Mono- and bis-ortho-chelated lithium and sodium phenolates. Molecular structures of the first lithium phenolate with a stable, trinuclear structure and of a tetranuclear sodium analog, [MOC6H2(CH2NMe2)2-2,6-Me-4]x (M = Li, x = 3; M = Na, x = 4)

Abstract

The lithium and sodium phenolates of 2-[ (dimethylamino)methyl]phenol, la and 2a, 2-[(dimethylamino)methyl]-4,6-dimethylphenol, l b and 2b, and 2,6-bis[(dimethylamino)methyl]-4-methylphenol, IC and 2c, respectively, have been synthesized. The structures of these complexes in solution were studied by variable-temperature lH and l3C NMR spectroscopy and cryoscopic molecular weight measurements. The solid-state structures of complexes IC and 2c derived from 2,6-bis[ (dimethylamino)methyl]-4-methylphenol, were determined by X-ray diffraction. The complexes containing only one ortho-chelating (dimethy1amino)methyl group, i.e. la,b and 2a,b, are soluble in weakly polar solvents, like tetrahydrofuran. Complexes la and l b are tetramers in benzene. These tetramers occur in solution in two isomeric forms, Le. as aggregates with 0 2 and S 4 symmetry. The lithium "pincer-phenolate" containing two ortho-chelating (dimethy1amino)methyl groups (IC) is a trimer in apolar solvents as well as in the solid-state. It is the first example of a phenolate complex with a stable, trinuclear structure. In contrast, the sodium analog (2c) is a dimer in solution and crystallizes as a tetramer with a cubic-likeNa404 core. Crystals of Li3C3&N603, lc,aremonoclinic,spacegroupP21/n,withunit celldimensionsa= 42.381(5)A,b=8.8417(11)&~= 11.1802(10) A, fi = 90.539( 8)", and Z = 4. The structure was refined to R = 0.068 for 4106 reflections and 610 parameters.The trimeric structure contains a Li303-ring which is almost perfectly planar (within 0.05 A), and very short Li-0 and C-0 bond lengths (averages of 1.865( 9) and 1.317(6) A, respectively). As a result of intramolecular amine coordination IC is a "propeller-like" molecule with screw-type chirality. Crystals of Na4C52Hg4N8O4.C6H6, 2c, are monoclinic, space group P2/c, with a = 16.021(2) A, b = 10.275(1) A, c = 24.190(2) A, B = 130.35(1)O, 2 = 2, and final R = 0.064 for 3476 reflections and 400 parameters. This tetramer consists of a double dimer in which the NMe2 groups of one dimer do exclusively coordinate to the sodium atoms of the same dimer.

Sodiated β‐Diphosphonate Carbanions: Characterization of the Tetrameric Cubane and the Hexameric Ladder Complexes [{(iPrO)2P(O)}2CHNa]4 and [{(EtO)2P(O)}2CHNa]6

“…[17] The closest structural analog to 1 is the complex [4-Me-2,6-(Me 2 NCH 2 ) 2 C 6 H 2 ONa] 4 , in which the ''pincer phenolate'' ligands coordinate to three sodium centers of a Na 4 O 4 cubane. [18] However, the phenolate possesses approximate D 2 symmetry, whereas 1 is rendered closer to C 2 symmetry due to the ''secondary'' chelation of the iPrO groups.…”

Synthesis and structural characterization of Pd(II) complexes containing 2,6-bis[(dimethylamino)methyl]-4-methylphenolate ligand

“…2 Cl 2 ][6],[Pd(COD)Cl 2 ][7] and 2,6-bis[(dimethylamino)methyl]-4-methylphenol[8] were prepared according to the literature procedures. Other chemicals were obtained from commercial sources and used without further purification.…”

Reaction of aryl azides with tris(trimethylsilyl)silyllithium: Synthesis of tmeda or thf adducts of [Li{N(Ar)Si(SiMe3)3}] and 1,4-trimethylsilyl migration from oxygen to nitrogen

“…The atoms N(1), Li (1) (11), Li (1)-O(1) 1.884 (11), Li (1)-O(2) 1.928 (11), Li(1)-C(1) 2.603 (12), N(1)-Si (1) 1.720 (4) (1) 122.3(4). (1) [13]. The structure of 4 was also determined by single crystal X-ray diffraction techniques, but the quality of the data is relatively poor.…”