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Heterostructures of single- and few-layer black phosphorus (2D bP) functionalized with gold nanoparticles (Au NPs) have been recently reported in the literature, exploiting their intriguing properties and biocompatibility for catalytic, therapeutical and diagnostic applications. However, a deeper insight on the structural and electronic properties at the interface of the 2D bP/Au NP heterostructure is still lacking. In this work, 2D bP is functionalized with Au nanoparticles (NPs) through in situ deposition-precipitation heterogeneous reaction. The smallest realized Au NPs have a diameter around 10 nm as revealed by atomic-force and scanning electron microscopy, and are partially positively charged as revealed by X-ray Photoelectron Spectroscopy (XPS). XPS, UV-vis and Raman spectroscopy, supported by density functional theory (DFT) calculations, confirmed that while the structural and electronic properties of 2D bP are overall preserved, a soft-pairing between P atoms at the surface of 2D bP and Au atoms at the surface of Au NPs occurs, leading to a partial charge transfer at the 2D bP/Au interface, with a positive charge being localized on the Au atoms directly bonded to 2D bP. DFT calculations also predicted a band gap lowering, by 0.8 eV, for phosphorene functionalized with a tetranuclear Au cluster. Larger effects are expected as the Au cluster nuclearity (and coverage) increases.

Functionalization is one of the most powerful tools in materials science for the development of new and innovative materials with tailored properties purposefully designed to enhance the overall stability of the system. This is particularly true for exfoliated black phosphorus, which suffers from easy decomposition by air and moisture, hampering its highly desirable applications, especially in electronics. The present work suggests an innovative approach to the functionalization process of this 2D-material based on the selective introduction of chalcogen atoms on the material surface through a reaction with suitable molecular precursors such as stibine chalcogenides (R3Sb(X), X = O or S; R = organyl group). These molecules may readily act as chalcogen-transfer agents and, upon releasing the chalcogen atom atop the bP surface, leave stable stibines (R3Sb) as byproducts, which may be easily removed from the functionalized bP surface. The work provides an overview of all the possible structural, electronic and energy aspects associated with the chalcogen-atom transfer from the stibine to phosphorus based compounds, exemplified by trialkyl phosphines and single layer exfoliated black phosphorus, i.e. phosphorene, Pn. In both cases the oxygen transfer is more exergonic than the sulfur transfer, with the associated free energy barrier for the phosphine process being higher. Although the sulfur transfer for the Pn is found to be endergonic (ca. +3.6 kcal mol-1), the process may surely occur at high temperature. The evolution of the band structure upon the chalcogen transfer has been depicted in detail.

The transition metal mediated functionalization of P4 is an approach to develop a more sustainable production of organophosphorus compounds. In this paper a ruthenium complex is presented, in which the P4 unit can be selectively converted into new P4R2 molecules in a two-step synthesis. The unsaturated 16 electron species [RuX(Cp*)(PCy3)] (Cp* = C5Me5, X = Cl, Br) reacts with a half equivalent of P4 affording a bimetallic complex bearing a planar P4X2 moiety as a ligand. The latter eliminates chloride anions under reduction with magnesium. In this process the butadiene-like P4Cl2 ligand is converted into two weakly bound P2 units which bridge the ruthenium centers. In the presence of n-BuLi, the P4Cl2 unit can be selectively alkylated, yielding the planar organophosphorus ligand P4nBu2. A detailed analysis of the electronic properties and solid state structures of the compounds combined with DFT calculations and AIM analyses demonstrate that the P4 unit in all complexes acts as an electronically highly flexible, non-innocent ligand.

