CONSTRUCTION OF HETEROBIMETALLICS BRIDGED BY (OXYALKYL)PHOSPHINES - SYNTHESES OF TRANS-ME2TA(MU-CH2)(MU-OCME2CH2PH2P)2PTME AND (TMEDA)TA(MU-CH2)(MU-ME)(MU-OCME2CH2PH2P)2NI

Precursors to potentially bridging (oxyalkyl)phosphine ligands, μ-OCR2(CH2)nPh2P (R = ’Bu, n = 1; R = Me, n = 1, 2), were synthesized through the addition of LiCH2PPh2-TMEDA and LiPPh2 totBu2C=O and [inline formula omitted], Treatment of ZrCl4 with 2.0 equiv of LiOCtBu2CH2Ph2P ·xTHF provided [inline formula omitted], which could be alkylated with MeLi to generate pseudo-Oh trans- [inline formula omitted] and with lBuCH2Li to give pseudo-Td (PH2 PHC2CtBu2O)2Zr(CH2tBu)2 (3). The fluxional, five-coordinate tris (Ph2PCH2CtBu2O)2 [inline formula omitted], prepared from 1 and LiOCtBu2CH2Ph2P · xTHF, was methylated to afford four-coordinate (Ph2PCH2CtBu2O)3ZrMe (5). No heterobimetallics were produced when 1-5 were exposed to several substitutionally labile late-metal complexes. ThetBu groups apparently place severe conformational contraints on the potential bridging ligands. Alcoholysis of Zr(CH2Ph)4 by HOCMe2(CH2)2Ph2P provided (Ph2P(CH2)2CMe2O)2Zr(CH2Ph)2 and (Ph2P(CH2)2CMe2O)4Zr (7), which was shown to conproportionate with Zr(CH2Ph)4 to give 6. Complex mixtures were obtained when 6 was utilized in the preparation of heterobimetallics. Metathesis of Me3TaCl2 with 2 equiv of LiOCMe2CH2Ph2P afforded (PPh2CH2CMe2O)2TaMe3 (8). Treatment of (COD)PtMe2 with 8 produced irans-Me2Ta(μ-CH2)(μ-OCMe2CH2Ph2P)2PtMe (10, 21%) via thermolysis of an intermediate oligomer, ([μ-(Me)3Ta [inline formula omitted]. Similarly, (TMEDA)NiMe2 and 8 yielded (TMEDA)Ta(μ-CH2)(μ-Me)(μ-OCMe2CH2Ph2P)2Ni (11,30%). During the formation of 10 and 11, bimetallic Me/Me exchange reactions were prevalent, as shown via labeling experiments and isotopic shifts observed in the 196PtpH| NMR spectra of 10-dn, a mixture of isotopomers prepared from (CD3)3TaCl2 (8-d9). Plausible mechanisms rationalizing the generation of the μ-CH2 and μ-CH3 ligands of 10 and 11 are also discussed. © 1990, American Chemical Society. All rights reserved.