Abstract
The pentaborate(1-) salt, [Cu(dmen)2(H2O)2][B5O6(OH)4]2.2B(OH)3(dmen = N,N′-dimethylethylenediamine, MeHNCH2CH2NHMe), has been synthesized in 48% yield as a crystalline product by reaction of B(OH)3 with [Cu(dmen)2](OH)2]2 (10:1 ratio) in aqueous solution. Single-crystal XRD analysis confirms its ionic structure with one interstitial B(OH)3 per pentaborate(1-) unit. The pentaborate(1-) anions and B(OH)3 molecules are involved in a supramolecular giant H-bonded lattice with B(OH)3 units serving as ‘spacers’ to help accommodate the relatively large [Cu(dmen)2(H2O)2]2+ cations.
Graphical Abstract
![](/cms/asset/28b53918-0aed-4caa-984e-4bada93c43b9/gpss_a_1631307_uf0001_c.jpg)
Acknowledgements
We thank the EPSRC for the NCS X-ray crystallographic service (Southampton).