Stereoselective Synthesis of 1,5,9-Triphosphacyclododecane and Tertiary Derivatives
Selective oxidation of Mo(CO)3 complexes of tritertiary 1,5,9-triphosphacyclododecane macrocycles (R3L) by halogens (X2 = Cl2, Br2, I2) to Mo(II) triphospha macrocycle complexes of the type (R3L)Mo(CO)2X2 [R = (CH3)2CH (2), (CH3)3SiCH2 (3), C2H5 (4), (CH3)2CHCH2 (5)] allows the high yield and stereo...
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Veröffentlicht in: | Inorganic chemistry 1996-07, Vol.35 (16), p.4563-4568 |
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Sprache: | eng |
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Zusammenfassung: | Selective oxidation of Mo(CO)3 complexes of tritertiary 1,5,9-triphosphacyclododecane macrocycles (R3L) by halogens (X2 = Cl2, Br2, I2) to Mo(II) triphospha macrocycle complexes of the type (R3L)Mo(CO)2X2 [R = (CH3)2CH (2), (CH3)3SiCH2 (3), C2H5 (4), (CH3)2CHCH2 (5)] allows the high yield and stereoselective liberation of the corresponding tritertiary macrocycles [syn,syn-R3L, R = (CH3)2CH (6), (CH3)3SiCH2 (7), C2H5 (8), (CH3)2CHCH2 (9)] in good yield (75−80%) by digestion in strong base. This method fails for the parent trisecondary macrocycle (H3L) and also for the intermediate Mo(II) salts, [(R3L)Mo(CO)3X]A- [X = halide, A- = halide, BPh4 (1)]. Addition of halogen to (H3L)Cr(CO)3 gives rise to the new blue-violet complexes (H3L)Cr(CO)2X2 [X = Cl2 (11), Br2 (12)]. Paramagnetic susceptibilities indicate that 11 and 12 are low-spin d4 six coordinate dicarbonyl halo−halide complexes of the type [(H3L)Cr(CO)2X]X. In this case, the trisecondary 1,5,9-triphosphacyclododecane (H3L, 13) may be liberated stereoselectively and in reasonable yield (60−70%) from 11 or 12. The macrocycles may alternatively be liberated from the Mo(II) dihalo complexes by action of CN-. The free trisecondary macrocycle can be alkylated nonstereoselectively to give the tritertiary macrocycles [syn,anti-R3L; R = CH3 (24), C2H5 (8b), (CH3)3C (25)]. The inversion of phosphorus in the syn,syn isomer 8 to its syn,anti analogue, 8b, was shown to be slow at 156 °C. Exhaustive oxidation of the Mo(0) macrocycle complexes with H2O2 or O3 results in liberation of the corresponding macrocycle trioxides in good yield. All free macrocycles (and oxides) have been characterized by spectroscopic methods and as the hydrochlorides for selected ligands. |
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ISSN: | 0020-1669 1520-510X |
DOI: | 10.1021/ic960322x |