A Monometallic Bis(cyaphido) Complex.

The first example of a bis(cyaphido) complex, trans-[Ru(dppe)2(C≡P)2], is described, unequivocally demonstrating the synthetic accessibility and stability of complexes that feature more than one cyaphido ligand. Synthesis is achieved from the precedent cation [Ru(dppe)2(C≡P)]+ via sequential coordination and desilylation of the phosphaalkyne Me3SiC≡P. The heteroleptic analogue trans-[Ru(dppe)2(C≡N)(C≡P)] is also prepared from the same cation and NaCN; both cyaphido complexes are structurally characterized, enabling the first direct comparison of cyaphide with cyanide, its isoelectronic and isolobal counterpart. This demonstrates an enhanced π-acidity for -C≡P over -C≡N, while computational studies reveal also a higher π-donor character for the cyaphido ligand.

A Benzodiphosphaborolediide.

The first example of a diphosphaborolediide, the benzo-fused [C6 H4 P2 BPh]2- (12- ), is prepared from ortho-bis(phosphino)benzene (C6 H4 {PH2 }) and dichlorophenylborane, via a sequential lithiation approach. The dilithio-salt can be obtained as an oligomeric THF solvate or discrete TMEDA adduct, both of which are fully characterized, including by X-ray diffraction. Alongside NICS calculations, data strongly suggest some aromaticity within 12- , which is further supported by preliminary coordination studies that demonstrate η5 -coordination to a zerovalent molybdenum center, as observed crystallographically for the oligomeric [{Mo(CO)3 (η5 -1)}{µ-η1 -Mo(CO)3 (TMEDA)}2 ] ⋅ [µ-Li(THF)][µ-Li(TMEDA)].

Diphosphametacyclophanes: Structural and Electronic Influences of Substituent Variation within a Family of Bis(diketophosphanyl) Macrocycles.

The condensation of MeP(SiMe3)2 with a series of 5-substituted isophthaloyl chlorides (5-R'C6H3-2,6-{C(O)Cl}2) affords the diphosphametacyclophanes m-{-C(O)-C6H3-5-R'-(C(O)PMe)}2 (R' = I, Me, tBu, Ph, and p-NCC6H4); the analogues m-{-C(O)-C5H3N-(C(O)PMe)}2 and m-{-C(O)-C6H4-(C(O)PPh)}2 are similarly obtained in preference to higher oligomers, in contrast to precedent reports. The cyclophanes all adopt butterfly-like conformations in the solid state with the P-organyl substituents adopting mutually exo arrangements. Structural and computational data suggest the nature of the 5-R substituent is key in directing the inter-ring angle and the extent of LUMO stabilization about the diketophophanyl scaffold. The latter is substantiated by UV/vis spectroscopy and cyclic voltammetry, which demonstrate these cyclophanes to be appreciably comparable to the diketophosphanyl systems commonly explored in the context of organic electronic materials; intriguingly, the distinct dikeophosphanyl moieties within the macrocycles appear effectively "insulated" by the macrocycle geometry, rather than acting as a through-conjugate.

Phosphacycloalkyldiones: synthesis and coordinative behaviour of 6- and 7-member cyclic diketophosphanyls.

Glutaryl and adipoyl chlorides undergo facile condensation with the bis(silyl)phosphanes RP(SiMe3)2 (R = Me, nBu, tBu, Ph, Mes) to afford exclusively the phosphacycloalkyldiones (CH2)n(C[double bond, length as m-dash]O)2PR (n = 3, 4). Characterised spectroscopically and, for R = Ph, Mes (n = 3) crystallographically, the macrocycles are conformationally fluxional in solution and appreciably moisture sensitive. Though seemingly resistant to chemical oxidation at phosphorus, coordination is readily achieved, as illustrated by isolation of trans-[Pt(PEt3){P(Ph)(CO)2(CH2)3}Cl2] and a series of tungsten pentacarbonyl complexes, which are characterised crystallographically and by infrared and NMR spectroscopy. Together, these data suggest the macrocycles to be relatively weak σ-donors with no appreciable π-acceptor character.

Controlled Reactivity of Terminal Cyaphide Complexes: Isolation of the 5-Coordinate [Ru(dppe)2(C≡P)].

The novel cyaphide complex trans-[Ru(dppe)2Me(C≡P)] is obtained in excellent yields and exhibits the first instance of controlled reactivity of any terminal cyaphide complex. Its treatment with ZnX2/PPh3 effects selective metathesis of the methyl moiety to afford the unprecedented halocyaphide complexes trans-[Ru(dppe)2(X)(C≡P)] (X = Cl, Br, I), which are structurally characterized (X = Cl, Br). Exemplified with the trans-bromide, these compounds are susceptible to substitution of the halides by nucleophilic reagents-illustrated with Me2Mg-and also readily undergo halide abstraction by TlOTf to afford the first hypocoordinate cyaphide complex, viz., [Ru(dppe)2(C≡P)]·OTf, which is isolable in bulk and exhibits good stability. NMR spectroscopic and crystallographic data reveal the latter to adopt a square-pyramidal geometry with an accessible coordinate vacancy, which is susceptible to the addition of nucleophiles. This is illustrated analytically by reactions with Me2Mg and LiC≡CPh and with its facile bulk carbonylation to afford trans-[Ru(dppe)2(CO)(C≡P)]+.

