Darstellung,spektroskopische Charakterisierung und Kristallstrukturen von [(C5H5N)2CH2][PtCl5(SCN)] und cis-[(C5H5N)2CH2][PtCl4(SCN)2]

Preparation, Spectroscopic Characterization, and Crystal Structures of [(C₅H₅N)₂CH₂][PtCl₅(SCN)] and cis -[(C₅H₅N)₂CH₂][PtCl₄(SCN)₂] By treatment of [PtCl₆]^2– with SCN^– in aqueous solution a mixture of chlorothiocyanatoplatinates(IV) is formed, from which [PtCl₅(SCN)]^2– and cis-[PtCl₄(SCN)₂]^2– have been separated by ion exchange chromatography on diethylaminoethyl cellulose. X-Ray structure determinations on single crystals of [(C₅H₅N)₂CH₂][PtCl₅(SCN)] ( 1 ) (tetragonal, space group P 4₃, a = 7.687(1), c = 29.698(4), Z = 4) and cis-[(C₅H₅N)₂CH₂][PtCl₄(SCN)₂] ( 2 ) (monoclinic, space group P 2₁/n, a = 11.2467(9), b = 15.0445(10), c = 11.3179(13), β = 92.840(9)°, Z = 4) show, that the thiocyanate groups are coordinated via S atoms with average Pt–S distances of 2.339 Å and Pt–S–C angles of 104.7° up to 107.1°. Using the molecular parameters of the X-ray determinations the low temperature (10 K) IR and Raman spectra have been assigned by normal coordinate analyses. The valence force constants of the S–Pt–Cl˙ axes are f_d(PtS) = 1.81 ( 1 ) and 1.87 ( 2 ), f_d(PtCl ^× ) = 1.77 ( 1 ) and 1.81 ( 2 ), of the Cl–Pt–Cl axes are f_d(PtCl) = 1.93 ( 1 ) and 1.90 mdyn/Å ( 2 ). The ¹⁹⁵Pt NMR spectra from dichlormethane solutions exhibit each one sharp signal at 3975.6 ( 1 ) and 3231.6 ppm ( 2 ), respectively.     

Kristallstrukturen der Fluorochloroplatinate(IV) cis-[(C5H5N)2CH2][PtF4Cl2], trans-[(C5H5N)2CH2][PtF4Cl2] · H2O und [(C5H5N)2CH2][PtF5Cl]

Crystal Structures of the Fluorochloroplatinates(IV) cis-[(C₅H₅N)₂CH₂][PtF₄Cl₂], trans-[(C₅H₅N)₂CH₂][PtF₄Cl₂] · H₂O, and [(C₅H₅N)₂CH₂][PtF₅Cl] The complex ions cis-[PtF₄Cl₂]^2?, trans-[PtF₄Cl₂]^2? and [PtF₅Cl]^2? have been synthesized by stereoselective ligand exchange reactions utilizing the trans effect and are separated by ion exchange chromatography on diethylaminoethyl cellulose. These anions form stable AB-type salts with the doubly charged cation dipyridiniomethane, [(C₅H₅N)₂CH₂]²⁺. X-ray structure determinations on single crystals of cis-[(C₅H₅N)₂CH₂][PtF₄Cl₂] ( 1 ) (monoclinic, space group P2₁/n with a = 10.379(10), b = 9.635(2), c = 13.738(2) Å, β = 99.142(10)°, Z = 4), trans-[(C₅H₅N)₂CH₂][PtF₄Cl₂] · H₂O ( 2 ) (triclinic, space group P1 with a = 7.757(4), b = 10.059(7), c = 10.408(6) Å, α = 82.49(5), β = 68.92(4), γ = 75.46(4)°, Z = 2) and [(C₅H₅N)₂CH₂][PtF₅Cl] ( 3 ) (orthorhombic, space group Pnma with a = 10.394(3), b = 13.320(2), c = 9.2694(10) Å, Z = 4), reveal the perfect ordering of the anion sublattice. The stronger trans influence of Cl compared with F is observed in asymmetric axes $ {\rm F}^ \bullet $? Pt? Cl′. The bond lengths Pt? $ {\rm F}^ \bullet $ are 0.026 Å (1.4%) longer and the Pt? Cl′ distances are 0.078 Å (3,3%) shorter in comparison with those of symmetrically coordinated axes. The weakening of the Pt? $ {\rm F}^ \bullet $ bond and the strengthening of the Pt? Cl′ bond is better recognizable from shifts of the stretching vibrations by 8% to lower and by 13% to higher frequencies, respectively. Correspondingly, the valence force constants are found to be 15% lower and 22% higher. The trans influence is observed most distinctly in the ¹⁹F-nmr spectra exhibiting the coupling constant ¹J($ {\rm F}^ \bullet $Pt) to be 29% smaller than ¹J(FPt).     

