Reactions of Sodium N,N-Diethyldithiocarbamate with the Chlorides and Bromides of Niobium(V), Tantalum(V), and Protactinium(V)

Abstract

Reactions between niobium(V), tantalum(V), and protactinium(V) chlorides and bromides and sodium N,N-diethyldithiocarbamate (Nadtc) have been examined in non-aqueous, non-oxygenated organic solvents. Complexes obtained are of the types Mdtc4X, Mdtc3X2, Mdtc3S, Mdtc2X3, and Mdtc2X3.nC6H6 (n = 0.7-1.0); not all complexes have been isolated for each metal. W~thln each group the niobium(V) and tantalum(V) complexes are isostructural; possible structures are discussed in the light of results from infrared (i.r.) and nuclear magnetic resonance (n.m.r.) spectra, molecular weight, and electrical conductivity measurements. IntroductionAs part of our studies (1) on reactions between sodium N,N-diethyldithiocarbamate (Nadtc) and anhydrous metal halides in non-aqueous solvents, we have studied reactions (which have been the subject of a preliminary communication (2)), involving the niobium(V), tantalum(V), and protactinium(V) halides. Almost all of the work on dithiocarbamate complexes of these elements has been reported only recently (3). For example, it has been shown (4) that carbon disulfide can be inserted into the niobium(V) and tantalum(V) pentamides forming, in the latter case Tadtc, (dimethyl derivative) while the niobium(V) pentamide is reduced, Nbdtc, being the final product. The reduction is thought to occur because of the steric strain imposed on an intermediate complex, Nbdtc,, which liberates a dithiocarbamate radical; the latter subsequently forms tetramethyl thiuram disulfide. This is one of the relatively

The chemistry of niobium and tantalum dithiocarbamato-complexes. Part 4. The co-ordination isomers of NbCl3(S2CNEt2)2 and the X-ray crystal structure of [NbCl3(S2CNEt2)2]

“…However, we note that there is a significant difference between the two Nb-Cl,, distances in our complex, viz. 2.377(1) and 2.327(1) A; similar differences (although none quite so large) have been observed in other pentagonal bipyramidal complexes of Nb and Ta,438-1 and have been related to interligand contacts. In our complex, there are no such controlling intramolecular contacts, but Cl (3) has one intermolecular contact, 3.584(4) A, to a methyl C( 6 There is good, tight packing of molecules in the crystal, with several interactions at less than van der Waals distances.…”

Rhodium(I) and (III) Complexes of Some Phospholes and Their Behavior as Homogeneous Hydrogenation Catalysts

“…Reactions generally involved the appropriate rhodium compound in quantities corresponding to -50 mg Rh in -I00 ml of solvent, and the products were dried by heating under vacuum Torr) at 30-50 "C. Microanalyses (Table 2) were carried out on a PerkinElmer 240 Elemental Analyzer at this institution. Chloride analyses (2) and physical measurements were made as described previously (18).…”

Protactinium

“…Numerous halide complexes of Pa(IV) and Pa(V) are formed with oxygen donor ligands, such as substituted phosphine oxides (Brown et al, , 1970a, hexamethylphosphoramide , DMSO (Bagnall et al, 1968b), tropolone (Brown and Rickard, 1970), N,N-dimethylacetamide (Bagnall et al, 1969), acetylacetone (Brown and Rickard, 1971b), and N,N-diethyldithiocarbamate (Heckley et al, 1971). In addition, complexes with sulfur and selenium donors have been reported .…”