质谱中若干金属配合物及簇合物的碎片重组反应

在质谱实验中,我们发现了与一般单分子分解反应相悖的四种类型碎片产物的重组反应物即(Ⅰ)裂解碎片的自组合产物如S_8~+及不同聚合度的聚硫离子;(Ⅱ)裂解碎片之间的相互组合物如Fe(S_2CNC_4H_8)_3]~+和Fe(S_2CNEt_2)_3]~+;(Ⅲ)裂解碎片的阴离子和阳离子部分碎片间的组合物如Fe_2S_2(NO)_4(CH_3)_2]~+;(Ⅳ)歧化反应产物Cp_3Yb~+和YbL_3~+(Cp=C_5H_5),L=β-二酮)。本文阐述了这种重组反应或离子—分子反应在质谱条件下产生的可能性及其理论根据。

Recombination Reaction of Fragment Species of Some Metal Complexes and Clusters in Mass Spectrometry

Recombination reaction of fragment products or of ion-molecules different from the uni-molecular reaction has been found in a series of El mass spectroscopic experiments at an ion-source pressure of 1. 33×10-5Pa.These recombination reactions can be further classified in following types: (1)The self-combination product S8+ of fragmentation species formed from MoFe3S4-(S2CNC4H8)5],MoFe3S4(S2CNEt2)5]-1 and Fe4S3(NO)7]-1, may further decompose into Sn(n = 1-7).(2)The combination products Fe(S2CNC4H8)3]+ ,Fe(S2CNEt2)3]+ between the fragmentation species, which were formed fromMoFe3S4(S2CNC4H8)5] and MoFe3S4(S2CNEt2)5]-1.(3)The combination reaction between the fragment species of both cation and anion in the metal cluster N(CH3)4]2Fe2S2(NO)4 produces Fe2S2(NO)4(CH3)2]+.(4)The disproportionation reaction products Cp3Yb+ and YbL3+, which were formed from Cp2YbL and CpYbL2 when these compounds reach a certain evaporation temperature. (Cp =η5-C5H5 ,L =β-diketonato e. g. HL =acetylacetone ; 2,2,6,6-tetramethyl-3,5-heptanedione; 1,1,1-trifluoroacetylacetone; benzoylacetone ; 4-benzoyl-3-methyl-l-phenyl-5-pyrazolone; trifluoroace-toacetyl-a-thiophene).The presence of these ions indicates that the combination reactions of fragment products or ion-molecules may occur, when these compounds are present at 'high-pressure' of inlet system and at a low-pressure of ion-source. These stable combination products are first formed at the inlet system and then further decompose and ionize into a series of fragment ions.