| Abstract
| - The reactions of the binuclear oxomolybdenum(V) complex[Cl2(O)Mo(μ-OEt)2(μ-HOEt)Mo(O)Cl2](1) with Me3Si(allyl) and SbF3 produce the compounds[Mo6O6Cl6(μ3-O)2(μ2-OEt)6(μ2-Cl)2](2) and[Mo8O8Cl6(μ3-O)4(OH)2(μ2-OH)4(μ2-OEt)4(HOEt)4](3), respectively. Treatment of 1 with theLewis base PMe3 affords the tetramericcomplex[Mo4O4Cl4(μ2-OEt)4(HOEt)2(μ3-O)2](4), which represents another link in the chain of clustersproducedby the reactions of 1 and simulating the build-up ofpolymeric molybdenum oxides by sol−gel methods. Thecrystal structure of 4 has been determined[C12H32Cl4Mo4O12,triclinic, P1̄, a = 7.376(2)Å, b = 8.807(3) Å, c =11.467(4) Å, α = 109.61(1)°, β = 92.12(3)°,γ = 103.75(2)°, Z = 1]. By contrast,reaction of 1 with the nitrogenbase NEt3, followed by treatment with[PPN]Cl·2H2O ([PPN]+ =[Ph3PNPPh3]+), gives thecomplex[PPN]+[Et3NH]+[Cl2(O)Mo(μ2-O)2Mo(O)Cl2]2-(6) in 90% yield. Its crystal structure[C36H30Cl4MoNOP2,triclinic,Pna21, a = 21.470(6) Å,b = 16.765(2) Å, c = 9.6155(14)Å, α = 90°, β = 90°, γ = 90°, Z = 16]includes theanion[Cl2(O)Mo(μ2-O)2Mo(O)Cl2]2-,which is a charged derivative of the species forming the gels insol−gelprocesses starting from chloromolybdenum ethoxides. Furthermore,compound 1 is found to be catalyticallyactive in esterification and dehydration reactions ofalcohols.
- The chemistry of the binuclearoxomolybdenum(V) complex[Cl2(O)Mo(μ-OEt)2(μ-HOEt)Mo(O)Cl2](1) has been investigated, particularly for its relevance tosol−gel methods for the synthesis of molybdenum oxides. To therecently discovered ethoxomolybdenum oxide clusters[Mo6O6Cl6(μ3-O)2(μ2-OEt)6(μ2-Cl)2](2) and[Mo8O8Cl6(μ3-O)4(OH)2(μ2-OH)4(μ2-OEt)4(HOEt)4](3) has now been added the tetrameric complex[Mo4O4Cl4(μ2-OEt)4(HOEt)2(μ3-O)2](4) derived from the reaction of 1 withPMe3 and characterized by its crystal structure. Bycontrast, treatment of 1 with the nitrogen baseNEt3, followed by [PPN]Cl·2H2O([PPN]+ =[Ph3PNPPh3]+), affordsthe complex[PPN]+[Et3NH]+[Cl2(O)Mo(μ2-O)2Mo(O)Cl2]2-(6), incorporating in the anion a charged derivative of thegel-forming species in sol−gel processes starting fromchloromolybdenum ethoxides.
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