Complexes of guanidinium ion (NH2)3C+ with super Lewis acidic XH4+(X = B and Al): comparison with XH3 complexes and protonated and methylated guanidinium dications.
Structures of the complexes (1 and 8) of the guanidinium ion (H(2)N)(3)C(+) with super Lewis acidic BH(4)(+) and AlH(4)(+) were calculated using the DFT method at the B3LYP/6-311+G** level. (13)C NMR chemical shifts were also calculated by the GIAO-MP2 method. Each of the dicationic complexes contains a hypercoordinate boron or aluminum atom with a two-electron three-center (2e-3c) bond. Guanidinium ion was found to form a strong complex with BH(4)(+) but a relatively weak one with AlH(4)(+). On the other hand, complexations of guanidinium ion with neutral BH(3) and AlH(3) lead only to very weak complexes (5 and 9). The structures of mono- and dicationic complexes were compared with the structures of protonated and methylated guanidinium dications.
Rasul
Golam
G
Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, California 90089-1661, USA. olah@usc.edu
Olah
George A
GA
Prakash
G K Surya
GK