Tetrakis(1‐naphthylamino)silane and its tetrahydrofuran trisolvate

In both title structures, C₄₀H₃₂N₄Si and C₄₀H₃₂N₄Si·3C₄H₈O, the angles around the Si atom deviate significantly from the tetrahedral value [104.34 (7)–116.63 (7)° in the nonsolvate and 99.91 (15)–116.85 (15)° in the solvate]. The amino H atoms in the solvated structure are involved in hydrogen bonding with two of the tetrahydrofuran solvent molecules.     

A monomeric selenium(IV) diimide and a dimeric seleninylamine

The selenium(IV) diimide AdN=Se=NAd (Ad = 1-adamantyl) adopts a monomeric structure with a Z,E configuration in the solid state whereas the seleninylamine OSe(mu-NBut)2SeO crystallizes as the cis-dimer.     

Chalcogenide derivatives of imidotin cage complexes

Reaction of the secocubane [Sn3(mu2-NHtBu)2(mu2-NtBu)(mu3-NtBu)] (1) with dibutylmagnesium produces the heterobimetallic cubane [Sn3Mg(mu3-NtBu)4] (4) which forms the monochalcogenide complexes of general formula [ESn3Mg(mu3-NtBu)4] (5a, E = Se; 5b, E = Te) upon reaction with elemental chalcogens in THF. By contrast, the reaction of the anionic lithiated cubane [Sn3Li(mu3-NtBu)4]- with the appropriate quantity of selenium or tellurium leads to the sequential chalcogenation of each of the three Sn(II) centres. Pure samples of the mono- or dichalcogenides are, however, best obtained by stoichiometric redistribution reactions of [Sn3Li(mu3-NtBu)4]- and the trichalcogenides [E3Sn3Li(mu3-NtBu)4]- (E = Se, Te). These reactions are conveniently monitored by using 119Sn NMR spectroscopy. The anion [Sn3Li(mu3-NtBu)4]- also acts as an effective chalcogen-transfer reagent in reactions of selenium with the neutral cubane [{Snmu3-N(dipp)}4] (8) (dipp = 2,6-diisopropylphenyl) to give the dimer [(thf)Sn{mu-N(dipp)}2Sn(mu-Se)2Sn{mu-N(dipp)}2Sn(thf)] (9), a transformation that results in cleavage of the Sn4N4 cubane into four-membered Sn2N2 rings. The X-ray structures of 4, 5a, 5b, [Sn3Li(thf)(mu3-NtBu)4(mu3-Se)(mu2-Li)(thf)]2 (6a), [TeSn3Li(mu3-NtBu)4][Li(thf)4] (6b), [Te2Sn3Li(mu3-NtBu)4][Li([12]crown-4)2] (7b') and 9 are presented. The fluxional behaviour of cubic imidotin chalcogenides and the correlation between NMR coupling constants and tin-chalcogen bond lengths are also discussed.     

Redox chemistry of tellurium bis(tert-butylamido)cyclodiphosph(V)azane disulfide and diselenide systems: a spectroscopic and structural study