Ligand‐to‐Ligand Charge‐Transfer Transitions of Platinum(II) Complexes with Arylacetylide Ligands with Different Chain Lengths: Spectroscopic Characterization,Effect of Molecular Conformations,and Density Functional Theory Calculations

The complexes [Pt(tBu₃tpy){C?C(C₆H₄C?C)_n?1R}]⁺ (n=1: R=alkyl and aryl (Ar); n=1–3: R=phenyl (Ph) or Ph‐N(CH₃)₂‐4; n=1 and 2, R=Ph‐NH₂‐4; tBu₃tpy=4,4’,4’’‐tri‐tert‐butyl‐2,2’:6’,2’’‐terpyridine) and [Pt(Cl₃tpy)(C?CR)]⁺ (R=tert‐butyl (tBu), Ph, 9,9’‐dibutylfluorene, 9,9’‐dibutyl‐7‐dimethyl‐amine‐fluorene; Cl₃tpy=4,4’,4’’‐trichloro‐2,2’:6’,2’’‐terpyridine) were prepared. The effects of substituent(s) on the terpyridine (tpy) and acetylide ligands and chain length of arylacetylide ligands on the absorption and emission spectra were examined. Resonance Raman (RR) spectra of [Pt(tBu₃tpy)(C?CR)]⁺ (R=n‐butyl, Ph, and C₆H₄‐OCH₃‐4) obtained in acetonitrile at 298 K reveal that the structural distortion of the C?C bond in the electronic excited state obtained by 502.9 nm excitation is substantially larger than that obtained by 416 nm excitation. Density functional theory (DFT) and time‐dependent DFT (TDDFT) calculations on [Pt(H₃tpy)(C?CR)]⁺ (R= n‐propyl (nPr), 2‐pyridyl (Py)), [Pt(H₃tpy){C?C(C₆H₄C?C)_n?1Ph}]⁺ (n=1–3), and [Pt(H₃tpy){C?C(C₆H₄C?C)_n?1C₆H₄‐N(CH₃)₂‐4}]⁺/+H⁺ (n=1–3; H₃tpy=nonsubstituted terpyridine) at two different conformations were performed, namely, with the phenyl rings of the arylacetylide ligands coplanar (“cop”) with and perpendicular (“per”) to the H₃tpy ligand. Combining the experimental data and calculated results, the two lowest energy absorption peak maxima, λ₁ and λ₂, of [Pt(Y₃tpy)(C?CR)]⁺ (Y=tBu or Cl, R=aryl) are attributed to ¹[π(C?CR)→π*(Y₃tpy)] in the “cop” conformation and mixed ¹[d_π(Pt)→π*(Y₃tpy)]/¹[π(C?CR)→π*(Y₃tpy)] transitions in the “per” conformation. The lowest energy absorption peak λ₁ for [Pt(tBu₃tpy){C?C(C₆H₄C?C)_n?1C₆H₄‐H‐4}]⁺ (n=1–3) shows a redshift with increasing chain length. However, for [Pt(tBu₃tpy){C?C(C6H4C?C)_n?1C₆H₄‐N(CH₃)₂‐4}]⁺ (n=1–3), λ₁ shows a blueshift with increasing chain length n, but shows a redshift after the addition of acid. The emissions of [Pt(Y₃tpy)(C?CR)]⁺ (Y=tBu or Cl) at 524–642 nm measured in dichloromethane at 298 K are assigned to the ³[π(C?CAr)→π*(Y₃tpy)] excited states and mixed ³[d_π(Pt)→π*(Y₃tpy)]/³[π(C?C)→π*(Y₃tpy)] excited states for R=aryl and alkyl groups, respectively. [Pt(tBu₃tpy){C?C(C₆H₄C?C)_n?1C₆H₄‐N(CH₃)₂‐4}]⁺ (n=1 and 2) are nonemissive, and this is attributed to the small energy gap between the singlet ground state (S₀) and the lowest triplet excited state (T₁).     

