Cyclische Bis(amino)-arsa-, -stiba-, bismachloride und ein spezielles Tris(amino)bismutan

Recent advances in the chemistry of isolable carbene analogues with group 13-15 elements

Carbenes (R2C:), compounds with a divalent carbon atom containing only six valence shell electrons, have evolved into a broader class with the replacement of the carbene carbon or the RC moiety with main group elements, leading to the creation of main group carbene analogues. These analogues, mirroring the electronic structure of carbenes (a lone pair of electrons and an empty orbital), demonstrate unique reactivity. Over the last three decades, this area has seen substantial advancements, paralleling the innovations in carbene chemistry. Recent studies have revealed a spectrum of unique carbene analogues, such as monocoordinate aluminylenes, nitrenes, and bismuthinidenes, notable for their extraordinary properties and diverse reactivity, offering promising applications in small molecule activation. This review delves into the isolable main group carbene analogues that are in the forefront from 2010 and beyond, spanning elements from group 13 (B, Al, Ga, In, and Tl), group 14 (Si, Ge, Sn, and Pb) and group 15 (N, P, As, Sb, and Bi). Specifically, this review focuses on the potential amphiphilic species that possess both lone pairs of electrons and vacant orbitals. We detail their comprehensive synthesis and stabilization strategies, outlining the reactivity arising from their distinct structural characteristics.

Stack by Stack: From the Free Cyclopentadienylgermanium Cation Via Heterobimetallic Main-Group Sandwiches to Main-Group Sandwich Coordination Polymers

Heterobimetallic cationic sandwich complexes [M(μ-Cp)M'Cp]+ of group 13 (M=Ga, In) and group 14 (M'=Ge, Sn) elements have been prepared as [WCA]- salts (WCA=Al(ORF )4 ; ORF =OC(CF3 )3 ). Their molecular structures include free apical gallium or indium atoms. The sandwich complexes were formed in the reactions of [M(HMB)]+ [WCA]- (HMB=C6 Me6 ) with the free metallocenes [M'Cp2 ]. Their structures are related to known stannocene and stannocenium salts; the unprecedented germanium analogues, namely the free germanocenium cation [GeCp]+ and the corresponding triple-decker complex cation [CpGe(μ-Cp)GeCp]+ , are described herein. By variation of the reaction conditions, these sandwich complexes can be transformed into the group 13/14 mixed cationic coordination polymer [{In(HMB)(μ-SnCp2 )}n ][WCA]n . This polymeric chain motif was also successfully replicated by the synthesis of complexes [{Ga/In(HMB)(μ-FeCp2 )}n ][WCA]n containing FeCp2 as a bridging ligand.

Crystal structure of 1,3-di-tert-butyl-2-chloro-1,3,2-di-aza-phospho-rinane - a saturated six-membered phospho-rus nitro-gen heterocycle with a partially flattened chair conformation and a long PIII-Cl bond

Colourless blocks of 1,3-di-tert-butyl-2-chloro-1,3,2-di-aza-phospho-rinane, C11H24ClN2P (1), were obtained by sublimation in vacuo slightly above room temperature. The asymmetric unit of the monoclinic crystal structure of the six-membered N-heterocyclic compound is defined by one mol-ecule in a general position. The six-membered ring of the mol-ecule adopts a cyclo-hexane-like chair conformation; the chair at one side is to some extent flattened as a result of the approximately trigonal-planar coordination of both nitro-gen atoms. In detail, this modified chair conformation is characterized by an angle of 53.07 (15)° between the plane defined by the three carbon atoms and the best plane of the two nitro-gen atoms and the two carbon atoms bound to them, and an angle of 27.96 (7)° between the latter plane and the plane defined by the nitro-gen and phospho-rus atoms. The tert-butyl groups are oriented equatorially and the chloro substituent is oriented axially. The P-Cl bond length of 2.2869 (6) Å is substanti-ally longer than the P-Cl single-bond length in PCl3 [2.034 Å; Galy & Enjalbert (1982 ▸). J. Solid State Chem. 44, 1-23]. Inspection of the inter-molecular distances gives no evidence for inter-actions stronger than van der Waals forces. The closest contact is between the Cl atom and a methyl-ene group of a neighbouring mol-ecule with a Cl⋯C distance of 3.7134 (18) Å, excluding a significant influence on the P-Cl bonding.