This paper is a comparative outline of the potential acid-base adducts formed by an unsaturated main group or transition metal species and P atoms of phosphorene (P n ), which derives from black phosphorus exfoliation. Various possibilities of attaining a realistic covalent functionalization of the 2D material have been examined via DFT solid state calculations. The distribution of neighbor P atoms at one side of the sheet and the reciprocal directionalities of their lone pairs must be clearly understood to foreshadow the best possible acceptor reactants. Amongst the latter, the main group BH 3 or I 2 species have been examined for their intrinsic acidity, which favors the periodic mono-hapto anchoring at P n atoms. The corresponding adducts are systematically compared with other molecular P donors from a phosphine to white phosphorus, P 4 . Significant variations emerge from the comparison of the band gaps in the adducts and the naked phosphorene with a possible electronic interpretation being offered. Then, the P n covalent functionalization has been analyzed in relation to unsaturated metal fragments, which, by carrying one, two or three vacant σ hybrids, may interact with a different number of adjacent P atoms. For the modelling, the concept of isolobal analogy is important for predicting the possible sets of external coligands at the metal, which may allow the anchoring at phosphorene with a variety of hapticities. Structural, electronic, spectroscopic and energy parameters underline the most relevant pros and cons of some new products at the 2D framework, which have never been experimentally characterized but appear to be reasonably stable.

A detailed mechanism of the I 2 -induced transformation of white phosphorus into PI 3 emerges from a DFT analysis. This multi-step process implies that at any stage one P-P and two I-I bonds cleavages, associated with the formation of two P-I bonds plus an in situ generated brand new I 2 molecule. Significant electron transfer between the atoms is observed at any step, but the reactions are better defined as concerted rather than redox. Along the steepest descent to the product, no significant barrier is encountered except for the very first P 4 activation, which costs +14.6 kcal mol -1 . At the atomic level, one first I 2 molecule, a typical mild oxidant, is first involved in a linear halogen bonding interaction (XB) with one P donor, while its terminal I atom is engaged in an additional XB adduct with a second I 2 . Significant electron transfer through the combined diatomics allows the external I atom of the dangling I 3 grouping to convey electrons into the σ* level of one P-P bond with its consequent cleavage. This implies at some point the appearance of a six-membered ring, which alternatively switches its bonding and no-bonding interactions. The final transformation of the P 2 I 4 diphosphine into two PI 3 phosphines is enlightening also for the specific role of the I substituents. In fact, it is proved that an organo-diphosphine analogue hardly undergoes the separation of two phosphines, as reported in the literature. This is attributable to the particularly high donor power of the carbo-substituted P atoms, which prevents the concertedness of the reaction but favors charge separation in an unreactive ion pair.

The interaction of the η(1)-tetrahydroborate copper(i) complex (triphos)Cu(η(1)-BH4) () with proton donors [CF3CH2OH (TFE), (CF3)2CHOH (HFIP), (CF3)3COH (PFTB), PhOH, p-NO2C6H4OH (PNP), p-NO2C6H4N[double bond, length as m-dash]NC6H4OH (PNAP), CF3OH] was a subject of a combined IR spectroscopic and theoretical investigation. Spectral (Δν) and thermodynamic (ΔH) parameters of dihydrogen bond (DHB) formation were determined experimentally. The terminal hydride ligand (characterized by the basicity factor Ej(BH) = 0.87 ± 0.01) is found to be a site of proton transfer which begins with nucleophilic substitution of BH4(-) by the alcohol oxygen atom on the copper center (BH pathway). The activation barrier computed for (CF3)2CHOH in CH2Cl2 - ΔG = 20.6 kcal mol(-1) - is in good agreement with the experimental value (ΔG = 20.0 kcal mol(-1)). An abnormal dependence of the reaction rate on the proton donor strength found experimentally in dichloromethane is explained computationally on the basis of the variation of the structural and energetic details of this process with the proton donor strength. In the second reaction mechanism found (CuH pathway), DHB complexes with the initial ROH coordination to the bridging hydride lead to B-Hbr bond cleavage with BH3 elimination. "Copper assistance" via the CuO interaction is not involved. This mechanism can be evoked to explain the occurrence of proton transfer in coordinating solvents.

