Extending the coordination chemistry of molecular P(4)S(3): the polymeric Ag(P(4)S(3))(+) and Ag(P(4)S(3))(2)(+) cations

Upon reacting P(4)S(3) with AgAl(hfip)(4) and AgAl(pftb)(4) [hfip = OC(H)(CF(3))(2); pftb = OC(CF(3))(3)], the compounds Ag(P(4)S(3))Al(hfip)(4) 1 and Ag(P(4)S(3))(2)(+)[Al(pftb)(4)](-) 2 formed in CS(2) (1) or CS(2)/CH(2)Cl(2) (2) solution. Compounds 1 and 2 were characterized by single-crystal X-ray structure determinations, Raman and solution NMR spectroscopy, and elemental analyses. One-dimensional chains of [Ag(P(4)S(3))(x)](infinity) (x = 1, 1; x = 2, 2) formed in the solid state with P(4)S(3) ligands that bridge through a 1,3-P,S, a 2,4-P,S, or a 3,4-P,P eta(1) coordination to the silver ions. Compound 2 with the least basic anion contains the first homoleptic metal(P(4)S(3)) complex. Compounds 1 and 2 also include the long sought sulfur coordination of P(4)S(3). Raman spectra of 1 and 2 were assigned on the basis of DFT calculations of related species. The influence of the silver coordination on the geometry of the P(4)S(3) cage is discussed, additionally aided by DFT calculations. Consequences for the frequently observed degradation of the cage are suggested. An experimental silver ion affinity scale based on the solid-state structures of several weak Lewis acid base adducts of type (L)AgAl(hfip)(4) is given. The affinity of the ligand L to the silver ion increases according to P(4) < CH(2)Cl(2) < P(4)S(3) < S(8) < 1,2-C(2)H(4)Cl(2) < toluene.     

The facile preparation of weakly coordinating anions: structure and characterisation of silverpolyfluoroalkoxyaluminates AgAl(ORF)4, calculation of the alkoxide ion affinity

Purified LiAlH4 reacts with fluorinated alcohols HORF to give LiAl(ORF)4 (RF=-CH(CF3)2, 2a; -C(CH3)(CF3)2, 2b; -C(CF3)3, 2c) in 77 to 90% yield. The crude lithium aluminates LiAl(ORF)4 react metathetically with AgF to give the silver aluminates AgAl(ORF)4 (RF=-CH(CF3)2, 3a; -C(CH3)(CF3)2, 3b; -C(CF3)3, 3c) in almost quantitative yield. The solid-state structures of solvated 3a-c showed that the silver cation is only weakly coordinated (CN(Ag)=6-10; CN = coordination number) by the solvent and/or weak cation - anion contacts Ag-X (X=O, F, Cl, C). The strength of the Ag-X contacts of 3a-c was analysed by Brown's bond-valence method and then compared with other silver salts of weakly coordinating anions (WCAs), for example [CB11H6Cl6]- and [M(OTeF5)n]- (M=B, Sb, n=4, 6). Based on this quantitative picture we showed that the Al[OC(CF3)3]4 anion is one of the most weakly coordinating anions known. Moreover, the AgAl(ORF)4 species are certainly the easiest WCAs to access preparatively (20 g in two days), additionally at low cost. The Al-O bond length of Al(ORF)4- is shortest in the sterically congested Al[OC(CF3)3]4- anion-which is stable in H2O and aqueous HNO3 (35 weight%)--and indicates a strong and highly polar Al-O bond that is resistant towards heterolytic alkoxide ion abstraction. This observation was supported by a series of HF-DFT calculations of OR-, Al(OR)3 and Al(OR)4- at the MPW1PW91 and B3LYP levels (R= CH3, CF3, C(CF3)3). The alkoxide ion affinity (AIA) is highest for R=CF3 (AlA=384 +/- 9 kJ x mol(-1)) and R= C(CF3)3 (AIA=390 +/- 3 kJ x mol(-1)), but lowest for R=CH3 (AIA=363 +/- 7 kJ X mol(-1)). The gaseous AL(ORF)4-anions are stable against the action of the strong Lewis acid ALF3(g) by 88.5 +/- 2.5 (RF=CF3) and 63 +/- 12 kJ X mol(-1) (RF=C(CF3)3), while AL(OCH3)4- decomposes with -91 +/- 2 kJ X mol(-1). Therefore the presented fluorinated aluminates AL(ORF)4- appear to be ideal candidates when large and resistant WCAs are needed, for example, in cationic homogenous catalysis, for highly electrophilic cations or for weak cationic Lewis acid/base complexes.     

