Palladium and platinum dihalide complexes with dl-selenomethionine

Palladium and platinum dihalides react with dl-selenomethionine (sem), yielding the complexes [M(sem)X2](M=Pd,X=Cl or Br;M=Pt,X=Cl) and, in the presence of N,N-dimethylformamide (dmf), the species [M(sem)X2]·dmf (M=Pd, X=I; M=Pt, X=Cl, Br or I). The complexes were characterized by i.r. and proton n.m.r. spectroscopy and by thermogravimetric analysis, and their properties were compared with those of the dl-methionine analogues [M(Met)Cl2] and [Pt(Met)Cl2]·dmf. On the basis of n.m.r. data in deuteriated dimethyl sulfoxide, the platinum complexes undergo ligand rearrangement to form [Pt(sem)2]2+ moieties whereas the solvent does not seem to interact with the palladium coordination sphere, which contains the chelated N, Se ligand.     

Design and self-assembly of ditopic and tetratopic cavitand complexes

The self-assembly of open ditopic and tetratopic cavitand complexes has been investigated by using monofunctionalized cavitand ligands and suitable metal precursors. In the case of ditopic complexes, self-assembly protocols, leading exclusively to the formation of both thermodynamically stable cis-Pt square-planar complexes 8 and 9 and the kinetically inert fac-Re octahedral complex 14, have been elaborated. The use of cis-[Pt(CH3)CN)2Cl2] as metal precursor led to the formation of monotopic trans-10 and ditopic trans-11 cavitand complexes, while cis-[Pt(dmso)2Cl2] afforded both cis-13 and trans-11 isomers. The self-assembly of tetratopic cavitand complexes has been achieved by using mononuclear [Pd(CH3CN)4(BF4)2] and dinuclear [M2(tppb)(OTf)4] (19: M = Pt; 20: M = Pd) metal precursors. Only the tetratopic dinuclear complexes 21 and 22 were stable. The ligand configuration with two phosphorus and two cavitand ligands at the metal centers is the most appropriate to build tetratopic cavitand complexes with sufficient kinetic stability.     

Ring-opening reactions induced by gold(I) of five- and four-coordinate palladium(II) and platinum(II) complexes containing tripodal or linear polyphosphines

The tripodal ligands NP(3)(tris[2-(diphenylphosphino)ethyl]amine) and PP(3)(tris[2-(diphenylphosphino)ethyl]phosphine), form five-coordinate [Pd(NP(3))X]X [X = Cl (1), Br (2)], [M(PP(3))X]X [M = Pd: X = Cl (4), Br (5), I (6); M = Pt, X = Cl (7), Br (8), I (9)] and four-coordinate[Pd(NP(3))I]I (3) complexes containing three fused rings around the metal. The interaction between Au(tdg)X (tdg = thiodiglycol; X = Cl, Br) or AuI and the respective ionic halo complexes 1-9 in a 1:1 stoichiometric ratio occurs via a ring-opening reaction with formation of the heterobimetallic systems PdAu(NP(3))X(3)[X = Cl (11), Br (12), I (13)], [MAu(PP(3))X(2)]X [M = Pd: X = Cl (14), Br (15), I (16); M = Pt: X = Cl (17), Br (18), I (19)]. The cations of complexes 17 and 18 were shown, by X-ray diffraction, to contain a distorted square-planar Pt(II) arrangement (Pt(P(2)P)X) where PP(3) is acting as tridentate chelating ligand and an almost linear PAuX moiety bearing the dangling phosphorus formed in the ring-opening process. PPh(3) coordinates to Au(I) and not to M(II) when added in excess to 14 and 17. Complexes 14-17 and [Pt(P(4))](BPh(4))(2) (10) (P4=linear tetraphosphine) also react with A(I), via chelate ring-openings to give MAu(2)(PP(3))X(4) [M = Pd: X = Cl (20), Br (21), I (22); M = Pt: X = Cl (23)] and [Pt(2)Au(2)(mu-Cl)(2)(mu-P(4))(2)](BPh(4))(4) (24), respectively.     

