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A new synthesis that avoids the use of Me 2 PH is reported for (Me 2 PCH 2 BMe 2 ) 2 , and this method was extended to the synthesis of (Ph 2 PCH 2 BMe 2 ) 2 . The ligand precursor (Me 2 PCH 2 BMe 2 ) 2 did not react with [{M(μ-Cl)(cod)} 2 ] (cod = 1,5-cyclooctadiene; M = Ir and Rh) or [PtCl 2 (cod)] at room temperature. However, after 12-48 hours at 65-70 °C, these reactions afforded (a) [Ir(cod)(μ-Cl)(Me 2 PCH 2 BMe 2 )] (1), (b) an equilibrium mixture of (Me 2 PCH 2 BMe 2 ) 2 , [{Rh(μ-Cl)(cod)} 2 ] and [Rh(cod)(μ-Cl)(Me 2 PCH 2 BMe 2 )] (2), and (c) cis -[Pt(μ-Cl) 2 (Me 2 PCH 2 BMe 2 ) 2 ] (3), respectively. By contrast, reactions between the phenyl-substituted analogue, (Ph 2 PCH 2 BMe 2 ) 2 , and [{M(μ-Cl)(cod)} 2 ] (cod = 1,5-cyclooctadiene; M = Ir and Rh) proceeded over the course of 1 hour at 20 °C to generate [M(cod)(μ-Cl)(Ph 2 PCH 2 BMe 2 )] (M = Ir (4) and Rh (5)), indicative of room temperature (Ph 2 PCH 2 BMe 2 ) 2 dissociation. Room temperature reactions of (Ph 2 PCH 2 BMe 2 ) 2 with [{Rh(μ-Cl)(coe) 2 } 2 ] (coe = cyclooctene) using a 1 : 1 or 3 : 1 stoichiometry also afforded [{Rh(coe)(μ-Cl)(Ph 2 PCH 2 BMe 2 )} 2 ] (6) or [RhCl(Ph 2 PCH 2 BMe 2 ) 3 ] (7), respectively, where the latter is a borane-appended analogue of Wilkinson's catalyst, and reactions of (Ph 2 PCH 2 BMe 2 ) 2 with [PtX 2 (cod)] (X = Cl or Me) yielded cis -[Pt(μ-Cl) 2 (Ph 2 PCH 2 BMe 2 ) 2 ] (8) and cis -[PtMe 2 (Ph 2 PCH 2 BMe 2 ) 2 ] (9). Compounds 1-9, (Me 2 PCH 2 BMe 2 ) 2 and (Ph 2 PCH 2 BMe 2 ) 2 were crystallographically characterized. In compounds 1-5 and 8, each chloride co-ligand is coordinated by the borane of an R 2 PCH 2 BMe 2 ligand. Additionally, in the solid state structure of 6, each bridging chloride ligand interacts weakly with a pendent borane, and in 7, the chloride ligand is tightly coordinated to the borane of one Ph 2 PCH 2 BMe 2 ligand and weakly coordinated to the borane of a second Ph 2 PCH 2 BMe 2 ligand. By contrast, both boranes in 9 (and one of the three boranes in 7) are non-coordinated.

