Reaction of VCl(3)(THF)(3) with (3,5-Me(2)Ph)AdNLi.Et(2)O (Ad = adamantyl) yields the homoleptic vanadium complex [(3,5-Me(2)Ph)AdN](3)V (1), which reacts with chalcogens E (E = S, Se) to yield diamagnetic terminal chalcogenide derivatives [(3,5-Me(2)Ph)AdN](3)V=E [E = S (3a), Se (3b)] Crystal data for 1 and 3a are as follows. 1: C(54)H(72)N(3)V, fw 814.09, triclinic P&onemacr;, a = 10.441(1) Å, b = 11.648(4) Å, c = 19.321(2) Å, alpha = 83.69(2) degrees, beta = 83.89(1) degrees, gamma = 82.42(2) degrees, Z = 2. 3a: C(54)H(72)N(3)VS.(1)/(2)Et(2)O, fw 883.25, monoclinic C2/c, a = 43.400(9) Å, b = 11.744(3) Å, c = 20.705(4) Å, beta = 113.05(1) degrees, Z = 8.

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Anionic organic amides have proven to be versatile ligands in the chemistry of di-and trivalent vanadium. In addition to the stabilization of rare V-N 2 -V moieties, 1 these ligands can be involved in a number of vanadium metal center mediated transformations which include C-H σ-bond metathesis, 2 Htransfer, 3 dinitrogen cleavage, 4 azide coordination, 5 stabilization of alkyl groups, 6 and formation of metallacycles. 7 These observations prompted us to study the chemistry of low-valent niobium and tantalum amides for which only little information is available in terms of preparation and characterization. 8 We have recently reported that the reaction of [NbCl 4 (THF) 2 ] with Cy 2 NLi affords a Nb(V) niobaaziridine complex where the metallacycle is formed Via C-H σ-bond activation. 9 Given the potential offered by this type of reactivity, we are currently attempting to expand the accessibility to medium-valent Taamide derivatives through preparation of complexes with the formula [(R 2 N) n TaCl (5-n) ], which may work as a starting material for further reduction. In this paper, we describe our preliminary observations. The reaction of TaCl 5 with 4 equiv of Cy 2 NLi in diethyl ether at -78°C gave, upon mixing, an instantaneous color change and formation of a brown-reddish mixture. 10 After elimination