Dimeric dithiocarboxylate

X-Ray structural analysis of [Pt(dithiocumato)2] revealed a dimeric structure containing two bridging and two terminal dithiocarboxylate ligands (XXXII). The proximity of the two platinum atoms (278 pm) suggested that a Pt-Pt bond may be present (415). 

In the reaction of dithiocarboxylic acids 551 with DCC the unstable dithioacetyl-sulfide 552 is formed, which undergoes dimerization to give a mixture of 1,3,5,7-tetramethyl-3,4,6,8,9,10-hexathiaadamantane 553 and cis- and rra 5-2,4-dimethyl-2. 

C. Platinum Dimers with Dithiocarboxylates as Bridging Ligands (S—S)... 

The Ph2AsS2CC6H4Me-4 derivative reacts with piperidine to form piperidinium diphenyl-dithioarsinate (a hydrogen bond dimer, (46)) and A-4-methylthiobenzoyl-piperidine, thus converting a dithiocarboxylate into a dithioarsinate (Scheme 18) 375... 

The X-ray structure analysis of compound 2 has shown that the bismuth center is surrounded by six sulfur atoms to form a trigonal antiprismatic geometry. All three dithiocarboxylate ligands are non-equivalent and the Bi-S bonds can be divided into two types short (2.617(2), 2.626(1) and 2.647(1) A) and long (2.963(2), 3.040(1) and 3.108(2) A). One of the sulfur atom coordinates weakly to the neighboring bismuth center (3.689 A) to form a dimeric structure in the solid state [87IC1453]. 

Dihydrotetrazines (340), which can easily be oxidized to 1,2,4,5-tetrazines, can be formed by dimerization of thiohydrazides (337) or amidrazones (338). The ring closure of hydrazidines (339) in a [5 + 1] fashion proceeds well with activated carboxylic acid derivatives such as imidates (341), orthocarboxylates (342) or dithiocarboxylates (343). The [4 + 2] procedure is found in the transformation of 1,3,4-oxadiazoles (346) or 1,4-dichloroazines (345) with hydrazine. Finally diazoalkanes (344) can be dimerized in a [3 - - 3] manner under the influence of a base the dimerization of diazoacetic ester is an early example, leading to 3,6-tetrazinedicarboxylate (48), which is frequently used in (4 -I- 2) cycloaddition reactions with inverse electron demand. Nitrile imines, reactive intermediates which are formed from many precursors, can dimerize in a [3 -I- 3] fashion to form 1,3,4,6-tetrasubstituted 1,4-dihydrotetrazines. These reactions are summarized in Scheme 57. 

It has been reported that dithiocarboxylic acids exist as monomers in dilute solution and as hydrogen-bonded dimers in concentrated solution. NMR spectra for neat dithioacetic acid 6 revealed that reversible covalent associations exist, resulting in dimer 7 and cyclic trimer 8 [22]. At 19.5 °C,the ratios of these spices are 61% monomer, 38% 7 and 1% 8. 

A series of 4-methyldithiobenzoate salts of potassium 3, rubidium 4 and cesium 5 show dimeric structures in which each dithiocarboxylate ligand is chelated to two metal cations (Fig. 3) [38]. The two metal atoms are located on the upper and lower sides of the plane involving four sulfur atoms of two dithiocarboxylate ligands. The metal cations further interact with the tolyl fragments in the neighboring molecules. The C-S bond lengths of the potassium... 

The zinc(II) complex 59 was obtained by the reaction of Zn(MeCN)4(BF4)2 with the corresponding sodium salt of dithiocarboxylic acid and subsequent recrystallization from pyridine (Fig. 15) [114]. The crystal structure was shown to be a distorted trigonal bipyramidal geometry with one sulfur atom from each of the dithiocarboxylato ligands occupying the axial sites. In the absence of donor molecules such as pyridine, one sulfur atom from the dithiocarboxylato ligand coordinates to another zinc center to form a dimer-like Zn(II) complex 60 in the crystalline state [115]. EXAFS study indicates that 60 retains the dimeric nature in the mesophase. 

Many dithiocarboxylate compounds of sulfur have been reported. Bis(thioacyl) disulfides 100, dimers of dithiocarboxylate ligands, are easily synthesized by oxidative dimerization of the corresponding dithiocarboxylic acids (Scheme 26) [151-154]. Their reactivities toward cycloaddition reactions and S-S bond cleavage have been investigated [155-157]. Bis(thioacyl) trisulfides 101 and tetrasulfides 102 are also prepared by treating the dithiocarboxylic acid with SCI2 and S2CI2, respectively [135]. 

Dithiocarboxylic acids (118) can be converted into 1,3-dithietans (119) by acid chlorides,iodine, HCl, DCCI, or upon standing for a long time, and they are formally thioketen dimers. The cycloaddition of two C=S groups yields thioketen dimers and (120) from methyl isothiocyanate. Derivatives (121) are prepared by the reaction of dithiocarboxylic acids (118) with phosgene. ... 

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