Reactions of the ethylene hydride complex trans -[(dmpe) 2 MnH(C 2 H 4 )] (1) with secondary hydrogermanes H 2 GeR 2 at 55-60 °C afforded the base-free terminal germylene hydride complexes trans -[(dmpe) 2 MnH(GeR 2 )] (R = Ph; 2a, R = Et; 2b). Room temperature reactions of 2a or 2b with an excess of the primary hydrogermanes H 3 GeR' (R' = Ph or n Bu) afforded trans -[(dmpe) 2 MnH(GeHR')] (R' = Ph; 3a, R' = n Bu; 3b) in rapid equilibrium with small amounts of 2a/b, as well as the digermyl hydride complex mer -[(dmpe) 2 MnH(GeH 2 R') 2 ] {R' = Ph (4a) or n Bu (4b)} and the trans -hydrogermane germyl complex trans -[(dmpe) 2 Mn(GeH 2 R')(HGeH 2 R')] {R' = Ph (5a) or n Bu (5b)}. Pure 3b was isolated from the reaction of 2b with H 3 Ge n Bu, whereas 3a decomposed readily in solution in the absence of free H 3 GePh, and a pure bulk sample was not obtained. Reactions of 1 with H 3 GeR' (R' = Ph or n Bu) also proceeded at 55-60 °C to afford mixtures of 3a/b, 4a/b and 5a/b, accompanied by remaining 1. However, upon continued heating to consume 1, various unidentified manganese-containing intermediates were formed, ultimately affording the germanide complex [{(dmpe) 2 MnH} 2 (μ-Ge)] (6) in 17-49% spectroscopic yield. Pure trans , trans -6 was isolated in 27% yield from the reaction of 1 with H 3 Ge n Bu, and it is notable that this reaction involves stripping of all four substituents from the hydrogermane. Complexes 2a, 3a, and 6 were crystallographically characterized, and the nature of the MnGe bonding in these species (as well as in 2b and 3b) was probed computationally.

Reaction of 2 equivalents of (Me 2 PCH 2 AlMe 2 ) 2 with [{RhCl(cod)} 2 ] (cod = 1,5-cyclooctadiene) afforded [{κ 2 P , P -(Me 3 Al)ClMeAl(CH 2 PMe 2 ) 2 }Rh(cod)] (1), which features a κ 2 -coordinated bis(phosphino)aluminate anion. In compound 1, an Al-Cl substituent bridges to a molecule of AlMe 3 , which could be removed in vacuo to provide [{κ 2 P , P -ClMeAl(CH 2 PMe 2 ) 2 }Rh(cod)] (2). By contrast, reaction of 1 equiv. of (Me 2 PCH 2 AlMe 2 ) 2 with [{RhCl(cod)} 2 ] yielded [Rh(cod)(μ-Cl)(Me 2 PCH 2 AlMe 2 )] (3) as the major product, where the phosphine donor of an intact Me 2 PCH 2 AlMe 2 ligand is coordinated to rhodium and a chloride ligand bridges between Rh and Al. [Rh(cod)(μ-Cl)(Me 2 PCH 2 AlClMe)] (3A) and 2 were also formed as minor products. The aforementioned reactions were carried out in benzene or toluene, whereas the 1 : 1 reaction of (Me 2 PCH 2 AlMe 2 ) 2 with [{RhCl(cod)} 2 ] in THF afforded [{Rh(μ-CH 2 PMe 2 )(cod)} 2 ] (4). Reactions of (Me 2 PCH 2 AlMe 2 ) 2 with iridium(I), gold(I) and platinum(II) precursors were also explored. A 1 : 1 reaction of (Me 2 PCH 2 AlMe 2 ) 2 with [{IrCl(cod)} 2 ] afforded [{κ 2 P , P -Cl 2 Al(CH 2 PMe 2 ) 2 }Ir(cod)] (5) as one of two major phosphine-containing products; unlike 3, this compound features two chlorine substituents on aluminium. For comparison, the rhodium analogue of 5, [{κ 2 P , P -Cl 2 Al(CH 2 PMe 2 ) 2 }Rh(cod)] (6), was also synthesized via the 1 : 1 reaction of {ClAl(CH 2 PMe 2 ) 2 } 2 with [{RhCl(cod)} 2 ]. Reactions of (Me 2 PCH 2 AlMe 2 ) 2 with [AuCl(CO)] or [PtCl 2 (cod)] also resulted in chloride-methyl group exchange between the transition metal and aluminium. However, these reactions generated free (Me 2 PCH 2 AlClMe) 2 accompanied by gold and ethane, or [PtMe 2 (cod)], respectively. Reaction of 1.5 equivalents of (Me 2 PCH 2 AlMe 2 ) 2 with [PtMe 2 (cod)] at 75 °C afforded zwitterionic [(PtMe{μ-κ 1 P :κ 2 P , P -MeAl(CH 2 PMe 2 ) 3 }) 2 ] (7) which features two tris(phosphino)aluminate anions bridging between PtMe units. Compounds 1-2, 3/3A, 4-7 and (Me 2 PCH 2 AlClMe) 2 were crystallographically characterized.

