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Porphyrin molecules are versatile building blocks that have been used for many different applications. They have been used as catalysts, their properties being very dependent on the metal that is in the core of the porphyrin. They have been also applied as a chromophore, and the light absorbing properties mainly depend on the aromatic ring. Lastly, they have been intensively used as molecular building blocks to construct supramolecular assemblies. For this purpose, mostly zinc(ii) porphyrin building blocks have been used, as their coordination chemistry is predictable, the binding of pyridyl type ligands is reversible and rapid yet of sufficient strength to allow assembly formation under a wide variety of conditions. In principle porphyrin building blocks can also be applied in photocatalysis, using self-assembled structures, thereby using a combination of all the key properties of the porphyrin building block. In this chapter we discuss the application of porphyrin building blocks in this area. We will start with a few examples in the application of self-assembled structures in catalysis, then we provide examples of the use of porphyrin building blocks in photophysics and conclude with the description of the application of self-assembled structures for photocatalysis.

The self-assembly of poly- A acetate) (st-PEA) into van der Waals-stabilized liquid-crystalline (LC) aggregates is reported. The LC behavior of these materials is unex- pected, and unusual for flexible sp 3 - carbon backbone polymers. Although the dense packing of polar ester func- tionalities along the carbon backbone of st-PEA could perhaps be expected to lead directly to rigid-rod behavior, molecular modeling reveals that indi- vidual st-PEA chains are actually highly flexible and should not reveal rigid-rod induced LC behavior. None- theless, st-PEA clearly reveals LC be- havior, both in solution and in the melt over a broad elevated temperature range. A combined set of experimental measurements, supported by MM/MD studies, suggests that the observed LC behavior is due to self-aggregation of st-PEA into higher-order aggregates. According to MM/MD modeling st- PEA single helices adopt a flexible hel- ical structure with a preferred trans- gauche syn-syn-anti-anti orientation. Unexpectedly, similar modeling experi- ments suggest that three of these heli- ces can self-assemble into triple-helical aggregates. Higher-order assemblies were not observed in the MM/MD sim- ulations, suggesting that the triple helix is the most stable aggregate configura- tion. DLS data confirmed the aggrega- tion of st-PEA into higher-order struc- tures, and suggest the formation of rod- like particles. The dimensions derived from these light-scattering experiments correspond with st-PEA triple-helix formation. Langmuir-Blodgett surface pressure-area isotherms also point to the formation of rod-like st-PEA ag- gregates with similar dimensions as st- PEA triple helixes. Upon increasing the st-PEA concentration, the viscosity of the polymer solution increases strongly, and at concentrations above 20 wt % st-PEA forms an organogel. STM on this gel reveals the formation of helical aggregates on the graphite surface-solution interface with shapes and dimensions matching st-PEA triple helices, in good agreement with the structures proposed by molecular mod- eling. X-ray diffraction, WAXS, SAXS and solid state NMR spectroscopy studies suggest that st-PEA triple heli- ces are also present in the solid state, up to temperatures well above the melting point of st-PEA. Formation of higher-order aggregates explains the observed LC behavior of st-PEA, em- phasizing the importance of the "terti- ary structure" of synthetic polymers on their material properties.

Nature has been a source of inspiration for scientists as billion years of evolution have resulted in magnificent examples of how processes can be controlled efficiently. In the field of supramolecular catalysis, enzymes have been the major source of inspiration. As such, many synthetic systems have been prepared to mimic certain aspects of enzymes, with a strong focus on connecting catalytically active sites to cavities or binding sites having affinity for the substrate.[1, 2] Although such approaches have resulted in interesting new tools to control selectivity,[3–5] we are not nearly close to the abilities of Nature to control chemical transformations. One of the major differences between Nature and synthetic approaches is that in biological systems, chemical processes take place in a complex out-of-equilibrium environment.[6] In a cell, many chemical transformations occur simultaneously or in controlled sequence, involving an impressive number of different components. An important challenge for biologists is to understand how this organized complexity leads to emerging properties. As a result, new fields such as systems biology[7] including non-equilibrium thermodynamics[ 8] have been developed. Synthetic chemists traditionally aim for systems that are as clean and pure as possible,[9] and it is only recently that complexity in chemical systems received attention.[10–12] Despite the interesting perspectives, complexity in homogeneous catalysis has not been a research focus in itself, although many aspects related to complexity have been reported. Product inhibition and catalyst poisoning are relevant to complex chemistry as they imply processes with feedback loops. Dynamic catalyst libraries and combinatorial catalysis require selection procedures,[6, 13] and nonlinear effect (NLE) in asymmetric catalysis[14–16] can lead to emerging properties. With this in mind we decided to study in detail NLE using dinuclear hydrogenation catalysts C that have four chiral ligands. Application of nonenantiopure ligands can lead to formation of heterochiral complexes (with more than two chiral ligands) with different properties and these complexes can theoretically be more active and selective than their homochiral analogues.[16] Catalytically active complexes with four chiral ligands are rare, and for hydrogenation complex C is, to the best of our knowledge, the only example. The use of a racemic ligand could lead to the formation of ten stereoisomers of C (Figure 1).

