GPCs - Gas Phase Cations as WCA-Salts...

Using the fascinating gas phase MS work as inspiration, we realized that good WCAs allow 'bottling' of GPC salts. This implies that excellent large WCAs induce Pseudo Gas Phase Conditions in the condensed phase. In the following, we exemplarily delineate the situation for Transition Metal Carbonyl Cations (TMCCs) as a prototype ‘GPC’ and ‘textbook’ cation class to show our general philosophy in this area.

Worked Example - Transition Metal Carbonyl Cations (TMCCs)

Apart from the group 7 cations, the TMCCs known until 2018 stem from 1990 to 2003 (Table in Figure) – typically from superacidic media (magic acid, HF/MF5, also H2SO4 etc.). Even doubly and triply charged superelectrophilic cations were accessible; many follow the 18 VE rule. As ‘non-classical’ or ‘predominantly σ-bonded’ they arose much attention. Yet, the advanced MS methods taught us that many more TMCCs, may they be mo­nomeric, clustered, closed or open shell, exist in the low-pressure environment of a MS. Their more stable and well-characterized versions are suitable targets and synthetic challenges for us. The Figure below gives some insight on this.

Therefore, our group set out to use the good WCAs to prepare the missing entries. Currently we succeeded to synthesize  six new metal entries to the Table: the metalloradicals [Ni(CO)4]+, [Cr(CO)6]+, [Mo(CO)6]+ and [W(CO)6]+, as well as the first heptacarbonyls [Nb(CO)7]+ and [Ta(CO)7]+. All of those, were earlier already fully characterized in the gas phase by MS.

scXRD [M(CO)6]+[Al(ORF)4] (M = Cr, Mo, W)

scXRD [M(CO)7]+[Al(ORF)4] (M = Nb, Ta)


Also the first homoleptic nitrosyl cation,  [Mn(NO)4]+[Al(ORF)4] was accessible with such an approach.

But this is only an exemplary selection on one topic. The next figure gives some ideas on the type and nature of GPCs that have been synthesized by the group as bottlable WCA-salts. Give it it a try and go for gold...