Mechanistic Studies on the Gas‐Phase Dehydrogenation of Alkanes at Cyclometalated Platinum Complexes

In the ion/molecule reactions of the cyclometalated platinum complexes [Pt(L? H)]⁺ (L=2,2′‐bipyridine (bipy), 2‐phenylpyridine (phpy), and 7,8‐benzoquinoline (bq)) with linear and branched alkanes C_nH_2n+2 (n=2–4), the main reaction channels correspond to the eliminations of dihydrogen and the respective alkenes in varying ratios. For all three couples [Pt(L? H)]⁺/C₂H₆, loss of C₂H₄ dominates clearly over H₂ elimination; however, the mechanisms significantly differs for the reactions of the “rollover”‐cyclometalated bipy complex and the classically cyclometalated phpy and bq complexes. While double hydrogen‐atom transfer from C₂H₆ to [Pt(bipy? H)]⁺, followed by ring rotation, gives rise to the formation of [Pt(H)(bipy)]⁺, for the phpy and bq complexes [Pt(L? H)]⁺, the cyclometalated motif is conserved; rather, according to DFT calculations, formation of [Pt(L? H)(H₂)]⁺ as the ionic product accounts for C₂H₄ liberation. In the latter process, [Pt(L? H)(H₂)(C₂H₄)]⁺ (that carries H₂ trans to the nitrogen atom of the heterocyclic ligand) serves, according to DFT calculation, as a precursor from which, due to the electronic peculiarities of the cyclometalated ligand, C₂H₄ rather than H₂ is ejected. For both product‐ion types, [Pt(H)(bipy)]⁺ and [Pt(L? H)(H₂)]⁺ (L=phpy, bq), H₂ loss to close a catalytic dehydrogenation cycle is feasible. In the reactions of [Pt(bipy? H)]⁺ with the higher alkanes C_nH_2n+2 (n=3, 4), H₂ elimination dominates over alkene formation; most probably, this observation is a consequence of the generation of allyl complexes, such as [Pt(C₃H₅)(bipy)]⁺. In the reactions of [Pt(L? H)]⁺ (L=phpy, bq) with propane and n‐butane, the losses of the alkenes and dihydrogen are of comparable intensities. While in the reactions of “rollover”‐cyclometalated [Pt(bipy? H)]⁺ with C_nH_2n+2 (n=2–4) less than 15 % of the generated product ions are formed by C? C bond‐cleavage processes, this value is about 60 % for the reaction with neo‐pentane. The result that C? C bond cleavage gains in importance for this substrate is a consequence of the fact that 1,2‐elimination of two hydrogen atoms is no option; this observation may suggest that in the reactions with the smaller alkanes, 1,1‐ and 1,3‐elimination pathways are only of minor importance.     

Complexes of 3,3′-Oxybis[(diphenylphosphino)methylbenzene] with Ni(II), Pd(II), Pt(II), Rh(I), and Ag(I). How Important is Backbone Rigidity in the Formation of trans-Spanning Bidenatate Chelates??

The bidentate diphosphine ligand, 3,3′-oxybis[(dipenylphosphino)methylbenzene] ( 1 ) forms monomeric, trans-square-planar complexes MX₂( 1 ) (M = Ni, Pd, Pt; X = Cl^?, Br^? I^?, and, in part, N, NCS^?, CN^?, NO) as well as Pt(H)Cl( 1 ), Pt(H)Br( 1 ), and RhCl(CO)( 1 ). Polymeric species have been observed with substitutionally inert metal centres: trans-[PtCl₂( 1 )]₂ and cis-[PtCl₂( 1 )]_n (mean value of n ≈ 4–5) ³¹P-NMR, and selected IR and UV/VIS parameters are reported. Ligand 1 shows a marked preference for trans-spanning and monomeric chelate formation, despite its various degrees of freedom of internal rotation in the lignad backbone. The readily available ligand 1 as well as analogues with other donor atoms, therefore, appear useful in most potential applications of trans-spanning chelate ligands. The crystal structure of AgCl( 1 )·0.5 (CH₃)₂C?O·0.39 C₆H₁₂ (space group C2/c,a = 21.02 Å, b = 14.57 Å, c = 24.79 Å, β = 99.77°, V = 7531.4 ų, Z = 8) confirms the presence of three-coordinate Ag( I ), with a coordination intermediate between a trigonal-planar and a T-shaped geometry (P-Ag-P = 145.61(8)°).     