Approaching the gas-phase structures of [AgS8]+ and [AgS16]+ in the solid state

Upon treating elemental sulfur with [AgSbF(6)], [AgAl(hfip)(4)], [AgAl(pftb)(4)] (hfip=OCH(CF(3))(2), pftb =OC(CF(3))(3)) the compounds [Ag(S(8))(2)][SbF(6)] (1), [AgS(8)][Al(hfip)(4)] (2), and [Ag(S(8))(2)](+)[[Al(pftb)(4)](-) (3) formed in SO(2) (1), CS(2) (2), or CH(2)Cl(2) (3). Compounds 1-3 were characterized by single-crystal X-ray structure determinations: 1 by Raman spectroscopy, 2 and 3 by solution NMR spectroscopy and elemental analyses. Single crystals of [Ag(S(8))(2)](+)[Sb(OTeF(5))(6)](-) 4 were obtained from a disproportionation reaction and only characterized by X-ray crystal structure analysis. The Ag(+) ion in 1 coordinates two monodentate SbF(6) (-) anions and two bidentate S(8) rings in the 1,3-position. Compound 2 contains an almost C(4v)-symmetric [AgS(8)](+) moiety; this is the first example of an eta(4)-coordinated S(8) ring (d(Agbond;S)=2.84-3.00 A). Compounds 3 and 4, with the least basic anions, contain undistorted, approximately centrosymmetric Ag(eta(4)-S(8))(2) (+) cations with less symmetric eta(4)-coordinated S(8) rings (d(Agbond;S)=2.68-3.35 A). The thermochemical radius and volume of the undistorted Ag(S(8))(2) (+) cation was deduced as r(therm)(Ag(S(8))(2) (+))=3.378+ 0.076/-0.120 A and V(therm)(Ag(S(8))(2) (+))=417+4/-6 A(3). AgS(8) (+) and several isomers of the Ag(S(8))(2) (+) cation were optimized at the BP86, B3LYP, and MP2 levels by using the SVP and TZVPP basis sets. An analysis of the calculated geometries showed the MP2/TZVPP level to give geometries closest to the experimental data. Neither BP86 nor B3LYP reproduced the longer weak dispersive Agbond;S interactions in Ag(eta(4)-S(8))(2) (+) but led to Ag(eta(3)-S(8))(2) (+) geometries. With the most accurate MP2/TZVPP level, the enthalpies of formation of the gaseous [AgS(8)](+) and [Ag(S(8))(2)](+) cations were established as Delta(f)H(298)([Ag(S(8))(2)](+), g)=856 kJ mol(-1) and Delta(f)H(298)([AgS(8)](+), g)=902 kJ mol(-1). It is shown that the [AgS(8)](+) moiety in 2 and the [AgS(8)](2) (+) cations in 3 and 4 are the best approximation of these ions, which were earlier observed by MS methods. Both cations reside in shallow potential-energy wells where larger structural changes only lead to small increases in the overall energy. It is shown that the covalent Agbond;S bonding contributions in both cations may be described by two components: i) the interaction of the spherical empty Ag 5s(0) acceptor orbital with the filled S 3p(2) lone-pair donor orbitals and ii) the interaction of the empty Ag 5p(0) acceptor orbitals with the filled S 3p(2) lone-pair donor orbitals. This latter contribution is responsible for the observed low symmetry of the centrosymmetric Ag(eta(4)-S(8))(2) (+) cation. The positive charge transferred from the Ag(+) ion in 1-4 to the coordinated sulfur atoms is delocalized over all the atoms in the S(8) ring by multiple 3p(2)-->3sigma* interactions that result in a small long-short-long-short Sbond;S bond-length alternation starting from S1 with the shortest Agbond;S length. The driving force for all these weak bonding interactions is positive charge delocalization from the formally fully localized charge of the Ag(+) ion.     

Self-assemblies based on [Cp2Mo2(CO)4(micro,eta2-P2)]-solid-state structure and dynamic behaviour in solution

Reaction of complex [Cp2Mo2(CO)4(micro,eta 2-P2)] (Cp=C5H5 (1)) with CuPF6, AgX (X=BF4, ClO4, PF6, SbF6, Al{OC(CF3)3}4) and [(Ph3P)Au(THF)][PF6] (THF=tetrahydrofuran), respectively, results in the facile formation of the dimers 3 b-h of the general formula [M2({Cp2Mo2 (CO)4(micro,eta 2:eta 2-P2)}2)({Cp2Mo2(CO)4 (micro,eta 2:eta 1:eta 1-P2)}2)][X]2 (M=Cu, Ag, Au; X=BF4, ClO4, PF6, SbF6, Al{OC(CF3)3}4). As revealed by X-ray crystallography, all these dimers comprise dicationic moieties that are well-separated from the weakly coordinating anions in the solid state. If 1 is allowed to react with AgNO2 and LAuCl (L=CO or tetrahydrothiophene), respectively, the dimer [Ag2{Cp2Mo2 (CO)4(micro,eta 2:eta 1:eta 1-P2)}2(eta 2-NO2)2] (5) and the complex [AuCl{Cp2Mo2(CO)4(micro,eta 2:eta 1-P2)}] (6) are formed, which have also been characterised by X-ray crystallography. In compounds 5 and 6, the anions remain coordinated to the Group 11 metal centres. Spectroscopic data suggest that the dimers 3 b-h display dynamic behaviour in solution and this is discussed by using the comprehensive results obtained for 3 g (M=Ag; X=Al{OC(CF3)3}4) as a basis. The interpretation of the experimental results is facilitated by density functional theory (DFT) calculations on 3 g (structures, energetics, NMR shielding tensors). The 31P magic angle spinning (MAS) NMR spectra recorded for the dimers 3 b (M=Cu; X=PF6) and 3c (M=Ag; X=BF4) as well as that of the previously reported one-dimensional (1 D) polymer [Ag2{Cp2Mo2(CO)4(micro,eta 2:eta 1:eta 1-P2)}3(micro,eta 1:eta 1-NO3)]n[NO3]n (4) are also discussed herein and the strong dependence of the chemical shift of the phosphorus atoms within each compound on subtle structural differences in the solid state is demonstrated. Furthermore, the X-ray crystallographic and 31P MAS NMR spectroscopic characterisation of a new polymorph of 1 is reported.     

The reaction of Li[Al(OR)4] R = OC(CF3)2Ph, OC(CF3)3 with NO/NO2 giving NO[Al(OR)4], Li[NO3] and N2O. The synthesis of NO[Al(OR)4] from Li[Al(OR)4] and NO[SbF6] in sulfur dioxide solution

