Ligand effects in the syntheses and structures of novel heteroleptic and homoleptic bismuth(iii) formamidinate complexes

Synthesis and characterization of a range of antimony(I/III) N,N'-bis(2,6-diisopropylphenyl)formamidinate complexes

Formamidinatoantimony(I/III) complexes have been successfully synthesized as monomers or dimers in the solid state featuring a variety of coordination geometries and have also been comprehensively characterized. The antimony(I) formamidinate complex bis[μ-N,N'-bis(2,6-diisopropylphenyl)formamidinato]diantimony(I)(2 Sb-Sb) tetrahydrofuran heptasolvate, [Sb₂(C₂₅H₃₅N₂)₂]·7C₄H₈O or [Sb₂(DippForm)₂]·7THF, (1), was obtained by a metathesis reaction between sodium bis(trimethylsilyl)amide [NaN(SiMe₃)₂] and N,N'-bis(2,6-diisopropylphenyl)formamidine (DippFormH), followed by SbCl₃. A range of trivalent haloformamidinatoantimony(III) complexes, namely, bis[N,N'-bis(2,6-diisopropylphenyl)formamidinato]chloridoantimony(III), [Sb(C₂₅H₃₅N₂)₂Cl] or [Sb(DippForm)₂Cl], (2), bis[N,N'-bis(2,6-diisopropylphenyl)formamidinato]bromidoantimony(III), [SbBr(C₂₅H₃₅N₂)₂] or [SbBr(DippForm)₂], (3), bis[N,N'-bis(2,6-diisopropylphenyl)formamidinato]iodidoantimony(III), [Sb(C₂₅H₃₅N₂)₂I] or [Sb(DippForm)₂I], (4), [N,N'-bis(2,6-diisopropylphenyl)formamidinato]dibromidoantimony(III), [SbBr₂(C₂₅H₃₅N₂)] or [SbBr₂(DippForm)], (5), and [N,N'-bis(2,6-diisopropylphenyl)formamidinato]diiodidoantimony(III), [Sb(C₂₅H₃₅N₂)I₂] or [Sb(DippForm)I₂], (6), were also synthesized by adding DippFormH and MN(SiMe₃)₂ (M = Li or Na) to the corresponding antimony halides SbX₃ (X = Cl, Br or I) in differing ratios. The complexes were all stable to rearrangement.

Highly Reactive Cyclic(alkyl)(amino) Carbene- and N-Heterocyclic Carbene-Bismuth(III) Complexes: Synthesis, Structure, and Computations

Cyclic(alkyl)(amino) carbene (CAAC)-stabilized complexes of phosphorus, one of the lightest group 15 elements, are well-established and can often be obtained in high yields. In contrast, analogous CAAC compounds of bismuth, the heaviest nonradioactive member of group 15, are unknown. Indeed, reactivity increases as you descend the group, and as a result there are only a few examples of N-heterocyclic carbene (NHC)-bismuth complexes. Moreover, activated bismuth compounds often readily extrude bismuth metal, making isolation of stable complexes highly challenging. We report that CAACs react with phenylbismuth dichloride (PhBiCl₂) to afford ^Et2CAAC-Bi(Ph)Cl₂ and ^CyCAAC-Bi(Ph)Cl₂. Significantly, these complexes represent the first structurally characterized examples of CAAC-coordination to bismuth. The CAAC-stabilized bismuth compounds can also be obtained from air-stable salts, [^Et2CAAC-H]₂²⁺ [Cl₂(Ph)Bi(μ-Cl₂)Bi(Ph)Cl₂]^2- and [^CyCAAC-H]₂²⁺ [Cl₂(Ph)Bi(μ-Cl₂)Bi(Ph)Cl₂]^2-, by deprotonation with potassium bis(trimethylsilyl)amide, K[N(SiMe₃)₂]. The electronic effects of the ligand on the bismuth center were investigated by comparing the CAAC-Bi(Ph)Cl₂ complexes to the NHC analogues, SIPr-Bi(Ph)Cl₂(THF) and IPr-Bi(Ph)Cl₂ (SIPr = 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazole-2-ylidene; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene). Interestingly, the "normal" IPr-Bi(Ph)Cl₂ slowly isomerizes to the "abnormal" carbene complex, Cl₂(Ph)Bi-IPr-H, at -37 °C. In the solid-state, the CAAC-, NHC-, and abnormal NHC-bismuth compounds exhibit Bi atomic centers in unique coordination environments. The complexes were fully characterized by NMR, elemental analysis, and single crystal X-ray diffraction studies. In addition, the bonding was probed by natural bond orbital (NBO) calculations.

