TY - JOUR
T1 - Mixed-metal cluster chemistry. 29. Core expansion and ligand-driven metal exchange at group 6-iridium clusters
AU - Usher, Alistair J.
AU - Lucas, Nigel T.
AU - Dalton, Gulliver T.
AU - Randles, Michael D.
AU - Viau, Lydie
AU - Humphrey, Mark G.
AU - Petrie, Simon
AU - Stranger, Robert
AU - Willis, Anthony C.
AU - Rae, A. David
PY - 2006/12/25
Y1 - 2006/12/25
N2 - Reactions of the tetrahedral clusters Molr3(μ-CO) 3(CO)8(η-L) (L = C5HMe4, C 5Me5) with the carbonylmetalate anions [Mo(CO) 3(η-L)]- afford the trigonal bipyramidal clusters Mo2lr3(μ3-H)(μ-CO)2(CO) 9(η-L)2 (L = C5HMe4 (3c), 74%; L = C5Me5 (3d), 55%) in which the group 6 metal atoms occupy the apexes; reaction of the cyclopentadienylmolybdenum-containing analogues or their cyclopentadienyltungsten-containing homologues failed to afford analogous products. Reactions of Mlr3(μ-CO) 3(CO)8(η-C5H5) (M = Mo, W) with [M(CO)3(η-L)]- (L = C5HMe4, C5Me5) afford the core-expanded heteroapex clusters M 2lr3(μ3-H)(μ-CO)2(CO) 9(η-C5H5)(η-L) (M = Mo, L = C 5HMe4 (5c), 9%, L = C5Me5 (5d), 4%; M = W, L = C5Me5 (6d), 5%) in low yield, together with the homoapex clusters M2lr3(μ3-H)(μ-CO) 2(CO)9(η-L)2 (M = Mo, L = C 5HMe4 (3c), 81%, L = C5Me5 (3d), 60%; M = W, L = C5Me5 (4d), 5%) in much higher yield for the Mo-containing examples. The identities of clusters 3c,d, 4d, and 5c,d have been confirmed by single-crystal X-ray diffraction studies, with the same disposition of ligands about the trigonal bipyramidal cluster cores being observed in each case, a ligand arrangement that has been examined by complementary density functional theory studies. While cluster 5d is accessible as above, no reaction is observed from Molr3(μ-CO) 3(CO)8(η-C5Me5) and [M(CO) 3(η-C5H5)]-. Treating Molr 3(μ-CO)3(CO)8(η-C5H 5) with 1 equiv of [M(CO)3(η-C5Me 5)]- affords 5d as the major product, a further 1 equiv affording some Molr3(μ-CO)3(CO)8(η- C5-Me5) and a third 1 equiv giving a good yield of 3d. This is consistent with reaction proceeding by apex fragment addition, followed by apex fragment elimination, and finally a further apex fragment addition, the homometallic incoming apexes being distinguished from the departing vertices by their highly methylated cyclopentadienyl ligands. Spectroscopic data suggest that the electron density at these disparate-metal-containing cluster cores is tunable by progressive (conceptual) cyclopentadienyl alkylation.
AB - Reactions of the tetrahedral clusters Molr3(μ-CO) 3(CO)8(η-L) (L = C5HMe4, C 5Me5) with the carbonylmetalate anions [Mo(CO) 3(η-L)]- afford the trigonal bipyramidal clusters Mo2lr3(μ3-H)(μ-CO)2(CO) 9(η-L)2 (L = C5HMe4 (3c), 74%; L = C5Me5 (3d), 55%) in which the group 6 metal atoms occupy the apexes; reaction of the cyclopentadienylmolybdenum-containing analogues or their cyclopentadienyltungsten-containing homologues failed to afford analogous products. Reactions of Mlr3(μ-CO) 3(CO)8(η-C5H5) (M = Mo, W) with [M(CO)3(η-L)]- (L = C5HMe4, C5Me5) afford the core-expanded heteroapex clusters M 2lr3(μ3-H)(μ-CO)2(CO) 9(η-C5H5)(η-L) (M = Mo, L = C 5HMe4 (5c), 9%, L = C5Me5 (5d), 4%; M = W, L = C5Me5 (6d), 5%) in low yield, together with the homoapex clusters M2lr3(μ3-H)(μ-CO) 2(CO)9(η-L)2 (M = Mo, L = C 5HMe4 (3c), 81%, L = C5Me5 (3d), 60%; M = W, L = C5Me5 (4d), 5%) in much higher yield for the Mo-containing examples. The identities of clusters 3c,d, 4d, and 5c,d have been confirmed by single-crystal X-ray diffraction studies, with the same disposition of ligands about the trigonal bipyramidal cluster cores being observed in each case, a ligand arrangement that has been examined by complementary density functional theory studies. While cluster 5d is accessible as above, no reaction is observed from Molr3(μ-CO) 3(CO)8(η-C5Me5) and [M(CO) 3(η-C5H5)]-. Treating Molr 3(μ-CO)3(CO)8(η-C5H 5) with 1 equiv of [M(CO)3(η-C5Me 5)]- affords 5d as the major product, a further 1 equiv affording some Molr3(μ-CO)3(CO)8(η- C5-Me5) and a third 1 equiv giving a good yield of 3d. This is consistent with reaction proceeding by apex fragment addition, followed by apex fragment elimination, and finally a further apex fragment addition, the homometallic incoming apexes being distinguished from the departing vertices by their highly methylated cyclopentadienyl ligands. Spectroscopic data suggest that the electron density at these disparate-metal-containing cluster cores is tunable by progressive (conceptual) cyclopentadienyl alkylation.
UR - http://www.scopus.com/inward/record.url?scp=33846518301&partnerID=8YFLogxK
U2 - 10.1021/ic061736l
DO - 10.1021/ic061736l
M3 - Article
SN - 0020-1669
VL - 45
SP - 10859
EP - 10872
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 26
ER -