The transformation of phosphorous oxyacids into the corresponding fluorophosphines was mediated by [RuCp(PPh3)2Cl] under mild reaction conditions using a soft deoxofluorinating agent. The reaction is selective, proceeds with high yields and can be extended to a wide range of phosphorous oxyacids once coordinated to the ruthenium synthon [RuCp(PPh3)2](+) as their hydroxyphosphine tautomer. Deoxofluorination of phenylphosphinic acid was also mediated by [RuCp(R)(CH3CN)3]PF6, where Cp(R): Cp = C5H5, Cp* = C5Me5, and [Ru(η(6)-p-cymene)(μ-Cl)Cl]2. X-Ray single crystal structures of the two new derivatives, [RuCp(PPh3)2{PhP(OH)2}]CF3SO3 and [Ru(η(6)-p-cymene)Cl2{PhP(OH)2}] have been determined.

Catalytic dehydrogenation of ammonia-borane (NH(3)·BH(3), AB) and dimethylamine borane (NHMe(2)·BH(3), DMAB) by the Pd(II) complex [((tBu)PCP)Pd(H(2)O)]PF(6) [(tBu)PCP = 2,6-C(6)H(3)(CH(2)P(t)Bu(2))(2)] leads to oligomerization and formation of spent fuels of general formula cyclo-[BH(2)-NR(2)](n) (n = 2,3; R = H, Me) as reaction byproducts, while one equivalent of H(2) is released per amine-borane equivalent. The processes were followed through multinuclear ((31)P, (1)H, (11)B) variable temperature NMR spectroscopy; kinetic measurements on the hydrogen production rate and the relative rate constants were also carried out. One non-hydridic intermediate could be detected at low temperature, whose chemical nature was explored through a DFT modeling of the reaction mechanism, at the M06//6-31+G(d,p) computational level. The computational output was of help to propose a reliable mechanistic picture of the process.

The selective formic acid dehydrogenation to a mixture of CO(2) and H(2) was achieved with moderate to good productivities in the presence of homogeneous Ru catalysts bearing the polydentate tripodal ligands 1,1,1-tris-(diphenylphosphinomethyl)ethane (triphos) and tris-[2-(diphenylphosphino)ethyl]amine (NP(3)), either made in situ from suitable Ru(III) precursors or as molecular complexes. Preliminary mechanistic studies highlighting subtle differences due to ligand effects in the corresponding systems under study are also presented.

Dynamic processes involving the P(4) cage coordinated to transition metal fragments were observed for the mononuclear complex trans-[Ru(dppm)(2)(H)(η(1)-P(4))]BF(4) and for the bimetallic derivative trans-[Ru(dppm)(2)(H)(μ ,η(1:2)-P(4)){Pt(PPh(3))(2)}]BF(4) as demonstrated by NMR experiments and DFT calculations.

Reaction of the pincer hydride complex ((tBu)PCP)Ni(H) [(tBu)PCP = 2,6-C(6)H(3)(CH(2)P(t)Bu(2))(2)] with BH(3)·thf in THF at 190 K generates the corresponding borohydride complex ((tBu)PCP)Ni(BH(4)). The kinetically stable (but thermodynamically unstable) species undergoes reversible borane loss. The related fluoride complex ((tBu)PCP)Ni(F) shows the same reactivity towards BF(3)·Et(2)O, producing ((tBu)PCP)Ni(BF(4)) as the main final product. The processes were followed through multinuclear NMR spectroscopy and DFT calculations, at the M06//6-31+G(d,p) level of theory.

