MONO(DIBENZOTETRAMETHYLTETRAAZA[14]ANNULENE) AND BIS(DIBENZOTETRAMETHYLTETRAAZA[14]ANNULENE) COMPLEXES OF GROUP-IV METALS, INCLUDING THE STRUCTURE OF THE LITHIUM DERIVATIVE OF THE MACROCYCLIC LIGAND

The deprotonation of tmtaaH-2 by LiBu(n) or LiMe gave a red solid, which upon recrystallization from DME was isolated as crystals suitable for X-ray analysis, [(tmtaa)2Li4(DME)3] (2). The lithium derivative was used in situ for the synthesis of [(tmtaa)Ti(Cl)] (3), [(tmtaa)Ti(Cl)2].C6H6 (4), and [(tmtaa)M(Cl)2].2THF (M = Zr, 5; M = Hf, 6). The structure of 2 shows a very pronounced bent cavity derived from the saddle-shape conformation of the ligand where the CS-MCl2 moiety is located. All these complexes should be considered as interesting starting materials for novel early transition metal organometallic chemistry. The reaction of MCl4(THF)2 with 2 equiv of [(tmtaa)Li2] and the reaction of [(tmtaa)M(Cl)2] with [(tmtaa)Li2] both led to thc formation of sandwich complexes [(tmtaa)2M] (M = Ti, 7; M = Zr, 8; M = Hf, 9), in which the metal achieves a cubic-type octacoordination (through bonding to the eight nitrogen donor atoms, in two staggered N4 units). The first H-1 NMR study on [(tmtaa)M] diamagnetic complexes is reported. Crystallographic details are as follows: 2, space group P1BAR, triclinic, a = 14.433 (2) angstrom, b = 17.319 (3) angstrom, c = 11.961 (2) angstrom, alpha = 94.76 (2)-degrees, beta = 101.24 (2)-degrees, gamma = 104.22 (2)-degrees, Z = 2, and R = 0.070 for 7201 independent observed reflections; 3, space group C2/m, monoclinic, a = 34.239 (7) angstrom, h = 10.101 (2) angstrom, c = 18.403 (3) angstrom, alpha = gamma = 90-degrees, beta = 100.96 (2)-degrees, Z = 8, and R = 0.059 for 1822 independent observed reflections; 5, space group P1BAR, triclinic, a = 12.437 (3) angstrom, b = 15.414 (4) angstrom, c = 9.337 (2) angstrom, alpha = 95.42 (3)-degrees, beta = 109.16 (3)-degrees, gamma = 111.47 (3)-degrees, Z = 2, and R = 0.044 for 3601 independent observed reflections; 8, space group P2(1)/n, monoclinic, a = 11.604 (5) angstrom, b = 19.073 (3) angstrom, c = 19.220 (3) angstrom, alpha = gamma = 90-degrees, beta = 91.34 (2)-degrees, Z = 4, and R = 0.049 for 3764 independent observed reflections.