3 18-ELECTRON TANTALUM(I) COMPOUNDS, TACL(CO)(2)(DPPE)(2), [TACL(CO)(2)(DPPE)(2)](2), AND TACL(CO)(4)(DPPE) (DPPE=1,2-BIS(DIPHENYLPHOSPHINO)ETHANE), WHICH EXHIBIT LOW-LEVELS OF PARAMAGNETISM

Reductive carbonylation of TaCl5 in the presence of 1,2-bis(diphenylph osphino)ethane (dppe) under the appropriate conditions results in the formation of TaCl(CO)(2)(dppe)(2) (1), as the major product, and the p ossibly cyclic oligomer [TaCl(CO)(2)(dppe)(2)](2x), (2, 2x greater tha n or equal to 4) as a minor product. Carbonylation of 1 (1 atm) result s in the rapid but reversible formation of TaCl(CO)(4)(dppe) (3). Solu tions of all three compounds exhibit low levels of paramagnetism, poss ibly attributable to thermal population of low-lying triplet excited s tates. Crystal data for the toluene solvate of 1, C68H64ClO2P4Ta: tric linic, P (1) over bar (No. 2), a = 13.937(12) Angstrom, b = 14.811(7) Angstrom, c = 14.929(9) Angstrom, alpha = 102.30(5)degrees, beta = 95. 60(7)degrees, gamma = 98.41(5)degrees, Z = 2.