Vanadium nitride functionalization and denitrogenation by carbon disulfide and dioxide.

A dramatic difference in behavior is observed for the dithiocarbamate and carbamate complexes [Ar(But)N]3V(NCE2)Na(THF)2(E = S or O, respectively), prepared from the corresponding nitride species ([Ar(But)N]3V identical to NNa)2 by way of a nucleophilic addition reaction involving carbon disulfide or dioxide, and is rationalized with the aid of DFT calculations.

Imido Analogues of Common Oxo Anions: A New Episode in the Chemistry of Cluster Compounds.

Oxo anions of p- and d-block elements, for example, SiO(4)(4-), PO(4)(3-), SO(4)(2-), and CrO(4)(2-), are commonly encountered species. The full or partial replacement of the oxo ligands by isoelectronic imido (NR) groups generates homoleptic polyimido anions of the type [E(NR)(x)](z-) or heteroleptic imidooxo anions with the general formula [O(y)E(NR)(x-y)](z-) (where E=main group element or transition metal). The alkali metal derivatives of this new class of anions form ternary or quaternary cluster systems, respectively. The structures of these clusters can be rationalized in terms of the self-assembly of fundamental building blocks. An understanding of the factors that control this process may allow the design of functional materials with specific properties. In addition, these anions are attracting attention as multidentate ligands with unique electronic and stereochemical properties that may engender novel metal-centered chemistry.

Template Effects of Lithium Salts on the Crystallization of Diazasulfates: X-ray Structures of {THF.Li(2)[O(2)S(N(t)Bu)(2)]}(8).2LiOH.2LiCl and {(THF.Li)(2)[O(2)S(N(t)Bu)(2)].(THF)LiCl}(2).

The addition of 2 equiv of (n)BuLi to solutions of O(2)S[N(H)R](2) (R = (i)Pr, (t)Bu) produces the dilithium diazasulfates {Li(2)[O(2)S(N(i)Pr)(2)]}(n)() (2) and {THF.Li(2)[O(2)S(N(t)Bu)(2)]}(n)() (3), which were characterized by solid-state (7)Li and (13)C NMR spectroscopy. Crystals were obtained from a THF/n-hexane solution of 3 and determined by X-ray crystallography to be {THF.Li(2)[O(2)S(N(t)Bu)(2)]}(8).2LiOH.2LiCl (4), which consists of a 64-atom (Li(20)S(8)N(16)O(18)Cl(2)) cluster composed of two Li(4)O(4) cubes and a central Li(4)O(4) step-shaped ladder. The eight [O(2)S(N(t)Bu)(2)](2)(-) dianions in 4 exhibit three distinct modes of bonding to the Li(+) cations: (a) bis-(N,O),(N',O')-chelate, (b) N,O-chelate, bis-N',O'-monodentate, and (c) bis-(N,O),(N,N')-chelate, O'-monodentate. The synthesis of 3 in the presence of 1 equiv of LiCl produces the dimer {(THF.Li)(2)[O(2)S(N(t)Bu)(2)].(THF)LiCl}(2) (5). The structure of 5 incorporates an 18-atom (Li(6)S(2)N(4)O(4)Cl(2)) quinary cluster in which two {[THF.Li(&mgr;-O)(&mgr;-N(t)Bu)](2)S} molecules are held together by two (THF.LiCl) units. The mean Li-Cl distance (2.348 Å) linking the {[THF.Li(&mgr;-O)(&mgr;-N(t)Bu)](2)S} molecules to the (THF.LiCl) units is significantly shorter than the corresponding value of 2.483 Å within these units. Crystal data: 4, monoclinic, P2(1)/n, a = 18.557(1) Å, b = 15.731(1) Å, c = 28.063(2) Å, beta = 107.381(1) degrees, V = 7817.9(9) Å(3), and Z = 2; 5, monoclinic, P2(1)/n, a = 11.583(3) Å, b = 17.126(5) Å, c = 13.891(4) Å, beta = 94.613(4) degrees, V = 2747(1) Å(3), and Z = 2.

ESR Investigations of the Radicals {Li(3)[E(N(t)Bu)(3)](2)}(*) (E = S, Se) and the Radical Anions SO(x)()(N(t)Bu)(3)(-)(x)()(*)(-) (x = 1, 2).

The air oxidation of the cluster compounds [Li(2)E(N(t)Bu)(3)](2) (E = S, Se) in toluene produces deep blue (E = S) or green (E = Se) solutions. The ESR spectra of these solutions consist of a septet (1:3:6:7:6:3:1) of decuplets. The simulation of these spectra shows that the secondary hyperfine splitting results from interaction of the unpaired electron with three equivalent (7)Li ions consistent with the formation of the neutral radicals {Li(3)[E(N(t)Bu)(3)](2)}(*) (4a, E = S, g = 2.0039, a((14)N) = 5.69 G, a((7)Li) = 0.82 G; 4b, E = Se, g = 2.00652, a((14)N) = 5.41 G, a((7)Li) = 0.79 G). Over a period of 25 h the seven line pattern of 4b is replaced first by a five line (1:2:3:2:1) spectrum (g = 2.009, a((14)N) = 13.4 G) and, subsequently, by a three line (1:1:1) spectrum (g = 2.00946, a((14)N) = 15.4 G, a((77)Se) = 4.3 G), neither of which exhibit (7)Li hyperfine splitting. These spectra are tentatively assigned to the radical anions SeO(N(t)Bu)(2)(*)(-) and SeO(2)(N(t)Bu)(*)(-), respectively. The cluster {Li(2)[O(2)S(N(t)Bu)]}(n)() (3) is prepared by the reaction of sulfur dioxide with 2 equiv of LiNH(t)Bu in toluene. The air oxidation of toluene solutions of {Li(2)[OS(N(t)Bu)(2)]}(6) (2a) or 3 produces deep blue species. In the former case the initial ESR spectrum is a 1:2:3:2:1 quintet (g = 2.009, a((14)N) = 13.3 G) which, after 16 h, evolves into a 1:1:1 triplet (g = 2.0088, a((14)N) = 15.9 G). The same triplet is observed in the ESR spectrum of oxidized solutions of 3 leading to the assignments OS(N(t)Bu)(2)(*)(-) and O(2)S(N(t)Bu)(*)(-) for the quintet and triplet, respectively. The disproportionation 2OS(N(t)Bu)(2)(*)(-) --> O(2)S(N(t)Bu)(*)(-) + S(N(t)Bu)(3)(*)(-) is indicated by the changes observed for the ESR spectra of oxidized solutions of 2a.