The redox chemistry of tellurium-chalcogenide systems is examined via reactions of tellurium(IV) tetrachloride with Li[(t)()BuN(E)P(mu-N(t)Bu)(2)P(E)N(H)(t)Bu] (3a, E = S; 3b, E = Se). Reaction of TeCl(4) with 2 equiv of 3a in THF generates the tellurium(IV) species TeCl(3)[HcddS(2)][H(2)cddS(2)] 4a [cddS(2) = (t)BuN(S)P(mu-N(t)Bu)(2)P(S)N(t)Bu] at short reaction times, while reduction to the tellurium(II) complex TeCl(2)[H(2)cddS(2)](2) 5a is observed at longer reaction times. The analogous reaction of TeCl(4) and 3b yields only the tellurium(II) complex TeCl(2)[H(2)cddSe(2)](2) 5b. The use of 4 equiv of 3a or 3b produces Te[HcddE(2)](2) (6a (E = S) or 6b (E = Se)). NMR and EPR studies of the 5:1 reaction of 3a and TeCl(4) in THF or C(6)D(6) indicate that the formation of the Te(II) complex 6a via decomposition of a Te(IV) precursor occurs via a radical process to generate H(2)cddS(2). Abstraction of hydrogen from THF solvent is proposed to account for the formation of 2a. These results are discussed in the context of known tellurium-sulfur and tellurium-nitrogen redox systems. The X-ray crystal structures of 4a.[C(7)H(8)](0.5), 5a, 5b, 6a.[C(6)H(14)](0.5), and 6b.[C(6)H(14)](0.5) have been determined. The cyclodiphosph(V)azane dichalcogenide ligand chelates the tellurium center in an E,N (E = S, Se) manner in 4a.[C(7)H(8)](0.5), 6a.[C(6)H(14)](0.5), and 6b.[C(6)H(14)](0.5) with long Te-N bond distances in each case. Further, a neutral H(2)cddS(2) ligand weakly coordinates the tellurium center in 4a small middle dot[C(7)H(8)](0.5) via a single chalcogen atom. A similar monodentate interaction of two neutral ligands with a TeCl(2) unit is observed in the case of 5a and 5b, giving a trans square planar arrangement at tellurium.     

Lithium halide adducts of imidotellurium(IV) ligands: synthesis and X-ray structures of [Li(THF)2L](mu 3-I)[LiI(L)] [L = tBuNTe(mu-NtBu)2TeNtBu] and [(THF)3Li3(mu 3-I)(Te(NtBu)3)

The reaction of the chelating ligand tBuNTe(mu-NtBu)2TeNtBu (L) with LiI in THF yields [Li(THF)2L](mu 3-I)[LiI(L)] (3). This complex is also formed by the attempted oxidation of [Li2Te(NtBu)3]2 with I2. An X-ray analysis of 3 reveals that the tellurium diimide dimer acts as a chelating ligand toward (a) [Li(THF)2]+ cations and (b) a molecule of LiI. An extended structure is formed via weak Te...I interactions [3.8296(7)-3.9632(7) A] involving both mu 3-iodide counterions and the iodine atoms of the coordinated LiI molecules. Crystal data: 3, triclinic, space group P1, a = 10.1233(9) A, b = 15.7234(14) A, c = 18.8962(17) A, alpha = 86.1567(16) degrees, beta = 84.3266(16) degrees, gamma = 82.9461(16) degrees, V = 2965.8(5) A3, Z = 2. The oxidation by air of [Li2Te(NtBu)3]2 in toluene produces the radical (Li3[Te(NtBu)3]2), which exhibits an ESR spectrum consisting of a septet of decuplets (g = 2.00506, a(14N) = 5.26 G, a(7Li) = 0.69 G). The complexes [(THF)3Li3(mu 3-X)(Te(NtBu)3)] (4a, X = Cl; 4b, X = Br; 4c, X = I) are obtained from the reaction of [Li2Te(NtBu)3]2 with lithium halides in THF. The iodide complex, 4c, has a highly distorted, cubic structure comprised of the pyramidal [Te(NtBu)3]2- dianion which is linked through three [Li(THF)]+ cations to I- Crystal data: 4c, triclinic, space group P1, a = 12.611(8) A, b = 16.295(6) A, c = 10.180(3) A, alpha = 98.35(3) degrees, beta = 107.37(4) degrees, gamma = 108.26(4) degrees, V = 1829(2) A3, Z = 2.     