The clusters [Ma(ECp*)b] (M=Pd, Pt; E=Al, Ga, In): structures, fluxionality, and ligand exchange reactions

The synthesis and structural characterization of the novel homoleptic cluster complexes [Pd2(GaCp*)2(mu2-GaCp*)3] (1c), [Pd3(GaCp*)4(mu2-GaCp*)4] (2b) and [Pd3(AlCp*)2(mu2-AlCp*)2(mu3-AlCp*)2] (3) (Cp*=C5Me5) are presented. Furthermore, ligand exchange reactions of these cluster complexes are explored. In contrast to the electronically and sterically saturated complexes [M(ECp*)4] (M=Ni, Pd, Pt), the new unsaturated analogues [M(a)(ER)b] (E=Al, Ga, In) react with a variety of typical ligands (Cp*Al, CO, phosphines, isonitriles) to give new di- and tri-substituted compounds like [Pt2(GaCp*)2(mu2-AlCp*)3] (1d), [PdPt(GaCp*)(PPh3)(mu2-GaCp*)3] (4b), or [Pd3(PPh3)3(mu2-InCp*)(mu3-InCp*)2] (8). The trends of the reactivity of [M(a)(ER)b] as well as their fluxional behavior in solution has been elucidated by NMR spectroscopy, resulting in a mechanistic rationale for the ligand exchange reactions as well as the fluxional processes.     

Syntheses and Structures of the Complexes cis-[M(C(6)F(5))(2)(N&arcraise;X)] (M = Pd, Pt; N&arcraise;X = 2-Iodoaniline, 2-Benzoylpyridine) Containing N&arcraise;X Acting as a Didentate Chelating Ligand and Displaying I-->M or O-->M Interactions

Complexes cis-[M(C(6)F(5))(2)(THF)(2)] (M = Pd, Pt) are weak Lewis acids and react with the halocarbon ligand 2-iodoaniline (R-I) yielding the corresponding cis-[M(C(6)F(5))(2)(R-I)] [M = Pd (1), Pt (2)]. In these complexes a (C-)I-M bond is present. The use of other 2-haloanilines (halogen = F, Cl, Br) does not yield the analogous complexes because of the lesser nucleophilic character of the halogen involved. The presence of the (C-)I-Pt bond in 2 has been confirmed by an X-ray structure determination, which also reveals an N-H.M hydrogen bond between two neutral molecules. Complex 2 crystallizes in the space group P&onemacr;: Z = 4; a = 11.797(4) ?; b = 13.735(4) ?; c = 14.107(4) ?; alpha = 97.24(2) degrees; beta = 90.91(2) degrees; gamma = 99.44(2) degrees; V = 2235(2) ?(3). Similarly, complexes cis-[M(C(6)X(5))(2)(THF)(2)] (M = Pd, Pt; X = F, Cl) react with the ligand 2-benzoylpyridine {R-C(O)Ph}, in which the oxygen atom of the ketonic group can behave as a nucleophilic center, yielding the complexes cis-[M(C(6)X(5))(2){R-C(O)Ph}] [M = Pd, X = F (3); M = Pt, X = F (4), Cl (5)]. Complex 3 crystallizes in the space group C2/c: Z = 16; a = 26.284(3) ?; b = 10.623(1) ?; c = 31.423(4) ?; beta = 93.15(1) degrees; V = 8760(2) ?(3). The I-M or O-M bonds in complexes 1-5 are weak and can be easily broken by the addition of neutral (CO, PPh(3), and CH(3)CN) or anionic (Br(-)) ligands.     

Novel chelate ring-opening induced by silver(I) of five-coordinate palladium(II) and platinum(II) complexes containing tripodal polyphosphines

