Synthesis and spectroscopic studies of silver and rhodium mono- and polynuclear complexes with multidentate phosphines (Ph2P)2CHR (R = H, Me, PPh2)

Trinuclear [{(Ph{2}P){3}CH}Ag{3}(O{2}CR'){3}], dinuclear [{(Ph{2}P){2}CHR}Ag{2}(O{2}CR'){2}], [{(Ph{2}P){2}CHR}{2}Ag{2}](BF{4}){2} and (Rh{2}(Cl)(CO){2}{(Ph{2}P){2}CHMe}{2}][RhCl{2}(CO){2}], and mononuclear (Rh{(Ph{2}P){2}CHR}{2}](BF{4}), (Rh{(Ph{2}P){2}CHR}{2}HCl](BF{4}), d [Rh{(Ph{2}P){2}CHR}{2}Cl(HgCl)](BF{4}) and (Rh{(Ph{2}P){2}CHR}{2}O{2}](BF{4}) (R = H,Me) were synthesized from the phosphines tris(diphenylphosphino)methane ((Ph{2}P){3}CH), bis(diphenylphosphino)methane ((Ph{2}P){2}CH{2}) and 1,1-bis(diphenylphosphino)ethane ((Ph{2}P){2}CHMe). The }1{H, }1{}3{C and }3{}1{P NMR spectra were investigated and for the mononuclear rhodium compounds compared with their 1,2-bis(diphenylphosphino)ethane and 1,3-bis(diphenylphosphino)propane analogues. The }3{}1{P NMR spectra of the silver complexes revealed besides normal values for J(}1{}0{}7{Ag-}3{}1{P) (640 and 500 Hz for the gAgP and AgP{2} systems, respectively) a small{3}J(}1{}0{}7{Ag-{3}{1}P) of about -4 Hz and an exceptionally large }2{J(}3{}1{P-}3{}1{P) of 170 Hz. A large positive charge on the P-atoms in [{(Ph{2}P){2}CH{2}}Ag{2}(O{2}CR){2}] and [{(Ph{2}P){2}CH{2}}Ag{2}](BF{4}){2} was calculated from the chemical shifts of the methylene protons.On the basis of }3{}1{P NMR data methyl substitution in (Ph{2}P){2}CHR resulted in formation of only one of the possible isomers for [{(Ph{2}P){2}CHMe}{2}Ag{2}](BF{4}){2}, [Rh{2}(CO){2}(Cl){(Ph{2}P){2}CHMe}{2}][RhCl{2}(CO){2}] and [Rh{(Ph{2}P){2}CHMe}{2}O{2}](BF{4}), but two isomers for [Rh{(Ph{2}P){2}CHMe}{2}](BF{4}) and [Rh{(Ph{2}P){2}CHMe}HCl](BF{4}). These results are interpreted in terms of metal@?chelate ring puckering

Synthesis and spectroscopic studies of silver and rhodium mono- and polynuclear complexes with multidentate phosphines (Ph2P)2CHR (R = H, Me, PPh2)

Trinuclear [{(Ph{2}P){3}CH}Ag{3}(O{2}CR'){3}], dinuclear [{(Ph{2}P){2}CHR}Ag{2}(O{2}CR'){2}], [{(Ph{2}P){2}CHR}{2}Ag{2}](BF{4}){2} and (Rh{2}(Cl)(CO){2}{(Ph{2}P){2}CHMe}{2}][RhCl{2}(CO){2}], and mononuclear (Rh{(Ph{2}P){2}CHR}{2}](BF{4}), (Rh{(Ph{2}P){2}CHR}{2}HCl](BF{4}), d [Rh{(Ph{2}P){2}CHR}{2}Cl(HgCl)](BF{4}) and (Rh{(Ph{2}P){2}CHR}{2}O{2}](BF{4}) (R = H,Me) were synthesized from the phosphines tris(diphenylphosphino)methane ((Ph{2}P){3}CH), bis(diphenylphosphino)methane ((Ph{2}P){2}CH{2}) and 1,1-bis(diphenylphosphino)ethane ((Ph{2}P){2}CHMe). The }1{H, }1{}3{C and }3{}1{P NMR spectra were investigated and for the mononuclear rhodium compounds compared with their 1,2-bis(diphenylphosphino)ethane and 1,3-bis(diphenylphosphino)propane analogues. The }3{}1{P NMR spectra of the silver complexes revealed besides normal values for J(}1{}0{}7{Ag-}3{}1{P) (640 and 500 Hz for the gAgP and AgP{2} systems, respectively) a small{3}J(}1{}0{}7{Ag-{3}{1}P) of about -4 Hz and an exceptionally large }2{J(}3{}1{P-}3{}1{P) of 170 Hz. A large positive charge on the P-atoms in [{(Ph{2}P){2}CH{2}}Ag{2}(O{2}CR){2}] and [{(Ph{2}P){2}CH{2}}Ag{2}](BF{4}){2} was calculated from the chemical shifts of the methylene protons.On the basis of }3{}1{P NMR data methyl substitution in (Ph{2}P){2}CHR resulted in formation of only one of the possible isomers for [{(Ph{2}P){2}CHMe}{2}Ag{2}](BF{4}){2}, [Rh{2}(CO){2}(Cl){(Ph{2}P){2}CHMe}{2}][RhCl{2}(CO){2}] and [Rh{(Ph{2}P){2}CHMe}{2}O{2}](BF{4}), but two isomers for [Rh{(Ph{2}P){2}CHMe}{2}](BF{4}) and [Rh{(Ph{2}P){2}CHMe}HCl](BF{4}). These results are interpreted in terms of metal@?chelate ring puckering