The synthesis of the novel C-3-symmetric tripodal, tetradentate ligand 1, bearing only phosphorus atoms as donor groups, is described, starting from commercially available o-tolyldiphenylphosphine, and its molecular structure has been determined by X-ray crystallographic analysis. Coordination to the cationic Ir-1 precursor [Ir(COE)(2)(acetone)(2)]PF6 led to a highly unsymmetrical species (90% yield) with four inequivalent phosphorus atoms, as evidenced by P-31 NMR spectroscopy. The corresponding H-1 NMR spectrum exhibited a pseudo doublet of quartets at delta -5.9 ppm with one large trans P-H coupling ((2)J(P-H) = 115.4 Hz) and a much smaller cis coupling ((2)J(P-H) = 10.8 Hz). X-ray crystallography confirmed the formation of complex 2, [Ir(H)(kappa P-5,P,P,P,C-1)]PF6, which is a rare example of a structurally characterized mononuclear Ir hydride species bearing an ortho-metalated phosphine ligand. This species does not react with hydride sources, but addition of 1 equiv of CF3COOH resulted in facile overall formal protonation of the Ir-C bond. DFT calculations support a pathway involving initial reductive elimination, forming the highly distorted four-coordinate species 2', followed by protonation at iridium to give the dicationic monohydride species 3, with an activation barrier Delta G(dagger) of 28.2 kcal mol(-1). Deuteration experiments support this mechanism. Reductive elimination can also be induced by reaction of 2 with carbon monoxide, yielding the monocationic carbonyl complex [Ir-1(CO)(1)]PF6 as the sole product.

P-chirogenic, supramolecular hydrogen-bonding C1-symmetrical sulfonamido–phosphinamides (METAMORPhos) have been successfully prepared. They were all found to possess a characteristic prototropic equilibrium between the PIII and the PV tautomers that is slow on the NMR spectroscopic timescale. Despite the dynamic and reversible protonation of the P centre, the P-chirogenic information was found to be retained in the tautomerization process, even in a protic solvent environment. Several strategies to access the corresponding enantiopure compounds were investigated, such as diastereoselective crystallization, or enantioselective synthesis. It was possible to resolve such a class of chiral ligands with up to 99 % ee, and apply them in the Rh-catalyzed asymmetric hydrogenation of alkenes. These ligands are interesting new building blocks in the area of acid/base-type noninnocent ligand catalysis.

The previous mechanistic studies of the Rh-mediated polymerization of carbenes suggests the involvement of organometallic compounds that have been derived from Rh(diene) species that contain a five-membered chelate ring of the type Rh{κ2-C,O-[-CH(COOR)-CH(Pol)-C(OR)=O-]} (Pol = polymer chain), which are characterized by the coordination of the β-ester group of the growing polymer chain to the metal. Herein we present our efforts to characterize the possibly related RhI(cod){κ2-C,O-[-CH(COOR)-CHR′-C(OR)=O-]} (cod = 1,5-cyclooctadiene) species. These structures can be generated by means of olefin exchange with an allyl complex and with the concomitant release of the corresponding 1,3-diene, which is derived from the allyl ligand. The product is unstable and further reacts by means of a bimolecular C-H activation process to form a related dinuclear complex [(cod)Rh(μ-{-CH(COOR)-CH-C(OR)=O-})2Rh(cod)], in which the carbon dianion of the dimethyl or diethyl succinate bridges two Rh(cod) moieties. The complex was synthesized in an independent way and was structurally characterized. We investigated the importance of these complexes in carbene polymerization.

