Group 1 Element Compounds Li, Na,K,Rb,Cs

A series of rubidium thio- 1 (M=Rb) [150], seleno- 4 (M=Rb) [171, 326] and telluro-carboxylates 5 (M=Rb) [174] have been isolated in moderate to good yields from the reactions of the corresponding chalcogenocarboxylic acids or 

0-trimethylsilyl esters with rubidium acetate or fluorides. 

Selected bond distances of alkali metal chalcogenocarboxylates are collected in Table 1. The molecular structure of lithium benzoate 2 is a centrosymmetric dimer with an eight-membered ring composed of coplanar C, O, and S atoms and tetrahedrally-coordinated Li atoms above and below this plane, where the C-0 [1.246(2) A] and C-S distances [1.704(2) A] show considerable multiple bond character [6]. From an ab initio optimization calculation on a dimeric lithium formate (HCOSLi)2, the PhCOS unit in 1-2 has been predicted to be predominantly ionic [6]. 

The two anion moieties in both potassium 1,2-dithio-oxalate 6, K2[SOC-COS] [213], and potassium trithio-oxalate 7, K2[S2C-C(0)S] (KC1), possess mutually perpendicular thiocarboxyl groups, respectively [224]. In contrast, those in the 

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