The ionic complexes [Pd(NP 3)X]X [NP 3 = tris[2-(diphenylphosphino)ethyl]amine, X = Cl (1), Br(2)] and [M(PP 3)X]X [PP 3 = tris[2-(diphenylphosphino)ethyl]phosphine, M = Pd, X = Cl (3), Br(4); M = Pt, X = Cl (5), Br (6)] contain square pyramidal (1, 2) and trigonal bipyramidal (3- 6) cations with three fused chelate rings to M and one M-X bond. By addition of AgX salts (X = Cl, Br, NO 3) an unexpected ring-opening reaction occurs with formation of the heteronuclear species PdAg(NP 3)X 3 [X = Cl (7), Br (8)], MAg(PP 3)X 3 [M = Pd, X = Cl (9), Br (10), NO 3 (13);M = Pt, X = Cl (11), Br (12), NO 3 (14)]. The complexes have been characterized in the solid state and solution. The X-ray crystal structures of 9 and 13 reveal a distorted square-planar arrangement to Pd(II) that is coordinated to three P of PP 3 (the central and two terminal atoms) and to one chloride (9) or one oxygen atom of NO 3 (13). The resultant dangling phosphorus of the ring opening is bound to Ag(I) that completes the three- [PAgCl 2 ( 9)] and four-coordination [PAg(ONO 2)(O 2NO) (13)] through the donor atoms of the anions with the nitrates in 13 unusually acting as both mono- and bidentate ligands. Complexes 7, 8, 10, and 11 undergo oligomerization in solution. Complex 10 oligomerizes giving rise to the ionic compound [Pd 4Ag 2(PP 3) 2 Br 9]Br ( 10a) whose X-ray crystal structure indicates the presence of cations with a Pd(mu-Br) 3Pd unit that connects via bromide bridges two BrPdP 2PPAg Br 2 fragments containing distorted square-planar and trigonal-planar Pd(II) and Ag(I) centers, respectively. The palladium(II) metal centers in the central unit afford the five-coordination (PdBr 5) with a distorted trigonal bipyramidal geometry. The ionic system [Pt 2Ag 2(PP 3) 2 Cl 5]Cl (11a) consists of chloride anions and heteronuclear monocations. The X-ray crystal structure reveals that the cations contain two distorted square-planar ClPtP 3 units bridged by one PAgCl(mu-Cl) 2AgP fragment that is bearing tetrahedral (PAgCl 3) and trigonal planar PAgCl 2 silver(I) centers. Further additions of the corresponding AgX salts to complexes 7- 14 did not give rise to any new ring-opening reaction.     

Pt(0) and Pd(0) olefin complexes of the metalloid N-heterocyclic carbene analogues [E(I)(ddp)] (ddp=2-{(2,6-diisopropylphenyl)amino}-4-{(2,6-diisopropylphenyl)imino}-2-pentene; E=Al, Ga): ligand substitution, H--H and Si--H bond activation, and cluster formation

Various products of the reaction of [E(ddp)] (ddp=2-{(2,6-diisopropylphenyl)amino}-4-{(2,6-diisopropylphenyl)imino}-2-pentene; E=Al, Ga) with Pt(0) and Pd(0) olefin complexes are reported. Thus, the reaction of [Pt(cod)(2)] (cod=1,5-cyclooctadiene) with two equivalents of [Ga(ddp)] yields [Pt(1,3-cod){Ga(ddp)}(2)] (1), whereas treatment of [Pd(2)(dvds)(3)] (dvds=1,1,3,3-tetramethyl1,3-divinyldisiloxane) with [E(ddp)] leads to the monomeric compounds [(dvds)Pd{E(ddp)}] (E=Ga (2 a), Al (2 b)) by substitution of the bridging dvds ligand. Both 1 and 2 a readily react with strong pi-acceptor ligands such as CO or tBuNC to give the dimeric compounds [M{mu(2)-Ga(ddp)}(L)] (L=CO, tBuNC; M=Pt (3 a, 5 a), Pd (3 b, 5 b)), respectively. Based on (1)H NMR spectroscopic data, [Pt{Ga(ddp)}(2)(CO)] is likely to be an intermediate in the formation of 3 a. Furthermore, reactions of 1 with H(2) and HSiEt(3) yield the monomeric compounds [Pt{Ga(ddp)}(2)(H)(2)] (7) and [Pt{Ga(ddp)}(2)(H)(SiEt(3))] (8). Finally, the reaction of [Pt(cod)(2)] with one equivalent of [Ga(ddp)] in the presence of H(2) in hexane gives the new dimeric cluster [Pt{mu(2)-Ga(ddp)}(H)(2)](2) (9).     

