Synthesis and Complexation Behavior of the Functionalized Tripodal Phosphane cis,cis ‐1,3,5‐Tris(cyano)‐1,3,5‐tris(diphenylphosphanyl)‐cyclohexane (tdppcycn)

The synthesis of the novel potentially bistripodal ligand cis‐cis ‐1,3,5‐tris(cyano)‐1,3,5‐tris(diphenylphosphanyl)cyclohexane (tdppcycn) ( 6 ) is described. Starting from the tricarboxylic acid cis,cis ‐1,3,5‐C 6 H 9 (COOH) 3 ( 1 ), which is converted stepwise into the triacid chloride cis,cis ‐1,3,5‐C 6 H 9 (COCl) 3 ( 2 ), the triphenyl ester cis,cis ‐1,3,5‐C 6 H 9 (COOPh) 3 ( 3 ), the tricarboxamide cis,cis ‐1,3,5‐C 6 H 9 (CONH 2 ) 3 ( 4 ), and the tricarbonitrile cis,cis ‐1,3,5‐C 6 H 9 (CN) 3 ( 5 ), we obtained tdppcycn ( 6 ) by α‐deprotonation of 5 followed by treatment with ClPPh 2 in good yield. Treatment of 6 with Mo(CO) 3 (‐C 7 H 8 ) and Ir(PPh 3 ) 2 (CO)Cl gave octahedral Mo(tdpp‐cycn)(CO) 3 ( 7 ) and pentacoordinate Ir(tdppcycn)(CO)Cl ( 8 ), respectively, with a facially P‐coordinated tdppcycn ligand. The stereochemistry of compounds 2–8 was established by 1 H‐, 13 C‐, 31 P‐NMR, and IR spectroscopy. An X‐ray crystal structure analysis of complex 8 confirms the trigonal‐bipyramidal ground‐state structure in the solid state.