Aspects of transmetallation reactions of 2-Me2NCH2C6H4- and 2,6-(Me2NCH2)-C6H3-metal (Pd,Pt,Hg,Tl) complexes with metal carboxylates and low-valent metal (Pd,Pt) complexes

A study has been made of reactions involving organometallic compounds containing ortho-Me{2}NCH{2} substituted aryl ligands. The single step syntheses of the new compounds [(2-Me{2}NCH{2}C{6}H{4}){2}TlCl], [ [{(S)-2-Me{2}NCH(Me)C{6}H{4}}{2}TlCl], [{(S)-2-Me{2}NCH(Me)C{6}H{4}}TlCl{2}], [{2, 6-(Me{2}NCH{2}){2}C{6}H{3}}TlClBr] and [{2,6-(Me{2}NCH{2}){2}C{6}H{3}}HgCl] are described. Stable internal N@?Tl coordination at low temperatures has been established for the C-chiral thallium compounds. Reactions of the other Tl and Hg compounds and of [(2-Me{2}NCH{2}C{6}H{4}){2}Hg] with Pd(O{2}CMe){2}, and also of the reverse reaction of cis-[(2-Me{2}NCH{2}C{6}H{4}){2}Pd] with Hg(O{2}CR){2} or Tl(O{2}CR){3}, gave transmetallation of one organo ligand and led to a single mono-organopalladium compound and corresponding by-products. Reaction of cis-[({2}-Me{2}NCH{2}C{6}H{4}){2}Pd] with Pd(O{2}CR){2} gave the dimeric compound [{(2-Me{2}NCH{2}C{6}H{4})Pd(O{2}CR)}{2}]. cis-[(2-Me{2}NCH{2}C{6}H{4}){2}Pt] did not react with Pd(O{2}CMe){2}, while reaction of trans-[(2-Me{2}NCH{2}C{6}H{4}){2}Pt] or cis-[(2-Me{2}NC{6}H{4}CH{2}){2}Pt] with Pd(O{2}CMe){2} resulted in decomposition. Upon heating, trans-[(2-Me{2}NCH{2}C{6}H{4}){2}Pt] was isomerized to cis-isomer. A redox reaction between [(2-Me{2}NCH{2}C{6}H{4}){2}Hg] and [Pt(COD){2}] (COD @? 1,5-cyclo-octadiene) and [Pd{2}(DBA){3}] (DBA @? dibenzylideneacetone) gave the cis-isomers of [(2-Me{2}NCH{2}C{6}H{4}){2}M] (M @? Pd, Pt).The results are discussed in terms of influence of internal coordination of the CH{2}NMe{2} group. It is concluded that although internal coordination of the CH{2}NMe{2} ligand can stabilize metal-carbon bonds it cannot prevent cleavage of such bonds by electrophiles. In this respect, there is no difference in the behaviour of Hg(O{2}CR){2} and Tl(O{2}CR){3}. The reactions are influenced by the metal-nitrogen bond strength, which follows the order Pt@?N > Pd@?N > Hg@?N, Tl@?N. The reactivity of Pt compounds is greatly influenced by their structure and type of ligand. It is proposed that cleavege of Pd@?C bonds occurs mainly by a mechanism involving direct electrophilic attack at the carbon centre

Silver complexes containing an Ag4O8 core imposed by multidentate ligands having fixed geometry. Crystal structure of**[bis(1,8-naphthalenedicarboxylato)] [tetrakis(triphenylphosphine)silver(I)] dibenzene