A series of organometallic compounds of general formula [(arene)M(PTA)(n)X(m)]Y (arene = eta(6)-C(10)H(14), eta-C(5)Me(5)); M = Ru(ii), Os(ii), Rh(iii) and Ir(iii); X = Cl, mPTA; Y = OTf, PF(6)) have been screened for their cytotoxicity and ability to inhibit cathepsin B in vitro, in comparison to the antimetastatic compound NAMI-A. The Ru and Os analogues and NAMI-A showed similar enzyme inhibition properties (with IC(50) values in the low muM range), whereas the Rh(iii) and Ir(iii) compounds were inactive. In order to build up a rational for the observed differences, DFT calculations of the metal complexes adducts with N-acetyl-l-cysteine-N'-methylamide, a mimic for the Cys residue in the cathepsin B active site, were performed to provide insights into binding thermodynamics in solution. Initial structure-activity relationships have been defined with the calculated binding energies of the M-S bonds correlating well with the observed inhibition properties of the compounds.

[Cp(*)RhCl(PTA)(2)]X (PTA = 7-phospha-1,3,5-triazaadamantane) undergoes an H/D exchange process between the methyl groups of Cp(*) and D(2)O whose rate depends on the coordinating ability of the counterion X(-). Kinetic studies and DFT calculations indicate that deuteration involves the abstraction of a Me-Cp(*) proton by a coordinated OH(-); the formation of the latter seems to be facilitated by the presence of the N-basic centers of PTA.

Generations 1 to 3 of dendrimers ended by water-soluble phosphines are synthesized and their ruthenium complexes are used as catalysts in aqueous media; a slightly positive dendritic effect on the regioselectivity is observed for hydration of alkynes and a large positive dendritic effect is observed in the biphasic (water/heptane) catalysed isomerisation of allylic alcohols to ketones where the products are easily isolated and the catalyst can be reused several times, even the first generation.

The reaction of the primary phosphane (ferrocenylmethyl)phosphane [PH(2)CH(2)Fc, ] with an equimolar amount of [M(cod)Cl(2)] (cod = 1,5-cyclooctadiene, M = Pd, Pt) gave the unusual monobridged M(ii) dinuclear complexes of formula [(cod)ClM(micro-PHCH(2)Fc)M(PH(2)CH(2)Fc)Cl(2)] [M = Pt, ; M = Pd, ]. The mechanism leading to and involves the preliminary formation of cis-[M(PH(2)CH(2)Fc)(2)Cl(2)] which further reacts with free [M(cod)Cl(2)] before undergoing dehydrochlorination. The reaction of with PPh(3) led to the unexpected formation of the cyclic trinuclear complex [Pd(3)(micro-PHCH(2)Fc)(3)(PPh(3))(2)(PH(2)CH(2)Fc)Cl(3)] (). Further reaction of with PPh(3) led to the substitution of the tertiary phosphane for the primary one with formation of two geometric isomers and of formula [Pd(micro-PHCH(2)Fc)(PPh(3))Cl](3) differing only for the position of the PPh(3) group replacing the PH(2)CH(2)Fc ligand. In complex each micro-PHCH(2)Fc group bridging two palladium atoms has a terminal PPh(3) ligand in trans position with respect to the first Pd (the cis position being occupied by a chlorine) and a chlorine ligand trans to the other Pd (the cis position being occupied by a terminal PPh(3) ligand) thus rendering chemically equivalent the three PPh(3) (and the three phosphides). In complex the three terminal PPh(3) as well as the three bridging phosphido ligands are chemically inequivalent. Complexes and coexist in equilibrium in solution, but only precipitates from CH(2)Cl(2)-n-hexane yielding crystals suitable for X-ray analyses. These crystals are water/n-hexane solvates and belong to the monoclinic space P2(1)/c with a = 25.063(6) A, b = 15.564(4) A, c = 26.089(5) A, beta = 120.017(16) degrees . They contain two identical couples of enantiomers of . The peculiar arrangement of three metals and three phosphorus atoms of the bridging ligands ascertained for trimers , and has no precedent in the rich class of palladium and platinum phosphido chemistry.