Reactions of trans-[(dmpe) 2 MnH(C 2 H 4 )] (1) with BH 3 (NMe 3 ), 9-BBN, and HBMes 2 yielded the manganese(i) borohydride complexes [(dmpe) 2 Mn(μ-H) 2 BR 2 ] (3: R = H, 4: R 2 = C 8 H 14 , 5: R = Mes). The reaction of 1 with BH 3 (NMe 3 ) proceeds via ethylene substitution. By contrast, a detuerium labelling study indicates that the reaction of 1 with HBMes 2 involves initial isomerization of 1 to an unobserved 5-coordinate ethyl intermediate, [(dmpe) 2 MnEt], which reacts with the hydroborane to afford EtBR 2 and [(dmpe) 2 MnH], followed by reaction with a second equivalent of hydroborane to generate 5 (an analogous pathway is likely followed for other base-free hydroboranes such as 9-BBN). Identification of 3-5 as κ 2 -borohydride complexes, as opposed to boryl dihydride or hydroborane hydride isomers, is supported by 11 B NMR spectroscopy, X-ray diffraction, and Atoms in Molecules calculations. Two byproducts were observed in the syntheses of 3-5: [{(dmpe) 2 MnH} 2 (μ-dmpe)] (6) and [(dmpe) 2 MnH(κ 1 -dmpe)] (7). These complexes were independently prepared by exposure of 1 to free dmpe under an atmosphere of Ar or H 2 , and the generality of this synthetic route was demonstrated by the reaction of 1 with PMe 3 (under H 2 ) to form [(dmpe) 2 MnH(PMe 3 )] (8). Complexes 6-8 can exist as isomers with either a trans or a cis relationship between the hydride and κ 1 -coordinated phosphine ligands on manganese. trans to cis isomerization of 6-8 is photochemically induced, whereas the reverse reaction occurs under thermal conditions. X-ray crystal structures were obtained for 3-5, trans,trans-6, cis,cis-6, trans-7, and trans-8.

The synthesis, and spectroscopic and structural characterization of bridged dicationic derivatives of benzo-2,1,3-selenadiazoles are reported. The chloride salt of [H 4 C 6 NSeN-CH 2 -CH 2 -NSeNC 6 H 4 ] 2+ crystallizes forming a macrocyclic structure in which two cations are bridged by SeCl chalcogen bonds (ChBs), with a third chloride at the centre of the macrocycle. The structure of [1,2-(H 4 C 6 NSeN) 2 -C 6 H 10 ]Cl 2 consists of two selenadiazolium cations linked by a chiral cyclohexane and capped by SeCl ChBs. Tetrafluoroborate salts of a xylene bridge crystallize in two pseudopolymorphs in which the cations form SeF ChBs in an anti- or syn-conformation. The triflate salt of ethylene-bridged cations dimerizes through the formation of the [Se-N] 2 supramolecular synthon with SeO ChBs capping the second selenium atom. In contrast, [H 4 C 6 NSeN-CH 2 -CH 2 -CH 2 -NSeNC 6 H 4 ](CF 3 SO 3 ) 2 only forms SeO ChBs.

