M. Aizenberg et al., RH(I) AND RH(III) SILYL PME3 COMPLEXES - SYNTHESES, REACTIONS AND RH-103 NMR-SPECTROSCOPY, Journal of organometallic chemistry, 551(1-2), 1998, pp. 81-92
Synthetic approaches to Rh(I) silyls are described. The complexes LnRh
SiR3 (L=PMe3; 6, n = 4, R-3 = (OEt)(3); 7, n = 4 R-3 = Me(OMe)(2); 21,
n = 3, R-3 = Ph-3) resulted from the reactions of MeRhL4 (1) with the
corresponding silanes HSiR4. Complex 21 was prepared alternatively fr
om PhRhL3 (2) and HSiPh3, while analogous reactions of HSi(OEt)(3), HS
iMe(OMe)(2) and HSiMe(OMe)(2) led to the bis(silyl)hydrides fac-L3Rh(S
iR3)(2)(H) (8, R-3 = (OEt)(3); 9, R-3 = Me(OMe)(2); 13, R-3 = (OMe)(3)
). Like in analogous iridium-based systems, the outcome of these react
ions largely depends on the nature of substituents at the silicon atom
. Synthesis of Rh(I) silyls inaccessible by this route, namely those w
ith alkyl substituents at the silicon, LnRhSiR3 (19, n = 3, R-3 = PhMe
2; 22, n = 4, R-3 = Me-3), was achieved utilizing nucleophilic attack
of the corresponding silyllithiums at [L4Rh]Cl. The solid-state struct
ure of 19 was determined by X-ray crystallography. C17H38P3SiRh, Fw =
466.38 monoclinic, C2/m, a = 13.304(3) Angstrom: b = 13.814(2) Angstro
m, c = 13.123(4) Angstrom, beta = 110.66(3) deg, V = 2257(1) Angstrom(
3), Z = 4, d(calcd) = 1.373 g cm(-3), mu = 1.019 mm(-1). A series of d
i(hydrido)silyls fac-L3Rh(H)(2)(SiR3) (10, R-3 =(OEt)(3); 15, R-3 = Ph
Me3; 16, R-3 = Ph-3) was synthesized using oxidative additions of HSiR
3 to HRhL4 (3). Complexes 10, 15, 16 we thermodynamically stable with
respect to H-H and SI-H reductive-elimination reactions at ambient con
ditions. Complex 8 reductively eliminates HSi(OEt), reversibly at room
temperature and complex 13 is capable upon heating of mediating dehyd
rogenative Si-Si coupling of HSi(OMe), and redistribution of [(MeO)(3)
Si](2). Rh-103 NMR data obtained for MeRhL4 (1), HRhL4 (3), L3RhSiPhMe
2 (19), L3RhSiPh3 (21) and for the di(hydrido) silyls (10, 15, 16) all
owed to qualitatively evaluate steric and electronic effects of methyl
, silyl, and hydride ligands on the Rh-103 chemical shift. (C) 1998 El
sevier Science S.A.