Experimental and First-Principles NMR Analysis of Pt(II) Complexes With O,O'-Dialkyldithiophosphate Ligands (original) (raw)
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Polyhedron, 2006
Cationic complexes of the type [Pt(L)(triphos)](ClO4)2, where L is a 4-substituted pyridine {L=4-R-py=4-cyanopyridine (4-CN-py), isonicotinic acid (4-COOH-py), methylisonicotinate (4-COOMe-py), 4-acetylpyridine (4-MeCO-py), pyridine (4-H-py), 4-methylpyridine (4-Me-py), 4-aminopyridine (4-NH2-py)} or a 4-substituted aniline {L=4-R-an=4-nitroaniline (4-NO2-an), 4-cyanoaniline (4-CN-an), 4-chloroaniline (4-Cl-an), aniline (4-H-an), 4-methylaniline (4-Me-an), 4-methoxyaniline (4-MeO-an)}, have been prepared from cis/trans-PtCl2(SMe2)2. The cis and trans1JPt–P coupling constants measured in CD3NO2 were found to
Inorganic Chemistry, 2008
The protonation of the dinuclear phosphinito bridged complex [(PHCy 2 )Pt(µ-PCy 2 ){κ 2 P,O-µ-P(O)Cy 2 }Pt(PHCy 2 )] (Pt-Pt) (1) by Brønsted acids affords hydrido bridged Pt-Pt species the structure of which depends on the nature and on the amount of the acid used. The addition of 1 equiv of HX (X ) Cl, Br, I) gives products of formal protonation of the Pt-Pt bond of formula syn-[(PHCy 2 )(X)Pt(µ-PCy 2 )(µ-H)Pt(PHCy 2 ){κP-P(O)Cy 2 }] (Pt-Pt) (5, X ) Cl; 6, X ) Br; 8, X ) I), containing a Pt-X bond and a dangling κP-P(O)Cy 2 ligand. Uptake of a second equivalent of HX results in the protonation of the P(O)Cy 2 ligand with formation of the complexes [(PHCy 2 )(X)Pt(µ-PCy 2 )(µ-H)Pt(PHCy 2 ){κP-P(OH)Cy 2 }]X (Pt-Pt) (3, X ) Cl; 4, X ) Br; 9, X ) I). Each step of protonation is reversible, thus reactions of 3, 4, with NaOH give, first, the corresponding neutral complexes 5, 6, and then the parent compound 1. While the complexes 3 and 4 are indefinitely stable, the iodine analogue 9 transforms into anti-[(PHCy 2 )(I)Pt(µ-PCy 2 )(µ-H)Pt(PHCy 2 )(I)] (Pt-Pt) (7) deriving from substitution of an iodo group for the P(OH)Cy 2 ligand. Complexes 3 and 4 are isomorphous crystallizing in the triclinic space group P1 and show an intramolecular hydrogen bond and an interaction between the halide counteranion and the POH hydrogen. The occurrence of such an interaction also in solution was ascertained for 3 by 35 Cl NMR. Multinuclear NMR spectroscopy (including 31 P-1 H HOESY) and density-functional theory calculations indicate that the mechanism of the reaction starts with a prior protonation of the oxygen with formation of an intermediate (12) endowed with a six membered Pt 1 -X · · · H-O-P-Pt 2 ring that evolves into thermodynamically stable products featuring the hydride ligand bridging the Pt atoms. Energy profiles calculated for the various steps of the reaction between 1 and HCl showed very low barriers for the proton transfer and the subsequent rearrangement to 12, while a barrier of 29 kcal mol -1 was found for the transformation of 12 into 5. † Dedicated to Prof. Cosimo Francesco Nobile on occasion of his 70th birthday. Evrard, D.; Clément, S.; Lucas, D.; Hanquet, B.; Knorr, M.; Strohmann, C.; Decken, A.; Mugnier, Y.; Harvey, P. D. Inorg. Chem. 2006, 45, 1305-1315; and references cited therein. (2) Gallo, V.; Latronico, M.; Mastrorilli, P.; Nobile, C. F.; Suranna, G. P.; Ciccarella, G.; Englert, U. Eur. J. Inorg. Chem. 2005, 4607-4616.