Correction: Cyaphide-alkynyl complexes: metal-ligand conjugation and the influence of remote substituents.

Correction for 'Cyaphide-alkynyl complexes: metal-ligand conjugation and the influence of remote substituents' by Samantha K. Furfari, et al., Dalton Trans., 2019, 48, 8131-8143.

Cyaphide-alkynyl complexes: metal-ligand conjugation and the influence of remote substituents.

A homologous series of novel trans-cyaphide-alkynyl complexes, viz. trans-[Ru(dppe)2(C[triple bond, length as m-dash]P)(C[triple bond, length as m-dash]CC6H4R-p)] (R = Me, H, F, CO2Me, NO2) is prepared and comprehensively characterised, alongside their parent phosphaalkyne-complex cations trans-[Ru(dppe)2(η1-P[triple bond, length as m-dash]CSiMe3)(C[triple bond, length as m-dash]CC6H4R-p)]+. Structural data for trans-[Ru(dppe)2(C[triple bond, length as m-dash]P)(C[triple bond, length as m-dash]CC6H4R-p)] (R = Me, F) and trans-[Ru(dppe)2(η1-P[triple bond, length as m-dash]CSiMe3)(C[triple bond, length as m-dash]CC6H4R-p)]+ (R = F, CO2Me) are described, along with that for the previously reported trans-[Ru(dppe)2(C[triple bond, length as m-dash]P)(C[triple bond, length as m-dash]CCO2Me)]. NMR spectroscopic data indicate significant influence of the remote aromatic substituent over the properties of the cyaphide ligand, in line with the Hammett parameter (σp), suggesting appreciable 'communication' along the through-conjugate chain. Cyclic voltammety shows irreversible oxidative behaviour, at more anodic Epa than in the respective alkynyl-chloride complexes, though apparently moderated by the remote substituent.

Through-conjugation of two phosphaalkyne ('C[triple bond, length as m-dash]P') moieties mediated by a bimetallic scaffold.

Through-conjugation of two phosphaalkyne moieties within an isolable molecule is demonstrated for the first time with the synthesis of [{Ru(dppe)2}2{µ-(C[triple bond, length as m-dash]C)2C6H4-p}(C[triple bond, length as m-dash]P)2], via base-induced desilylation of [{Ru(dppe)2}2{µ-(C[triple bond, length as m-dash]C)2C6H4-p}(η1-P[triple bond, length as m-dash]CSiMe3)2]2+. The nature of the cyaphide ligands and their influence upon the bimetallic core are studied electrochemically.

Synthesis of 3-stannyl and 3-silyl propargyl phosphanes and the formation of a phosphinoallene.

The group 14 chloropropargyls R3EC ≡ CCH2Cl (R3E = (n)Bu3Sn, Ph3Sn, Me2PhSi, (i)Pr3Si, (n)Pr3Si, (n)Bu3Si), obtained by a modified literature procedure, react with LiPPh2 to afford the novel propargyl phosphanes Ph2PCH2C ≡ CER3 in high yield, as viscous oils; (Me3Si)2PCH2C ≡ CSiPhMe2 is similarly obtained from LiP(SiMe3)2. In contrast, the reaction of PhC[triple bond, length as m-dash]CCH2MgCl with ClP(NEt2)2 fails to produce a comparable propargyl phosphane, but generates preferentially (>70%) the novel phosphinoallene (Et2N)2PC(Ph) = C = CH2, which is characterised spectroscopically, and through its reaction with HCl. The coordination chemistry of representative phosphanes is explored with respect to platinum and palladium for the first time.

Synthesis and electronic structure of the first cyaphide-alkynyl complexes.

The novel complexes trans-[Ru(dppe)2(C≡CR)(C≡P)] (R = CO2Me, C6H4OMe), the first to incorporate cyaphide as part of a conjugated system, are obtained in facile manner. The electronic structure of these compounds is probed by X-ray, DFT and UV/Vis studies.

Facile self-assembly of the first diphosphametacyclophane.

The reaction of isophthaloyl chloride and methyl-bis(trimethylsilyl)phosphane under mild conditions affords high yields of m-{-C(O)-C(6)H(4)(C(O)PMe)}(2) (1,10-dimethyl-1,10-diphospha-[3.3]-metacyclophane-2,9,11,18-tetraone): the first example of a diphosphametacyclophane.

The open-chain triphosphanes RMe2SiCH2P(PR'2)2 (R = Me, Ph; R' = SiMe3, Cy, Ph).

