title: Rapid differentiation of ortho-, meta-, and para-isomers of halogenated phenylmethylidene hydrazinecarbodithioates by metal complexation and electrospray ionization mass spectrometry.
abstract: BACKGROUND
  Development of mass spectrometry (MS)-based methods for isomeric differentiation remains a challenging analytical task, and has attracted the interest of many research groups. It is relevant to develop a general method to differentiate the isomeric halogenated phenylmethylidene hydrazinecarbodithioates (MX, X  =  F, Cl, Br).
  
  
  METHODS
  Diluted CH3 CN solutions containing NiCl2 and a title isomer (MX) were analyzed by electrospray ionization tandem mass spectrometry (ESI-MS(n)) in a quadrupole ion trap instrument equipped with an ESI source. Theoretical calculations were performed using the density functional theory (DFT) method at the uB3LYP/6-31+G(2d,p) level.
  
  
  RESULTS
  In MS(3) experiments, the complex [MX + SCH3 + Ni](+) ion, resulting from dissociation of the ESI-generated complex [2MX - H + Ni](+) ion, undergoes ligand-exchange reactions with residual gas molecules, such as water, acetonitrile, and nitrogen in the ion trap, and the o-isomers [Mo-X + SCH3 + Ni](+) were found to undergo the characteristic HX elimination reactions to afford several unique ions. Each set of three isomers [MX + SCH3 + Ni](+) show significantly different reactivity, which has been corroborated by MS(4) experiments and theoretical calculations.
  
  
  CONCLUSIONS
  A rapid method based on metal complexation and tandem mass spectrometric (MS(n)) analysis has been developed to differentiate three sets of positional isomers of halogenated phenylmethylidene hydrazinecarbodithioates (MX, X =  F, Cl, Br).
authors.affiliation: Key Laboratory of Organosilicon Chemistry and Material Technology, Hangzhou Normal University, Hangzhou, 311121, P.R. China.
authors.forename: Yanqing
authors.initials: Y
authors.lastname: Wu
authors.forename: Cheng
authors.initials: C
authors.lastname: Guo
authors.forename: Ningwen
authors.initials: N
authors.lastname: Zhang
authors.forename: Gaofeng
authors.initials: G
authors.lastname: Bian
authors.forename: Kezhi
authors.initials: K
authors.lastname: Jiang
mesh_terms: D006834:Hydrazines / Q000737:chemistry*; D007536:Isomerism; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry
chemical_list: D006834:Hydrazines