Metal "capture" by a heterotrimetalloligand, heterometallic d(10)-d(10) interactions, and unexpected iron-to-platinum silyl ligand migration: a combined experimental and theoretical study

The heterotrinuclear chain complex Hg[Fe{Si(OMe)(3)}(CO)(3)(dppm-P)](2) (dppm = Ph(2)PCH(2)PPh(2)) 1 which has a transoid arrangement of the phosphine donors was used as a versatile chelating metallodiphosphine ligand owing to the easy rotation of its metal core about the Fe-Hg sigma-bonds. Its reaction with the labile Pt(0) olefin complex [Pt(C(7)H(10))(3)] yielded [HgPt{Si(OMe)(3)}Fe(2)(CO)(6){Si(OMe)(3)}(mu-dppm)(2)] 5 which resulted, after coordination of the dangling phosphine donors to Pt, from an unprecedented intramolecular rearrangement involving a very rare example of silyl ligand migration between two different metal centers, and the first one in metal cluster chemistry. The major structural differences observed between the heterometallic complexes obtained from 1 and d(10) Cu(I), Pd(0), or Pt(0) precursors have been established by X-ray diffraction. The bonding situation in the silyl migrated Pt complex 5 was analyzed and compared to those in the isoelectronic, but structurally distinct complexes obtained from Cu(I) and Pd(0) precursors, [Hg{Fe[Si(OMe)(3)](CO)(3)(mu-dppm)}(2)Cu](+) (2) and [Hg{Fe[Si(OMe)(3)](CO)(3)(mu-dppm)}(2)Pd] (4), respectively, by means of extended Hückel interaction diagrams. DFT calculations then allowed the energy minima associated with the three structures to be compared for 2, 4, and 5. All three minima are in close competition for the Pd complex 4, but silyl migration is favored by approximately 10 kcal mol(-)(1) for 5, mainly due to the more electronegative character of Pt with respect to Pd.     

Reaction of a heterotopic P,SAs ligand with group 10 metal(II) complexes: As-S bond cleavage and the formation of two unusual trinuclear structural isomers for Pd and Pt

The synthesis of the heterotopic P,SAs ligand, 1-Ph(2)AsSC(6)H(4)-2-PPh(2) (1) and its reaction with [PdCl(2)(cod)], [PtI(2)(cod)] (cod = 1,5-cyclooctadiene) and NiCl(2)·6H(2)O is reported. Cleavage of the As-S bond of 1 and coordination of the resulting phosphanylthiolato ligand (SC(6)H(4)-2-PPh(2))(-) (SC(6)H(4)-2-PPh(2) = P,S) was observed with formation of [M(P,S)(2)] (M = Ni, Pd, Pt). In the case of Pd and Pt, not only the mononuclear complexes [M(P,S)(2)] formed, but also the trimers of [MX(P,S)] ([MX{(μ-S-SC(6)H(4)-2-PPh(2))-κ(2)S,P}](3) [M = Pd, X = Cl (2) and M = Pt, X = I (4)]). Formation of 2 and 4 was preceded by the trinuclear isomeric intermediates [(cis-M{(μ-S-SC(6)H(4)-2-PPh(2))-κ(2)S,P}(2))-MX(2)-MX{(μ-S-SC(6)H(4)-2-PPh(2))-κ(2)S,P}] [M = Pd, X = Cl (3) and M = Pt, X = I (5)]. The crystal structures of 1-5 and a possible reaction mechanism that leads to 2 and 4 are presented.     

Homo- and heteropolynuclear platinum complexes stabilized by dimethylpyrazolato and alkynyl bridging ligands: synthesis, structures, and luminescence

This work describes the synthesis of cis-[Pt(C[triple bond]CPh)2(Hdmpz)2] (1) and its use as a precursor for the preparation of homo- and heteropolynuclear complexes. Double deprotonation of compound 1 with readily available M(I) (M = Cu, Ag, Au) or M(II) (M = Pd, Pt) species affords the discrete hexanuclear clusters [{PtM2(mu-C[triple bond]CPh)2(mu-dmpz)(2)}(2)] [M = Cu (2), Ag (3), Au (4)], in which both "Pt(C[triple bond]CPh)2(dmpz)(2)" fragments are connected by four d(10) metal centers, and are stabilized by alkynyl and dimethylpyrazolate bridging ligands, or the trinuclear complexes [Pt(mu-C[triple bond]CPh)2(mu-dmpz)(2){M(C/\P)}2] (M = Pd (5), Pt (6); C/\P = CH(2)-C(6)H(4)-P(o-tolyl)2-kappaC,P), respectively. The X-ray structures of complexes 1-4 and 6 are reported. The X-ray structure of the platinum-copper derivative 2 shows that all copper centers exhibit similar local geometry being linearly coordinated to a nitrogen atom and eta(2) to one alkynyl fragment. However in the related platinum-silver (3) and platinum-gold (4) derivatives the silver and gold atoms present three different coordination environments. The complexes have been studied by absorption and emission spectroscopy. The hexanuclear complexes exhibit bright luminescence in the solid state and in fluid solution (except 4 in the solid state at 298 K). Dual long-lived emission is observed, being clearly resolved in low-temperature rigid media. The low-energy emission is ascribed to MLM'CT Pt(d)/pi(C[triple bond]CPh)-->Pt(p(z))/M'(sp)/pi*(C[triple bond]CPh) modified by metal-metal interactions whereas the high-energy emission is tentatively attributed to an emissive state derived from dimethylpyrazolate-to-metal (d(10)) LM'CT transitions pi(dmpz)-->M'(d(10)).     