The high-yielding synthesis and detailed characterization of two well-defined, linkage isomeric tripodal, tetradentate all-phosphorus ligands 1-3 is described. Coordination to Cu(I) resulted in formation of complexes 4-6, for which the molecular structures indicate overall tridentate coordination to the copper atom in the solid state, with one dangling peripheral phosphine. The solution studies suggest fast exchange between the three phosphine side-arms. For these new Cu(I) complexes, preliminary catalytic activity in the cyclopropanation of styrene with ethyldiazoacetate (EDA) is disclosed. The anticipated well-defined tetradentate coordination in a C(3)-symmetric fashion was achieved with Rh(I) and Ir(I), leading to the overall five-coordinated complexes 7-12. Complex 11 has the norbornadiene (nbd) ligand coordinated in an unprecedented monodentate 2,3-eta(2) mode to Rh. Furthermore, unexpected but very interesting redox-chemistry and reactivity was displayed by the Rh(Cl)-complexes 7 and 8. Oxidation resulted in the formation of stable Rh(II) metalloradicals [7]PF(6) and [8]PF(6) that were characterized by X-ray crystallography, magnetic susceptibility measurements, cyclic voltammetry, and electron paramagnetic resonance (EPR) spectroscopy. Subsequent redox-reactivity of these metalloradicals toward molecular hydrogen is described, resulting in the formation of Rh(III) hydride compounds.

We report the synthesis of a novel type of phosphinourea ligand, its coordination chemistry with rhodium, its use in the asymmetric hydroformylation of styrene, and investigations on the hydroformylation reaction mechanism. Complex studies on the 2:1 complex of phosphinourea to [Rh(acac)(CO)2] showed that a neutral trans-coordinating complex [Rh(HL-κP)(L-κ2O,P)(CO)] was formed. An anionic O,P-chelating ligand has displaced the anionic acac− ligand via an acid−base reaction involving the deprotonation of an acidic urea proton, giving Hacac. A second phosphinourea is coordinated as a neutral monodentate ligand and is linked to the chelating anionic ligand via an intramolecular hydrogen bond. The behavior of these supramolecular complexes in the hydroformylation reaction and the possible cooperative role of the ligands in the catalytic cycle were studied both experimentally and by computational methods. High-pressure NMR spectroscopy revealed that the catalytically active rhodium hydride species further consists of two neutral phosphinourea ligands and is in equilibrium with the neutral species [Rh(HL-κP)(L-κ2O,P)(CO)]. This equilibrium is likely an integrated part of a productive hydroformylation cycle involving a ligand-assisted reductive elimination of the aldehyde. DFT calculations revealed that the ligand-assisted mechanism could well be the preferred lower energetic pathway; however, the orientation of the anionic oxygen donor atom in [Rh(HL-κP)(L-κ2O,P)(CO)] prevented us from finding a direct (nonsolvent assisted) transition state to connect the intermediates. We therefore cannot exclude a mechanism where [Rh(HL-κP)(L-κ2O,P)(CO)] is a dormant species outside the productive hydroformylation cycle, although the intermediate associated with this mechanism is higher in energy. Finally, the synthesis of heteroligated complexes was investigated, consisting of two electronically different phosphinoureas, which sets the stage for combinatorial supramolecular ligand approaches in catalysis. Simply mixing two electronically different phosphinoureas with metal precursor [Rh(acac)(CO)2] resulted in the formation of a heterobidentate ligand. A set of six new phosphinoureas was used to prepare such rhodium complexes in a combinatorial fashion for the asymmetric hydroformylation of styrene, resulting in high conversions and selectivities for the branched product and moderate enantioselectivities.

We report the coordination behavior of ureaphosphane ligand 1[2-(diphenylphosphanyl)ethyl]-3-phenylurea (L1) towards different rhodium precursor complexes. Depending on the nature of the anion and the ligand/metal ratio, L1 acts either as a hybrid P, O-coordinating chelate, as an anionic P,N-coordinating chelate or as a supramolecular (hydrogen-bonded) bidentate ligand. The different types of complexes were investigated in the asymmetric hydrogenation of three olefinic substrates using ureaphosphanes L2 and L3, which are chiral analogues of L1. For methyl 2-acetamidoacrylate (Si) and dimethyl itaconate (S2) the neutral complex [Rh(L2-kappa P-2,N)(cod)], containing an anionic RN-coordinating ureaphosphane ligand, provided the best enantioselectivity (69.2 and 24.3 %, respectively). For N-(3,4-dihydro-2-naphth-alenyl)acetamide (S3) the best enantioselectivity was obtained with the cationic complex [Rh(L3-kappa P-2,O)(nbd)]BF4, containing a hybrid PO-coordinating ureaphosphane ligand (86.1 %).