NO[Al(OC(CF(3))(2)Ph)(4)] 1 and NO[Al(OC(CF(3))(3))(4)] 2 were obtained by the metathesis reaction of NO[SbF(6)] and the corresponding Li[Al(OR)(4)] salts in liquid sulfur dioxide solution in ca 40% (1) and 85% (2) isolated yield. 1 and 2, as well as Li[NO(3)] and N(2)O, were also given by the reaction of an excess of mixture of (90 mol%) NO, (10 mol%) NO(2) with Li[Al(OR)(4)] followed by extraction with SO(2). The unfavourable disproportionation reaction of 2NO(2)(g) to [NO](+)(g) and [NO(3)](-)(g)[DeltaH degrees = +616.2 kJ mol(-1)] is more than compensated by the disproportionation energy of 3NO(g) to N(2)O(g) and NO(2)(g)[DeltaH degrees =-155.4 kJ mol(-1)] and the lattice energy of Li[NO(3)](s)[U(POT)= 862 kJ mol(-1)]. Evidence is presented that the reaction proceeds via a complex of [Li](+) with NO, NO(2)(or their dimers) and N(2)O. NO(2) and Li[Al(OC(CF(3))(3))(4)] gave [NO(3)(NO)(3)][Al(OC(CF(3))(3))(4)](2), NO[Al(OC(CF(3))(3))(4)] and (NO(2))[Al(OC(CF(3))(3))(4)] products. The aluminium complex [Li[AlF(OC(CF(3))(2)Ph)(3)]](2) 3 was prepared by the thermal decomposition of Li[Al(OC(CF(3))(2)Ph)(4)]. Compounds 1 and 3 were characterized by single crystal X-ray structural analyses, 1-3 by elemental analyses, NMR, IR, Raman and mass spectra. Solid 1 contains [Al(OC(CF(3))(2)Ph)(4)](-) and [NO](+) weakly linked via donor acceptor interactions, while in the SO(2) solution there is an equilibrium between the associated [NO](+)[Al(OC(CF(3))(2)Ph)(4)](-) and separated solvated ions. Solid 2 contains essentially ionic [NO](+) and [Al(OC(CF(3))(3))(4)](-). Complex 3 consists of two [Li[AlF(OC(CF(3))(2)Ph)(3)]] units linked via fluorine lithium contacts. Compound 1 is unstable in the SO(2) solution and decomposes to yield [AlF(OC(CF(3))(2)Ph)(3)](-), [(PhC(CF(3))(2)O)(3)Al(mu-F)Al(OC(CF(3))(2)Ph)(3)](-) anions as well as (NO)C(6)H(4)C(CF(3))(2)OH, while compound 2 is stable in liquid SO(2). The [small nu](NO(+)) in 1 and [NO](+)(toluene)[SbCl(6)] are similar, implying similar basicities of [Al(OC(CF(3))(2)Ph)(4)](-) and toluene.     

Silver complexes of cyclic hexachlorotriphosphazene

The first solid-state structures of complexed P3N3X6 (X = halogen) are reported for X = Cl. The compounds were obtained from P3N3Cl6 and Ag[Al(OR)4] salts in CH2Cl2/CS2 solution. The very weakly coordinating anion with R = C(CF3)3 led to the salt Ag(P3N3Cl6)2+[Al(OR)4]- (1), but the more strongly coordinating anion with R' = C(CH3)(CF3)2 gave the molecular adduct (P3N3Cl6)AgAl(OR')4 (3). Crystals of [Ag(CH2Cl2)(P3N3Cl6)2]+[Al(OR)4]- (2), in which Ag+ is coordinated by two phosphazene and one CH2Cl2 ligands, were isolated from CH2Cl2 solution. The three compounds were characterized by their X-ray structures, and 1 and 3 also by NMR and vibrational spectroscopy. Solution and solid-state 31P NMR investigations in combination with quantum chemically calculated chemical shifts show that the 31P NMR shifts of free and silver-coordinated P3N3Cl6 differ by less than 3 ppm and indicate a very weakly bound P3N3Cl6 ligand in 1. The experimental silver ion affinity (SIA) of the phosphazene ligand was derived from the solid-state structure of 3. The SIA shows that (PNCl2)3 is only a slightly stronger Lewis base than P4 and CH2Cl2, while other ligands such as S8, P4S3, toluene, and 1,2-Cl2C2H4 are far stronger ligands towards the silver cation. The energetics of the complexes were assessed with inclusion of entropic, thermal, and solvation contributions (MP2/TZVPP, COSMO). The formation of the cations in 1, 2, and 3 was calculated to be exergonic by delta(r)G(degrees)(CH2Cl2) = -97, -107, and -27 kJ mol(-1), respectively. All prepared complexes are thermally stable; formation of P3N3Cl5+ and AgCl was not observed, even at 60 degrees C in an ultrasonic bath. Therefore, the formation of P3N3Cl5+ was investigated by quantum chemical calculations. Other possible reaction pathways that could lead to the successful preparation of P3N3X5+ salts were defined.     

Hydrolysis of dinuclear ruthenium complexes [{CpRu(PPh3)2}2(micro,eta(1:1)-L)][CF3SO3]2 (L=P4, P4S3): simple access to metal complexes of P2H4 and PH2SH

The reaction of [CpRu(PPh(3))(2)Cl] (1) with half an equivalent of P(4) or P(4)S(3) in the presence of AgCF(3)SO(3) as chloride scavenger affords the stable dimetal complexes [{CpRu(PPh(3))(2)}(2)(micro,eta(1:1)-P(4))][CF(3)SO(3)](2).3 CH(2)Cl(2) (2) and [{CpRu(PPh(3))(2)}(2)(micro,eta(1:1)-P(apical)-P(basal)-P(4)S(3))][CF(3)SO(3)](2).0.5 C(7)H(8) (3), in which the tetrahedral P(4) and mixed-cage P(4)S(3) molecules are respectively bound to two CpRu(PPh(3))(2) fragments through two phosphorus atoms. The coordinated cage molecules, at variance with the free ligands, readily react with an excess of water in THF under mild conditions. Among the hydrolysis products, the new, remarkably stable complexes [{CpRu(PPh(3))(2)}(2)(micro,eta(1:1)-P(2)H(4))][CF(3)SO(3)](2) (4) and [CpRu(PPh(3))(2)(eta(1)-PH(2)SH)]CF(3)SO(3) (8) were isolated. In the former, diphosphane, P(2)H(4), is coordinated to two CpRu(PPh(3))(2) fragments, and in the latter thiophosphinous acid, H(2)PSH, is coordinated to the metal centre through the phosphorus atom. All compounds were characterised by elemental analyses and IR and NMR spectroscopy. The crystal structures of 2, 3, 4 and 8 were determined by X-ray diffraction.     

