SYNTHESIS AND CHARACTERIZATION OF THE SIGMA-BONDED, QUASI-LINEAR, METAL(II) DIARYLS MMES-ASTERISK(2) (M=MG, MN, FE-MES-ASTERISK=2,4,6-T-BU(3)C(6)H(2)-)

Disproportionation of a THF solution of MesMgBr (Mes* = 2,4,6-t-Bu(3) C(6)H(2)) with 1,4-dioxane affords MgMes(2) (1). The treatment of act ivated MnCl2 or FeBr2 with MgMes(2) in ether, and in the presence of 1,4-dioxane, affords the manganese(II) and iron(II) diaryls MnMes(2) (2) and FeMes(2) (3) as thermally stable pale yellow or yellow crysta ls in moderate yield. The X-ray crystal structures of 1-3 feature rare examples of two-coordinate metal(II) diaryls. The Mg-C, Mn-C, and Fe- C distances are 2.116(3), 2.108(2), and 2.058(4) Angstrom, respectivel y, and the C-M-C angles are in the range 157.9(2)-159.66(10)degrees. T here are also close (ca. 2.2-2.3 Angstrom) contacts involving the meta l and hydrogens from the ortho-t-Bu groups. No reactions were observed between MMes(2) and THF, pyridine, or acetonitrile. Crystal data at 130 K with Mo K alpha (lambda = 0.710 73 Angstrom) (2 and 3) or Cu K a lpha (lambda = 1.541 78 Angstrom, alpha = radiation: C36H58Mg (1), M(r ) = 515.13, a = 9.823(2) Angstrom, b = 15.571(8) Angstrom, c = 22.501( 4) Angstrom, alpha = 96.88(3)degrees, beta = 97.85(2)degrees, gamma = 98.77(3)degrees, triclinic, space group P1 $$($) over bar, Z = 4, R = 0.059 for 6304 (I > 2 sigma(I) data; C36H58Mn (2), M(r) = 545.76, a = 17.705(10) Angstrom, b = 8.576(4) Angstrom, c = 23.252(11) Angstrom, b eta = 108.51(4)degrees, monoclinic, space group C2/c, Z = 4, R = 0.047 for 3133 (1 > 2 sigma(I)) data; C36H58Fe (3), M(r) = 546.67, a = 17.7 63(12) Angstrom, b = 8.593(4) Angstrom, c = 23.365(13) Angstrom, beta = 109.49(4)degrees, monoclinic, space group C2/c, Z = 4, R = 0.067 for 2740 (I > 2 sigma(I)) data.