The formation of a dimeric structure of a nonsymmetric Zn(II)salphen complex is reported. The X-ray molecular structure show the formation of an oxygen-bridged species (2). In addition to this structure, a pyridine-ligated complex and an 1:2 dabco/Zn(II)salphen supramolecular assembly (dabco = diazabicyclo[2.2.2]octane) are presented. Their coordination behavior has been studied and can be correlated with the substitution pattern of the salphen ligand and the donor-strength of the involved axial ligands. The Zn(II)salphen building blocks bind in a cooperative fashion to the dabco template, the second unit being bound 4 times more strongly.

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Hydrogen holds the potential to be one of the major energy carriers for the future. However, a hydrogen-based economy requires technology that allows efficient and safe storage and release of H2. In this light, the reversible storage of dihydrogen in the form of formic acid (HCOOH) provides an interesting H2 storage-release system. Formic acid can be obtained from the catalytic hydrogenation of CO2 [1a–c] or by direct hydrothermal oxidation of biomass.[1d–f] Since the early nineties, substantial developments in the production of HCOOH have stimulated interest in the reverse reaction for hydrogen release on demand.[2] Important recent breakthroughs are the highly active Fe-based dehydrogenation catalyst reported by Laurenczy, Beller, and coworkers[ 2h] and work by Fujita and co-workers on an iridium catalyst that is highly active for CO2 hydrogenation or HCOOH dehydrogenation, depending on pH.[2k] The dehydrogenation of HCOOH to H2 and CO2 is typically performed in the presence of substoichiometric amounts of base, which drastically decreases the hydrogen content (from the theoretical maximum of 4.4 wt% in pure HCOOH to 2.3 wt% based on the typical 5:2 HCOOH/ NEt3 mixture). In the context of developing efficient hydrogen- based fuel cells, HCOOH/base mixtures were recently optimized for H2 release using a ruthenium-based catalysts.[3] Ideally, catalytic dehydrogenation should be performed in the absence of base and other additives, thereby maximizing the overall hydrogen storage capacity (4.4 wt%). Besides this, hydrogen produced from HCOOH/NEt3 mixtures requires purification to remove traces of volatile amines prior to application in fuel cells.[

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The invention pertains to a diphosphine-transition metal complex comprising a diphosphine-transition metal ligand that is covalently bonded to an insoluble mesoporous support having an average pore diameter of from 4.5 nm to 50 nm, characterized in that the ligand as attached to the support has the formula: wherein R is aryl, C1-C4 alkyl, aralkyl, alkylaryl; C1-C4 alkoxy, aralkoxy, or alkylaryloxy; P is a phosphorous atom; M is a transition metal; X is a bond, CH2, 0, S or NH2; Y is C or N; A is a linking moiety which is bonded to the mesoporous support; the ring formed by X, Y and the two aromatic rings is a 5- or 6-membered ring; and wherein the aromatic rings may be unsubstituted or substituted.; The invention further relates to the use of the diphosphine- transition metal complex as a catalyst in a reaction selected from hydroformylation, hydrogenation, carbonylation or carbon-carbon coupling.

Phosphorylated sulfonimidamides (SIAPhos) undergo ion exchange reactions with cationic complexes, [Rh(cod)2BF4] and [Ir(cod)2BarF], or neutral complexes [Rh(cod)Cl]2 and [Ir(cod)Cl]2, leading to unprecedented neutral complexes with P-N-S-N chelates. Use of the resulting neutral iridium complexes in asymmetric hydrogenation reactions of tri- and tetrasubstituted enamides leads to products with high enantioselectivities (up to 92% ee).

The previous mechanistic studies of the Rh-mediated polymerization of carbenes suggests the involvement of organometallic compounds that have been derived from Rh(diene) species that contain a five-membered chelate ring of the type Rh{κ2-C,O-[–CH(COOR)–CH(Pol)–C(OR)=O–]} (Pol = polymer chain), which are characterized by the coordination of the β-ester group of the growing polymer chain to the metal. Herein we present our efforts to characterize the possibly related RhI(cod){κ2-C,O-[–CH(COOR)–CHR′–C(OR)=O–]} (cod = 1,5-cyclooctadiene) species. These structures can be generated by means of olefin exchange with an allyl complex and with the concomitant release of the corresponding 1,3-diene, which is derived from the allyl ligand. The product is unstable and further reacts by means of a bimolecular C–H activation process to form a related dinuclear complex [(cod)Rh(μ-{–CH(COOR)–CH–C(OR)=O–})2Rh(cod)], in which the carbon dianion of the dimethyl or diethyl succinate bridges two Rh(cod) moieties. The complex was synthesized in an independent way and was structurally characterized. We investigated the importance of these complexes in carbene polymerization.

