The First Copper Complexes Bearing the 1,3,5‐Triaza‐7‐phosphaadamantane (PTA) Ligand

The Cu I compound [Cu(PTAH) 4 ](NO 3 ) 5 ( 1 ) {PTAH = N ‐protonated form of 1,3,5‐triaza‐7‐phosphaadamantane (PTA)} was easily prepared by reacting hydrated Cu(NO 3 ) 2 and PTA in aqueous acidic solution at room temperature. Further treatment of 1 with sodium hydroxide in water led to an unprotonated PTA derivative [Cu(PTA) 4 ](NO 3 ) ( 2 ). Both compounds are water‐soluble and air‐stable, and were characterized by IR, 1 H‐, 13 C{ 1 H}‐, 31 P{ 1 H}‐ and 63 Cu NMR spectroscopy, FAB‐MS(+), elemental and single‐crystal X‐ray diffraction structural analyses. They exhibit a nearly regular tetrahedral coordination environment about each copper centre filled by the phosphorus atoms of the four PTAH/PTA moieties, which show distinct and unusual geometrical arrangements if viewed along the P–Cu bonds. The 31 P{ 1 H}‐ and 63 Cu NMR spectra of 2 in D 2 O solution show spin coupling between the 31 P and 63 Cu nuclei at room temperature. These compounds represent the first examples of Cu complexes bearing PTA or any derived ligand with a cagelike PTA core and expand the restricted family of aqua‐soluble copper phosphane complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)