Diphosphapodanden,[12]-,[15]- und[18]Diphosphacoronanden, Diphosphacryptand-8 und Alkalimetall-Komplexe

Abstract

Diphosphapodands, [12]-, [15]-, and [18]Diphosphacoronands, Diphosphacryptand-8, and Alkali-Metal Complexes The cyclizing bis-phosphonium-salt formation of the open-chain bis-phosphine 17a (1,1,7,7-tetrabenzyl〈P.O.P-podand-7〉) with diethylene glycol derived dibromide 13a yields the 12-membered cyclic bis-phosphonium salt 20 (4,4,10,10-tetrabenzyl-12〈O.P.O.P-coronand-4〉-4,10-diium dibromide) in yields as high as 50–60%. The 1,1,10,10-tetrabenzyl〈P.O2.P-podand-10〉 17b forms with 13a the 15-membered cyclic bis-phosphonium salt 21 (7,7,13,13-tetrabenzyl-15〈O2.P.O.P-coronand-5〉-7,13-diium dibromide) with the same high yield. By quaternization of the bis-phosphine 17b with triethylene glycol derived dibromide 13b, the 18-membered 7,7,16,16-tetrabenzyl-18〈O2.P.O2.P-coronand-6〉-7,16-diium dibromide 24 is obtained in 50% yield, too. The Wittig reaction of the cyclic phosphonium salts with benzaldehyde yields the 12-, 15-, and 18-membered cyclic bis-benzylphosphine dioxides 9, 10, and 11 as cis- and trans-isomers beside trans-stilbene. The 7,13-dioxido-7,13-dibenzyl-15〈O2.P.O2.P-coronand-5〉 10 forms a crystalline 1 : 1 Na-complex 23, which exists as a dimer. The structure of 23 was established by an X-ray analysis and spectroscopic data. The 7,16-dibenzyl-18〈O2.P.O2.P-coronand-6〉 28 that is available by reduction of 11 with CeCl3/LiAlH4 reacts with triethylene glycol derived dibromide 13b under RugglyZiegler-dilution conditions to give the bicyclic bis-phosphonium salt 29 (1,10-dibenzyl〈P[O2]3.P-cryptand-8〉-1,10-diium dibromide) in 18% yield. Again, by the Wittig procedure with benzaldehyde, the 7,16-dioxido〈P[O2]3P-cryptand-8〉 12 is obtained as the first diphosphacryptand. The FD-MS (CH2Cl2) of the cyclic bis-phosphine dioxides 10–12 show that they exist as [2M+Na]+ complexes. The complex formation constants Ka of 9–11 with alkali-metal cations are studied and compared with the complex formation of corresponding crown ethers.