ABSTRACT
Lowering the charge of Zintl anions by (element-)organic substituents allows their use as sources of (semi)metal nanostructures in common organic solvents, as realized for group 15 anions or Ge9 4- and Sn9 4- . We developed a new strategy for other anions, using low-coordinate 3d metal complexes as electrophiles. [K(crypt-222)]+ salts of (TrBi3 )2- anions dissolved in situ in Et2 O and/or THF when reacted with [Mn(hmds)2 ]. Work-up afforded soluble [K(crypt-222)]+ salts of [{(hmds)2 Mn}2 (TlBi3 )]2- (in 1), [{(hmds)2 Mn}2 (Bi2 )]2- (in 2), and [{(hmds)Mn}4 (Bi2 )2 ]2- (in 3) (crypt-222=4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane; Tr=Ga, In, Tl; hmds=N(SiMe3 )2 ), representing rare cases of Zintl clusters with open-shell metal atoms. 1 comprises the first coordination compound of the (TlBi3 )2- anion, 2 features a diamond-shaped {Pn2 M2 } unit, and 3 is a mixed-valent MnI /MnII compound. The uncommon electronic structures in 1-3 and magnetic coupling were studied by comprehensive DFT calculations.
ABSTRACT
Alkaline earth metal iodides were used as templates for the synthesis of novel silicon-based ligands. Siloxane moieties were (cross-)coupled and ion-specific, silicon-rich crown ether analogues were obtained. The reaction of 1,2,7,8-tetrasila[12]crown-4 (I) and 1,2-disila[9]crown-3 (II) with MgI2 yielded exclusively [Mg(1,2,7,8-tetrasila[12]crown-4)I2 ] (1). The larger Ca2+ ion was then employed for cross-coupling of I and II and yielded the complex [Ca(1,2,7,8-tetrasila[15]crown-5)I2 ] (2). Cross-coupling of I and 1,2,4,5-tetrasila[9]crown-3 (III) with SrI2 enables the synthesis of the silicon-dominant 1,2,4,5,10,11-hexasila[15]crown-5 ether complex of SrI2 (3). Further, the compounds [Sr(1,2,10,11-tetrasila[18]crown-6)I2 ] (4), [Sr(1,2,13,14-tetrasila[24]crown-8)I2 ] (5), and [Sr(1,2,13,14-tetrasila-dibenzo[24]crown-8)I2 ] (6) were obtained by coupling I, 1,2-disila[12]crown-4 (IV) or 1,2-disila-benzo[12]crown-4 (V), respectively. Using various anions, the (cross-)coupled ligands were also observed in an X-ray structure within the mentioned complexes. These template-assisted (cross-)couplings of various ligands are the first of their kind and a novel method to obtain macrocycles and/or their metal complexes to be established. Further, the Si-O bond activations presented herein might be of importance for silane or even organic functionalization.
ABSTRACT
The new quaternary iodate KCu(IO3)3 has been prepared by hydrothermal synthesis. KCu(IO3)3 crystallizes in the monoclinic space group P21/n with unit cell parameters a = 9.8143(4) Å, b = 8.2265(4) Å, c = 10.8584(5) Å, ß = 91.077(2)°, and z = 4. The crystals are light blue and translucent. There are three main building units making up the crystal structure: [KO10] irregular polyhedra, [CuO6] distorted octahedra, and [IO3] trigonal pyramids. The Jahn-Teller elongated [CuO6] octahedra connect to each other via corner sharing to form [CuO5]∞ zigzag chains along [010]; the other building blocks separate these chains. The Raman modes can be divided into four groups; the lower two groups into mainly lattice modes involving K and Cu displacements and the upper two groups into mainly bending and stretching modes of [IO3E], where E represents a lone pair of electron. At low temperatures, the magnetic susceptibility is characterized by a broad maximum centered at â¼5.4 K, characteristic for antiferromagnetic short-range ordering. Long-range magnetic ordering at T C = 1.32 K is clearly evidenced by a sharp anomaly in the heat capacity. The magnetic susceptibility can be very well described by a spin S = 1/2 antiferromagnetic Heisenberg chain with a nearest-neighbor spin exchange of â¼8.9 K.