One-Dimensional Zigzag Chains of Cs<sup>-</sup>: The Structures and Properties of
Li<sup>+</sup>(Cryptand[2.1.1])Cs<sup>-</sup> and Cs<sup>+</sup>(Cryptand[2.2.2])Cs<sup>-</sup>
Andrew S. Ichimura
Rui H. Huang
Qingshan Xie
Philip Morganelli
Amy Burns
James L. Dye
10.1021/jp061200l.s002
https://acs.figshare.com/articles/One_Dimensional_Zigzag_Chains_of_Cs_sup_sup_The_Structures_and_Properties_of_Li_sup_sup_Cryptand_2_1_1_Cs_sup_sup_and_Cs_sup_sup_Cryptand_2_2_2_Cs_sup_sup_/3073669
The crystal structure and properties of lithium (cryptand[2.1.1]) ceside, Li<sup>+</sup>(C211)Cs<sup>-</sup>, are reported.
Li<sup>+</sup>(C211)Cs<sup>-</sup> is the second ceside and third alkalide with a one-dimensional (1D) zigzag chain of alkali
metal anions. The distance between adjacent Cs<sup>-</sup> anions, 6 Å, is shorter than the sum of the van der Waals
radii, 7 Å. Optical, magic angle spinning NMR, two-probe alternating and direct current conductivity, and
electron paramagnetic resonance measurements reveal unique physical properties that result from the overlap
of adjacent Cs<sup>-</sup> wave functions in the chain structure. The properties of cesium (cryptand[2.2.2]) ceside,
Cs<sup>+</sup>(C222)Cs<sup>-</sup>, were also studied to compare the effects of the subtle geometric changes between the two 1D
zigzag chain structures. Li<sup>+</sup>(C211)Cs<sup>-</sup> and Cs<sup>+</sup>(C222)Cs<sup>-</sup> are both low-band-gap semiconductors with
anisotropic reflectivities and large paramagnetic <sup>133</sup>Cs NMR chemical shifts relative to Cs<sup>-</sup>(g). An electronic
structure model consistent with the experimental data has sp<sup>2</sup>-hybridized Cs<sup>-</sup> within the chain and sp-hybridized
chain ends. Ab initio multiconfiguration self-consistent field calculations on the ceside trimer, Cs<sub>3</sub><sup>3-</sup>, support
this model and indicate a net bonding interaction between nearest neighbors. The buildup of electron density
between adjacent Cs<sup>-</sup> anions is visualized through an electron density difference map constructed by subtracting
the density of three cesium atoms from the short Cs<sub>3</sub><sup>3-</sup> fragment.
2006-06-29 00:00:00
field calculations
electron density
cryptand
chain structure
7 Å. Optical
wave functions
van der Waals radii
1 D zigzag chain structures
structure model
magic angle
Ab initio multiconfiguration
electron density difference map
alkali metal anions
133 Cs NMR chemical shifts
cesium atoms
zigzag chain
Li
anisotropic reflectivities
ceside trimer
resonance measurements