Synthesis and crystal structure of 1,3-di-tert-butyl-2-chloro-4,4-diphenyl-1,3,2λ3,4-di-aza-phospha-siletidine

The chemical reaction of di-lithium N,N'-di( t but-yl)-Si,Si-di-phenyl-silanedi-amide and PCl3 yielded an off-white solid. Sublimation of the crude product under reduced pressure at elevated temperature gave colourless prismatic crystals of the title compound, C20H28ClN2PSi, which crystallizes in the non-centrosymmetric monoclinic space group Cc. The asymmetric unit of the crystal structure contains one mol-ecule and it is dominated by the central SiN2P four-membered ring, which is almost planar with a mean deviation of the atoms from the best plane of 0.014 Å. The angles between the plane defined by the silicon atom and the two nitro-gen atoms and the best planes of the Si-phenyl groups are 85.1 (2) and 77.4 (2)°, with the tilt of the phenyl rings in the opposite direction. Both tert-butyl groups suffer from a two-position rotational disorder with site occupancies of 0.752 (6)/0.248 (6) and 0.878 (9)/0.122 (9). The P-Cl bond [2.2078 (17) Å] is remarkably elongated compared to the P-Cl distance in PCl3 [2.034 Å; Galy & Enjalbert (1982). J. Solid State Chem. 44, 1-23].

Tetrazastannoles versus distannadiazanes - a question of the tin(ii) source

Various tin(ii) compounds such as Mes*2Sn (Mes* = 2,4,6-tri-tert-butylphenyl), Sn[N(SiMe3)2]2 and TerSnCl (Ter = 2,6-bis(2,4,6-trimethylphenyl)phenyl) could be readily oxidised by organic azides to release N2, forming nitrogen-tin compounds. Depending on the used Sn(ii) compound, the reactions with two equivalents of azide led to the formation of tetrazastannoles (R2N4SnR'2) or cyclo-distannadiazanes [R2Sn(μ-NR')]2. The reactivity was independent of the electronic situation of the organic azide. Additionally, Mes*2Sn formed an amido-azido compound of the type R(R')Sn(N(SiMe3)2)N3 in the presence of Me3SiN3. Presumably, the corresponding tetrazastannole was formed in the first step followed by a ring opening reaction. The same holds true for the reaction of Sn[N(SiMe3)2]2 with Me3SiN3 while TerSnCl showed no reaction in the presence of Me3SiN3, even after prolonged heating.

Crystal structure of 2-chloro-1,3-di-tert-pentyl-4,4-diphenyl-1,3,2λ 3,4-diazaphosphasiletidine, C22H32ClN2PSi

C22H32ClN2PSi, triclinic, P1̅ (no. 2), a = 11.8482(3) Å, b = 12.8044(3) Å, c = 15.6562(4) Å, α = 77.694(2)°, β = 84.144(2)°, γ = 89.029(2)°, V = 2308.48(10) Å3, Z = 4, R gt(F) = 0.0527, wR ref(F 2) = 0.1148, T = 173(2) K.

PCl bond length depression upon coordination of a diazaphosphasiletidine to a group 13 element Lewis acid or a transition metal carbonyl fragment – Synthesis and structural characterization of diazaphosphasiletidine adducts with P-coordination

Three P-chloro-substituted diazaphosphasiletidines, Me2Si(NtBu)2PCl (1) and Me2Si(NtBu)2P(E)Cl (E=BCl3 (2); W(CO)5 (3)), are presented for comparison. 1 was first prepared more than 30 years ago and studied by means of spectroscopic methods, however, no crystal structure has been reported until now. In the presence of the comparatively weak Lewis acid BCl3 and the labile metal carbonyl complex [W(CO)5(THF)], 1 can be easily converted into its corresponding adducts 2 and 3. All products were characterized by single-crystal X-ray diffraction studies. The structures of the new compounds 2 and 3 reveal a remarkable P–Cl bond contraction caused by the coordination of 1 to the Lewis acid or the Lewis acidic W(CO)5 fragment. Although the coordination number of the P atom is increased in 2 and 3, the P–Cl bond length is reduced dramatically, some kind of bond length paradoxon. A computational study suggests that these P–Cl bond shortenings result from a less effective donation of electron density from the lone pairs at the nitrogen atoms to the antibonding σ *(P–Cl) orbital in 2 and 3 as compared to 1.

Neutral and cationic bismuth compounds supported by bis(amidodimethyl)disiloxane ligands

Bis(amidodimethyl)disiloxane ligands derived from O{SiMe₂N(H)R}₂ (abbreviated as (NON^R)H₂) are a stable support for neutral and cationic bismuth compounds. Attempts to extend the series Bi(NON^R)Cl (R = Ar = 2,6-iPr₂C₆H₃; R = tBu) to include compounds where R = Ar' = 2,6-Me₂C₆H₃ were complicated by concomitant formation of the bimetallic compound {Bi(NON^Ar')}₂(μ-NON^Ar'). Compounds containing [Bi(NON^R)]⁺ cations were obtained from reactions with group 13 chlorides MCl₃ (M = Al, Ga). X-ray crystallographic analysis showed intermolecular interactions with the [M_nCl_(3n+1)] anion.

