CIS,CIS-1,3,5-TRIS(DIPHENYLPHOSPHINO) CYCLOHEXANE (TDPPCY) - A NEW TRIPODAL PHOSPHINE THAT FORMS METAL-COMPLEXES WITH ADAMANTANE-TYPE STRUCTURES - CRYSTAL-STRUCTURE OF IR(TDPPCY)CL3

The novel tridentate phosphine cis,cis-1,3,5-tris(diphenylphosphino)cy clohexane (tdppcy) (3) has been synthesized. Treatment of tdppcy with Mo(C7H8)(CO)3 and lr(PPh3)2(CO)CI yields octahedral Mo(tdppcy)(CO)3 (4 ) and trigonal-bipyramidal Ir(tdppcy)(CO)Cl.(5), respectively. Compoun d S is transformed into either Ir(tdppcy)(CO)H (6) or lr(tdppcy)(CO)(H )2+ (7) by treatment with NaBH4 in refluxing THF. Complex 5 can be oxi dized by dichloromethane or Cl2 to the trichloro complex lr(tdppcy)Cl3 (8), which can be converted into the dihydride Ir(tdppcy)(H)2Cl (9) b y treatment with NaBH4 in THF. The dynamic behavior of the highly flux ional pentacoordinate complexes 5 and 6 has been studied by VT P-31{H- 1} NMR spectroscopy. An X-ray diffraction study has been carried out o n 8 . 3CH2Cl2.