Imido Analogues of Group 15 Oxoanions

Reactions of binary group 15 halides with primary amines in the presence of base and subsequent by metallation with n-butyllithium produces imido anions of the group 15 elements. Applications of this methodology to a range of group 15 halides are described along with the syntheses and X-ray crystal structures of three complexes which are the imido analogues of the orthophosphate anion, the phosphite anion and the arsenate anion respectively.     

Titanium imido complexes of cyclooctatetraenyl ligands

Reaction of [Ti(NR)Cl2(py)3] (R=tBu or 2,6-iPr2C6H3) with K(2)[COT] (COT=C8H8) or Li2[COT'] (COT'=1,4-C8H6(SiMe3)2) gave the monomeric complexes [Ti(NR)(eta8-COT)] or [Ti(NR)(eta8-COT')], respectively. The pseudo-two coordinate, "pogo stick" geometry for these complexes is unique in both early transition-metal and cyclooctatetraenyl ligand chemistry. In contrast, reaction of [Ti(N-2,6-Me2C6H3)Cl2(py)3] with K2[COT] gave the mu-imido-bridged dimer [Ti2(mu-N-2,6-Me2C6H3)2(eta8-COT)2]. It appears that as the steric bulk of the imido and C8 ring substituents are decreased, dimerisation becomes more favourable. Aryl imido COT complexes were also prepared by imido ligand exchange reactions between anilines and [Ti(NtBu)(eta(8)-COT)] or [Ti(NtBu)(eta(8)-COT')]. The complexes [Ti(NtBu)(eta(8)-COT)], [Ti(N-2,6-iPr2C6H3)2(eta8-COT)] and [Ti2(mu-N-2,6-Me2C6H3)2(eta8-COT)2] have been crystallographically characterised. The electronic structures of both the monomeric and dimeric complexes have been investigated by using density functional theory (DFT) calculations and gas-phase photoelectron spectroscopy. The most striking aspect of the bonding is that binding to the imido nitrogen atom is primarily through sigma and pi interactions, whereas that to the COT or COT' ring is almost exclusively through delta symmetry orbitals. A DFT-based comparison between the bonding in [Ti(NtBu)(eta8-COT)] and the bonding in the previously reported late transition-metal "pogo stick"complexes [Os(NtBu)(eta6-C6Me6)], [Ir(NtBu)(eta5-C5Me5)] and [Ni(NO)(eta5-C5H5)] has also been undertaken.     

Synthese und Kristallstruktur von Rb8[P4N6(NH)4](NH2)2 mit dem adamantanartigen Anion [P4N6(NH)4]6−

Synthesis and Crystal Structure of Rb₈[P₄N₆(NH)₄](NH₂)₂ with the Adamantane-like Anion [P₄N₆(NH)₄]^6? RbNH₂ reacts with P₃N₅ (molar ratio 6:1) at 400°C within 5 d to colourless Rb₈[P₄N₆(NH)₄](NH₂)₂. Suitable crystals for a X-ray structure determination were obtained: The compound contains adamantane-like molecular anions [P₄N₆(NH)₄]^6?. Their centres of gravity are arranged in a distorted hexagonal primitive array. All trigonal prisms of this array contain one amide ion. Rubidium ions connect the anions irregularly.     

Neue amido‐ und imidoverbrückte Kupferkomplexe – Synthesen und Strukturen von [{Li(OEt2)}2][Cu(NPh2)3], [ClCuN(SnMe3)3], [{CuN(SnMe3)2}4], [Cu16(NH2tBu)12Cl16], [{CuNHtBu}8], [Li(dme)3][Cu6(NHMes)3(NMes)2], [PPh3(C6H4)CuNHMes], [{[Li(dme)][Cu(NHMes)(NHPh)]}2] und [{Li(dme)3}3][Li(dme)2][Cu12(NPh)8]