The crystal structure of 2-chloro-1,3-bis(2,4,6-trimethylphenyl)-4,4-dimethyl-1,3,2λ3,4-diazaphosphasiletidine

C20H28ClN2PSi, orthorhombic, Pbca (no. 61), a = 16.811(3) Å, b = 14.357(3) Å, c = 17.523(3) Å, V = 4229.3(14) Å3, Z = 8, R gt(F) = 0.0429, wR ref(F2 ) = 0.1233, T = 123(2) K.

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.

A neutral low-coordinate heterocyclic bismuth-tin species

The reaction of cyclodistannadiazane with an excess of antimonytrichloride led to the formation of tetrachlorodistibanes, while in the reaction with bismuthtrichloride a carbenoid bismuth species was obtained which can be regarded as a heavy atom analog of NHCs.

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

Metathesis reactions of the alkali metal formamidinates M(RNC(H)NR), M = Li or K; R = C(6)H(3)-2,6-Pr(i)(2) (L(1)), C(6)H(3)-2,6-Et(2) (L(2)); C(6)H(2)-2,4,6-Me(3) (L(3)), C(6)H(3)-2,6-Me(2) (L(4)) or C(6)H(4)-2-Ph (L(5)), with BiX(3) (X = Cl or Br) gave a range of bismuth(iii) formamidinate complexes [Bi(L)Br(micro-Br)(thf)](2) (L = L(1), L(4)), [{Bi(L(1))Cl(2)(thf)}(2)Bi(L(1))Cl(2)], [Bi(L)(2)X] (L = L(2), L(5), X = Br; L = L(1), X = Cl), and [Bi(L)(3)] (L = L(2), L(3)). An analogous organometallic complex Bi(L(1))(2)Bu(n) was also isolated as a side product in one instance. Structural characterisation of the di-halide complexes show symmetrical dimers for X = Br, with two bromide bridges, and a coordinated thf molecule on each Bi atom, whereas for X = Cl a thf deficient species was crystallised, and has a weakly associated trinuclear array with two coordinated thf molecules per three Bi atoms. Complexes of the form Bi(L)(2)X (X = Br, Cl, Bu(n)) and Bi(L)(3) all have monomeric structures but the Bi(L)(3) species show marked asymmetry of the formamidinate binding, suggesting that they have reached coordination saturation.

Preparation and structure of 2-chloro-1,3-dimethyldiaza-2-arsenane, 1,3-dimethyldiaza-2-arsenanium tetrachlorogallate, and butadiene cycloadducts of diazarsenium cations

1,3-Dimethyldiaza-2-arsenanium tetrachlorogallate (crystal data: C5H12AsCl4GaN2, M = 386.61, orthorhombic, space group Pca21, a = 14.432(3) Å, b = 6.7580(14) Å, c = 13.905(3) Å, V = 1356.2(5) Å3) is synthesized by the routine chloride ion abstraction procedure from 2-chloro-1,3-dimethyldiaza-2-arsenane (crystal data: C5H12AsClN2, M = 210.54, monoclinic, space group P21/n, a = 7.206(1) Å, b = 9.650(1) Å, c = 13.021(2) Å, β = 99.61(2)°, V = 892.8(2) Å3). X-ray crystallographic studies of both compounds are described together with that for 2-chloro-1,3-dimethyldiaza-2-arsolidine (crystal data: C4H10AsClN2, M = 196.51, monoclinic, space group P21/n, a = 6.959(7) Å, b = 9.23(2) Å, c = 12.14(2) Å, β = 95.4(1)°, V = 777(4) Å3) providing useful structural comparisons. In contrast to the closely related arsolidinium salts, the diazarsenanium gallate exhibits a monomeric solid state structure. Rapid and quantitative cycloaddition reactions of the diazarsolidinium and diazarsenanium cations with 2,4-dimethylbutadiene give similar cycloadducts. The Diels–Alder type arsolidinium adduct is structurally characterized (crystal data: C10H20AsCl4GaN2, M = 454.73, orthorhombic, space group Pca21, a = 18.471(2) Å, b = 7.000(2) Å, c = 13.738(1) Å, V = 1776.2(8) Å3), and the related structure of the arsenanium cycloadduct is confirmed by 2D NMR. Key words: arsenium, cycloadditions, arsenanium, Diels–Alder, cyclochloroarsines.