Ionic rotors. preparation, structure, and dynamic solid-state 2D NMR study of the 1,4-diethynylbenzenebis(triphenylborate) dianion.
The reaction between p-(LiC2)2C6H4 (generated in situ from butyllithium and dialkynylbenzene) and 2 equiv of BPh3 affords high yields of [Li(THF)4]2[p-(Ph3BC2)2C6H4], a heretofore missing member of the isoelectronic [p-(Ph3EC2)2C6H4] (E = groups 13-15 element) series. The central phenylene linker is free to rotate in the solid state, as determined by a variable-temperature solid-state 2D spin-echo NMR spectroscopic study. At room temperature, the rate of rotation is at least 20 times faster than that of its carbon-based analogue, presumably a result of Coulombic repulsions minimizing noncovalent interactions between rotating units in the borate salt.
Gardinier
James R
JR
Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, USA.
Pellechia
Perry J
PJ
Smith
Mark D
MD
D000838:Anions / Q000138:chemical synthesis / Q000737:chemistry; D001896:Boron Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008094:Lithium / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry
C507292:1,4-diethynylbenzenebis(triphenylborate); D000838:Anions; D001896:Boron Compounds; D009942:Organometallic Compounds; D008094:Lithium