The synthetic scope of proton‐responsive sulfonamidophosphorus (METAMORPhos) ligands is expanded and design principles for the selective formation of particular tautomers, ion pairs, or double ...condensation products are elucidated. These systems have been introduced in the coordination sphere of Ru for the first time, thereby enabling the exclusive coordination as a monoanionic P,O chelate. Depending on the Ru precursor, halide‐bridged dinuclear species 3–5 or cymene‐derived piano‐stool complexes 6–9 are isolated. The METAMORPhos framework is shown to play a role in the heterolytic cleavage of H2, with species 7 converted into neutral monohydride 10. Substitution chemistry with cymene complex 7 has also been examined, thereby giving rise to tetrakis(acetonitrile) adduct 11. Introduction of a second equivalent of METAMORPhos ligand to this species yielded the bis(ligated) derivative 13, for which variable‐temperature (VT) NMR spectroscopy indicates coalescence of the phosphine donors at high temperature. Solid‐state structures of 3, 6, 11, and 13 are presented to establish the precise bonding situation of the inorganic PNSO framework within METAMORPhos upon coordination as a proton‐responsive monoanionic P,O chelate.
The synthesis of an extended family of highly tunable proton‐responsive sulfonamidophosphorus (METAMORPhos) ligands are reported, together with the first Ru complexes in which these ligands coordinate as anionic P,O chelates. A bis(ligated) derivative is reported, which is proposed to undergo an autoprotonolysis process.
Novel bis(azidophenyl)phosphole sulfide building block 8 has been developed to give access to a plethora of phosphole-containing pi-conjugated systems in a simple synthetic step. This was explored ...for the reaction of the two azido moieties with phenyl-, pyridyl- and thienylacetylenes, to give bis(aryltriazolyl)-extended pi-systems, having either the phosphole sulfide (9) or the phosphole (10) group as central ring. These conjugated frameworks exhibit intriguing photophysical and electrochemical properties that vary with the nature of the aromatic end-group. The λ3-phospholes 10 display blue fluorescence (λem = 460-469 nm) with high quantum yield (ΦF = 0.134-0.309). The radical anion of pyridyl-substituted phosphole sulfide 9b was observed with UV/Vis spectroscopy. TDDFT calculations on the extended pi-systems showed some variation in the shape of the HOMOs, which was found to have an effect on the extent of charge transfer, depending on the aromatic end-group. Some fine-tuning of the emission maxima was observed, albeit subtle, showing a decrease in conjugation in the order thienyl < phenyl < pyridyl. These results show that variations in the distal ends of such pi-systems have a subtle but significant effect on photophysical properties. PUBLICATION ABSTRACT
Abstract 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{κ 2 ‐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 Rh I (cod){κ 2 ‐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–}) 2 Rh(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.
DFT calculations were performed on copper(I) complexes of neutral scorpion ligands based on either pyrazolyl (Pz) or triazolyl (Tz) rings with both methane and phosphine oxide apexes, that is, ...HC(Pz)3, OP(Pz)3, HC(Tz)3, and OP(Tz)3. The analyses reveal that all four ligands have similar donor properties and that their differences are easily compensated by the proper choice of substituents. This computational study strongly suggests that the readily synthesizable neutral phosphine oxide capped scorpion ligands should have broad applicability. Experimentally, the two OP‐capped ligands act differently on copper(I) complexation. With OP(Tz)3, a crystallographically characterized dimeric tris(triazolyl)phosphine oxide based copper(I) complex was obtained, whereas instead a monomer was reported for OP(Pz)3.
Phosphorus‐centered scorpion ligands OP(Pz)3 (Pz = pyrazolyl) and OP(Tz)3 (Ty = triazolyl) were found to be similar to their carbon analogues HC(Pz)3 and HC(Tz)3, also on CuI complexation, according to DFT calculations. Experimentally, the two OP‐capped ligands act differently from each other, giving the expected monomer for the CuI complex of OP(Pz)3, but a dimer for that of OP(Tz)3.
