Mechanistic views on aromatic substitution reactions by gaseous cations

Fornarini, Simonetta

doi:10.1002/(sici)1098-2787(1996)15:6<365::aid-mas2>3.0.co;2-g

Cited by 57 publications

(75 citation statements)

References 78 publications

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“…Because anhydrous methanol is critical to the success of this reaction, a molecular sieve (Mallinckrodt Baker Inc., Paris, KY) is used to dry the methanol before these reactions. Both synthetic products are confirmed by electrospraying the reaction mixture and observing the relevant (M ϩ H) ϩ peak (DIEN-(thioether) 2 , m/z 280; DIEN-(thio) 2 , m/z 296). In addition, 1 2 .…”

Section: Ligand Synthesismentioning

confidence: 87%

“…The first group consists of the following ligands: DIEN-(pyr) 2 , DIEN-(imi) 2 , DIEN-(phen) 2 , and DIEN-(fur) 2 . The syntheses of each of these ligands have been published previously [54, 58 -60].…”

Section: Ligand Synthesismentioning

confidence: 99%

“…This mixture is then reacted for 24 h in a Parr shaking hydrogenator under a 60 psi atmosphere of H 2 over Pd (10% Pd on carbon). DIEN is reacted with the following aldehydes: 2-pyridinecarboxaldehyde, 4(5)-imidazolecarboxaldehyde, benzaldehyde, and 2-furaldehyde, to produce DIEN-(pyr) 2 , DIEN-(imi) 2 , DIEN-(phen) 2 , and DIEN-(fur) 2 respectively. Because each of these ligands has been synthesized previously, the product is confirmed by simply electrospraying the reaction mixture and observing the relevant (M ϩ H) ϩ peak (DIEN-(pyr) 2 , m/z 286; DIEN-(imi) 2 , m/z 264; DIEN-(phen) 2 , m/z 284; DIEN-(fur) 2 , m/z 264).…”

Section: Ligand Synthesismentioning

confidence: 99%

“…The second group of ligands consists of DIEN-(thioether) 2 and DIEN-(thio) 2 . These ligands are made by reacting 3-(methylthio)propionaldehyde or 2-thiophenecarboxaldehyde with DIEN at a 2:1 ratio for 24 h in anhydrous methanol.…”

Section: Ligand Synthesismentioning

confidence: 99%

“…Because of this, ion molecule (I-M) experiments can be used to study the intrinsic properties of charged species and their chemical reactions [1][2][3][4]. Along with collision-induced dissociation (CID), I-M reactions can also be tools that provide structural information in a mass spectrometric experiment [5][6][7].…”

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confidence: 99%

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Gas-phase oon-molecule reactions of transition metal complexes: The effect of different coordination spheres on complex reactivity

Combariza

Vachet

2002

J. Am. Soc. Mass Spectrom.

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Using a modified quadrupole ion trap mass spectrometer, a series of metal complex ions have been reacted with acetonitrile in the gas phase. Careful control of the coordination number and the type of coordinating functionality in diethylenetriamine-substituted ligands enable the effects of the coordination sphere on metal complex reactivity to be examined. The association reaction kinetics of acetonitrile with these pentacoordinate complexes are followed in order to obtain information about the starting complexes and the reaction dynamics. The kinetics and thermodynamics of acetonitrile addition to the metal complex ions are strongly affected by the chemical environment around the metal center such that significant differences in reactivity are observed for Co(II) and Cu(II) complexes with various coordination spheres. When thiophene, furan, or benzene moieties are present in the coordination sphere of the complex, addition of two acetonitrile molecules is readily observed. In contrast, ligands with better donors react mainly to add one acetonitrile molecule. Among the ligands with good donors, a clear trend in reactivity is observed in which complexes with nitrogen-containing ligands are the least reactive, sulfur-containing complexes are more reactive, and oxygen-containing complexes are the most reactive. In general, equilibrium and reaction rate constants seem to be consistent with the hard and soft acid and base (HSAB) principle. Interestingly, the presence of certain groups (e.g., pyridine and imidazole) in the coordination sphere clearly can change the acid character of the metal as seen by their effect on the binding properties of other functional groups in the same ligand. Finally, we conclude that because complexes with different coordination spheres react to noticeably different extents, ion-molecule (I-M) reactions may be potentially useful for obtaining coordination structure information for transition metal complexes. Along with collision-induced dissociation (CID), I-M reactions can also be tools that provide structural information in a mass spectrometric experiment [5][6][7]. I-M reactions are advantageous as structural probes for several reasons. They are highly selective, efficient, and fast. They are also relatively simple, and there are numerous possible combinations of ions and neutrals that can be analytically useful [7][8][9]. Finally, I-M reactions are inherently softer than CID methods, which require "heating up" ions to induce dissociation.CID of metal complexes has been studied by several investigators but mainly in order to determine the binding strengths of ligands to monovalent metals [10]. Studying the dissociation dynamics of metal complex ions from a structural elucidation standpoint, however, has received less attention. Brodbelt and co-workers have studied the dissociation patterns of polyether, crown ether, and polypyridyl complexes of singly- [11,12] and doubly-charged transition metal ions [13,14]. Details about the effect of ligand flexibility and metal type on dissociation...

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