Crystal structure of 5-di-tert-butylphosphinoyl-25,26,27,28-tetrabenzoyloxy- calix[4]arene – dichloromethane (1:1), C64H65O5P – CH2Cl2, C65H67Cl2O5P

Abstract

C 65 H 67 Cl 2 O 5 P, monoclinic, P2 1 /c (no. 14), a =16.118(1) Å, b =10.0843(7) Å, c =35.113(2) Å, b =104.009(3)°, V =5537.5 Å 3 , Z =4,R gt (F) =0.0930, wR ref (F 2 ) =0.1855, T =173 K. Source of materialTo as olution of 5-bromo-25,26,27,28-tetrabenzyloxycalix[4]arene (2.270 g, 2.63 mmol) in THF (100 mL) at -78°C was slowly added n-buthyllithium (5.26 mmol). After 0.5 h, the resulting organolithium compound was quenched with chloro(ditert-butyl)-phosphane (0.951 g, 5.26 mmol). The solution was allowed to reach room temperature and was stirred for an additional 16 h. Hydrogen peroxide (30% in water, 20 mL) was then added, and the mixture was stirred for 1h .T he aqueous phase was washed with CH 2 Cl 2 (2´20 mL). Thecombined organic phases were dried over Na 2 SO 4 and evaporated under reduced pressure. Experimental detailsThe cell parameters were determined using APEX2 software [6]. DiscussionThe asymmetric unit contains one molecule of the title compound. Thecalix[4]arene core adopts atypicalpinched cone conformation [1-3],w ith dihedral anglesb etween thep airs of opposite phenolic rings of -20.9°and 106.3°. The separation between the centroids of the distal phenoxy ring pairs are 4.82 Åand 7.72 Å, respectively. Note that the two distal phenoxy rings displaying the smaller interplane angle have their upper part, that is the carbon atomspara to the oxygen atomsO2and O4, slightly turned towards the calixarene axis (C18×××C46 :4 .36 Å; vs. C4×××C32 :9.98 Å). The P=O bond and the phenol ring to which it is attached arecoplanar. As aresult, oneofthe t-Bu groups is located above the upper cavity entrance, the other one is lying outside the cone. However, the solution 1 HN MR spectrum of the title complex shows two equivalent t-Bu groups, this being consistent with afast rotation of the P(O)(t-Bu) 2 substituent about the C4-P1 bond. The P-O bond length (1.49 Å) lies in the range expected for tertiary phosphine oxides [3][4][5].