1,7-Dihydro-1,4,7,10-tetraazacyclododecanephosphine oxide iodide

The title compound, C8H18N4OP+.I- or [ H(2)cyclenPO][I], contains a five-coordinate P atom arranged in a slightly distorted trigonal bipyramid. The asymmetric unit contains half the cyclen moiety of the Hsimilar to2similar tocyclenPO unit and two distinct iodide positions. The full molecule can be symmetry generated around the P atom using the symmetry code 1/3 + x-y, 2/3-y, 5/3-z. The P - N bond length in the equatorial plane is 1.656 (5) Angstrom and the apical P - N interaction is much longer, 1.891 (4) Angstrom. The cyclen moieties are linked together via N-H...O hydrogen bonds and form a spiral chain along [001]. Crystallographically, there are two distinct anion sites, both in special positions, one of them with partial occupancy. One anion site may participate in an extremely weak hydrogen bond, linking the cyclen spiral chains into a pseudo-hexagonal three-dimensional array.