The triphosphanes RMe(2)SiCH(2)P(PR'(2))(2) (R = Me, Ph; R' = SiMe(3), Cy) are synthesised in good yield via metathesis of organodichlorophosphanes and LiPR'(2), while for R' = Ph a propensity to form (Ph(2)P)(2) precludes isolation of the in situ characterised triphosphanes. Where R = Me and R' = SiMe(3) the triphosphane has also been characterised by single crystal X-ray diffraction and exhibits a single geometric conformer in the solid state, though solution-phase NMR spectra are indicative of facile conformational exchange across a wide temperature range. All of the described triphosphanes exhibit comparable behaviour, with their respective (31)P{(1)H} NMR spectra manifesting anomalous 'second-order' characteristics, which are considered using full spin-Hamiltonian simulation. Preliminary studies of coordination chemistry and ancillary reactivity of the triphosphanes are described.

Synthesis of gold(I) fluoroalkyl and fluoroalkenyl-substituted phosphine complexes and factors affecting their crystal packing.

A series of gold(I) phosphine complexes of the type [AuCl{PR(2)(R(f))}] (R = Et, i-Pr, Cy; R(f) = CF = CF(2); R = Ph, R(f) = C = CFH, CCl = CF(2), C ≡ CCF(3), CF(3), i-C(3)F(7), s-C(4)F(9)) have been prepared and most have been structurally characterised. All of the complexes are monomeric in the solid state, and a number of secondary interactions are observed--including short intramolecular AuF distances, metal-bound Au-ClH non-classical hydrogen bonds, fluorous domains and phenyl embraces. Only in the case of [AuCl{PEt(2)(CF = CF(2))}] is an aurophilic interaction with an AuAu contact less than the sum of the van der Waals radii observed. Even then, the distance, 3.3458(10) Å, is longer than that previously observed for the related complex with R = Ph; R(f) = CF = CF(2).

Methimazole-based ionic liquids.

The alkylation reaction of 2-mercapto-1-methylimidazole 1a with iodoethane and chlorobutane produced S-alkylmethimazole halides 2a and 2b which were subjected to anion metathesis with two different metal salts (MA) to afford methimazole-based room-temperature ionic liquids 3a, 3b, and 3c in 82%, 85%, and 87% yields, respectively. S-Alkylation giving 2a and 2b suggests that methimazole reacts through the thione tautomer.

Unlocking the metallaboratrane cage: reversible B-H activation in platinaboratranes.

The reaction of the new platinaboratrane salt [PtH(PTol3){B(mt)3}]Cl(Pt-->B)8 (mt = methimazolyl, Tol = C6H4Me-4) with 2 equivalents of PR3 (R = Me, Et) affords, via hydride migration to boron and ligand substitution, the salts [Pt(PR3)2{kappa 2-S,S'-HB(mt)3}]Cl, which slowly undergo B-H reactivation, to afford, ultimately, the platinaboratrane salts [PtH(PR3){B(mt)3}]Cl(Pt-->B)8.

The first rhodaboratrane: [RhCl(PPh3){B(mt)3}](Rh-->B)(mt = methimazolyl).

The reaction of [Rh(C6H5)Cl2(PPh3)2] with Na[HB(mt)3](mt = methimazolyl) provides [RhCl(PPh3){B(mt)3}](Rh-->B) the first authentic example of a compound with a rhodium-boron dative bond.

Caveats for poly(methimazolyl)borate chemistry: the novel inorganic heterocycles [H2C(mt)2BR2]Cl (mt = methimazolyl; BR2 = BH2, BH(mt), 9-BBN).

Whilst frequently used for reactions of poly(methimazolyl)borates, dichloromethane is not an innocent solvent, but rather slowly forms heterocyclic salts [H(2)C(mt)(2)BR(2)]Cl, three examples of which (BR(2) = BH(2), BH(mt), 9-borabicyclononyl) have been structurally characterised to confirm the unprecedented B(NCS)(2)C connectivity.

Tricarbonyl(eta6-chlorobenzene)chromium.

The title compound, [Cr(C(6)H(5)Cl)(CO)(3)], is the first group 6 tricarbonyl eta(6)-monohaloarene compound to be structurally characterized. It adopts a classic piano-stool structure, with the Cr(CO)(3) tripod assuming a syn-eclipsed conformation relative to the arene ring (varphi = 2.0 degrees ). The extended structure is dominated by intermolecular pi.H interactions (H.ring centroid = 2.94 A) and non-classical hydrogen bonds between carbonyl and arene moieties (O.H = 2.50-2.58 A).

Hydrofluorocarbon 245fa: a versatile new synthon in alkyne chemistry.

The CFC replacement 1,1,1,3,3-pentafluoropropane (HFC 245 fa) has been established as a convenient source of trifluoropropynyllithium under mild conditions; a range of novel and known trifluoropropynyl-containing systems has been prepared in a one-pot procedure.