The development of selective functionalization strategies of white phosphorus (P4) is important to avoid the current chlorinated intermediates. The use of transition metals (TMs) could lead to ...catalytic procedures, but these are severely hampered by the high reactivity and unpredictable nature of the tetrahedron. Herein, we report selective first steps by reacting P4 with a metal anion Cp*Fe(CO)2− (Cp*=C5(CH3)5), which, in the presence of bulky Lewis acids (LA; B(C6F5)3 or BPh3), leads to unique TM‐substituted LA‐stabilized bicyclo1.1.0tetraphosphabutanide anions Cp*Fe(CO)2(η1‐P4⋅LA)−. Their P‐nucleophilic site can be subsequently protonated to afford the transient LA‐free neutral butterflies exo,endo‐ and exo,exo‐Cp*Fe‐ (CO)2(η1‐P4H), allowing controllable stepwise metalate‐mediated functionalization of P4.
P4 functionalization: Reacting P4 with Cp*Fe(CO)2− (Cp*=C5(CH3)5) in the presence of bulky Lewis acids (LAs) grants unprecedented access to unique transition‐metal‐substituted LA‐stabilized bicyclic tetraphosphide anions 1 (LA=B(C6F5)3 (a) or BPh3 (b)). Their P‐nucleophilic site (see HOMO 1 a−) can be protonated to afford transient LA‐free exo,endo‐ and exo,exo‐Cp*Fe(CO)2(η1‐P4H) 2, allowing controllable stepwise metalate‐mediated functionalization of P4.
A new catalytic method has been investigated to obtain either O‐ or C‐allylated phenolic products using allyl alcohol or diallyl ether as the allyl donor. With the use of new cationic ruthenium(II) ...complexes as catalyst, both reactions can be performed with good selectivity. Active cationic Ru(II) complexes, having cyclopentadienyl and bidentate phosphine ligands are generated from the corresponding Ru(II) chloride complexes with a silver salt. The structures of three novel (diphosphine)Ru(II)CpCl catalyst precursor complexes are reported. It appears that the structure of the bidentate ligand has a major influence on catalytic activity as well as chemoselectivity. In addition, a strong cocatalytic effect of small amounts of acid is revealed. Model experiments are described that have been used to build a reaction network that explains the origin and evolution in time of both O‐allylated and C‐allylated phenolic products. Some mechanistic implications of the observed structure vs. performance relation of the (diphosphine)RuCp+ complexes and the cocatalytic role of added protons are discussed.
Invited for the cover of this issue is the group of Bert Klein Gebbink at Utrecht University, The Netherlands. The cover image shows the structures of the enzyme deacetoxycephalosporin C synthase ...(DAOCS) and its synthetic analogue.
This overall geometry is difficult to achieve outside a protecting protein environment and represents an “open end” for further coordination studies and the development of new and environmentally friendly catalysts...
Read more about the story behind the cover in the Cover Profile and about the research itself on p. 1319 ff.
The cover picture shows the structure of the enzyme deacetoxycephalosporin C synthase (DAOCS) in the upper left corner, with a zoom-in on the active site on the right. The structure of the synthetic ...analogue presented in the manuscript is depicted in the lower right corner, with a schematic representation on the left. Details are discussed in the article by R. J. M. Klein Gebbink et al. on . For more on the story behind the cover research, see the .
A wide-bite-angle diphosphinine ligand has been designed and synthesized, which exhibits structural features for a preferred formation of trans complexes. Due to the linear orientation of the ...lone-pair electrons of the phosphorus donors in combination with an appropriate P−P distance, trans coordination toward a Rh center was observed and the corresponding LRh(CO)I complex could be characterized crystallographically. Although typical reactivities usually observed for trans complexes were found, reaction of the diphosphinine with the cis-enforcing precursor Rh(nbd)2BF4 did result in the formation of several species at low temperature, to which cis-structures were attributed.
The kinetics of association of ureido-pyrimidinone (U) dimers, present either in the 41H-keto form or in the pyrimidin-4-ol form, with 2,7-diamido-1,8-naphthyridine (N) into a complementary ...heterodimer have been investigated. The formation of heterodimers with 2,7-diamido-1,8-naphthyridine from pyrimidin-4-ol dimers is much faster than from 41H-pyrimidinone dimers. Using a combination of simple measurements and simulations, evidence for a bimolecular tautomerization step is presented. Finally, the acquired kinetic knowledge of the different pathways leading from ureido-pyrimidinone homodimers to ureido-pyrimidinone:diamido-naphthyridine (U:N) heterodimers allows the prediction and observation of kinetically determined ureido-pyrimidinone heterodimers which slowly convert back to the corresponding homodimers.
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