Incorporation of alkyne and vinylidene ligands into tetrazolate groups at a sulfur-rich dimolybdenum site using sodium azide

Treatment of either the mu-alkyne complex [Mo2Cp2(mu-SMe)(3)(mu-PhCCH)](BF4) (1) or the mu-vinylidene derivatives [Mo2Cp2(mu-Sme)(3)(mu-eta(1):eta(2)-(CCHR)](BF4) (2) (R = Ph, Tol, nPr, C(CH3)=CH2) with NaN3 in ethanol at room temperature readily afforded mu-tetrazolate carbene complexes [Mo2Cp2(mu-SMe)(3)){mu-eta(1) (C):eta(1) (N)-N4CCR)}] (R = Ph (4a), Tol (4b), nPr (4c), C(CH3)=CH2 (4d)). A mechanism which accounts for the formation of 4 by intramolecular 1,3-dipolar cycloaddition of metal-coordinated azide ligands to metal-coordinated nitrites is discussed. The structure of complex 4a has been determined by single X-ray diffraction analysis. (C) 2003 Elsevier Science B.V. All rights reserved.