STERIC EFFECTS IN HETEROBORANES .8. STERICALLY-INDUCED EXO-SKELETAL ISOMERIZATION OF DI-COPPER CARBAMETALLABORANES - SYNTHESES AND CRYSTAL-STRUCTURES OF (PH(3)PCU)(2)PH(2)C(2)B(9)H(9) AND ((O-TOL)(3)PCU)(2)PH(2)C(2)B9H9
Kj. Adams et al., STERIC EFFECTS IN HETEROBORANES .8. STERICALLY-INDUCED EXO-SKELETAL ISOMERIZATION OF DI-COPPER CARBAMETALLABORANES - SYNTHESES AND CRYSTAL-STRUCTURES OF (PH(3)PCU)(2)PH(2)C(2)B(9)H(9) AND ((O-TOL)(3)PCU)(2)PH(2)C(2)B9H9, Journal of organometallic chemistry, 481(2), 1994, pp. 9-11
In (Ph(3)PCu)(2)Ph(2)C(2)B(9)H(9) (Ia) and {(o-tol)(3)PCu}(2)Ph(2)C(2)
B(9)H(9) (Ic) one copper atom occupies a polyhedral vertex position bu
t is slipped away from the cage carbon atoms (the latter the more so)
to relieve phosphine ... C-cage-phenyl crowding. The second copper ato
m is exo-facially bonded to the B(8)B(9)B(12) triangular face, in cont
rast to the situation in (Ph(3)PCu)(2)C2B9H11, where the exo-metal cap
s the Cu(3)B(4)B(8) triangle. Compounds Ia, Ic and the related species
(Cy(3)PCu)(2)Ph(2)C(2)B(9)H(9) (Ib) display fluxionality in solution
at room temperature that renders equivalent the two phosphorus nuclei.
It is speculated that this fluxional process involves a unique bis(ex
o-metal) nido carbaborane.