Dithiooxamides

Dithiooxamide (rubeanic acid) [79-40-3] M 120.2, m >300 . Crystd from EtOH and sublimed in a vacuum. 

Roseocobalt — see Cobalt, aquapentaammine-Roseopentaammine —see Aquapentaammine Roussin s black, 4, 1191 Roussin s red, 4, 1191 Roussin s salts, 4,240, 1243 Rubber vulcanization zinc complexes in, 5, 998 Rubeanic acid — see Dithiooxamid Rubidium complexes... 

Weisman and Reed have developed a route to cyclen (1,4,7,10-tetraazacyclododecane) via a fused 5 6 5 tricyclic system which was formed from condensation of triethylenetetramine 383 and dithiooxamide 381 to give 2,3>5,6,8,9-hexahydrodiimidazo[l,2- 2, l -c]pyrazine 382 in 69% yield (Scheme 30) <1996JOC5186>. 

In addition to stabilizing organic products by reaction with metal-exchanged clays, as indicated above, aluminosilicate minerals may enable the preparation of metal organic complexes that cannot be formed in solution. Thus a complex of Cu(II) with rubeanic acid (dithiooxamide) could be prepared by soaking Cu montmorillonite in an acetone solution of rubeanic acid (93). The intercalated complex was monomeric, aligned with Its molecular plane parallel to the interlamellar surfaces, and had a metal ligand ratio of 1 2 despite the tetradentate nature of the rubeanic acid. 

Diaminofurazan (DAF) (24) is a starting material for the synthesis of many nitro-substituted furazans and is readily prepared from the cyclization of 1,2-diaminoglyoxime (23) in the presence of aqueous base under pressure at 180 °C the latter prepared from the reaction of glyoxal/ glyoxime/ cyanogen or dithiooxamide with hydroxylamine. 

With hydrogen sulfide, the products are thiocyanoformamide, NCC(=S)NH2 and dithiooxamide, H2NC(=S)C(=S)NH2. 

West PW, Pitombo LR (1967) Microdetermination of copper using dithiooxamide crayons and the ring-oven technique. Anal Chim Acta 37 374-378. 

The only recorded complex is the product of composition UF4 SC3N2H2 which results from the reaction of UF6 with dithiooxamide.137... 

Dithiomalonamide (L) and its dimethyl and diphenyl derivatives form complexes of the stoichiometry ZnLX2 and ZnL2(C104)2 (X = Cl, Br or I). Both contain tetrahedrally coordinated zinc the dimethyl ligand is N,S-chelate-bonded while the others are S,S-bonded.897 The complexes [MLJ [C104]2 have also been prepared and do not contain coordinated perchlorate. The complexes ZnL (H2L = dithiooxamide, 7V,./V-dimethyl- and N, TV-dicyclohexy 1-dithioox-amide) have been isolated,898 and consist of linear chains containing four-coordinate zinc. 

With A,A-dimethyl- and N, TV-dicyclohexyl-dithiooxamide, Zn, Cd and Hg form the non-electrolyte MLX2 (X = Cl, Br or I) and electrolyte ML2X2 and ML3X2 (X = C104) complexes.8 9 IR studies show that all the complexes are S,N-coordinated for die ZnLX2 complexes, a tetrahedral coordination is indicated, while the analogous Cd complexes contain a halide-bridged octahedral structure. 

The reaction of dithiooxamide and its tetramethyl and tetraethyl derivatives with zinc, cadmium and mercury halides leads to complexes of stoichiometry MLX2 (M = Zn, Cd or Hg X = C1, Br or I).900,9 1 M—S bonding is involved IR spectra show that the zinc and mercury complexes are four-coordinate, while the cadmium complexes are octahedral with halogen bridges. 

Unless steric and electronic constraints prevail, vicinal dithiodiketones (10) can exist in an equilibrium mixture with their dithiacyclobutene (dithiete or dithietene) isomers (11). Strongly electron-withdrawing substituents, such as in (12), appear to favor the latter form, but the donor-substituted dithione (13) is also known22 to show such an equilibrium. As a czs-fixed dithiooxamide, the ligand (14) is particularly stable and presumably exists only in the dithione form. 

In contrast to the dithiolenes, we refer to dithiolato complexes as those in which the typical dithiolene resonance (and the properties which are associated with it) are absent because the ligand exists entirely in its dinegative form. In the neutral compound (22) above, the 2 — charge of the ethylenedithiolato ligand is balanced by the 2 + charge of the nickel atom and approximately square planar coordination is provided by the neutral dithiooxamide-type ligand. 

Readily accessible aryliminodithiazoles 56 can be converted by LiAlH4 reduction into the rearranged A-aryl-dithiooxamides 112 (Equation 24) <1999S1345>. Although the yields are moderate (35—42%), this reaction provides a convenient two-step synthesis of unsymmetrical rubeanic acid derivatives from arylamines. 

The thermal condensation of dithiooxamide with trichlorophenyl malo-nates results in thioamide 19, which with an excess of malonate gives a symmetric bis-TA 20. With other carbonyl compounds, thioamide 19 may be converted into other TAs with heterocyclic substituents, 21 and 22 (73JHC223) (Scheme 3). 

Similar insoluble salts form with many cationic chelates of heavy metal atoms. Thus, 12-molybdosilicic acid precipitates Cu+2, Ag+, Cd+2, Zn+2, Sn+2, Cr+3, Ni+2, and Co+2 in the presence of ethylenediamine, thiourea, hexamethylenetetramine, dithiooxamide, or similar chelating agents 106 ... 

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