Pt(ii) and Rh(iii) readily form complexes with 3-methyl-5-aryl-1,2-tellurazole 2-oxides (L = (3-Me-5-Ar-1,2-C3HTe(NO)). The aryl group is either phenyl or 3,5-di-tert-butylphenyl, the latter case being a new derivative with enhanced solubility. The compound [Pt(3-Me-5-(3,5-tBu2C6H3)-1,2-C3HTe(NO))4](BF4)2 crystallizes in the P21/C space group featuring a square planar complex in the lattice. The crystal of [RhCl2(3-Me-5-(C6H5)-1,2-C3HTe(NO))4](BF4) belongs to the I4[combining macron] space group and contains an octahedral complex. In both instances, the iso-tellurazole N-oxide molecules are linked by TeO chalcogen bonding interactions confirming an annular tetramer that binds the metal ion as a κ4Te macrocycle in a boat conformation. Low-frequency shifts of the 125Te magnetic resonance upon coordination and the observation of 125Te-195Pt and 125Te-103Rh 1J coupling constants indicate that the complexes are stable species in solution. The complex ions were also observed in the electrospray mass spectra.

Iodine oxidation of bis[2-(hydroxyiminomethyl)phenyl] dichalcogenides yields benzo-1,2-chalcogenazole 2-oxides. Annulated derivatives of iso-tellurazole N-oxides spontaneously aggregate into cyclic tetra- and hexamers through TeO chalcogen bonding; the structures of the co-crystals with benzene and CH 2 Cl 2 illustrate the ability of these macrocycles to interact with small guest molecules. The selenium congener crystallizes forming a supramolecular polymer. VT NMR indicates that both compounds aggregate in solution but only at low temperature in the selenium case. The different abilities of these molecules to engage in supramolecular interactions are interpreted on the basis of their electronic properties evaluated with DFT-D3 calculations.

Despite their versatility, the application of telluradiazoles as supramolecular building blocks is considerably constrained by their sensitivity to moisture. Albeit more robust, their selenium analogues form weaker supramolecular interactions. These, however, are enhanced when one nitrogen atom is bonded to an alkyl group. Here we investigate general methods for the synthesis of such derivatives. Methyl, iso-propyl and tert-butyl benzo-2,1,3-selenadiazolium cations were prepared by direct alkylation or cyclo-condensation of the alkyl-phenylenediamine with selenous acid. While the former reaction only proceeds with the primary and tertiary alkyl iodides, the latter is very efficient. Difficulties reported in earlier literature are attributable to the formation of adducts of benzoselenadiazole with its alkylated cations and side reactions initiated by aerobic oxidation of iodide. However, the cations themselves are resilient to oxidation and stable in acidic to neutral aqueous medium. X-ray crystallography was used in the identification and characterization of the following compounds: [C6H4N2(R)Se](+)X(-), (R = CH(CH3)2, C(CH3)3; X = I(-), I3(-)], [C6H4N2(CH3)Se](+)I(-), and [C6H4N2Se][C6H4N2(CH3)Se]2I2. Formation of SeN secondary bonding interactions (chalcogen bonds) was only observed in the last structure as anion binding to selenium is a strong competitor. The relative strengths of those forces and the structural preferences they enforce were assessed with DFT-D3 calculations supplemented by AIM analysis of the electron density.

