Organo-tricyanoborates as tectons: illustrative coordination polymers based on copper(I) derivatives

The first systematic study on the use of tricyanoborates as ligands is presented. The tricyanoborates RB(CN)3]- (R = oct and Ph) can be prepared by direct cyanation of RBCl2 precursors as well as by thermolysis of the corresponding isocyanides RB(NC)3]-. The first organo-cyanogallates RGa(CN)3]- (R = Bu, C6H2-2,4,6-Me3) were prepared from the corresponding dichloride, the structure of Et4NmesGa(CN3] being confirmed crystallographically. The reaction of equimolar RB(CN)3]- (R = oct, Ph) and Cu(MeCN)4]+ afforded two-dimensional polymers RB(CN)3Cu(NCMe)]. The sheets arise via conjoined hexagonal B3Cu3(CN)6 rings with chair conformations. The reaction of excess PhB(CN)3]- and Cu(MeCN)4]+ gives the polymer K(18-crown-6)]{CuPhB(CN)3]2}. Treatment of PhB(CN)3]- with Cu(PCy3)2(NCMe)x]PF6 gave the one-dimensional polymer PhB(CN)3Cu(PCy3)2], wherein two of the three BCN substituents are coordinated.