In this paper we report the application of bis-(thiosemicarbazonato) Zn(II) complexes as building blocks in the construction of supramolecular transition metal assemblies. We investigated their coordination behaviour towards pyridylphosphine molecules and found these systems comparable to those based on Zn(porphyrin) and Zn(salphen) complexes. Additionally, catalytic experiments and an in situ high-pressure FTIR study of the supramolecular rhodium hydroformylation catalysts, assembled using the bis-(thiosemicarbazonato) Zn(II) complexes, demonstrate their applicability in supramolecular catalysis and their potential for application in other areas of supramolecular chemistry.

The supramolecular interactions between a Rh phosphine catalyst equipped with an anion-binding pocket and alkenes that contain anionic functionalities (see picture) provide an excellent design concept to achieve remote control of the regioselectivity in hydroformylation reactions. The 4-pentenoate and 3-butenylphosphonate, which fit tightly between the Rh center and the pocket, were hydroformylated with unprecedented selectivity.

We report an achiral bisphosphine rhodium complex equipped with a binding site for the recognition of chiral anion guests. Upon binding small chiral guests—cofactors—the rhodium complex becomes chiral and can thus be used for asymmetric catalysis. Screening of a library of cofactors revealed that the best cofactors lead to hydrogenation catalysts that form the products with high enantioselectivity (ee’s up to 99%). Interestingly, a competition experiment shows that even in a mixture of 12 cofactors high ee is obtained, indicating that the complex based on the best cofactor dominates the catalysis.

A new family of monoanionic hemilabile ligands L1H−L3H with a PNN donor set has been developed, based on Pd-catalyzed C−N bond formation and straightforward phosphorylation. For these structurally related compounds with a hybrid set of donor atoms, the coordination chemistry with both Rh and Ir has been studied. The anticipated hemilabile character of the dimethylamino group was assessed by NMR and IR competition experiments, using isopropyl isocyanide as exogenous substrate. Supporting DFT calculations were used to quantify the electronic differences between the various members of the ligand family. In effect, we have constructed a modular ligand class that exhibits tunable hemilability.

The binuclear iridium complex [(cod)(Cl)Ir(bpi)Ir(cod)]PF6 (bpi = (pyridin-2-ylmethyl)(pyridin-2-ylmethylene)amine; cod = 1,5-cyclooctadiene) reveals a noteworthy asymmetric binuclear coordination geometry, wherein the bpi ligand acts as a heteroditopic ligand and has an unusual π-coordinated imine moiety. This species is an effective precatalyst for water oxidation. After a short incubation time the catalyst reveals a turnover frequency of 3400 mol mol-1 s-1 with an overall turnover number >1000. © 2011 American Chemical Society., Financial support from the European Research Council (ERC Grant Agreement 202886-CatCIR), NWO-CW (VIDI grant 700.55.426, VENI grant 700.59.410), the MEC/FEDER (Project CTQ2008-03860, Spain), and the University of Amsterdam is gratefully acknowledged.

The power of natural selection through survival of the fittest is nature’s ultimate tool for the improvement and advancement of species. To apply this concept in catalyst development is attractive and may lead to more rapid discoveries of new catalysts for the synthesis of relevant targets, such as pharmaceuticals. Recent advances in ligand synthesis using combinatorial methods have allowed the generation of a great diversity of catalysts. However, selection methods are few in number. We introduce a new selection method that focuses on the stability of catalytic intermediates measured by mass spectrometry. The stability of the intermediate relates inversely to the reactivity of the catalyst, which forms the basis of a catalyst-screening protocol in which less-abundant species represent the most-active catalysts, ‘the survival of the weakest’. We demonstrate this concept in the palladium-catalysed allylic alkylation reaction using diphosphine and IndolPhos ligands and support our results with high-level density functional theory calculations.

Herein, we wish to describe the efficient three-step synthesis of a novel highly hindered, but flexible, N-heterocyclic carbene and its coordination chemistry to Ag(I) and Rh(I).

New coordination polymers based on different combinations of silver atoms and pyridyl-substituted N-heterocyclic carbene moieties are described. The addition of Zn(II) templates leads to Ag-Zn supramolecular assemblies via selective Zn⋯N interactions; a process that can be reverted.

