TY - JOUR
T1 - Synthesis, spectroscopy, and reactivity of a metallapyrylium
AU - Bleeke, John R.
AU - Blanchard, Jonathan M.B.
AU - Donnay, Edward
PY - 2001/1
Y1 - 2001/1
N2 - The first example of a stable metallapyrylium complex, [CH double bond C(Me)CH double bond C(Me)O double bond Ir(PEt3)3]+BF4- (2), has been prepared, and its reaction chemistry has been explored. Compound 2 is obtained in approximately 50% yield upon treatment of mer-CH double bond C(Me)CH double bond C(Me)OIr(H)(PEt3)3 (3) with silver tetrafluoroborate in tetrahydrofuran. The other major product of this reaction, [mer-CH double bond C(Me)CH2C(Me) double bond OIr(H)(PEt3)3]+BF4- (4), is readily converted back to 3 (by treating with base) and can be reused. Compound 2 exhibits downfield 1H NMR chemical shifts for its ring protons, consistent with its characterization as an aromatic metallacycle. The iridium center in 2 is reactive toward a variety of 2e- donor reagents, including hydride reagents, methyllithium, chloride reagents, and trimethylphosphine. The products of these reactions are octahedral Ir(III) compounds containing the iridaoxacyclohexa-1,3-diene ring skeleton. The chloride reaction product, mer-CH double bond C(Me)CH double bond C(Me)OIr(Cl)(PEt3)3 (6), has been characterized by X-ray diffraction. Compound 2 also undergoes [4+2] cycloaddition reactions with various unsaturated substrates, including acetone, alkynes, alkenes, and sulfur dioxide. In each of these reactions, the substrate adds across iridium and the central carbon atom of the ring (C3) to produce octahedral Ir(III) compounds containing the iridaoxacyclohexa-1,4-diene ring skeleton. The X-ray crystal structure of the sulfur dioxide cycloadduct, {fac-[CH double bond C(Me)CHC(Me) double bond OIrS(O)2](PEt3)3}+BF4- (13), has been obtained. Finally, treatment of 2 with nitrosobenzene generates a novel adduct containing two fused five-membered rings, {fac-[C(Me)CH double bond C(Me)OIrON(Ph) double bond CH](PEt3)3}+BF4- (14). This reaction probably involves initial [2+2] cycloaddition, followed by rearrangement. The structure of 14 has been confirmed by X-ray diffraction.
AB - The first example of a stable metallapyrylium complex, [CH double bond C(Me)CH double bond C(Me)O double bond Ir(PEt3)3]+BF4- (2), has been prepared, and its reaction chemistry has been explored. Compound 2 is obtained in approximately 50% yield upon treatment of mer-CH double bond C(Me)CH double bond C(Me)OIr(H)(PEt3)3 (3) with silver tetrafluoroborate in tetrahydrofuran. The other major product of this reaction, [mer-CH double bond C(Me)CH2C(Me) double bond OIr(H)(PEt3)3]+BF4- (4), is readily converted back to 3 (by treating with base) and can be reused. Compound 2 exhibits downfield 1H NMR chemical shifts for its ring protons, consistent with its characterization as an aromatic metallacycle. The iridium center in 2 is reactive toward a variety of 2e- donor reagents, including hydride reagents, methyllithium, chloride reagents, and trimethylphosphine. The products of these reactions are octahedral Ir(III) compounds containing the iridaoxacyclohexa-1,3-diene ring skeleton. The chloride reaction product, mer-CH double bond C(Me)CH double bond C(Me)OIr(Cl)(PEt3)3 (6), has been characterized by X-ray diffraction. Compound 2 also undergoes [4+2] cycloaddition reactions with various unsaturated substrates, including acetone, alkynes, alkenes, and sulfur dioxide. In each of these reactions, the substrate adds across iridium and the central carbon atom of the ring (C3) to produce octahedral Ir(III) compounds containing the iridaoxacyclohexa-1,4-diene ring skeleton. The X-ray crystal structure of the sulfur dioxide cycloadduct, {fac-[CH double bond C(Me)CHC(Me) double bond OIrS(O)2](PEt3)3}+BF4- (13), has been obtained. Finally, treatment of 2 with nitrosobenzene generates a novel adduct containing two fused five-membered rings, {fac-[C(Me)CH double bond C(Me)OIrON(Ph) double bond CH](PEt3)3}+BF4- (14). This reaction probably involves initial [2+2] cycloaddition, followed by rearrangement. The structure of 14 has been confirmed by X-ray diffraction.
UR - https://www.scopus.com/pages/publications/0035138777
U2 - 10.1021/om0008068
DO - 10.1021/om0008068
M3 - Article
AN - SCOPUS:0035138777
SN - 0276-7333
VL - 20
SP - 324
EP - 336
JO - Organometallics
JF - Organometallics
IS - 2
ER -