The reactions of cyclenphosphorane (cyclenPH) with group 12 metal halides MC12(M = Zn, Cd) yield the 1:1 complexes cyclenPH-MCl2[M = Zn (1), Cd (2)], in which coordination to the metal most likely occurs through the axial nitrogen atom on cyclenPH. A mixture of cyclenPH and MC12in a 1:0.5 molar ratio gives one peak in the31P NMR spectrum at a chemical shift between the resonances for cyclenPH and the 1:1 complexes, indicating that 1 (or 2) readily exchanges MC12with free cyclenPH. Treatment of these 1:1 complexes with HC1 yields the adducts cyclenPH-HMCl3[M = Zn (3), Cd (4)]. The X-ray crystal structure of 3 was obtained and shows the phosphorus to form a distorted trigonal bipyramid with a hydrogen and two nitrogens occupying the equatorial positions and two nitrogens at the axial positions. One axial nitrogen is attached to a ZnCl3unit and the other to a proton. The compound crystallizes as “head-to-toe” dimers linked by N—H C1 hydrogen bonds. X-ray data: C8H18N4PCl3Zn, monoclinic, space group P21/c, a = 10.578 8 (14) ⇋, b = 9.611 (2) ⇋, c = 14.604 (2) ⇋,β = 103.6 (1)°, Z = 4, R = 0.027, Rw= 0.031. © 1990, American Chemical Society. All rights reserved.