Reversible Hydrogen Activation by the Pt Complex Pt(Sn^<i>t</i>Bu₃)₂(CN^<i>t</i>Bu)₂

The new platinum complex Pt(SntBu3)2(CNtBu)2(H)2, 1, was obtained in 32% yield from the reaction of Pt(COD)2 with tBu3SnH and CNtBu at room temperature. Compound 1 is a mononuclear 18 electron platinum complex in an octahedral geometry which contains two SntBu3's, two CNtBu's, and two hydride ligands. The two hydride ligands in 1 can be eliminated, both in solution and in the solid state, to yield the 16 electron complex Pt(SntBu3)2(CNtBu)2, 2. Compound 2 reacts with hydrogen at room temperature in solution and in the solid state to regenerate 1

Reversible Hydrogen Activation by the Pt Complex Pt(Sn^<i>t</i>Bu₃)₂(CN^<i>t</i>Bu)₂

The new platinum complex Pt(SntBu3)2(CNtBu)2(H)2, 1, was obtained in 32% yield from the reaction of Pt(COD)2 with tBu3SnH and CNtBu at room temperature. Compound 1 is a mononuclear 18 electron platinum complex in an octahedral geometry which contains two SntBu3's, two CNtBu's, and two hydride ligands. The two hydride ligands in 1 can be eliminated, both in solution and in the solid state, to yield the 16 electron complex Pt(SntBu3)2(CNtBu)2, 2. Compound 2 reacts with hydrogen at room temperature in solution and in the solid state to regenerate 1

Intramolecular C–C Bond Coupling of Nitriles to a Diimine Ligand in Group 7 Metal Tricarbonyl Complexes

Dissolution of M­(CO)₃(Br)­(L^Ar) [L^Ar = (2,6-Cl₂-C₆H₃-NCMe)₂CH₂] in either acetonitrile [M = Mn, Re] or benzonitrile (M = Re) results in C–C coupling of the nitrile to the diimine ligand. When reacted with acetonitrile, the intermediate adduct [M­(CO)₃­(NCCH₃)­(L^Ar)]Br forms and undergoes an intramolecular C–C coupling reaction between the nitrile carbon and the methylene carbon of the β-diimine ligand

Intramolecular C–C Bond Coupling of Nitriles to a Diimine Ligand in Group 7 Metal Tricarbonyl Complexes

Dissolution of M­(CO)₃(Br)­(L^Ar) [L^Ar = (2,6-Cl₂-C₆H₃-NCMe)₂CH₂] in either acetonitrile [M = Mn, Re] or benzonitrile (M = Re) results in C–C coupling of the nitrile to the diimine ligand. When reacted with acetonitrile, the intermediate adduct [M­(CO)₃­(NCCH₃)­(L^Ar)]Br forms and undergoes an intramolecular C–C coupling reaction between the nitrile carbon and the methylene carbon of the β-diimine ligand

Pendant Alkyl and Aryl Groups on Tin Control Complex Geometry and Reactivity with H₂/D₂ in Pt(SnR₃)₂(CNBu^t)₂ (R = Bu^t, Prⁱ, Ph, Mesityl)

