Additionsreaktionen von (CO) 5CrEPhH 2(E  P As) an di(ethinyl)-phosphane und stannane; stufenweise darstellung von komplex-gebundenen 1,4-dihetero-cyclohexa-2,5-dienen

Abstract

The compounds (CO) 5CrEPhH 2 (E  P, II; E  As, VIII) react with RP(CCH) 2 (R  tBu, Ia; R  CH 2Ph, Ib) and Me 2Sn(CCPh)2 ( V) via insertion into the EH bonds to give 1,4-dihetero-cyclohexa-2,5-diene complexes of the type [(CO) 5Cr](Ph) PCHCHXCHC H (X  RP, III; X  PhAs, IX) and [(CO) 5Cr](Ph)PC(Ph)CHSnMe 2CHC (Ph) ( VII) in high yields. The insertion of the dialkynes is stereospecific: trans addition of II to V yields first [(CO) 5Cr](Ph)(H)PC(Ph)CHSnMe 2C CPh ( VI) a compound in which the phosphorus group and the Me 2Sn(CCPh) unit are in cis position to each other. Ring closure by insertion of the second phenylethynyl group in VI into the PH bond affords the six membered cycle of [(CO) 5Cr](Ph) P  C(Ph)CHSnMe 2CHC (Ph) ( VII). Another way to synthesize complexes of the type VII is given in the reaction of I with H 2Sn nBu 2 ( XIII). In the presence of KOH/18-Crown-6, the cycles of R PCHCHSn nBu 2CHC H (R  tBu, XIVa; R  CH 2Ph, XIVb) are formed, which then yields by treatment with (CO) 5Cr(Thf) ( XV), [(CO) 5Cr](R) PCHCHSn nBu 2CHC H (R  tBu, XVIa; R  CH 2Ph, XVIb). A compound, in which both hetero-atoms of the 1-phospha-4-arsacyclohexa-2,5-diene ( IXa) are bonded to a 16-electron complex fragment can be synthesized by the reaction of IXa with (CO) 5Mo(Thf) ( X). [(CO) 5Cr]( tBu) P CHCHAs(Ph)[Mo(CO) 5]CHC H ( XII) can be isolated in high yields. The identity of all new synthesized compounds III, VI, VII, IX, XII, XIV and XVI is confirmed by analytical and spectroscopic (IR, MS, 1H, 13C and 31P NMR) data as well as by an X-ray diffraction study of IXa.