TY - JOUR
T1 - A less carbocentric view of agostic interactions
T2 - The complexes [Rh(η4-cod){H2A(mt)2}] (A = B, C +; mt = Methimazolyl)
AU - Crossley, Ian R.
AU - Hill, Anthony F.
AU - Humphrey, Elizabeth R.
AU - Smith, Matthew K.
PY - 2006/4/24
Y1 - 2006/4/24
N2 - The reaction of [Rh2(μ-Cl)2(cod)2] (cod = 1,5-cyclooctadiene) with Na[H2B(mt)2] (mt = methimazolyl) provides the complex [Rh(cod){H2B(mt)2}] (1), which in turn reacts with CO or CNC6H3Me 2-2,6 to provide the derivatives [RhL2{H 2B(mt)2}] (L = CO (2), CNC6H3Me 2-2,6 (3)). In a similar manner [Rh2-(μ-Cl) 2(cod)2] reacts with H2C(mt)2 to provide the cationic complex [Rh(cod){H2C(mt)2}] + (4+), which was isolated after counteranion metathesis as either 4·BF4 or 4·PF6. Carbonylation of 4·PF6 provides [Rh(CO)2{H2C(mt) 2}]PF6 (5·PF6); however, the reaction is reversible in the presence of cod, regenerating 4·PF6 under reduced pressure. The reactions of 4·PF6 with CNC 6H3Me2-2,6 or CNCMe3 provide respectively the salts [Rh(CNC6H3Me2-2,6) 2{H2C(mt)2}]PF6 (6·PF 6) and [Rh(CNCMe3)4]PF6. The crystal structures of 1, 4·BF4, 4·PF6, and 6·BF4 reveal long B-H⋯Rh or C-H⋯Rh interactions; however, such an interaction is effectively absent for 5·PF 6-CHCl3, while solution spectroscopy (1H NMR and IR) indicates that none of these interactions persist in solution. The complexes 1 and 4+ represent the first structurally characterized isoelectronic pair involving, albeit weak, three-center-two-electron B-H-metal or C-H-metal interactions.
AB - The reaction of [Rh2(μ-Cl)2(cod)2] (cod = 1,5-cyclooctadiene) with Na[H2B(mt)2] (mt = methimazolyl) provides the complex [Rh(cod){H2B(mt)2}] (1), which in turn reacts with CO or CNC6H3Me 2-2,6 to provide the derivatives [RhL2{H 2B(mt)2}] (L = CO (2), CNC6H3Me 2-2,6 (3)). In a similar manner [Rh2-(μ-Cl) 2(cod)2] reacts with H2C(mt)2 to provide the cationic complex [Rh(cod){H2C(mt)2}] + (4+), which was isolated after counteranion metathesis as either 4·BF4 or 4·PF6. Carbonylation of 4·PF6 provides [Rh(CO)2{H2C(mt) 2}]PF6 (5·PF6); however, the reaction is reversible in the presence of cod, regenerating 4·PF6 under reduced pressure. The reactions of 4·PF6 with CNC 6H3Me2-2,6 or CNCMe3 provide respectively the salts [Rh(CNC6H3Me2-2,6) 2{H2C(mt)2}]PF6 (6·PF 6) and [Rh(CNCMe3)4]PF6. The crystal structures of 1, 4·BF4, 4·PF6, and 6·BF4 reveal long B-H⋯Rh or C-H⋯Rh interactions; however, such an interaction is effectively absent for 5·PF 6-CHCl3, while solution spectroscopy (1H NMR and IR) indicates that none of these interactions persist in solution. The complexes 1 and 4+ represent the first structurally characterized isoelectronic pair involving, albeit weak, three-center-two-electron B-H-metal or C-H-metal interactions.
UR - http://www.scopus.com/inward/record.url?scp=33646424645&partnerID=8YFLogxK
U2 - 10.1021/om050942i
DO - 10.1021/om050942i
M3 - Article
SN - 0276-7333
VL - 25
SP - 2242
EP - 2247
JO - Organometallics
JF - Organometallics
IS - 9
ER -