Oxidation of triisopropylphosphane with iodine: The role of dry or moist solvent

i-Pr3P (1) and iodine give i-Pr3PI2 (2) In crystals obtained from CH2Cl2 so lution, ion pairs [i-Pr3PI+I-] of 2 exhibiting I I interactions are linked by CH2Cl2 molecules. With a second equivalent of iodine, i-Pr3PI+ I-3(-) (3 ) is formed; the reaction of 2 with AgSbF6 provides i-Pr3PI+SbF6- (6). The presence of moisture and air leads to the formation of iPr(3)POH(+) salts. Solid i-Pr3POH+I- (4) exhibits P-O-H ... I cation-anion contacts, solid (i- Pr3PO)(2)H+I3- (5) contains a centrosymmetric P=O ... H ... O=P-bridged cat ion. Distinguishing i-Pr3PI+ salts 2, 3 from hydrolysis products 4, 5 by P- 31-NMR in reaction mixtures is not trivial, because both kinds of cations e xihibit similar P-31-NMR shifts and both participate in interactions with t heir anions, and in equilibria with uncharged donors: rapid I+ transfer rea ctions and I ... I soft-soft interactions involving 1, and rapid H+ transfe r reactions and hydrogen bonds involving i-Pr3P=O (7).