Dalton Transactions, 2004
The dynamic behaviour of the binuclear µ-hydrido µ-carbonyl cations with chelating diphosphines, [Pt 2 (P-P) 2-(µ-H)(µ-CO)] ϩ [P-P = dppe, 1, dppp, 2, and dppb, 3] have been investigated by multinuclear (1 H, 31 P and 195 Pt) variable temperature NMR spectroscopy. The 195 Pt and 1 H results are consistent with intramolecular mutual exchange of the P atoms with respect to the bridging ligands in all of the complexes 1-3. A detailed dynamical analysis carried out on complexes 2 and 3 shows that the dynamical process exchanges the P atoms within a single diphosphino ligand, and excludes the simultaneous P atom exchange in both ligands. The bite of the diphosphino ligands affects the rate of this process in the order 3 > 2 > 1. The process follows an activation law with ∆H ‡ = 67 and 60 kJ mol Ϫ1 for 2 and 3, respectively, so that P-Pt bond breaking should not be involved. The positive activation entropy (17-19 J K Ϫ1 mol Ϫ1) hints at a mechanism where the intermediate(s) have a less ordered structure than that of the stable complex. In accordance with the NMR results, two reactivity experiments provided further evidence of the intramolecular nature of the observed dynamics and exclude any equilibration path via Pt-P and/or Pt-Pt bond breaking. On these grounds, a mechanism involving rotation about a Pt-Pt bond could be proposed.
Inorganic Chemistry, 1992
The synthesis and characterization of a new platinum(1) phosphine complex, [Pt,(p-dppm)(q'-dppm)dppeCl]Cl, is reported. This unique complex is the fmt example of a stable Pt(1) dimer in which all three types of coordination possible for a diphosphine ligand are observed. To structurally characterize this complex, we have employed one-and two-dimensional 31P NMR spectroscopy. Using 14 other structurally simpler platinum phosphine complexes, it is established that the 31P homonuclear shift correlated spectroscopy (COSY) technique provides valuable information about both the phosphorus-phosphorus and platinum-phosphorus couplings, especially when the rtSOnanceS in the onedimensional spectra are poorly resolved. The ,JRP and 3JR-p coupling constants are obtained from the relative positions of the observed cross-correlations with respect to the main phosphorus resonances. From the analysis of the coupling patterns observed and the coupling constants measured from the two-dimensional data sets, determination of the geometrical arrangement of the phosphine ligands is demonstrated. The structural assignment of the new Pt complex is based on the analysis of its ,IP COSY map and further supported by the COSY studies of the other platinum complexes.
Inorganic Chemistry, 1992
Two-dimensional homonuclear shift correlated spectroscopy (COSY) is applied to the analysis of a series of dinuclear R(1) complexes containing phosphine ligands. On the basis of the spectra of known symmetrical dimers, it is established that cross-peak positions of the Pt-P satellite signals can be used to determine the sign and magnitude of the 2JR_p coupling constant. This coupling constant has been correlated with the strength of the Pt-Pt interaction in these complexes. Using cross-peak positions present in the spectra of unsymmetrical dimers which contain five or more phosphorus nuclei, previously unobtainable values for the 2Jpt-p coupling constants are determined. The signs and the magnitudes of these coupling constants are found to follow the trans effect trend established for ligands in other Pt complexes.
Polyhedron, 1997
Deprotonation of the primary phosphine complex [Mo(CO),(PPhH2)] generated [Mo(C-O),(PPhH)]-, a chiral anionic ligand which reacted readily with cis-or trans-[PtCL(PEt&] via tkile nucleophilic substitution of one or both chloride ligands to afford rrans-[PtCI(PEt,)Z(/l-PPhH) (Mo(CO),}] (I) and cisand trans-[Pt(PEt,)Z(~-PPhH)2(Mo(CO),}Z] (2), respectively. These are rare examples of heterometallic complexes containing primary phosphido bridges. Compound 1 can be described either as the square-planar Pt" complex with the anionic ligand PPhHjMo(CO),)-or as the Pt-Mo phosphido-bridged dimer trans-[PtCl(PEt,)z(~-PPhH){Mo(CO),)l. As a phosphido-bridged heterobimetallic 1 possesses an exceptionally large Pt-P-MO angle [120.9(l) '1 reflecting the long Pt-Mo nonbonding interaction (4.5 A). Compound 2 can correspondingly be described either as a phosphido-bridged PtMo, trimer or a square-planar arrangement of two neutral PEt, and two anionic PPhH{Mo(CO),) ligands at Pt. The low-temperature "'P('Hl NMR spectrum of 1 showed several ABXY spin systems together with their associated ABXYM (M = 19'Pt) counterparts and variable-temperature studies revealed the dynamic interconversion of several rotametric isomers arising from restricted rotation about the Pt-Pp bond. The "P('HJ NMR spectrum of tram-2 shows its two possible RRjSS and meso diastereoisomers, the latter existing in clearly identifiable rotameric forms which interconvert slowly at-75 C. We note very different values between 'J(P-P) and 'J("'Pt-P) for the anionic ligands [PPhH{Mo(CO),)]-and PEt,, unattributable to bond length variation but which must reflect reduced s-orbital contribution to the Pt-P bond of the anionic phosphines PPhH (Mo(CO),).
