Synthesis of chelating bidentate and tridentate cyano ligands and their complexes with Group VII metal carbonyls

Two new bidentate cyano ligands, DiCN-3 (2) and DEN-4 (3) (a,w-bis(2-cyanophenoxy)propane and -butane, respectively), have been prepared. These ligands and the ethane analogue DEN-2 (1) react with Mn(C0)5Br to afford complexes of the composition Mr~(cO)~(DicN-n)Br (n= 2, 9; n = 3, 10; n = 4, 11). Complexes 9 and 10 appear to be mononuclear and contain 13- and 14-membered chelate rings, respectively. Ligand 3 in 11 might be either chelated or bridged. IR studies of the reaction between 1-3 and Mn2(C0)6(CH&N)2(p-Br)2 show that, under identical conditions, more nitrile groups of 1 than of 2 and 3 are bound to the Mn(C0)3Br unit; this results suggests that DiCN-2 is a better chelating ligand than DiCN-3 or DiCN-4. A novel tricyano ligand, TriCN (1,3,5-tris(2-cyanophenyl)benzene (8)) has been synthesized from 2methylacetophenone. TriCN functions either as a bidentate ligand, as in M(CO)3(TriCN)Br (M = Mn, 12; M = Re, 14), or as a tridentate ligand, as in [M(CO),(TriCN)]PF6 (M = Mn, 13; M = Re, IS). Complexes 13 and 15 of TriCN are the first examples in which a tridentate cyano ligand chelates to a single metal center through its nitrogen lone pairs

High Rate Detection of Volatile Products Using Differential Electrochemical Mass Spectrometry: Combining an Electrode-Coated Membrane with Hydrodynamic Flow in a Wall-Tube Configuration

We present an experimental system that combines differential electrochemical mass spectrometry with hydrodynamic flow consisting of an impinging jet in a wall-tube configuration. This assembly allows simultaneous detection of electrochemical signals along with monitoring of dissolved gas species using differential electrochemical mass spectrometry under well-defined hydrodynamic conditions and over a wide range of mass transfer rates. The working electrode is deposited directly onto a thin, hydrophobic membrane, which also serves as the inlet to the mass spectrometer. This inlet provides extremely rapid mass detection as well as a high flux of products from the electrode surface into the mass spectrometer. The impinging jet is designed in a wall-tube configuration, in which the jet diameter is large compared to the electrode diameter, thus providing uniform and rapid mass transfer conditions over the entirety of the electrode surface. This combination of rapid detection and controllable flow conditions allows a wide range of hydrodynamic conditions to be accessed with simultaneous electrochemical and mass spectrometric detection of dissolved gas species, which is important in the analysis of a range of electrochemical reactions. The capabilities of this configuration are illustrated using a platinum-coated electrode and several electrochemical reactions, including ferrocyanide oxidation, proton reduction, and oxalic acid oxidation

Addition of Amines to a Carbonyl Ligand: Syntheses, Characterization, and Reactivities of Iridium(III) Porphyrin Carbamoyl Complexes

Treatment of (carbonyl)chloro(meso-tetra-p-tolylporphyrinato)iridium(III), (TTP)Ir(CO)Cl (1), with excess primary amines at 23 °C in the presence of Na2CO3 produces the trans-amine-coordinated iridium carbamoyl complexes (TTP)Ir(NH2R)[C(O)NHR] (R = Bn (2a), n-Bu (2b), i-Pr (2c), t-Bu (2d)) with isolated yields up to 94%. The trans-amine ligand is labile and can be replaced with quinuclidine (1-azabicyclo[2.2.2]octane, ABCO), 1-methylimidazole (1-MeIm), triethyl phosphite (P(OEt)3), and dimethylphenylphosphine (PMe2Ph) at 23 °C to afford the hexacoordinated carbamoyl complexes (TTP)Ir(L)[C(O)NHR] (for R = Bn: L = ABCO (3a), 1-MeIm (4a), P(OEt)3 (5a), PMe2Ph (6a)). On the basis of ligand displacement reactions and equilibrium studies, ligand binding strengths to the iridium metal center were found to decrease in the order PMe2Ph \u3e P(OEt)3 \u3e 1-MeIm \u3e ABCO \u3e BnNH2 ≫ Et3N, PCy3. The carbamoyl complexes (TTP)Ir(L)[C(O)NHR] (L = RNH2 (2a,b), 1-MeIm (4a)) undergo protonolysis with HBF4 to give the cationic carbonyl complexes [(TTP)Ir(NH2R)(CO)]BF4 (7a,b) and [(TTP)Ir(1-MeIm)(CO)]BF4 (8), respectively. In contrast, the carbamoyl complexes (TTP)Ir(L)[C(O)NHR] (L = P(OEt)3 (5a), PMe2Ph (6a,c)) reacted with HBF4 to afford the complexes [(TTP)Ir(PMe2Ph)]BF4 (9) and [(TTP)IrP(OEt)3]BF4 (10), respectively. The carbamoyl complexes (TTP)Ir(L)[C(O)NHR] (L = RNH2 (2a–d), 1-MeIm (4a), P(OEt)3 (5b), PMe2Ph (6c)) reacted with methyl iodide to give the iodo complexes (TTP)Ir(L)I (L = RNH2 (11a–d), 1-MeIm (12), P(OEt)3(13), PMe2Ph (14)). Reactions of the complexes [(TTP)Ir(PMe2Ph)]BF4 (9) and [(TTP)IrP(OEt)3]BF4 (10) with [Bu4N]I, benzylamine (BnNH2), and PMe2Ph afforded (TTP)Ir(PMe2Ph)I (14), (TTP)Ir[P(OEt)3]I (13), [(TTP)Ir(PMe2Ph)(NH2Bn)]BF4 (16), and trans-[(TTP)Ir(PMe2Ph)2]BF4 (17), respectively. Metrical details for the molecular structures of 4a and17 are reported