Transition-Metal Complexes with Bidentate Ligands Spanning trans-Positions. IX. Preparation and 1H-NMR. Studies of complexes [MX2(1)] and [M′Cl(CO)(1)] (M = Pd,Pt; M′ = Rh,Ir; X = Cl,Br, I; 1 = 2, 11-Bis-(diphenylarsinomethyl)benzo[c]phenanthrene) and crystal and molecular structure of [PtCl2(1)]

The preparation of the bidentate ligand 2, 11-bis(diphenylarsinomethyl)benzo-[c]-phenanthrene ( 1 ) is described. This ligand reacts with appropriate substrates to give mononuclear square planar complexes of type [MX₂( 1 )] (M = Pd, Pt; X = Cl, Br, I) and [M′Cl(CO)( 1 )] (M′ = Rh, Ir) in which ligand 1 spans trans-positions. This is confirmed by the crystal structure of [PtCl₂( 1 )]. ¹H-NMR. spectra of the complexes are discussed and compared with those of model compounds trans-[MCl₂( 12 )₂] (M = Pd, Pt) and [M'Cl(CO)( 12 )₂] (M′ = Rh, Ir; 12 = AsBzPh₂).     

M...HNR interactions in imino-bound diaryltriazene complexes: structure and fluxionality

The nominally square-planar coordination of the d(8) complexes [MClL(1)L(2)(p-XC(6)H(4)NNNHC(6)H(4)X-p)](M = Rh, L(1)= L(2)= CO, X = H, Me, Et or F; M = Ir, L(1)= L(2)= CO, X = Me; M = Pd or Pt, L(1)= Cl, L(2)= PPh(3), X = Me; M = Pd, L(1)L(2)=eta(3)-C(3)H(5), X = Me), with the triazene N-bonded via the imine group, is supplemented by an axial M...H-N interaction involving the terminal amino group.     

Bimetallic cluster complexes: the synthesis, structures, and bonding of ruthenium carbonyl cluster complexes containing palladium and platinum with the bulky tri-tert-butyl-phosphine ligand

The bis-phosphine compounds M(PBut3)2, M = Pd and Pt, readily eliminate one PBut3 ligand and transfer MPBut3 groups to the ruthenium-ruthenium bonds in the compounds Ru3(CO)12, Ru6(CO)17(micro6-C), and Ru6(CO)14(eta6-C6H6)(micro6-C) without displacement of any of the ligands on the ruthenium complexes. The new compounds, Ru3(CO)12[Pd(PBut3)]3, 10, and Ru6(CO)17(micro6-C)[Pd(PBut3)]2, 11, Ru6(CO)17(micro6-C)[Pt(PBut3)]n, n = 1 (12), n = 2 (13), and Ru6(CO)14(eta6-C6H6)(micro6-C)[Pd(PBut3)]n, n = 1 (15), n = 2 (16), have been prepared and structurally characterized. In most cases the MPBut3 groups bridge a pair of mutually bonded ruthenium atoms, and the associated Ru-Ru bond distance increases in length. Fenske-Hall calculations were performed on 10 and 11 to develop an understanding of the electron deficient metal-metal bonding. 10 undergoes a Jahn-Teller distortion to increase bonding interactions between neighboring Ru(CO)4 and Pd(PBut3) fragments. 11 has seven molecular orbitals important to cluster bonding in accord with cluster electron-counting rules.     