Rhodium and palladium complexes of a pyridyl-centred polyphenylene derivative

2-(2'-Pyridyl)-3,4,5,6-tetraphenylpyridine 2 (HL), a ligand with both N,N-bidentate and N,N,C-terdentate coordination potential, was prepared in excellent yield by the Diels-Alder [2+4] cycloaddition of 2-cyanopyridine and tetraphenylcyclopentadien-1-one. Monometallic Pd(II) and Rh(III) complexes were formed which exhibit both types of ligand coordination (trans-[RhCl2(L)(NCMe)] 3, cis-[RhCl(L)(NCMe)2]PF6, cis-[RhCl2(HL)2]PF6 6, [RhCl(L)(HL)]PF6 7, [Rh(L)2]PF6 8, [Pd(OAc)(L)] 9 and [Pd(eta3-methallyl)(HL)]PF6) 10. The molecular structures of the ligand and six complexes, including the chloro-bridged dimer [RhCl(L)(micro-Cl)]2 5, were obtained by single crystal X-ray diffraction.     

Homoleptic Cu-phosphorus and Cu-ethene complexes

Stable salts of the first homoleptic Cu-phosphorus and Cu-ethene complexes, [Cu(eta2-P4)2]+ and [Cu(eta2-C2H4)3]+, isolated by the aid of the weakly coordinating anion (WCA) [Al(OC(CF3)3)4]-, were obtained.     

Triazenide-bridged rhodium-palladium complexes: [I2Rh(mu-p-MeC6H4NNNC6H4Me-p)2Pd(eta(3)-C3H5)]-, a stable paramagnetic [RhPd]4+ species with a localised Rh(II) centre

Deprotonation of mixtures of the triazene complexes [RhCl(CO)2(p-MeC6H4NNNHC6H4Me-p)] and [PdCl(eta(3)-C3H5)(p-MeC6H4NNNHC6H4Me-p)] or [PdCl2(PPh3)(p-MeC6H4NNNHC6H4Me-p)] with NEt3 gives the structurally characterised heterobinuclear triazenide-bridged species [(OC)2Rh(mu-p-MeC6H4NNNC6H4Me-p)2PdLL'] {LL' = eta(3)-C3H5 1 or Cl(PPh3) 2} which, in the presence of Me3NO, react with [NBu(n)4]I, [NBu(n)4]Br, [PPN]Cl or [NBu(n)4]NCS to give [(OC)XRh(mu-p-MeC6H4NNNC6H4Me-p)2PdCl(PPh3)]- (X = I 3-, Br 4-, Cl 5- or NCS 6-) and [NBu(n)4][(OC)XRh(mu-p-MeC6H4NNNC6H4Me-p)2Pd(eta(3)-C3H5)], (X = I 7- or Br 8-). The allyl complexes 7- and 8- undergo one-electron oxidation to the corresponding unstable neutral complexes 7 and 8 but, in the presence of the appropriate halide, oxidative substitution results in the stable paramagnetic complexes [NBu(n)4][X2Rh(mu-p-MeC6H4NNNC6H4Me-p)2Pd(eta(3)-C3H5)], (X = I 9- or Br 10-). X-Ray structural (9-), DFT and EPR spectroscopic studies are consistent with the unpaired electron of 9- and 10- localised primarily on the Rh(II) centre of the [RhPd]4+ core, which is susceptible to oxygen coordination at low temperature to give Rh(III)-bound superoxide.     

Relative Lewis basicities of six AI(ORF)4- superweak anions and the structures of LiA

The relative Lewis basicities of six Al(ORF)4- ions, Al[OC(CH3)(CF3)2]4-, Al(OC(CF3)3]4-, Al(OCPh(CF3)2]4-, Al[OC[4-C6H4(tBu)](CF3)2]4-, Al(OC(Cy)(CF3)2]4-, and Al(OCPh2(CF3)]4-, have been determined by measuring their relative coordinating abilities towards Li+ in dichloromethane. The relative Li- Lewis basicities of the Al(ORF)4- ions are linearly related to the aqueous pKa values of the corresponding parent HORF fluoroalcohols. The Lewis basicity of Al[OCH(CF3)2]4- could not be measured because two of these anions can coordinate to one Li+ cation. The structures of LiAl[OCH(CF3)2]4 and [1-Et-3-Me-1,3-C3H3N2][Li[Al[OCH(CF3)2)4]2] were determined.     

Unprecedented eta(1)-P(basal) coordination of P(4)X(3) molecules (X = S, Se). An experimental and theoretical study of the apical vs basal complexation dichotomy

Reaction of [(triphos)Re(CO)(2)(OTf)] (1) [triphos = MeC(CH(2)PPh(2))(3); OTf = OSO(2)CF(3)] with P(4)S(3) and P(4)Se(3) yields pairs of coordination isomers, namely, [(triphos)Re(CO)(2)[eta(1)-P(apical)-P(4)X(3)]](+) (X = S, 2; Se, 5) and [(triphos)Re(CO)(2)[eta(1)-P(basal)-P(4)X(3)]](+) (X = S, 3; Se, 6). The latter represent the first examples of the eta(1)-P(basal) coordination achieved by the P(4)X(3) molecular cage. Further reaction of 2/3 and 5/6 mixtures with 1 affords the dinuclear species [[(triphos)Re(CO)(2)](2)[mu,eta(1:1)-P(apical,)P(basal)-P(4)X(3)]](2+) (X = S, 4; Se, 7) in which the unprecedented M-eta(1)-P(basal)/eta(1)-P(apical)-M' bridging coordination of the P(4)X(3) molecule is accomplished. A theoretical analysis of the bonding properties of the two coordination isomers is also presented. The directionality of apical vs basal phosphorus lone pairs is also discussed in terms of MO arguments.     