Reactions of (1,8-naphthaIenedicarbxylato)disilver(I), (c&@4)Ag~, with phosphines yielded the products (C&O&(LAg),, where L = triphenylphosphine or tri-p-tolylphosphine and 2L = bis(dipheny1phosphino)methane (dppm) or 1,2-bis(dipheny1phosphino) ethane (dppe). An X-ray crystallographic study revealed the molecular structure of [bis( 1,8-naphthalenedicarboxylato)][ tetrakis(triphenylphosphine)silver(I)]-dibenzene, (C12H604)2(Ph3PAg),.2csp6aHc6e :g roup Pi with unit cell dimensions a = 11.804 (4) A, b = 18.390 (4) A, c = 22.046 (1) A, 01 = 103.23 (7)O, p = 95.81 (3)O, y = 90.08 (7)O, V = 4.633 X lo3 A3, and Z = 2. The crystal structure was solved for the heavy atoms by direct methods and completed by standard Fourier techniques. Block-diagonal least-squares refinement with 8664 observed diffractometer data converged to RF = 0.055 (R, = 0.054). The coordination geometry is different for each of the four silver atoms, each of which is bonded to one phosphine and positioned against a core of eight oxygen atoms. The four shortest Ag-Ag distances are in the range of 3.672-3.961 A while the Ag-P distances amount to 2.378 (5), 2.346 (5), 2.341 (5): and 2.363 (4) A. The carboxylato groups act as monodentate, chelating, or bridging ligands. The coordination is interpreted in terms of a weak ionic interaction between the oxygen atoms and the Ph3PAg+ ions containing a strong covalent P-Ag bond. Molecular weight determinations together with 31P NMR data show that the tetranuclear structure is retained in solution. The ,IP resonances of the four Ph3PAg units are isochronous (J(3'P-107Ag) = 650 Hz) pointing to the occurrence of an intramolecular process which renders these groups equivalent. A process involving intermolecular exchange with excess phosphine at low temperature could be excluded. In order to obtain additional information concerning J(Ag-P) in these compounds, the ,'P NMR spectra of novel dppm(AgOAc)2 (J(,IP-'07Ag) = 680 Hz) and dppe(AgOAc)2 (J(31P-'07Ag) = 663 Hz) were recorded

Dinuclear formamidino and triazenido compounds [{2,6(Me2NCH2)2-C6H3}(p-tolNYNR)PtHgBrCl] (Y = CH, N) containing a platinum-to-mercury donor bond

Complexes [{2, 6-(Me{2}NCH{2}){2}C{6}H{3}} (p-tolylNYNR)PtHgBrCl] (Y @? CH, N; R @? Me, Et, i-Pr) have been prepared by the reaction of [{2,6-(Me{2}NCH{2}){2}C{6}H{3}}-PtBr] with [Hg(p-tolylNYNR)Cl]. Similar complexes were obtained, although in lower yields, from exchange reactions of [{2,6-(Me{2}NCH{2}){2}C{6}H{3}} (RCO{2})-PtHg(O{2}CR)Br] with p-tolylNNN(H)-p-tolyl and p-tolylNC(H)N(H)Et.The proposed structure for these heterodinuclear compounds involves a Pt-to-Hg donor bond which is bridged by a triazenido (Y @? N) or a formamidino (Y @? CH) group, the five-membered ring thus formed acting as a stabilizing factor. The absence of a subsequent electron transfer reaction is ascribed to the constraints of the terdentate 2,6-(Me{2}NCH{2}){2}C{6}H{3} ligand, which fixes the N-donor atoms in mutual trans-positions.The use of p-tolylNYNR, where R is an alkyl group, results in the formation of two isomers of [{2,6-(Me{2}NCH{2}){2}C{6}H{3}} (p-tolylNYNR)PtHgBrCl] with p-tolyl-N and alkyl-N sites bonded either to Pt or Hg. The relative abundance of these isomers varies systematically with the nature of the group R. It is suggested that the ratio is determined during the formation of the complexes and that both steric and electronic factors are important

Synthesis of novel binuclear palladium-thallium carboxylates of the type PdTl(O2CR)5 and their structural characterization based on observation of J(203,205T1-1H) and J(203,205T1-13C)