New Amido and Imido Bridged Complexes of Copper – Syntheses and Structures of [{Li(OEt₂)}₂][Cu(NPh₂)₃], [ClCuN(SnMe₃)₃], [{CuN(SnMe₃)₂}₄], [Cu₁₆(NH₂^tBu)₁₂Cl₁₆], [{CuNH^tBu}₈], [Li(dme)₃][Cu₆(NHMes)₃(NMes)₂], [PPh₃(C₆H₄)CuNHMes], [{[Li(dme)][Cu(NHMes)(NHPh)]}₂], and [{Li(dme)₃}₃][Li(dme)₂][Cu₁₂(NPh)₈] The reactions of stannylated and lithiated amines with coppersalts (halogenides, thiocyanates) lead to amido and imido bridged complexes which contain one to twelve metal atoms. [{Li(OEt₂)}₂][Cu(NPh₂)₃] ( 1 ) results from the reaction of CuCl with LiNPh₂ in the presence of trimethylphosphine. With N(SnMe₃)₃, CuCl reacts to the donor‐acceptor complex [ClCuN(SnMe₃)₃] ( 2 ) that is transformed into the tetrameric complex [{CuN(SnMe₃)₂}₄] ( 3 ) by thermolysis. 3 can also be obtained by the reaction of LiN(SnMe₃)₂ with Cu(SCN)₂. While terminally bound in 1 , the amido ligand is μ₂‐bridging between copper atoms in compound 3 . The influence of the alkyl amide's leaving group can be seen from a comparison of the reactivity of Me₃SnNH^tBu and LiNH^tBu, respectively. With Me₃SnNH^tBu, CuCl₂ forms the polymeric compound [Cu₁₆(NH₂^tBu)₁₂Cl₁₆] ( 4 ) whereas in the case of LiNH^tBu with both CuCl and CuSCN, the complex [{CuNH^tBu}₈] ( 5 ) is obtained. The latter contains two planar Cu₄N₄‐rings similar to those in 3 . If a mesityl group is introduced at the lithium amide, different products are accessible. Both, CuBr and CuSCN, lead to the formation of [Li(dme)₃][Cu₆(NHMes)₃(NMes)₂] ( 6 ) whose anion consists of a prismatic copper core with μ₂‐bridging amido and μ₃‐bridging imido ligands. In the presence of PPh₄Cl, a mixture of Cu(SCN)₂ and LiNHMes enables an ortho‐metallation reaction that produces [PPh₃(C₆H₄)CuNHMes] ( 7 ). From the reaction of CuSCN with LiNHMes and LiNHPh either the dimeric complex [{[Li(dme)][Cu(NHMes)(NHPh)]}₂] ( 8 ) or the cluster [{Li(dme)₃}₃][Li(dme)₂][Cu₁₂(NPh)₈] ( 9 ) results. The anion in 9 exhibits a cubo‐octahedron of copper atoms μ₃‐bridged by (NPh)^2–‐ligands. The solid state structures of compounds 1 – 9 have been determined by single crystal X‐ray diffraction.     

Monodentate imido coordination of 2-aminodiphenylamine to rhenium(V)

The complex trans-[Re(ada)Cl₃(PPh₃)₂] (H₂ada?=?2-aminodiphenylamine) was prepared from the reaction of trans-[ReOCl₃(PPh₃)₂] with H₂ada in acetonitrile. The ligand ada is coordinated to the rhenium(V) centre solely through a dianionic imido nitrogen, with distorted octahedral coordination geometry around the metal ion. Surprisingly, the Re–Cl bond trans to the Re=N bond is shorter than the two equatorial Re–Cl bonds. The Re?=?N–C bond angle of the phenylimido moiety equals 178.7(4)°.     

Investigation of Uranium Tris(imido) Complexes: Synthesis,Characterization, and Reduction Chemistry of [U(NDIPP)3(thf)3]

Addition of KC₈ to trivalent [UI₃(thf)₄] in the presence of three equivalents of 2,6‐diisopropylphenylazide (N₃DIPP) results in the formation of the hexavalent uranium tris(imido) complex [U(NDIPP)₃(thf)₃] ( 1 ) through a facile, single‐step synthesis. The X‐ray crystal structure shows an octahedral complex that adopts a facial orientation of the imido substituents. This structural trend is maintained during the single‐electron reduction of 1 to form dimeric [U(NDIPP)₃{K(Et₂O)}]₂ ( 2 ). Variable‐temperature/field magnetization studies of 2 show two independent U^V 5f ¹ centers, with no antiferromagnetic coupling present. Characterization of these complexes was accomplished using single‐crystal X‐ray diffraction, variable‐temperature ¹H NMR spectroscopy, as well as IR and UV/Vis absorption spectroscopic studies.     

Experimental and Computational Studies on the Formation of Thorium–Copper Heterobimetallics

The formation of actinide–transition metal heterobimetallics mediated by a terminal actinide imido complex was comprehensively studied. The reaction of the thorium imido complex [(η⁵‐C₅Me₅)₂Th=N(mesityl)(DMAP)] ( 3 ), prepared from [(η⁵‐C₅Me₅)₂ThMe₂] ( 1 ) and mesitylNH₂ or [(η⁵‐C₅Me₅)₂Th(NHmesityl)₂] ( 2 ) in the presence of 4‐(dimethylamino)pyridine (DMAP), with copper(I) halides gave the first thorium–copper heterobimetallic compounds [(η⁵‐C₅Me₅)₂Th(X){N(mesityl)Cu(DMAP)}] (X=Cl ( 4 ), Br ( 5 ), I ( 6 )). Complexes 4 – 6 feature an unusual geometry with a short Th?Cu distance, which DFT studies attribute to a weak donor–acceptor bond from the Cu⁺ atom to the electropositive Th⁴⁺ atom. They are reactive species, as was shown by their reaction with the dimethyl complex [(η⁵‐C₅Me₅)₂ThMe₂] ( 1 ). Furthermore, a comparison between Th and early transition metals confirmed that Th⁴⁺ exhibits distinctively different reactivity from d‐transition metals.