Palladium complexes of a phosphorus ylide with two stabilizing groups: synthesis, structure, and DFT study of the bonding modes

The phosphorus ylide ligand [Ph3P=C(CO2Me)C(=NPh)CO2Me] (L1) has been prepared and fully characterized by spectroscopic, crystallographic, and density functional theory (DFT) methods (B3LYP level). The reactivity of L1 toward several cationic Pd(II) and Pt(II) precursors, with two vacant coordination sites, has been studied. The reaction of [M(C/\X)(THF)2]ClO4 with L1 (1:1 molar ratio) gives [M(C/\X)(L1)]ClO4 [M = Pd, C/\X = C6H4CH2NMe2 (1), S-C6H4C(H)MeNMe2 (2), CH2-8-C9H6N (3), C6H4-2-NC5H4 (4), o-CH2C6H4P(o-tol)2 (6), eta3-C3H5 (7); M = Pt, C/\X = o-CH2C6H4P(o-tol)2 (5); M(C/\X) = Pd(C6F5)(SC4H8) (8), PdCl2 (9)]. In complexes 1-9, the ligand L1 bonds systematically to the metal center through the iminic N and the carbonyl O of the stabilizing CO2Me group, as is evident from the NMR data and from the X-ray structure of 3. Ligand L1 can also be orthopalladated by reaction with Pd(OAc)2 and LiCl, giving the dinuclear derivative [Pd(mu-Cl)(C6H4-2-PPh2=C(CO2Me)C(CO2Me)=NPh)]2 (10). The X-ray crystal structure of 10 is also reported. In none of the prepared complexes 1-10 was the C(alpha) atom found to be bonded to the metal center. DFT calculations and Bader analysis were performed on ylide L1 and complex 9 and its congeners in order to assess the preference of the six-membered N,O metallacycle over the four-membered C,N and five-membered C,O rings. The presence of two stabilizing groups at the ylidic C causes a reduction of its bonding capabilities. The increasing strength of the Pd-C, Pd-O, and Pd-N bonds along with other subtle effects are responsible for the relative stabilities of the different bonding modes.     

Highly fluorous complexes of nickel, palladium and platinum: solubility and catalysis in high pressure CO2

A variety of Group 10 metal complexes [MXY(dfppp)], M = Ni, X, Y = Cl, Br, M = Pd, Pt, X, Y = Cl or CH(3), containing the recently reported highly fluorous diphosphine ligand, dfppp, 1,3-bis[di(fluoroponytail)phosphino]propane, {(p-F(13)C(6)C(6)H(4))(2)P}(2)(CH(2))(3) have been synthesised. They have been characterised by NMR, mass spectrometry and microanalysis, with two platinum complexes, [PtCl(2)(dfppp)] and [PtClMe(dfppp)], structurally characterised by single crystal X-ray diffraction studies. The highly fluorous nature of the ligands affords the complexes good supercritical CO(2) solubility as measured by supercritical fluid extraction (SFE), and has allowed for the copolymerisation of CO and ethylene using [PdClMe(dfppp)] as the catalyst precursor and CO(2) as the solvent. Additionally, PtCl(2) complexes of the new ligands dfppb, {(p-F(13)C(6)C(6)H(4))(2)P}(2)(CH(2))(4), and dfpop, {(p-F(13)C(6)C(6)H(4)O)(2)P}(2)(CH(2))(3), have also been prepared and characterised.     

Experimental and quantum-chemical studies of 1H, 13C and 15N NMR coordination shifts in Pd(II) and Pt(II) chloride complexes with methyl and phenyl derivatives of 2,2'-bipyridine and 1,10-phenanthroline