Reactions of palladium(II) carboxylates with thallium(III) carboxylates in toluene yield complexes of the type PdTl(O{2}CR){5} (I), R = Me, Et, i-Pr, or PdTl(O{2}CR){2}(O{2}CR'){3}(II), R = Me, Et, i-Pr, Ph; R' = Me, Et, i-Pr. Substitution of the ligands in PdTl(O{2}CMe){5} by free carboxylic acid has shown to be a second preparative route for compounds of type I. No reaction was observed for Pd(O{2}CMe){2} with Hg(O{2}CMe){2}, PhHg(O{2}CMe) or Ag(O{2}CMe) nor was any reaction observerd between {Pd(O{2}CMe)(C{6}H{4}NNC{6}H{5})}{2} and Tl(O{2}CMe){3}. Reaction of Pd(O{2}CME){2} with Hg(O{2}C-i-Pr){2} yields Hg(O{2}CMe)(O{2}C-i-PR).The PdTl(O{2}CR){5} complexes are the first examples of heterobinuclear palladium compounds lacking CO or phosphine ligands. Interaction of PdTl(O{2}CR){5} with CO or phosphines leads to a breakdown of the binuclear unit. On the basis of }1{H and }1{}3{ C NMR spectra, which reveal coupling of the thallium nucleus with the respective carbon and hydrogen atoms, a structure is proposed which contains four carboxylato ligands bridging the PdTl unit and one apical ligand bonded to thallium. This structure does not involve a direct Pd-to-Tl bond. The dynamic }1{H and }1{}3{C NMR spectra show in solution the occurrence of two distinct processes, i.e. dissociation of the apical ligand and exchange of bridging and apical ligands

Electron and ligand transfer reactions between cyclometallated platinum(II) compounds and thallium(III) carboxylates

Reaction of trans-[(2-Me{2}NCH{2}C{6}H{4}{2}Pt}I{}I{] with Tl}I{}I{}I{(O{2}CR){3} (R = Me, i-Pr) gave direct elimination of Tl}I{(O{2}CR) and formation of the oxidative addition product [(2-Me{2}NCH{2}C{6}H{4}){2}Pt}I{}V{ (O{2}CR){2}], in two isomeric forms. A structure with the carbon ligands in trans positions is proposed for the main isomer, whereas the second isomer has the nitrogen ligands in trans positions. Conversion of the first isomer into the second was induced by addition of free carboxylic acid; evidence for rupture of a Pt@?O bond is given and a five-coordinate intermediate proposed. Pt@?O rupture does not occur for the trans-N-isomer.For [{2, 6-(Me{2}NCH{2}){2}C{6}H{3}}PtBr] with Tl(O{2}CR){3} (R = Me, i-Pr) two competing reactions have been observed, i.e. cis oxidative addition resulting in formation of cis-O-[{2,6-(Me{2}NCH{2}){2}C{6}H{3}}Pt(O{2}CR){2}Br] with elimination of Tl}I{(O{2}CR), and exchange of the bromide atom and a carboxylato group between the two metal centres. For R = Me a product has been isolated with stoichiometry [{2,6-(Me{2}NCH{2}){2}C{6}H{3}}Pt(O{2}CMe)]{2}.Tl(O{2}CMe)].2H{2}O, which is the adduct of some of the products of the above reactions. Adduct formation has been observed as the only reaction for [{2,6-(Me{2}NCH{2}){2}C{6}H{3}}Pt(O{2}CR)] and Tl(O{2}CR){3}, resulting in [{2,6-(me{2}NCH{2}){2}C{6}H{3}}Pt(O{2}CR).Tl(O{2}CR){3}]. The reactions of cis-[(2-Me{2}NCH{2}C{6}H{4}){2}Pt] and cis-[(2-Me{2}NC{6}H{4}CH{2}){2}Pt)] with Tl}I{}I{}I{(O{2}CR){3} (R = Me, i-Pr) are less well understood as compared with the corresponding reactions with Hg}I{}I{(O{2}CR){2}.In none of the reactions has evidence for covalent Pt@?Tl bonded intermediates been obtained. This result has been interpreted with an inner-sphere mechanism operating in electron transfer reactions involving Tl}I{}I{}I{(O{2}CR){3}

Arylmercury(II) compounds involving intramolecular coordination via the 2- Me2NCH2- and chiral (S)-2-Me2NCHMe-ring substituents

Arylmercury compounds of the type Ar{2}Hg and ArHgX (X = Cl, OAc) have been synthesized and characterized by }1{H and }1{}3{C NMR spectroscopy; the Ar group was either 2-Me{2}NCH{2}C{6}H{4} or (S)-2-Me{2}NCH(Me)C{6}H{4}, both of which contain N-donor ligands. The observation of anisochronous NMe resonances in (S)-2-Me{2}NCH(Me)C{6}H{4}HgX (X = Cl, OAc) at low temperature indicates that in solution the mercury centre is three-coordinate as a result of stable intramolecular Hg@?N coordinatio