Treatment of [CpRu(PPh(3))(2)Cl] 1 with the stoichiometric amount of H(3)PO(2) or H(3)PO(3) in the presence of chloride scavengers (AgCF(3)SO(3) or TlPF(6)) yields compounds of formula [CpRu(PPh(3))(2)(HP(OH)(2))]Y (Y = CF(3)SO(3) 2a or PF(6) 2b) and [CpRu(PPh(3))(2)(P(OH)(3))]Y (Y = CF(3)SO(3) 3aor PF(6) 3b) which contain, respectively, the HP(OH)(2) and P(OH)(3) tautomers of hypophosphorous and phosphorous acids bound to ruthenium through the phosphorus atom. The triflate derivatives 2a and 3a react further with hypophosphorous or phosphorous acids to yield, respectively, the complexes [CpRu(PPh(3))(HP(OH)(2))(2)]CF(3)SO(3) 4 and [CpRu(PPh(3))(P(OH)(3))(2)]CF(3)SO(3) 5 which are formed by substitution of one molecule of the acid for a coordinated triphenylphosphine molecule. The compounds 2 and 3 are quite stable in the solid state and in solutions of common organic solvents, but the hexafluorophosphate derivatives undergo easy transformations in CH(2)Cl(2): the hypophosphorous acid complex 2b yields the compound [CpRu(PPh(3))(2)(HP(OH)(2))]PF(2)O(2) 6, whose difluorophosphate anion originates from hydrolysis of PF(6)(-); the phosphorous acid complex 3b yields the compound [CpRu(PPh(3))(2)(PF(OH)(2))]PF(2)O(2) 7, which is produced by hydrolysis of hexafluorophosphate and substitution of a fluorine for an OH group of the coordinated acid molecule. All the compounds have been characterized by elemental analyses and NMR measurements. The crystal structures of 2a, 3a and 7 have been determined by X-ray diffraction methods.

The P4 molecule bound to ruthenium as an eta1-ligand in [CpRu(PPh3)2(eta1-P4)]Y (Y = PF6, CF3SO3) undergoes an easy reaction with water in exceedingly mild conditions to yield PH3, which remains coordinated to the [CpRu(PPh3)2] fragment, and oxygenated derivatives.

A family of new Fischer-type rhenium(III) benzoyldiazenido-2-oxacyclocarbenes of formula [(ReCl2[eta1-N2C(O)Ph][=C(CH2)nCH(R)O](PPh3)2][n = 2, R = H (2), R = Me (3); n = 3, R = H (4), R = Me (5)] have been prepared by reaction of [ReCl2[eta2-N2C(Ph)O](PPh3)2] (1) with omega-alkynols, such as 3-butyn-1-ol, 4-pentyn-1-ol, 4-pentyn-2-ol, 5-hexyn-2-ol in refluxing THF. The correct formulation of the carbene derivatives 2-5 has been unambiguously determined in solution by NMR analysis and confirmed for compounds 2-4 by X-ray diffraction methods in the solid state. All complexes are octahedral with the benzoyldiazenido ligand, Re[N2C(O)Ph], adopting a "single bent" conformation. The coordination basal plane is completed by an oxacyclocarbene ligand and two chlorine atoms. Two triphenylphosphines in trans positions with respect to each other complete the octahedral geometry around rhenium. The reactivity of 1 towards different alkynes and alkenes including propargyl- and allylamine has been also studied. With propargyl amine, monosubstituted or bisubstituted complexes, [(ReCl2[eta1-N2C(O)Ph][eta1-NH2CH2C triple bond CH]n(PPh3)(3-n)][n= 1 (6); n = 2 (7)], have been isolated depending on the reaction conditions. In contrast, the reaction with allylamine gave only the disubstituted complex [(ReCl2[eta1-N2C(O)Ph][eta1-NH2CH2CH=CH2]2(PPh3)] (8). The molecular structure of the monosubstituted adduct has been confirmed by X-ray analysis in the solid state.