Treatment of (CO)5W[C(N(CH3)2)CH3] (1) with nBuLi followed by 5-10 equiv. of a diiodoalkane (diiodomethane, 1,2-diiodoethane, 1,3-diiodopropane, 1,4-diiodobutane, or 1,5-diiodopentane) gave the respective (iodoalkylaminocarbene)tungsten complexes (CO)5W[C(N(CH3)2)CH2(CH2)nI] (n=1-5) (2). For the reaction of the α-lithio anion of 1 with diiodomethane, only a 5% yield of the corresponding complex 2a (n = 1) was obtained. Moreover, the reaction of the α-lithio anion of 1 with 1,2-diiodoethane gave no product 2b (n = 2). On the other hand, good to excellent yields (69-93%) of complexes 2c-e (n = 3-5) were obtained using 1,3-diiodopropane, 1,4-diiodobutane, or 1,5-diiodopentane. Complexes 2c-e were further treated with the α-lithio anion of 1 to afford the new (μ-bis(aminocarbene))ditungsten complexes (CO)5W[C(N(CH3) 2)CH2(CH2)nCH2C(N(CH3)2)]W(CO)5 (n=3-5) (3c-e) in yields ranging from 52 to 61%.
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We wish to thank the Bureau of General Research (Kansas State University) for support of this research. High resolution mass spectra were performed by the Midwest Center for Mass Spectroscopy, a National Science Foundation Regional Instrumentation Facility (Grant No. CHE 8211164). We also wish to thank Pressure Chemical Co. for their generous gift of tungsten hexacarbonyl.
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