Unusual pathways for metal-assisted C[bond]C and C[bond]P coupling reactions using allenylidenerhodium complexes as precursors

The rhodium allenylidenes trans-[RhCl[[double bond]C[double bond]C[double bond]C(Ph)R](PiPr(3))(2)] [R = Ph (1), p-Tol (2)] react with NaC(5)H(5) to give the half-sandwich type complexes [(eta(5)-C(5)H(5))Rh[[double bond]C[double bond]C[double bond]C(Ph)R](PiPr(3))] (3, 4). The reaction of 1 with the Grignard reagent CH(2)[double bond]CHMgBr affords the eta(3)-pentatrienyl compound [Rh(eta(3)-CH(2)CHC[double bond]C[double bond]CPh(2))(PiPr(3))(2)] (6), which in the presence of CO rearranges to the eta(1)-pentatrienyl derivative trans-[Rh[eta(1)-C(CH[double bond]CH(2))[double bond]C[double bond]CPh(2)](CO)(PiPr(3))(2)] (7). Treatment of 7 with acetic acid generates the vinylallene CH(2)[double bond]CH[bond]CH[double bond]=C=CPh(2) (8). Compounds 1 and 2 react with HCl to give the five-coordinate allenylrhodium(III) complexes [RhCl(2)[CH[double bond]C[double bond]C(Ph)R](PiPr(3))(2)] (10, 11). An unusual [C(3) + C(2) + P] coupling process takes place upon treatment of 1 with terminal alkynes HC[triple bond]CR', leading to the formation of the eta(3)-allylic compounds [RhCl[eta(3)-anti-CH(PiPr(3))C(R')C[double bond]C[double bond]CPh(2)](PiPr(3))] [R' = Ph (12), p-Tol (13), SiMe(3) (14)]. From 12 and RMgBr the corresponding phenyl and vinyl rhodium(I) derivatives 15 and 16 have been obtained. The previously unknown unsaturated ylide iPr(3)PCHC(Ph)[double bond]C[double bond]C[double bond]CPh(2) (17) was generated from 12 and CO. A [C(3) + P] coupling process occurs on treatment of the rhodium allenylidenes 1, 2, and trans-[RhCl[[double bond]C[double bond]C[double bond]C(p-Anis)(2)](PiPr(3))(2)] (20) with either Cl(2) or PhICl(2), affording the ylide-rhodium(III) complexes [RhCl(3)[C(PiPr(3))C[double bond]C(R)R'](PiPr(3))] (21-23). The butatrienerhodium(I) compounds trans-[RhCl[eta(2)-H(2)C[double bond]C[double bond]C[double bond]C(R)R'](PiPr(3))(2)] (28-31) were prepared from 1, 20, and trans-[RhCl[[double bond]C[double bond]C[double bond]C(Ph)R](PiPr(3))(2)] [R = CF(3) (26), tBu (27)] and diazomethane; with the exception of 30 (R = CF(3), R' = Ph), they thermally rearrange to the isomers trans-[RhCl[eta(2)-H(2)C[double bond]C[double bond]C[double bond]C(R)R'](PiPr(3))(2)] (32, 33, and syn/anti-34). The new 1,1-disubstituted butatriene H(2)C[double bond]C[double bond]C[double bond]C(tBu)Ph (35) was generated either from 31 or 34 and CO. The iodo derivatives trans-[RhI(eta(2)-H(2)C[double bond]C[double bond]C[double bond]CR(2))(PiPr(3))(2)] [R = Ph (38), p-Anis (39)] were obtained by an unusual route from 1 or 20 and CH(3)I in the presence of KI. While the hydrogenation of 1 and 26 leads to the allenerhodium(I) complexes trans-[RhCl[eta(2)-H(2)C[double bond]C[double bond]C(Ph)R](PiPr(3))(2)] (40, 41), the thermolysis of 1 and 20 produces the rhodium(I) hexapentaenes trans-[RhCl(eta(2)-R(2)C[double bond]C[double bond]C[double bond]C[double bond]C[double bond]CR(2))(PiPr(3))(2)] (44, 45) via C-C coupling. The molecular structures of 3, 7, 12, 21, and 28 have been determined by X-ray crystallography.     

C-C coupling reactions in the coordination sphere of rhodium(I) and rhodium(III): New routes for the di- and trimerization of terminal alkynes

