TY - JOUR

T1 - Multinuclear NMR studies on substituted derivatives of Rh6(CO)16 in solution

AU - Tunik, Sergey P.

AU - Podkorytov, Ivan S.

AU - Heaton, Brian T.

AU - Iggo, Jonathan A.

AU - Sampanthar, Jeyagowry

N1 - Funding Information: This work was supported by INTAS-RFBR grant No. 95-IN-RU-242 and by an ORS award (to JS). We thank also Dr. V.A. Gindin of the Research Institute of Antibiotics and Medical Enzymes, St. Petersburg, Russia, for permission to use the Bruker AC-200 instrument and Johnson-Matthey Ltd. for the generous loan of rhodium chloride.

PY - 1998/1/15

Y1 - 1998/1/15

N2 - Multinuclear NMR data (13C, 31P, 13C-{31P}, 13C-(103Rh) and 31P-{103Rh}) for a series of mono- and di-substituted derivatives of Rh6(CO)16 containing neutral two electron donor ligands [Rh6(CO)15L, (L = NCMe, py, cyclooctene, PPh3, P(OPh)3,1/2(μ2,η1η 1-dppe)); Rh6(CO)14(LL), (LL = cis-CH2=CMe-CMe=CH2, dppm, dppe, (P(OPh)3)2)] are reported; these data show that the solid state structure is maintained in solution. Detailed assignments of the 13CO NMR spectra of Rh6(CO)15(PPh3) and Rh6(CO)14(dppm) clusters have been made on the basis 13C-{103Rh} double resonance measurements and the specific stereochemical features of the observed long range couplings in these clusters have been studied. The stereochemical dependence of 3J(P-C) for terminal carbonyl ligands is discussed and the values of 3J(P-C) are found to be mainly dependent on the bond angles in the P-Rh-Rh-C fragment; these data enable the fine structure of the complex multiplets in the 13C-{1H} and 31P-{1H} NMR spectra of Rh6(CO)14 (dppm) to be simulated. Variable temperature 13C-{1H} NMR measurements on Rh6(CO)15(PPh3) reveal the carbonyl ligands in this complex to be fluxional. The fluxional process involves exchange of all the CO ligands except the two terminal CO's associated with the rhodium trans to the substituted rhodium and can be explained by a simple oscillation of the PPh3 on the substituted rhodium atom aided by concomitant exchange of the unique terminal CO on this rhodium with adjacent μ3-CO's.

AB - Multinuclear NMR data (13C, 31P, 13C-{31P}, 13C-(103Rh) and 31P-{103Rh}) for a series of mono- and di-substituted derivatives of Rh6(CO)16 containing neutral two electron donor ligands [Rh6(CO)15L, (L = NCMe, py, cyclooctene, PPh3, P(OPh)3,1/2(μ2,η1η 1-dppe)); Rh6(CO)14(LL), (LL = cis-CH2=CMe-CMe=CH2, dppm, dppe, (P(OPh)3)2)] are reported; these data show that the solid state structure is maintained in solution. Detailed assignments of the 13CO NMR spectra of Rh6(CO)15(PPh3) and Rh6(CO)14(dppm) clusters have been made on the basis 13C-{103Rh} double resonance measurements and the specific stereochemical features of the observed long range couplings in these clusters have been studied. The stereochemical dependence of 3J(P-C) for terminal carbonyl ligands is discussed and the values of 3J(P-C) are found to be mainly dependent on the bond angles in the P-Rh-Rh-C fragment; these data enable the fine structure of the complex multiplets in the 13C-{1H} and 31P-{1H} NMR spectra of Rh6(CO)14 (dppm) to be simulated. Variable temperature 13C-{1H} NMR measurements on Rh6(CO)15(PPh3) reveal the carbonyl ligands in this complex to be fluxional. The fluxional process involves exchange of all the CO ligands except the two terminal CO's associated with the rhodium trans to the substituted rhodium and can be explained by a simple oscillation of the PPh3 on the substituted rhodium atom aided by concomitant exchange of the unique terminal CO on this rhodium with adjacent μ3-CO's.

KW - Multinuclear NMR

KW - Rh(CO)

KW - Rhodium

UR - http://www.scopus.com/inward/record.url?scp=0001577171&partnerID=8YFLogxK

U2 - 10.1016/S0022-328X(97)00189-7

DO - 10.1016/S0022-328X(97)00189-7

M3 - Article

AN - SCOPUS:0001577171

VL - 550

SP - 221

EP - 231

JO - Journal of Organometallic Chemistry

JF - Journal of Organometallic Chemistry

SN - 0022-328X

IS - 1-2

ER -