STRUCTURE OF [(LI(OET2))(2)NI(CH2NME2)(4)], A HOMOLEPTIC NICKELATE COMPLEX

A crystal of the title compound [{Li(OEt2)}(2) Ni(CH2NMe2)(4)] (1), gr own from diethyl ether, was investigated by single-crystal X-ray analy sis. 1 crystallizes in the monoclinic space group P2(1)/n with a = 9.1 00(2) Angstrom, b = 11.721(2) Angstrom, c = 13.773(3) Angstrom, beta = 93.47(3)degrees, and Z = 2. The crystal structure was solved by the h eavy atom method (wR2 = 0.1290 for 3532 reflections; R1 = 0.0453 for 2 458 observed reflections). The molecular structure of the very air sen sitive compound was found to be centrosymmetric with a square planar a rrangement of the four methylene carbon atoms and nickel. The Ni-C bon d lengths amount to 2.028(2) Angstrom and 2.037(2) Angstrom, respectiv ely. The lone pair of nitrogen is strongly involved in the lithium coo rdination (Li-N bond lengths: 1.954(5) Angstrom, 1.995(5) Angstrom). T his fact and the absence of beta-hydrogen atoms seem to be responsible for an unusual thermal stability of complex 1 (T-dec. = 363-388 K).