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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The first tritertiary (1,5,9-triphosphacyclododecane)chromium(0) complexes have been prepared from the secondary phosphine macrocycle precursor complex tricarbonyl(1,5,9-stiphosphacyclododecane)chromium(0), and the range of molybdenum(0) complexes with tritertiary 1,5,9-triphosphacyclododecane ligands has been extended. The synthetic routes involve either deprotonation of the secondary phosphine precursor followed by alkylation with alkyl halide or by radical-catalysed hydrophosphination of selected alkenes. These routes are general and allow access to a range of macrocyclic triphosphines with alkyl functions or with alkyl arms containing pendant donor functions (N, P, O, S) attached to phosphorus for both chromium and molybdenum. All compounds have been spectroscopically and analytically characterised.