Synthesis of mono-, di-, and triaminobismuthanes and observation of C–C coupling of aromatic systems with bismuth(iii) chloride

Mono-, di- or triaminobismuthanes were synthesized depending on the sterical demand of the organic substituent. In one case, a C–C coupling product was observed as main product in the reaction of BiCl₃ with Mes*(SiMe₃)NLi.

Molecular nitrides with titanium and Group 13-15 elements

Several heterometallic nitrido complexes were prepared by reaction of the imido-nitrido titanium complex [{Ti(eta(5)-C(5)Me(5))(mu-NH)}(3)(mu(3)-N)] (1) with amido derivatives of Group 13-15 elements. Treatment of 1 with bis(trimethylsilyl)amido [M{N(SiMe(3))(2)}(3)] derivatives of aluminum, gallium, or indium in toluene at 150-190 degrees C affords the single-cube amidoaluminum complex [{(Me(3)Si)(2)N}Al{(mu(3)-N)(2)(mu(3)-NH)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)}] (2) or the corner-shared double-cube compounds [M(mu(3)-N)(3)(mu(3)-NH)(3){Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)}(2)] [M = Ga (3), In (4)]. Complexes 3 and 4 were also obtained by treatment of 1 with the trialkyl derivatives [M(CH(2)SiMe(3))(3)] (M = Ga, In) at high temperatures. The analogous reaction of 1 with [{Ga(NMe(2))(3)}(2)] at 110 degrees C leads to [{Ga(mu(3)-N)(2)(mu(3)-NH)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)}(2)] (5), in which two [GaTi(3)N(4)] cube-type moieties are linked through a gallium-gallium bond. Complex 1 reacts with one equivalent of germanium, tin, or lead bis(trimethylsilyl)amido derivatives [M{N(SiMe(3))(2)}(2)] in toluene at room temperature to give cube-type complexes [M{(mu(3)-N)(2)(mu(3)-NH)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)}] [M = Ge (6), Sn (7), Pb (8)]. Monitoring the reaction of 1 with [Sn{N(SiMe(3))(2)}(2)] and [Sn(C(5)H(5))(2)] by NMR spectroscopy allows the identification of intermediates [RSn{(mu(3)-N)(mu(3)-NH)(2)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)}] [R = N(SiMe(3))(2) (9), C(5)H(5) (10)] in the formation of 7. Addition of one equivalent of the metalloligand 1 to a solution of lead derivative 8 or the treatment of 1 with a half equivalent of [Pb{N(SiMe(3))(2)}(2)] afford the corner-shared double-cube compound [Pb(mu(3)-N)(2)(mu(3)-NH)(4){Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)}(2)] (11). Analogous antimony and bismuth derivatives [M(mu(3)-N)(3)(mu(3)-NH)(3){Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)}(2)] [M = Sb (12), Bi (13)] were obtained through the reaction of 1 with the tris(dimethylamido) reagents [M(NMe(2))(3)]. Treatment of 1 with [AlCl(2){N(SiMe(3))(2)}(OEt(2))] affords the precipitation of the singular aluminum-titanium square-pyramidal aggregate [{{(Me(3)Si)(2)N}Cl(3)Al(2)}(mu(3)-N)(mu(3)-NH)(2){Ti(3)(eta(5)-C(5)Me(5))(3)(mu-Cl)(mu(3)-N)}] (14). The X-ray crystal structures of 5, 11, 13, 14, and [AlCl{N(SiMe(3))(2)}(2)] were determined.