The alkynyl(vinylidene)rhodium(I) complexes trans-[Rh(C[triple bond, length as m-dash]CR)(=C=CHR)(PiPr3)2] 2, 5, 6 react with CO by migratory insertion to give stereoselectively the butenynyl compounds trans-[Rh{eta1-(Z)-C(=CHR)C[triple bond, length as m-dash]CR}(CO)(PiPr3)2](Z)-7-9, of which (Z)-7 (R=Ph) and (Z)-8 (R=tBu) rearrange upon heating or UV irradiation to the (E) isomers. Similarly, trans-[Rh{eta1-C(=CH2)C[triple bond, length as m-dash]CPh}(CO)(PiPr3)2] 12 and trans-[Rh{eta1-(Z)-C(=CHCO2Me)C[triple bond, length as m-dash]CR}(CO)(PiPr3)2](Z)-15, (Z)-16 have been prepared. At room temperature, the corresponding "non-substituted" derivative trans-[Rh{eta1-C(=CH2)C[triple bond, length as m-dash]CH}(CO)(PiPr3)2] 18 is in equilibrium with the butatrienyl isomer trans-[Rh(eta1-CH=]C=C=CH2)(CO)(PiPr3)2] 19 that rearranges photochemically to the alkynyl complex trans-[Rh(C[triple bond, length as m-dash]CCH=CH2)(CO)(PiPr3)2] 20. Reactions of (Z)-7, (E)-7, (Z)-8 and (E)-8 with carboxylic acids R'CO2H (R'=CH3, CF3) yield either the butenyne (Z)- and/or (E)-RC[triple bond, length as m-dash]CCH=CHR or a mixture of the butenyne and the isomeric butatriene, the ratio of which depends on both R and R'. Treatment of 2 (R=Ph) with HCl at -40 degrees C affords five-coordinate [RhCl(C[triple bond, length as m-dash]CPh){(Z)-CH=CHPh}(PiPr3)2] 23, which at room temperature reacts by C-C coupling to give trans-[RhCl{eta2-(Z)-PhC[triple bond, length as m-dash]CCH=CHPh}(PiPr3)2](Z)-21. The related compound trans-[RhCl(eta2-HC[triple bond, length as m-dash]CCH=CH2)(PiPr3)2] 27, prepared from trans-[Rh(C[triple bond, length as m-dash]CH)(=C=CH2)(PiPr3)2] 17 and HCl, rearranges to the vinylvinylidene isomer trans-[RhCl(=C=CHCH=CH2)(PiPr3)2] 28. While stepwise reaction of 2with CF3CO2H yields, via alkynyl(vinyl)rhodium(III) intermediates (Z)-29 and (E)-29, the alkyne complexes trans-[Rh(kappa1-O2CCF3)(eta2-PhC[triple bond, length as m-dash]CCH=CHPh)(PiPr3)2](Z)-30 and (E)-30, from 2 and CH3CO2H the acetato derivative [Rh(kappa2-O2CCH3)(PiPr3)2] 33 and (Z)-PhC[triple bond, length as m-dash]CCH=]CHPh are obtained. From 6 (R=CO2Me) and HCl or HC[triple bond, length as m-dash]CCO2Me the chelate complexes [RhX(C[triple bond, length as m-dash]CCO2Me){kappa2(C,O)-CH=CHC(OMe)=O}(PiPr3)2] 34 (X=Cl) and 35 (X=C[triple bond, length as m-dash]CCO2Me) have been prepared. In contrast to the reactions of [Rh(kappa2-O2CCH3)(C[triple bond, length as m-dash]CE)(CH=CHE)(PiPr3)2] 37(E=CO2Me) with chloride sources which give, via intramolecular C-C coupling, four-coordinate trans-[RhCl{eta2-(E)-EC[triple bond, length as m-dash]CCH=CHE}(PiPr3)2](E)-36, treatment of 37with HC[triple bond, length as m-dash]CE affords, via insertion of the alkyne into the rhodium-vinyl bond, six-coordinate [Rh(kappa2-O2CCH3)(C[triple bond, length as m-dash]CE){eta1-(E,E)-C(=CHE)CH=CHE}(PiPr3)2] 38. The latter reacts with MgCl2 to yield trans-[RhCl{eta2-(E,E)-EC[triple bond, length as m-dash]CC(=CHE)CH=CHE}(PiPr3)2] 39, which, in the presence of CO, generates the substituted hexadienyne (E,E)-EC[triple bond, length as m-dash]CC(=CHE)CH=CHE 40.     

A convenient route to dinuclear chloro-bridged platinum(II) derivatives via nitrile complexes

The syntheses of the complexes [PtCl(2)(NCR)L] [R = Me, Et; L = PPh(3); R = Et, L = Py, CO] and [PtCl{(κ(2)-P,C)P(OC(6)H(4))(OPh)(2)}(NCEt)] are described starting from the easily available [PtCl(2)(NCR)(2)]. The stability of the products under different experimental conditions is discussed as well as their use as precursors to dinuclear complexes [Pt(μ-Cl)ClL](2). The crystal and molecular structures of cis-[PtCl(2)(NCEt)(PPh(3))], [SP-4-2]-[PtCl{(κ(2)-P,C)P(OC(6)H(4))(OPh)(2)}(NCEt)] and trans-[Pt(μ-Cl){(κ(2)-P,C)P(OC(6)H(4))(OPh)(2)}](2) are reported.     

Iridium-imine and -amine complexes relevant to the (S)-metolachlor process: structures, exchange kinetics, and C-H activation by Iri causing racemization

Iridium complexes of DMA-imine [2,6-dimethylphenyl-1'-methyl-2'-methoxyethylimine, 1 a) and (R)-DMA-amine [(1'R)-2,6-dimethylphenyl-1'-methyl-2'-methoxyethylamine, 2 a] that are relevant to the catalytic imine hydrogenation step of the Syngenta (S)-Metolachlor process were synthesized: metathetical exchange of [Ir2Cl2(cod)2] (cod=1,5-cyclooctadiene) with [Ag(1 a)2]BF4 and [Ag((R)-2 a)2]BF4 afforded [Ir(cod)(kappa2- -1 a)]BF4 (11) and [Ir(cod)(kappa2-(R)-2 a)]BF4 ((R)-19)), respectively. These complexes were then used in stopped-flow experiments to study the displacement of amine 2 a from complex 19 by imine 1 a to form the imine complex 11, thus modeling the product/substrate exchange step in the catalytic cycle. The data suggest a two-step associative mechanism characterized by k1=(2.6+/-0.3) x 10(2) M(-1) s(-1) and k2=(4.3+/-0.6) x 10(-2) s(-1) with the respective activation energies EA1=(7.5+/-0.6) kJ mol(-1) and EA2=(37+/-3) kJ mol(-1). Furthermore, complex 11 reacted with H2O to afford the hydrolysis product [Ir(cod)(eta(6-)-2,6-dimethylaniline)]BF4 (12), and with I2 to liberate quantitatively the DMA-iminium salt 14. On the other hand, the chiral amine complex (R)-19 formed the optically inactive eta6-bound compound [Ir(cod)(eta6-rac-2 a)]BF4 (rac-18) upon dissolution in THF at room temperature, presumably via intramolecular C-H activation. This racemization was found to be a two-step event with k'1=9.0 x 10(-4) s(-1) and k2=2.89 x 10(-5) s(-1), featuring an optically active intermediate prior to sp3 C-H activation. Compounds 11, 12, rac-18, and (R)-19 were structurally characterized by single-crystal X-ray analyses.     