The mechanism of the Indol- Phos–Rh-catalyzed asymmetric hydrogenation of prochiral olefins has been investigated by means of X-ray crystal structure determination, kinetic measurements, high-pressure NMR spectroscopy, and DFT calculations. The mechanistic study indicates that the reaction follows an unsaturate/dihydride mechanism according to Michaelis– Menten kinetics. A large value of KM (KM=5.01 0.16m) is obtained, which indicates that the Rh–solvate complex is the catalyst resting state, which has been observed by high-pressure NMR spectroscopy. DFT calculations on the substrate–catalyst complexes, which are undetectable by experimental means, suggest that the major substrate–catalyst complex leads to the product. Such a mechanism is in accordance with previous studies on the mechanism of asymmetric hydrogenation reactions with C1-symmetric heteroditopic and monodentate ligands.

The new INDOLPhosphole ligands 3a,b are obtained in good yield in a two-step synthetic sequence from 3-methylindole, (S)-BINOL, and the corresponding cyanophosphole. Palladium−allyl complexes have been prepared from INDOLPhosphole (3b) and INDOLPhos (1a) of the type [Pd(INDOLPhos(phole))(η3-C3H5)]PF6 and studied by multidimensional NMR spectroscopy and X-ray crystallography. The allyl ligand undergoes a η3−η1−η3 isomerization in these complexes, which is selective when 1a is the ligand. A tetrameric, boxlike structure, encapsulating a PF6− counteranion, is formed in the solid state in the case of complex 5 ([Pd(3b)(η3-C3H5)]PF6). INDOLPhosphole ligands 3a,b and a small library of INDOLPhos ligands were screened in the Pd-catalyzed asymmetric allylic alkylation of mono- and disubstituted allylic acetates. The catalysts derived from these ligands were highly active, and enantioselectivities were obtained for 1,3-diphenylprop-2-enyl acetate up to 90% ee. Cinnamyl acetate was converted quantitatively with low regioselectivity (b/l = 14/86) and good enantioselectivity up to 81% ee. In the case of disubstituted substrates, the absolute configuration of the product could be rationalized by a model of selective attack on one of the enantiotopic termini in the Pd−allyl intermediate.

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New RhI(cod) complexes of N-heterocyclic carbene ligands containing a pending pyridyl moiety for subsequent binding of ZnII-templates were designed for supramolecular catalyst control in carbene polymerization reactions. ZnII-templates indeed have an influence on the yields and the polymer molecular weights (and weight distributions) produced by these supramolecular assemblies. However, control experiments reveal that the effect of the ZnII-template on the polymerization results is general and not due to the assembly formation.

Sulfonamido−phosphoramidite ligands lead to the formation of Rh−Rh dinuclear complexes through the anionic P−N− bridging character. The resulting “boat-shaped” dinuclear catalysts activate molecular H2 through a cooperative dinuclear endocyclic mechanism, resulting in one bridging and one classical hydride on the dinuclear complex. These new complexes are very active hydrogenation catalysts that operate via a new cooperative hydrogenation activation mechanism, as calculated with density functional theory, and they display unequaled high selectivities in the hydrogenation of hindered cyclic acetamidoalkenes.

We report the assembly of supramolecular boxes and coordination polymers based on a rigid bis-zinc(II)-salphen complex and various ditopic nitrogen ligands. The use of the bis-zinc(II)-salphen building block in combination with small ditopic nitrogen ligands gave organic coordination polymers both in solution as well as in the solid state. Molecular modeling shows that supramolecular boxes with small internal cavities can be formed. However, the inability to accommodate solvent molecules (such as toluene) in these cavities explains why coordination polymers are prevailing over well-defined boxes, as it would lead to an energetically unfavorable vacuum. In contrast, for relatively longer ditopic nitrogen ligands, we observed the selective formation of supramolecular box assemblies in all cases studied. The approach can be easily extended to chiral analogues by using chiral ditopic nitrogen ligands.

The synthesis and resolution of chiral phenoxaphosphane 3, with the stereogenic center at the phosphorus atom, is described. Compound 3 has been synthesized following a wellknown procedure for trapping a phosphorus atom within a six-membered ring. The resolution of the racemic mixture of 3 was achieved through separation of its diastereomeric palladacycle derivatives 7a,b and 9a,b. The absolute configuration of enantiopure phosphanes 3a,b was assigned unequivocally by means of X-ray crystal structure determination for complex 9a and by combination of NOE(1H–1H)/COSY- (1H,1H) spectroscopy and DFT calculations for complexes 7a,b, which in both cases led to identical results.