Inorganic Chemistry, 1992
Two-dimensional homonuclear shift correlated spectroscopy (COSY) is applied to the analysis of a series of dinuclear R(1) complexes containing phosphine ligands. On the basis of the spectra of known symmetrical dimers, it is established that cross-peak positions of the Pt-P satellite signals can be used to determine the sign and magnitude of the 2JR_p coupling constant. This coupling constant has been correlated with the strength of the Pt-Pt interaction in these complexes. Using cross-peak positions present in the spectra of unsymmetrical dimers which contain five or more phosphorus nuclei, previously unobtainable values for the 2Jpt-p coupling constants are determined. The signs and the magnitudes of these coupling constants are found to follow the trans effect trend established for ligands in other Pt complexes.
Polyhedron, 1997
Deprotonation of the primary phosphine complex [Mo(CO)5(PPhH2)] generated [Mo(CO)5(PPhH)]−, a chiral anionic ligand which reacted readily with cis- or trans-[PtCl2(PEt3)2] via facile nucleophilic substitution of one or both chloride ligands to afford trans-[PtCl(PEt3)2(μ-PPhH)∗Mo(CO)5∗] (1) and cis- and trans-[Pt(PEt3)2(μ-PPhH)2∗Mo(CO)5∗2] (2), respectively. These are rare examples of heterometallic complexes containing primary phosphido bridges. Compound (1) can be described either as the square-planar Pt11 complex with the anionic ligand PPhH∗Mo(CO)5∗− or as the PtMo phosphido-bridged dimer trans-[PtCl(PEt3)2(μ-PPhH)∗Mo(CO)5∗]. As a phosphido-bridged heterobimetallic (1) possesses an exceptionally large PtPMo angle [120.9(1) °] reflecting the long PtMo nonbonding interaction (4.5 Å). Compound 2 can correspondingly be described either as a phosphido-bridged PtMo2 trimer or a square-planar arrangement of two neutral PEt3 and two anionic PPhH∗Mo(CO)5∗ ligands at Pt. The low-temperature 31P∗1H∗ NMR spectrum of 1 showed several ABXY spin systems together with their associated ABXYM () counterparts and variable-temperature studies revealed the dynamic interconversion of several rotametric isomers arising from restricted rotation about the PtPμ bond. The 31P∗1H∗ NMR spectrum of trans-2 shows its two possible RR/SS and meso diastereoisomers, the latter existing in clearly identifiable rotameric forms which interconvert slowly at −75°C. We note very different values between for the anionic ligands [PPhH∗Mo(CO)5∗]− and PEt3, unattributable to bond length variation but which must reflect reduced s-orbital contribution to the PtP bond of the anionic phosphines PPhH∗Mo(CO)5∗.
Inorganic Chemistry, 2009
The relevance of cis and trans influences of some anionic ligands X and Y in cis-[PtX 2 (PPh 3) 2 ] and cis-[PtXY(PPh 3) 2 ] complexes have been studied by the X-ray crystal structures of several derivatives (X 2 = (AcO) 2 (3), (NO 3) 2 (5), Br 2 (7), I 2 (11); and XY = Cl(AcO) (2), Cl(NO 3) (4), and Cl(NO 2) (13)), density functional theory (DFT) calculations, and one bond Pt-P coupling constants, 1 J PtP. The latter have allowed an evaluation of the relative magnitude of both influences. It is concluded that such influences act in a cooperative way and that the cis influence is not irrelevant when rationalizing the 1 J PtP values, as well as the experimental Pt-P bond distances. On the contrary, in the optimized geometries, evaluated through B3LYP/def2-SVP calculations, the cis influence was not observed, except for compounds ClPh (21), Ph 2 (22), and, to a lesser extent, Cl(NO 2) (13) and (NO 2) 2 (14). A natural bond order analysis on the optimized structures, however, has shown how the cis influence can be related to the s-character of the Pt hybrid orbital involved in the Pt-P bonds and the net atomic charge on Pt. We have also found that in the X-ray structures of cis-[PtX 2 (PPh 3) 2 ] complexes the two Pt-X and the two Pt-P bond lengths are different each other and are related to the conformation of the phosphine groups, rather than to the crystal packing, since this feature is observed also in the optimized geometries.