The complex Pt­(SnBut3)2­(CNBut)2­(H)2, 1, was obtained from the reaction of Pt­(COD)2 and But3SnH, followed by addition of CNBut. The two hydride ligands in 1 can be eliminated, both in solution and in the solid state, to yield Pt­(SnBut3)2­(CNBut)2, 2. Addition of hydrogen to 2 at room temperature in solution and in the solid state regenerates 1. Complex 2 catalyzes H2−D2 exchange in solution to give HD. The proposed mechanism of exchange involves reductive elimination of But3SnH from 1 to afford vacant sites on the Pt center, thus facilitating the exchange process. This is supported by isolation and characterization of Pt­(SnMes3)­(SnBut3)­(CNBut)2, 3, when the addition of H2 to 2 was carried out in the presence of free ligand Mes3SnH (Mes = 2,4,6-Me3C6H2). Complex Pt­(SnMes3)2­(CNBut)2, 5, can be prepared from the reaction of Pt­(COD)2 with Mes3SnH and CNBut. The exchange reaction of 2 with Ph3SnH gave Pt­(SnPh3)3(CNBut)2­(H), 6, wherein both SnBut3 ligands are replaced by SnPh3. Complex 6 decomposes in air to form square planar Pt­(SnPh3)2­(CNBut)2, 7. The complex Pt­(SnPri3)2­(CNBut)2, 8, was also prepared. Out of the four analogous complexes Pt­(SnR3)2­(CNBut)2 (R = But, Mes, Ph, or Pri), only the But analogue does both H2 activation and H2−D2 exchange. This is due to steric effects imparted by the bulky But groups that distort the geometry of the complex considerably from planarity. The reaction of Pt­(COD)2 with But3SnH and CO gas afforded trans-Pt­(SnBut3)2­(CO)2, 9. Compound 9 can be converted to 2 by replacement of the CO ligands with CNBut via the intermediate Pt­(SnBut3)2­(CNBut)2­(CO), 10

Pendant Alkyl and Aryl Groups on Tin Control Complex Geometry and Reactivity with H₂/D₂ in Pt(SnR₃)₂(CNBu^t)₂ (R = Bu^t, Prⁱ, Ph, Mesityl)

The complex Pt­(SnBu^t₃)₂­(CNBu^t)₂­(H)₂, <b>1</b>, was obtained from the reaction of Pt­(COD)₂ and Bu^t₃SnH, followed by addition of CNBu^t. The two hydride ligands in <b>1</b> can be eliminated, both in solution and in the solid state, to yield Pt­(SnBu^t₃)₂­(CNBu^t)₂, <b>2</b>. Addition of hydrogen to <b>2</b> at room temperature in solution and in the solid state regenerates <b>1</b>. Complex <b>2</b> catalyzes H₂−D₂ exchange in solution to give HD. The proposed mechanism of exchange involves reductive elimination of Bu^t₃SnH from <b>1</b> to afford vacant sites on the Pt center, thus facilitating the exchange process. This is supported by isolation and characterization of Pt­(SnMes₃)­(SnBu^t₃)­(CNBu^t)₂, <b>3</b>, when the addition of H₂ to <b>2</b> was carried out in the presence of free ligand Mes₃SnH (Mes = 2,4,6-Me₃C₆H₂). Complex Pt­(SnMes₃)₂­(CNBu^t)₂, <b>5</b>, can be prepared from the reaction of Pt­(COD)₂ with Mes₃SnH and CNBu^t. The exchange reaction of <b>2</b> with Ph₃SnH gave Pt­(SnPh₃)₃(CNBu^t)₂­(H), <b>6</b>, wherein both SnBu^t₃ ligands are replaced by SnPh₃. Complex <b>6</b> decomposes in air to form square planar Pt­(SnPh₃)₂­(CNBu^t)₂, <b>7</b>. The complex Pt­(SnPrⁱ₃)₂­(CNBu^t)₂, <b>8</b>, was also prepared. Out of the four analogous complexes Pt­(SnR₃)₂­(CNBu^t)₂ (R = Bu^t, Mes, Ph, or Prⁱ), only the Bu^t analogue does both H₂ activation and H₂−D₂ exchange. This is due to steric effects imparted by the bulky Bu^t groups that distort the geometry of the complex considerably from planarity. The reaction of Pt­(COD)₂ with Bu^t₃SnH and CO gas afforded <i>trans</i>-Pt­(SnBu^t₃)₂­(CO)₂, <b>9</b>. Compound <b>9</b> can be converted to <b>2</b> by replacement of the CO ligands with CNBu^t via the intermediate Pt­(SnBu^t₃)₂­(CNBu^t)₂­(CO), <b>10</b>

