Metal-hydride anions of main group elements, such as BaH3 - and InH4 -, were generated by dissociating formate adducts of the respective metal formates. Upon activation, these adducts fragment by formate-ion ejection or by decarboxylation. For adducts of alkali-metal formates, the formate-ion ejection is the preferred pathway, whereas for those of alkaline-earth and group 13-15 metals, the expulsion of CO2 is the more favorable pathway. Decarboxylation is deemed to yield a metal-hydrogen bond presumably by a hydride transfer to the metal atom. For example, the decarboxylation of Al(η-OCOH)4 - and Ga(η-OCOH)4 - generated AlH4 - and GaH4 -, respectively. The initial fragment-ion with a H-M bond formed in this way from adducts of the heavier metals of group 13 (Ga, In, and Tl) undergo a unimolecular reductive elimination, ascribable to the "inert-pair" effect, to lower the metal-ion oxidation state from +3 to +1. As group 13 is descended, the tendency for this reductive elimination process increases. PbH3 -, generated from the formate adduct of lead formate, reductively eliminated H2 to form PbH-, in which Pb is in oxidation state zero. In the energy-minimized structure [H-Pb(η2-H2)]-, proposed as an intermediate for the process, a H2 molecule is coordinated with PbH- as a dihapto ligand. The formate adducts of strontium and barium produce monoleptic ions such as [M(0)(η2-O2CH)1]-, in which the formate ion is chelated to a neutral metal atom. The bismuth formate adduct undergoes a double reductive elimination process whereby the oxidation state of Bi is reduced from +3 to +1 and then to -1. Upon activation, the initially formed [H-Bi-H]- ion transforms to an anionic η2-H2 complex, which eliminates dihydrogen to form the bismuthide anion (Bi-).

中文翻译：

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气相产生阴离子的周期性趋势，例如[AlH4]-，[GaH4]-，[InH4]-，[SrH3]-，[BaH3]-，[Ba（0）（η2-O2CH）1]- ，[Pb（0）H]-，[Bi（I）H2]-和Bi-的格式。

通过分解各个金属甲酸酯的甲酸酯加成物，可以生成主要族元素的金属氢化物阴离子，例如BaH3-和InH4-。活化后，这些加合物通过甲酸酯离子喷射或通过脱羧而碎裂。对于碱金属甲酸盐的加合物，甲酸盐离子的排出是优选的途径，而对于碱土金属和13-15族金属的加合物，更优选的排出途径是CO2的排出。认为脱羧作用可能是由于氢化物转移到金属原子上而产生金属-氢键。例如，Al（η-OCOH）4-和Ga（η-OCOH）4-的脱羧分别产生了AlH4-和GaH4-。由第13组重金属（Ga，In和Tl）的加合物以这种方式形成的带有HM键的初始片段离子经历了单分子还原消除，这归因于“