1H, 13C and 15N NMR studies of platinide(II) (M=Pd, Pt) chloride complexes with methyl and phenyl derivatives of 2,2'-bipyridine and 1,10-phenanthroline [LL=4,4'-dimethyl-2,2'-bipyridine (dmbpy); 4,4'-diphenyl-2,2'-bipyridine (dpbpy); 4,7-dimethyl-1,10-phenanthroline (dmphen); 4,7-diphenyl-1,10-phenanthroline (dpphen)] having a general [M(LL)Cl2] formula were performed and the respective chemical shifts (delta1H, delta13C, delta15N) reported. 1H high-frequency coordination shifts (Delta1Hcoord=delta1Hcomplex-delta1Hligand) were discussed in relation to the changes of diamagnetic contribution in the relevant 1H shielding constants. The comparison to literature data for similar [M(LL)(XX)], [M(LL)X2] and [M(LL)XY] coordination or organometallic compounds containing various auxiliary ligands revealed a large dependence of delta1H parameters on inductive and anisotropic effects. 15N low-frequency coordination shifts (Delta15Ncoord=delta 15Ncomplex-delta15Nligand) of ca 88-96 ppm for M=Pd and ca 103-111 ppm for M=Pt were attributed to both the decrease of the absolute value of paramagnetic contribution and the increase of the diamagnetic term in the expression for 15N shielding constants. The absolute magnitude of Delta15Ncoord parameter increased by ca 15 ppm upon Pd(II)-->Pt(II) transition and by ca 6-7 ppm following dmbpy-->dmphen or dpbpy-->dpphen ligand replacement; variations between analogous complexes containing methyl and phenyl ligands (dmbpy vs dpbpy; dmphen vs dpphen) did not exceed+/-1.5 ppm. Experimental 1H, 13C, 15N NMR chemical shifts were compared to those quantum-chemically calculated by B3LYP/LanL2DZ+6-31G**//B3LYP/LanL2DZ+6-31G*, both in vacuo and in DMSO or DMF solution.     

Unprecedented coordination of dithiocarbimate in multinuclear and heteroleptic complexes

An uncommon coordination protocol induced by the p-tolylsulfonyl dithiocarbimate ligand (L) [L = p-CH(3)C(6)H(4)SO(2)N[double bond, length as m-dash]CS(2)(2-)] in conjunction with PPh(3) allowed the formation of novel homodimetallic, Cu(2)(PPh(3))(4)L (1), trinuclear heterometallic Cu(2)Ni(L)(2)(PPh(3))(4) (2) and heteroleptic complexes of general formula cis-[M(PPh(3))(2)L] [M = Pd(ii) (3), Pt(ii) (4)]. The complexes have been characterized by microanalysis, mass spectrometry, IR, (1)H, (13)C and (31)P NMR and electronic absorption spectra and single-crystal X-ray crystallography. 2 uniquely consists of square planar, trigonal planar and tetrahedral coordination spheres within the same molecule. In both heteroleptic complexes 3 and 4 the orientation of aromatic protons of PPh(3) ligand towards the Pd(ii) and Pt(ii) center reveals C-HPd and C-HPt rare intramolecular anagostic or preagostic interactions. These complexes exhibit photoluminescent properties in solution at room temperature arising mainly from intraligand charge transfer (ILCT) transitions. The assignment of electronic absorption bands has been corroborated by time dependent density functional theory (TD-DFT) calculations. Complexes 1 and 2 with σ(rt) values ～ 10(-6) S cm(-1) show semi-conductor properties in the temperature range 313-403 K whereas 3 and 4 exhibit insulating behaviour.     

Cyclometallated Pt(II) and Pd(II) complexes with a trithiacrown ligand

We report the synthesis and full characterization for a series of cyclometallated complexes of Pt(II) and Pd(II) incorporating the fluxional trithiacrown ligand 1,4,7-trithiacyclononane ([9]aneS3). Reaction of [M(C insertion mark N)(micro-Cl)]2 (M = Pt(II), Pd(II); C insertion mark N = 2-phenylpyridinate (ppy) or 7,8-benzoquinolinate (bzq)) with [9]aneS3 followed by metathesis with NH4PF6 yields [M(C insertion mark N)([9]aneS3)](PF6). The complexes [M(C insertion mark P)([9]aneS3)](PF6) (M = Pt(II), Pd(II); Cinsertion markP = [CH2C6H4P(o-tolyl)2-C,P]-) were synthesized from their respective [Pt(C insertion mark P)(micro-Cl)]2 or [Pd(C insertion mark P)(micro-O2CCH3)]2 (C insertion mark P) starting materials. All five new complexes have been fully characterized by multinuclear NMR, IR and UV-Vis spectroscopies in addition to elemental analysis, cyclic voltammetry, and single-crystal structural determinations. As expected, the coordinated [9]aneS3 ligand shows fluxional behavior in its NMR spectra, resulting in a single 13C NMR resonance despite the asymmetric coordination environment of the cyclometallating ligand. Electrochemical studies reveal irreversible one-electron metal-centered oxidations for all Pt(II) complexes, but unusual two-electron reversible oxidations for the Pd(II) complexes of ppy and bzq. The X-ray crystal structures of each complex indicate an axial M-S interaction formed by the endodentate conformation of the [9]aneS3 ligand. The structure of [Pd(bzq)([9]aneS3)](PF6) exhibits disorder in the [9]aneS3 conformation indicating a rare exodentate conformation as the major contributor in the solid-state structure. DFT calculations on [Pt([9]aneS3)(ppy)](PF6) and [Pd([9]aneS3)(ppy)](PF6) indicate the HOMO for both complexes is primarily dz2 in character with a significant contribution from the phenyl ring of the ppy ligand and p orbital of the axial sulfur donor. In contrast, the calculated LUMO is primarily ppy pi* in character for [Pt([9]aneS3)(ppy)](PF6), but dx2-y2 in character for [Pd([9]aneS3)(ppy)](PF6).     