Pendant Alkyl and Aryl Groups on Tin Control Complex Geometry and Reactivity with H₂/D₂ in Pt(SnR₃)₂(CNBu^t)₂ (R = Bu^t, Prⁱ, Ph, Mesityl)

The complex Pt­(SnBut3)2­(CNBut)2­(H)2, 1, was obtained from the reaction of Pt­(COD)2 and But3SnH, followed by addition of CNBut. The two hydride ligands in 1 can be eliminated, both in solution and in the solid state, to yield Pt­(SnBut3)2­(CNBut)2, 2. Addition of hydrogen to 2 at room temperature in solution and in the solid state regenerates 1. Complex 2 catalyzes H2−D2 exchange in solution to give HD. The proposed mechanism of exchange involves reductive elimination of But3SnH from 1 to afford vacant sites on the Pt center, thus facilitating the exchange process. This is supported by isolation and characterization of Pt­(SnMes3)­(SnBut3)­(CNBut)2, 3, when the addition of H2 to 2 was carried out in the presence of free ligand Mes3SnH (Mes = 2,4,6-Me3C6H2). Complex Pt­(SnMes3)2­(CNBut)2, 5, can be prepared from the reaction of Pt­(COD)2 with Mes3SnH and CNBut. The exchange reaction of 2 with Ph3SnH gave Pt­(SnPh3)3(CNBut)2­(H), 6, wherein both SnBut3 ligands are replaced by SnPh3. Complex 6 decomposes in air to form square planar Pt­(SnPh3)2­(CNBut)2, 7. The complex Pt­(SnPri3)2­(CNBut)2, 8, was also prepared. Out of the four analogous complexes Pt­(SnR3)2­(CNBut)2 (R = But, Mes, Ph, or Pri), only the But analogue does both H2 activation and H2−D2 exchange. This is due to steric effects imparted by the bulky But groups that distort the geometry of the complex considerably from planarity. The reaction of Pt­(COD)2 with But3SnH and CO gas afforded trans-Pt­(SnBut3)2­(CO)2, 9. Compound 9 can be converted to 2 by replacement of the CO ligands with CNBut via the intermediate Pt­(SnBut3)2­(CNBut)2­(CO), 10

A Nickel-Based, Tandem Catalytic Approach to Isoindolinones from Imines, Aryl Iodides, and CO

We describe herein a modular nickel-catalyzed synthesis of isoindolinones from imines, aryl iodides, and CO. This reaction is catalyzed by Ni­(1,5-cyclooctadiene)₂ in concert with chloride salts and postulated to proceed via a tandem nickel-catalyzed carbonylation to form <i>N</i>-acyl iminium chloride salts, followed by a spontaneous nickel-catalyzed cyclization. A range of aryl iodides and imines have been found to be viable substrates in this reaction, providing a modular route to generate substituted isoindolinones with high atom economy

Oxidative Addition of Haloalkanes to Metal Centers: A Mechanistic Investigation

Photolysis of CpRe­(CO)₃ in the presence of dichloromethane results in the initial formation of the CpRe­(CO)₂(ClCH₂Cl) complex followed by insertion of the metal into the C–Cl bond. The activation enthalpy is determined to be 20.4 kcal/mol, and with the assistance of DFT calculations, a radical mechanism is proposed for the oxidative addition reaction. Photolysis of Ni­(CO)₂(PPh₃)₂ with dihalomethanes also results in oxidative addition, but the intermediacy of a halogen-bound adduct has not been established

Oxidative Addition of Haloalkanes to Metal Centers: A Mechanistic Investigation

Photolysis of CpRe­(CO)₃ in the presence of dichloromethane results in the initial formation of the CpRe­(CO)₂(ClCH₂Cl) complex followed by insertion of the metal into the C–Cl bond. The activation enthalpy is determined to be 20.4 kcal/mol, and with the assistance of DFT calculations, a radical mechanism is proposed for the oxidative addition reaction. Photolysis of Ni­(CO)₂(PPh₃)₂ with dihalomethanes also results in oxidative addition, but the intermediacy of a halogen-bound adduct has not been established