Lithiation of (tBuNH)3PNSiMe3 and formation of tetraimidophosphate complexes containing M3O3 rings (M = Li, K): X-ray structure of the stable radical [(Me3SiN)P(mu3-N(t)Bu)3[mu3-Li(THF)]3(OtBu))

The reaction of ((t)BuNH)(3)PNSiMe(3) (1) with 1 equiv of (n)BuLi results in the formation of Li[P(NH(t)Bu)(2)(N(t)Bu)(NSiMe(3))] (2); treatment of 2 with a second equivalent of (n)BuLi produces the dilithium salt Li(2)[P(NH(t)Bu)(N(t)Bu)(2)(NSiMe(3))] (3). Similarly, the reaction of 1 and (n)BuLi in a 1:3 stoichiometry produces the trilithiated species Li(3)[P(N(t)Bu)(3)(NSiMe(3))] (4). These three complexes represent imido analogues of dihydrogen phosphate [H(2)PO(4)](-), hydrogen phosphate [HPO(4)](2)(-), and orthophosphate [PO(4)](3)(-), respectively. Reaction of 4 with alkali metal alkoxides MOR (M = Li, R = SiMe(3); M = K, R = (t)Bu) generates the imido-alkoxy complexes [Li(3)[P(N(t)Bu)(3)(NSiMe(3))](MOR)(3)] (8, M = Li; 9, M = K). These compounds were characterized by multinuclear ((1)H, (7)Li, (13)C, and (31)P) NMR spectroscopy and, in the cases of 2, 8, and 9.3THF, by X-ray crystallography. In the solid state, 2 exists as a dimer with Li-N contacts serving to link the two Li[P(NH(t)Bu)(2)(N(t)Bu)(NSiMe(3))] units. The monomeric compounds 8 and 9.3THF consist of a rare M(3)O(3) ring coordinated to the (LiN)(3) unit of 4. The unexpected formation of the stable radical [(Me(3)SiN)P(mu(3)-N(t)Bu)(3)[mu(3)-Li(THF)](3)(O(t)Bu)] (10) is also reported. X-ray crystallography indicated that 10 has a distorted cubic structure consisting of the radical dianion [P(N(t)Bu)(3)(NSiMe(3))](.2)(-), two lithium cations, and a molecule of LiO(t)Bu in the solid state. In dilute THF solution, the cube is disrupted to give the radical monoanion [(Me(3)SiN)((t)BuN)P(mu-N(t)Bu)(2)Li(THF)(2)](.-), which was identified by EPR spectroscopy.     

Octahedral Tin(IV) Complexes of the Chalcogen‐Centered Ligands [EC(PPh2S)2]2– (E = S,Se)

The metathetical reactions between SnBr₄ and Li₂[E'C(PPh₂E)₂] in toluene produce the homoleptic tin(IV) complexes Sn[E′C(PPh₂E)₂]₂ [E = E′ = S ( 1b ); E = S, E′ = Se ( 1c )], which were isolated as red crystals and structurally characterized by X‐ray crystallography. The metrical parameters of these octahedral complexes are compared with those of the all‐selenium analog Sn[E′C(PPh₂E)₂]₂ (E = E′ = Se, 1a ), which was prepared previously by a different route.     

An asymmetrically substituted borazine

The B₃N₃ ring in the title compound, 1,3,5‐tri‐tert‐butyl‐2,4‐difluoro‐6‐phenyl­cyclo­triborazane, [PhF₂B₃N₃^tBu₃] or C₁₈H₃₂B₃F₂N₃, an asymmetrically substituted borazine, is distorted from planarity. The molecule resides on a twofold axis. The N atoms of the N—B(Ph)—N group lie on opposite sides of the least‐squares plane formed by the four remaining ring atoms, due to steric accommodation of the tert‐butyl groups, a conformation not previously observed for a borazine. The B—N bond lengths are in the range 1.4283 (14)–1.4493 (12) Å, due to the F substituents residing on two of the B atoms, which also produce a large deviation from 120° in one of the B—N—B angles [ca 113.6 (1)°]. The phenyl group is twisted with respect to the B₃N₃ ring, the interplanar angle being 62.87 (5)°.