Metallic Macrocycle with a 1,3-Alternate Calix[4]arene Phosphorus Ligand

The preparation of an 1,3-alternate calix[4]arene phosphorus ligand, 25,27-bis(2-(diphenylphosphino)ethoxy)-26,28-bis(1-propyloxy)calix[4]arene (3), is presented. Ligand 3 is obtained in three steps in 64% overall yield.
Reaction of 3 with [Rh(cot)2]BF4 produced the encapsulated rhodium complex [Rh{(P,P)-diphen-calix[4]arene}]BF4
(4). As revealed by a single-crystal X-ray diffraction study, the rhodium center has a bent coordination environment
with a P−Rh−P angle of 135.66(3)°. Palladation of 3 employing [Pd(MeCN)4](BF4)2 yielded the chelate palladium
complex 7 in which the palladium center has a slightly bent configuration. Treatment of the ligand with Pd(cod)Cl2
and [Pd(η3-C4H7)(THF)2]BF4 leads to the isolation of the monometallic complex. Full characterization includes X-ray
structural studies of compounds 3, 4, and 6.