexeswere grown from chloroform solution. Thestructures of two crystals from different preparations, usingNa2Se and K2Se as reagents, weredetermined andfound to have different compositions,[W6Se7.0Cl1.0(PEt3)6][Cl(CHCl3)6]and[W6Se6.4Cl1.6(PEt3)6][Cl(CHCl3)6],respectively. In the latter case the crystal contains both the20-electron cluster[W6Se7Cl(PEt3)6]+and the 21-electron cluster[W6Se6Cl2(PEt3)6]+in the mole fractions 0.40 and 0.60, respectively. The twocrystals wereisomorphous: hexagonal, R3̄, Z = 3,a = 18.921(4) Å, c = 21.275(4) Åand a = 18.908(5) Å, c = 21.306(5)Å,respectively. The bridging chlorine and selenium atoms aredisordered over all the bridging ligand sites in bothstructures. In the unique[Cl(CHCl3)6]- anion unit,six chloroform solvent molecules are octahedrallycoordinatedto a chloride anion via hydrogen bonding.
- While efforts to produce mixed chloride−selenidetungsten clusters(W6Se8-xClx)failed in amine solvents, the first such complexes were produced byreactions of W6Cl12 withNa2Se or K2Se and PEt3 inrefluxing toluene. The 20-electron[W6Se7Cl(PEt3)6]+and its solid solution with the 21-electron[W6Se6Cl2(PEt3)6]+were isolated as salts containing the novel hydrogen-bonded anion[Cl(HCCl3)6]- uponcrystallization fromchloroform.
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