Solution and solid-state dynamics of metal-coordinated white phosphorus

The dynamic behavior in solution of eight mono-hapto?tetraphosphorus transition metal-complexes, trans-[Ru(dppm)(2) (H)(η(1) -P(4) )]BF(4) ([1]BF(4) ), trans-[Ru(dppe)(2) (H)(η(1) -P(4) )]BF(4) ([2]BF(4) ), [CpRu(PPh(3) )(2) (η(1) -P(4) )]PF(6) ([3]PF(6) ), [CpOs(PPh(3) )(2) (η(1) -P(4) )]PF(6) ([4]PF(6) ), [Cp*Ru(PPh(3) )(2) (η(1) -P(4) )]PF(6) ([5]PF(6) ), [Cp*Ru(dppe)(η(1) -P(4) )]PF(6) ([6]PF(6) ), [Cp*Fe(dppe)(η(1) -P(4) )]PF(6) ([7]PF(6) ), [(triphos)Re(CO)(2) (η(1) -P(4) )]OTf ([8]OTf), and of three bimetallic Ru(μ,η(1:2) -P(4) )Pt species [{Ru(dppm)(2) (H)}(μ,η(1:2) -P(4) ){Pt(PPh(3) )(2) }]BF(4) ([1-Pt]BF(4) ), [{Ru(dppe)(2) (H)}(μ,η(1:2) -P(4) ){Pt(PPh(3) )(2) }]BF(4) ([2-Pt]BF(4) ), [{CpRu(PPh(3) )(2) )}(μ,η(1:2) -P(4) ){Pt(PPh(3) )(2) }]BF(4) ([3-Pt]BF(4) ), [dppm=bis(diphenylphosphanyl)methane; dppe=1,2-bis(diphenylphosphanyl)ethane; triphos=1,1,1-tris(diphenylphosphanylmethyl)ethane; Cp=η(5) -C(5) H(5) ; Cp*=η(5) -C(5) Me(5) ] was studied by variable-temperature (VT) NMR and (31) P{(1) H} exchange spectroscopy (EXSY). For most of the mononuclear species, NMR spectroscopy allowed to ascertain that the metal-coordinated P(4) molecule experiences a dynamic process consisting, apart from the free rotation about the M?P(4) axis, in a tumbling movement of the P(4) cage while remaining chemically coordinated to the central metal. EXSY and VT (31) P?NMR experiments showed that also the binuclear complex cations [1-Pt](+) -[3-Pt](+) are subjected to molecular motions featured by the shift of each metal from one P to an adjacent one of the P(4) moiety. The relative mobility of the metal fragments (Ru vs. Pt) was found to depend on the co-ligands of the binuclear complexes. For complexes [2]BF(4) and [3]PF(6) , MAS, (31) P?NMR experiments revealed that the dynamic processes observed in solution (i.e., rotation and tumbling) may take place also in the solid state. The activation parameters for the dynamic processes of complexes 1(+) , 2(+) , 3(+) , 4(+) , 6(+) , 8(+) in solution, as well as the X-ray structures of 2(+) , 3(+) , 5(+) , 6(+) are also reported. The data collected suggest that metal-coordinated P(4) should not be considered as a static ligand in solution and in the solid state.     

Metal-metal bonded homo- and heterobimetallic compounds of Pt(I) and Pd(I) supported by a bridging-N,P:N',P' moiety of a potentially hexadentate ligand

Reactions of metal-metal bonded homobimetallic (Pd(2)) and heterobimetallic (PtPd) complexes, supported by a P,P'-bridging-bis(P,N-chelating) coordination mode of the potentially hexadentate ligand 1,1-bis[di(o-N,N-dimethylanilinyl)phosphino]methane (dmapm), with CO, diethylacetylenedicarboxylate (DEAD), and thiols (RSH) in CH(2)Cl(2) are described. At room temperature, rac-Pd(2)Cl(2)(mu-N,P:P',N'-dmapm) gives the stable complexes Pd(2)Cl(2)(mu-CO)(2)(mu-P:P'-dmapm) and PdCl(eta2-DEAD)(mu-P:P',N-dmapm)PdCl (which is fluxional in solution), while rac-PtPdCl(2)(mu-N,P:P',N'-dmapm) disproportionates to PtCl(2)(P,P'-dmapm) and Pd metal, although at low temperature intermediate carbonyl species are detected in the CO reaction. The reactions with thiols in the presence of triflic acid (HOTf) generate rac-[MPdCl(2)(mu-SR)(mu-N,P:P',N'-dmapm)][OTf] and H(2) for both M = Pt and Pd. In CH(2)Cl(2), PdX(2)(dmapm) species (X = halide or CN) exist as equilibrium mixtures of P,P'- and P,N-ligated forms. For X = Cl, the P,P'-P,N equilibrium is governed by DeltaH degrees = -5.5 +/- 0.5 kJ mol(-1) and DeltaS degrees = 10 +/- 1 J mol(-1) K(-1), and the ring-strain energy within the P,P'-isomer is approximately 32 kJ mol(-1); the equilibrium increasingly favors the P,N-form with X = CN > I > Br > Cl. The solid-state structures of rac-[PtPdCl(2)(mu-SEt)(mu-N,P:P',N'-dmapm)][OTf] and PdCl(2)(P,N-dmapm) are presented; the latter contains both bound and free N- and P-atoms of identical types in the same molecule and permits an assessment of sigma- and pi-bonding between these atoms and Pd.     