Activation of 1, 2‐Dihydrodisilanes at Platinum(0) Phosphine Complexes: Syntheses and Structures of Bissilyl Platinum(II) Complexes

The bissilyl complexes 3 – 6 were synthesized by reactions of the platinum(0) complexes [Pt(η²‐C₂H₄)(diphos)] ( 1 : diphos = dppe; 2 : diphos = dcpe) with the disilanes 1, 1,2, 2‐tetramethyldisilane and 1, 1,2, 2‐tetraphenyldisilane via Si–Si bond activation. The molecular structures of 4 and 5 in the solid state are reported. The reaction of 2 with HPh₂SiSiPh₂H led to the immediate formation of the hydrido disilanyl complex [Pt(H)(SiPh₂SiPh₂H)(dcpe)] ( 7 ), which converts slowly into the bissilyl complex [Pt(SiHPh₂)₂(dcpe)] ( 6 ). The latter was reported before to be a η²‐disilene complex.     

The Synthesis of Mono- and Bi-Metallic Platinum(II) and/or (IV) Complexes Containing the Ligand Bis(diphenylphosphino) Methylamine

Complexes of the type [Pt R₂ (dppma-PP′)] (R─Me, Et, Ph, CH₂Ph, C₆H₄ Me-p, C₆H₄OMe-2, CH₂CMe₃, 1-naphthyl, C₆H₄Me-o, dppma = Ph₂PNMe PPh₂) have been prepared from [PtCl₂, (dppma-PP′)] and the corresponding alkyl-lithium or Grignard reagents. Equilibrium constants, k, for the conversion of [PtR₂ (dppma-PP′)] into cis-[PtR₂(dppma-P)₂] with dppma were studied using ³¹P NMR spectroscopy at room temperature. Equilibrium is rapidly established for R─C₆H₄-Me-o, at 20°C. Complex of the type cis-[PtR₂ (dppma-P)₂] was isolated R─C₆H₄ Me-o. The complexes [PtMe₂(dppma-P)₂] and [Pt(o-methoxyphenyl)₂(dppma-P)₂] were prepared, but unfortunately decomposed once isolated, the only evidence for its formation being from ³¹P-{¹H} NMZR spectroscopy. The o-tolyl or 1-naphthyl complexes exist as syn-anti mixtures in solution, due to restricted rotation around the platinum aryl bonds. Treatment of several complexes of the type [PtR₂(dppma-PP′)] with MeI gives [PtR₂Me(I)(dppma-PP′)] with trans addition of MeI. Treatment of [PtR₂(dppma-PP′)] with HCl gives [Pt Cl (R) (dppma-PP′)] for R─C₆H₂Me₃-2,4,6, C₆H₄-CH₃-2, C₆H₄-Me-4, Me, 1-naphthyl. The ¹H, ³¹P NMR parameters for these complexes are discussed. Attempted preparation of complexes of the type [PtR₂ (dppma-P)₂M] (R─C₆H₄-Me-2, Me CN-C₆H₄-Me-4); M─Pd, Pt, Au,) are reported.     

“Roll‐over” Cyclometalation of 2,2′‐Bipyridine Platinum(II) Complexes in the Gas Phase: A Combined Experimental and Computational Study

In a combined experimental/computational investigation, the gas‐phase behavior of cationic [Pt(bipy)(CH₃)((CH₃)₂S)]⁺ ( 1 ) (bipy=2,2′‐bipyridine) has been explored. Losses of CH₄ and (CH₃)₂S from 1 result in the formation of a cyclometalated 2,2′‐bipyrid‐3‐yl species [Pt(bipy?H)]⁺ ( 2 ). As to the mechanisms of ligand evaporation, detailed labeling experiments complemented by DFT‐based computations reveal that the reaction follows the mechanistically intriguing “roll‐over” cyclometalation path in the course of which a hydrogen atom from the C(3)‐position is combined with the Pt‐bound methyl group to produce CH₄. Activation of a C? H‐bond of the (CH₃)₂S ligand occurs as well, but is less favored (35 % versus 65 %) as compared to the C(3)? H bond activation of bipy. In addition, the thermal ion/molecule reactions of [Pt(bipy?H)]⁺ with (CH₃)₂S have been examined, and for the major pathway, that is, the dehydrogenative coupling of the two methyl groups to form C₂H₄, a mechanism is suggested that is compatible with the experimental and computational findings. A hallmark of the gas‐phase chemistry of [Pt(bipy?H)]⁺ with the incoming (CH₃)₂S ligand is the exchange of one (and only one) hydrogen atom of the bipy fragment with the C? H bonds of dimethylsulfide in a reversible “roll‐over” cyclometalation reaction. The Pt^II‐mediated conversion of (CH₃)₂S to C₂H₄ may serve as a model to obtain mechanistic insight in the dehydrosulfurization of sulfur‐containing hydrocarbons.     