Platinum(II) and Palladium(II) Bis(chelate) Complexes Containing both Tri(1‐cyclohepta‐2, 4, 6‐trienyl)phosphane,P(C7H7)3, and Dichalcogenolato Ligands

Tri(1‐cyclohepta‐2, 4, 6‐trienyl)phosphane, P(C₇H₇)₃ ([P] when coordinated to a metal atom), was used to stabilize complexes of platinum(II) and palladium(II) with chelating dichalcogenolato ligands as [P]M(E∩E) [E = S, ∩ = CH₂CH₂, M = Pt ( 3a ); E = S, ∩ = 1, 2‐C₆H₄, M = Pt ( 5a ), Pd ( 6a ); E = S, ∩ = C(O)C(O), M = Pt ( 7a ), Pd ( 8a ); E = S, Se, ∩ = 1, 2‐C₂(B₁₀H₁₀), M = Pt ( 9a, 9b ), Pd ( 10a, 10b ); E = S, ∩ = Fe₂(CO)₆, M = Pt ( 11a ), Pd ( 12a )]. Starting materials in all reactions were [P]MCl₂ with M = Pt ( 1 ) and Pd ( 2 ). Attempts at the synthesis of [P]M(ER)₂ with non‐chelating chalcogenolato ligands were not successful. All new complexes were characterized by multinuclear magnetic resonance spectroscopy in solution (¹H, ¹³C, ³¹P, ⁷⁷Se and ¹⁹⁵Pt NMR), and the molecular structures of 5a and 12a were determined by X‐ray analysis. Both in the solid state and in solution the ligand [P] is linked to the metal atom by the P‐M bond and by η²‐C=C coordination of the central C=C bond of one of the C₇H₇ rings. In solution, intramolecular exchange between coordinated and non‐coordinated C₇H₇ rings is observed, the exchange process being markedly faster in the case of M = Pd than for M = Pt.     

Bimetallic clusters of iron with palladium and platinum. Synthesis and structures of Fe2(CO)9[M(PBu(t)3)]2 (M = Pd or Pt) and Fe2(CO)8[Pt(PBu(t)3)]2(mu-H)2

The reaction of Fe2(CO)9 with Pd(PBu(t)3)2 and Pt(PBu(t)3)2 yielded the Fe-Pd and Fe-Pt cluster complexes Fe2(CO)9[M(PBu(t)3)]2, M = Pd (8) or Pt (9). The structures of 8 and 9 are analogous and consist of nearly planar butterfly clusters of two palladium/platinum atoms in the wing-tip positions and two mutually bonded iron atoms, Fe-Fe = 2.9582(11) A in 8 and 2.9100 (9) A in 9. Compound 8 decomposes to form the mononuclear iron compound Fe(CO)4(PBu(t)3) (11) when heated at 68 degrees C. The reaction of Pt(PBu(t)3)2 with Fe2(CO)9 in the presence of hydrogen at 127 degrees C yielded the dihydrido complex Fe2(CO)8[Pt(PBu(t)3)]2(mu-H)2 (10). Compound 10 contains a closed Fe2Pt2 tetrahedral cluster with hydrido ligands bridging two of the Fe-Pt bonds. Compounds 8, 9, and 10 were structurally characterized crystallographically.