Homocatenation of Aluminum: Alkane‐like Structures of Li₂Al₂H₆ and Li₃Al₃H₈

Abstract

A new class of aluminum homocatenated compounds (LinAlnH2n+2) is proposed based on quantum chemical calculations. In these compounds, Al abstracts an electron from Li, becoming valence isoelectronic with C, Si, and Ge, thus mimicking respective structural features of Group 14 hydrides. Using the Coalescence Kick search program coupled with density functional theory calculations, we investigated the potential energy surfaces of Li2Al2 H6 and Li3Al3H6 . Then single-point-energy coupled-cluster calculations were performed for the lowest energy structures found. Indeed, the global minima established for Li2 Al2 H6 and Li3 Al3 H6 contain the Al2 H6(2-) and Al3H6(3-) kernels, which are isostructural with ethane (C2H6), disilane (Si2H6), digermane (Ge2 H6) and propane (C3H8), trisilane (Si3H8), trigermane (Ge3H8) molecules, respectively. Structural, energetic, and electronic characteristics of the Li2 Al2 H6 and Li3 Al3 H8 compounds are presented and the viability of their synthesis is discussed.

d‐AO spherical aromaticity in Ce6O8

“…To understand the unique chemical bonding in the bare Ce 6 O 8 cluster, we have utilized natural bond orbital analysis (NBO) and its extension adaptive natural density partitioning (AdNDP) method at the UPBE0/Ce/Stuttgart RSC 1997 ECP/O/6‐311++G(d,p) level of theory. AdNDP was shown to be a useful tool for deciphering chemical bonding in various clusters and solid‐state systems …”

Electronic Transmutation (ET): Chemically Turning One Element into Another

“…The similarities between the transmutated element Z and the targeted element Z+1 could range from the chemical bonding they possess to the geometries of the compounds they form, so that many key features that were thought only belong to element Z+1 can now belong to element Z. Alchemists once spent great efforts in transmutating common elements into precious others, which now we know is not possible merely with chemistry, but based on ET, the element Z can now be chemically “turned into” element Z+1. After the proposal of the ET concept, a plethora of successful examples, including the transmutation of Groups 13, 14, and 15 elements into Group 14, 15, and 16 elements, have been reported . In this Minireview, we will summarize these examples on both the theoretical and experimental fronts, and outlook for wider applications and future research directions of this new concept.…”

The Existence of a Designer Al=Al Double Bond in the LiAl2H4− Cluster Formed by Electronic Transmutation

“…[1] Yet, it was recently shown that formation of conventional AlÀAl bonds is possible in clusters [2,3] and in solid-state compounds. [1] Yet, it was recently shown that formation of conventional AlÀAl bonds is possible in clusters [2,3] and in solid-state compounds.…”

“…[4] Reports of double Al=Al and triple AlAl bonds are scarce. In the early 1990s it was shown that this compound could be reduced to [R 2 AlAlR 2 ] À anions (R = CH(SiMe 3 ) 2 [6b,c] or C 6 H 2 -2,4,6-iPr 3 ), [6d,e] which had AlÀAl bonds of formal order 1.5 owing to the occupation of a p-orbital by as ingle electron. In the early 1990s it was shown that this compound could be reduced to [R 2 AlAlR 2 ] À anions (R = CH(SiMe 3 ) 2 [6b,c] or C 6 H 2 -2,4,6-iPr 3 ), [6d,e] which had AlÀAl bonds of formal order 1.5 owing to the occupation of a p-orbital by as ingle electron.…”

“…[7] Theu tilization of electron-donating,b ulky ligands forced the sa nd pv alence electrons of Al to hybridize and form homodinuclear multiple bonds to fulfill the octet rule, which is in as imilar way that the BBt riple bonds were synthesized by Zhou [8a] and Braunschweig. [2,3,9,10] Based on this,i tc ould be anticipated that by adding one electron to each Al atom in the H 2 AlAlH 2 molecule,A lm ight be transmutated into Si, yielding amolecule that is isoelectronic to the H 2 Si=SiH 2 molecule.T he doubly charged H 2 AlAlH 2 2À anion is not expected to be stable in the isolated state owing to the Coulomb repulsion between the two excess electrons. Herein we adopt the electronic transmutation method that was developed by our group; [9] briefly,w hen an atom acquires an extra electron, it starts to behave as the isoelectronic,neighboring element.…”