Molecular Structure of the Synthetic Molecular Oxygen Carrier O 2 IrCl(CO)(P[C 6 H 5 ] 3 ) 2

The synthetic molecular oxygen carrier O(2)lrCl(CO)(P[C(6)H(5)](3))(2), discovered by Vaska, has been characterized in a complete molecular structure determination. The structure surmised by Vaska from spectroscopic data has been confirmed and, in addition, definitive details on the attachment of molecular oxygen to iridium in this 1 : 1 reversible oxygen carrier have been obtained. The two oxygen atoms are equidistant from the metal atom, as in Griffith's model of the oxygen atoms in oxyhemoglobin. The O-O bond length of 1.30 +/- 0.03 A is intermediate between those characteristic of O(2) (1.20 A) and O(2)(-2) (1.48 A), and corresponds closely to O(2)(-)(1.28 A).