A rigid NSN-donor proligand, 4,5-bis(2,6-diisopropylanilino)-2,7-di-tert-butyl-9,9-dimethylthioxanthene (H(2)[TXA(2)], 1) was prepared by palladium-catalyzed coupling of 2,6-diisopropylaniline with 4,5-dibromo-2,7-di-tert-butyl-9,9-dimethylthioxanthene. Deprotonation of 1 using (n)BuLi provided Li(2)(DME)(2)[TXA(2)] (2), and subsequent reaction with UCl(4) afforded [Li(DME)(3)][(TXA(2))UCl(3)] (4). The analogous NON-donor ligated complex [(XA(2))UCl(3)K(DME)(3)] [3; XA(2) = 4,5-bis(2,6-diisopropylanilino)-2,7-di-tert-butyl-9,9-dimethylxanthene] was prepared by the reaction of K(2)(DME)(x)[XA(2)] with UCl(4). A cyclic voltammogram (CV) of 3 in THF/[NBu(4)][B(C(6)F(5))(4)] at 200 mV s(-1) showed an irreversible reduction to uranium(III) at E(pc) = -2.46 V versus FeCp(2)(0/+1), followed by a product wave at E(1/2) = -1.83 V. Complex 4 also underwent irreversible reduction to uranium(iii) [E(pc) = -2.56 V], resulting in an irreversible product peak at E(pa) = -1.83 V. One-electron reduction of complexes 3 and 4 using K(naphthalenide) under an argon atmosphere in DME yielded 6-coordinate [(XA(2))UCl(DME)] (5) and the thermally unstable 7-coordinate [(TXA(2))U(DME)Cl(2)Li(DME)(2)] (6), respectively. The U-S distances in 4 and 6 are uncommonly short, the C-S-U angles are unusually acute, and the thioxanthene backbone of the TXA(2) ligand is significantly bent. By contrast, the xanthene backbone in XA(2) complexes 3 and 5 is planar. However, κ(3)-coordination and an approximately meridional arrangement of the ancillary ligand donor atoms is maintained in all complexes. DFT and Atoms in Molecules (AIM) calculations were carried out on 3, 4, 5, 6, [(XA(2))UCl(3)](-) (3B), [(TXA(2))UCl(2)(DME)](-) (6B) and [(TXA(2))UCl(DME)] (6C) to probe the extent of covalency in U-SAr(2) bonding relative to U-OAr(2) bonding.

Reaction of [PtCl(2)(COD)] and [PtI(2)(COD)] with 2,7-di-tert-butyl-5-diphenylboryl-4-diphenylphosphino-9,9-dimethylthioxanthene (TXPB) afforded square planar [PtCl(2)(TXPB)] (1B) and [PtI(2)(TXPB)] (4B), both of which were crystallographically characterized. Single-crystal X-ray quality crystals were also obtained for [PdCl(2)(TXPB)] (2B; Emslie et al., Organometallics, 2008, 27, 5317) as 2B·2CH(2)Cl(2) and solvent-free 2B. Both the chloro and iodo TXPB complexes exhibit metal-halide-borane bridging interactions similar to those in previously reported [RhCl(CO)(TXPB)] (3B) and [RhI(CO)(TXPB)] (5B) (Emslie et al., Organometallics, 2006, 25, 583 and Inorg. Chem., 2010, 49, 4060). To facilitate a more detailed analysis of M-X-BR(3) (X = Cl and I) interactions, a borane-free analogue of the TXPB ligand, 2,7-di-tert-butyl-4-diphenylphosphino-9,9-dimethylthioxanthene (TXPH), was prepared. Reaction with [PtX(2)(COD)] (X = Cl or I), [PdCl(2)(COD)] and 0.5 [{RhCl(CO)(2)}(2)] provided square planar [PtCl(2)(TXPH)] (1H), [PdCl(2)(TXPH)] (2H), [RhCl(CO)(TXPH)] (3H) and [PtI(2)(TXPH)] (4H). M-Cl-BR(3) and M-I-BR(3) bonding in 1B-5B was then probed through the use of structural comparisons, IR and NMR spectroscopy, cyclic voltammetry, and DFT calculations (Slater-type orbitals, Mayer bond orders, Hirshfeld charges, fragment analysis, SCF deformation density isosurfaces, and energy decomposition analysis).

Methyl and n-butyl thorium complexes of a rigid 2,6-bis(anilidomethyl)pyridine ligand have been prepared; the n-butyl complex is thermally stable, even at 60 degrees C, while the methyl complexes exhibit a high tendency to eliminate methane via sigma-bond metathesis.

The dilithio salts of two chelating diamidosilylether ligands undergo a retro-Brook rearrangement from oxygen to the amido-nitrogen, thereby directly yielding a new mixed-donor amido/amino/siloxo ligand. When reacted with chromium(II), siloxo-bridged dimers and a very strong eta(2)-(N,C(ipso)) arylamido interaction are featured.