Mixed-transition-metal acetylides: synthesis and characterization of complexes with up to six different transition metals connected by carbon-rich bridging units

The synthesis and reaction chemistry of heteromultimetallic transition-metal complexes by linking diverse metal-complex building blocks with multifunctional carbon-rich alkynyl-, benzene-, and bipyridyl-based bridging units is discussed. In context with this background, the preparation of [1-{(eta(2)-dppf)(eta(5)-C(5)H(5))RuC[triple bond]C}-3-{(tBu(2)bpy)(CO)(3)ReC[triple bond]C}-5-(PPh(2))C(6)H(3)] (10) (dppf = 1,1'-bis(diphenylphosphino)ferrocene; tBu(2)bpy = 4,4'-di-tert-butyl-2,2'-bipyridyl; Ph = phenyl) is described; this complex can react further, leading to the successful synthesis of heterometallic complexes of higher nuclearity. Heterotetrametallic transition-metal compounds were formed when 10 was reacted with [{(eta(5)-C(5)Me(5))RhCl(2)}(2)] (18), [(Et(2)S)(2)PtCl(2)] (20) or [(tht)AuC[triple bond]C-bpy] (24) (Me = methyl; Et = ethyl; tht = tetrahydrothiophene; bpy = 2,2'-bipyridyl-5-yl). Complexes [1-{(eta(2)-dppf)(eta(5)-C(5)H(5))RuC[triple bond]C}-3-{(tBu(2)bpy)(CO)(3)ReC[triple bond]C}-5-{PPh(2)RhCl(2)(eta(5)-C(5)Me(5))}C(6)H(3)] (19), [{1-[(eta(2)-dppf)(eta(5)-C(5)H(5))RuC[triple bond]C]-3-[(tBu(2)bpy)(CO)(3)ReC[triple bond]C]-5-(PPh(2))C(6)H(3)}(2)PtCl(2)] (21), and [1-{(eta(2)-dppf)(eta(5)-C(5)H(5))RuC[triple bond]C}-3-{(tBu(2)bpy)(CO)(3)ReC[triple bond]C}-5-{PPh(2)AuC[triple bond]C-bpy}C(6)H(3)] (25) were thereby obtained in good yield. After a prolonged time in solution, complex 25 undergoes a transmetallation reaction to produce [(tBu(2)bpy)(CO)(3)ReC[triple bond]C-bpy] (26). Moreover, the bipyridyl building block in 25 allowed the synthesis of Fe-Ru-Re-Au-Mo- (28) and Fe-Ru-Re-Au-Cu-Ti-based (30) assemblies on addition of [(nbd)Mo(CO)(4)] (27), (nbd = 1,5-norbornadiene), or [{[Ti](mu-sigma,pi-C[triple bond]CSiMe(3))(2)}Cu(N[triple bond]CMe)][PF(6)] (29) ([Ti] = (eta(5)-C(5)H(4)SiMe(3))(2)Ti) to 25. The identities of 5, 6, 8, 10-12, 14-16, 19, 21, 25, 26, 28, and 30 have been confirmed by elemental analysis and IR, (1)H, (13)C{(1)H}, and (31)P{(1)H} NMR spectroscopy. From selected samples ESI-TOF mass spectra were measured. The solid-state structures of 8, 12, 19 and 26 were additionally solved by single-crystal X-ray structure analysis, confirming the structural assignment made from spectroscopy.     

Rhodium(I) and rhodium(III) complexes formed by coordination and C-H activation of bulky functionalized phosphanes

The reaction of [[RhCl(C(8)H(14))(2)](2)] (2) with iPr(2)PCH(2)CH(2)C(6)H(5) (L(1)) led, via the isolated dimer [[RhCl(C(8)H(14))(L(1))](2)] (3), to a mixture of three products 4 a-c, of which the dinuclear complex [[RhCl(L(1))(2)](2)] (4 a) was characterized by Xray crystallography. The mixture of 4a-c reacts with CO, ethene, and phenylacetylene to give the square-planar compounds trans-[RhCl(L)(L(1))(2)] (L=CO (5), C(2)H(4) (6), C=CHPh (9)). The corresponding allenylidene(chloro) complex trans-[RhCl(=C=C=CPh(2))(L(1))(2)] (11), obtained from 4 a-c and HC triple bond CC(OH)Ph(2) via trans-[RhCl[=C=CHC(OH)Ph(2)](L(1))(2)] (10), could be converted stepwise to the related hydroxo, cationic aqua, and cationic acetone derivatives 12-14, respectively. Treatment of 2 and [[RhCl(C(2)H(4))(2)](2)] (7) with two equivalents of tBu(2)PCH(2)CH(2)C(6)H(5) (L(2)) gave the dimers [[RhCl(C(8)H(14))(L(2))](2)] (15) and [[RhCl(C(2)H(4))(L(2))](2)] (16), which both react with L(2) in the molar ratio of 1:2 to afford the five-coordinate aryl(hydrido)rhodium(III) complex [RhHCl(C(6)H(4)CH(2)CH(2)PtBu(2)-kappa(2)C,P)(L(2))] (17) by C-H activation. The course of the reactions of 17 with CO, H(2), PhC triple bond CH, HCl, and AgPF(6), leading to the compounds 19-21, 24, and 25 a, respectively, indicate that the coordinatively unsaturated isomer of 17 with the supposed composition [RhCl(L(2))(2)] is the reactive species. Labeling experiments using D(2), DCl, and PhC triple bond CD support this proposal. With either [Rh(C(8)H(14))(eta(6)-L(2)-kappaP]PF(6) or [Rh(C(2)H(4))(eta(6)-L(n)-kappaP]PF(6) (n=1 and 2) as the starting materials, the corresponding halfsandwich-type complexes 27, 28, and 32 were obtained. The nonchelating counterpart of the dihydrido compound 32 with the composition [RhH(2)(PiPr(3))(eta(6)-C(6)H(6))]PF(6) (35) was prepared stepwise from [Rh(C(2)H(4))(PiPr(3))(eta(6)-C(6)H(6))]PF(6) and H(2) in acetone via the tris(solvato) species [RhH(2)(PiPr(3))(acetone)(3)]PF(6) (34) as intermediate. The synthesis of the bis(chelate) complex [Rh(eta(4)-C(8)H(12))(C(6)H(5)OCH(2)CH(2)PtBu(2)-kappa(2)O,P)]BF(4) (39) is also described. Besides 4 a, the compounds 17, 25 a, and 39 have been characterized by Xray crystal structure analysis.