Ab Initio Calculations of Hydroxoplatinum Compounds: II. Binuclear Platinum(IV) Superoxo Complexes

The structural and spectral data have been obtained by ab initio methods for the [(OH)₄Pt(μ-O₂)(μ- OH)Pt(OH)₄]^2?, [(OH)₄Pt(μ-O₂)(μ-OH)Pt(OH)₄(OH)]^3?, [(OH)₅Pt(μ-O₂)Pt(OH)₅]^3?, and [(H₂O)(OH)₄Pt(μ- O₂)Pt(OH)₄(H₂O)]- clusters, corresponding to binuclear platinum(IV) superoxo complexes with one and two bridges. The data obtained are in good agreement with experimental data and make it possible to judge the structure of available complexes.     

Synthese und Struktur der Platin(O)-Verbindungen [(dipb)Pt]2(COD) und (dipb)3Pt2 sowie des clusters Hg6[Pt(dipb)]4 (dipb = (i-Pr)2P(CH2)4P(i-Pr)2)

Synthesis and Structure of the Platinum(0) Compounds [(dipb)Pt]₂(COD) and (dipb)₃Pt₂ and of the Cluster Hg₆[Pt(dipb)]₄ (dipb = (i-Pr)₂P(CH₂)₄P(i-Pr)₂) The reduction of (dipb)PtCl₂ with Na/Hg yields (dipb)Pt as an intermediate which reacts with the amalgam to form the cluster Hg₆[Pt(dipb)]₄ ( 3 ) or decomposes to (dipb)₃Pt₂ ( 2 ) and Pt. In the presence of COD [(dipb)Pt]₂(COD) ( 1 ) is obtained. 1 crystallizes monoclinicly in the space group P2₁/c with a = 1596.1(4), b = 996.5(2), c = 1550.4(3) pm, β = 113.65(2)°, Z = 2. In the dinuclear complex two (dipb)Pt units are bridged by a 1,2-η²-5,6-η² bonded COD ligand. Whereby the C = C double bonds are lengthened to 145 pm. 2 forms triclinic crystals with the space group P1 and a = 1002.0(2), b = 1635.9(3), c = 868.2(2) pm, α = 94.70(2)°, β = 94.45(2)°, σ = 87.95(1)°, Z = 1. In 2 two (dipb)Pt moieties are connected by a μ-dipb ligand in a centrosymmetrical arrangement. 3 is monoclinic with the space group C2/c and a = 1273.8(3), b = 4869.2(6), c = 1660.2(3) pm, β = 95.16(2)°, Z = 4. The clusters Hg₆[Pt(dipb)]₄ have the symmetry C₂. Central unit is a Hg₆ octahedron of which four faces are occupied by Pt(dipb) groups. The bonding in the cluster is discussed on the basis of eight Pt? Hg two center bonds of 267.6 pm and two Pt? Hg? Pt three center bonds with Pt? Hg = 288.0 pm.     

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.     

Synthesis and Platinum Complexes of an Alane‐Appended 1,1′‐Bis(phosphino)ferrocene Ligand

An aryldimethylalane‐appended analogue of 1,1′‐bis(diphenylphosphino)ferrocene, FcPPAl, was prepared, and reaction with [Pt(nb)₃] (nb=norbornene) afforded [Pt(η²‐nb)(FcPPAl)] ( 1 ). Heating a solution of 1 to 80 °C resulted in crystallization of [{Pt(FcPPAl)}₂] ( 2 ), whereas treatment of 1 with C₂H₄, C₂Ph₂, H₂, or CO provided [PtL(FcPPAl)] [L=C₂H₄ ( 3 ), C₂Ph₂ ( 4 )], [PtH₂(FcPPAl)] ( 5 ), and [Pt(CO)(FcPPAl)] ( 6 ). In all complexes, the FcPPAl ligand is coordinated through both phosphines and the alane. Whereas 2 adopts a T‐shaped geometry at platinum, 3 – 5 are square‐pyramidal, and 6 is distorted square‐planar. The hydride and carbonyl complexes feature unusual multicenter bonding involving platinum, aluminum, and a hydride or carbonyl ligand.     

Transition metal complexes with bidentate ligands spanning trans-positions. Part XIV. Some complexes of 2,11-bis(diphenylphosphinomethyl)benzo[c]phenanthrene with platinum (0) and their reactivities

The ligand 2,11-bis(diphenylphosphinomethyl)benzo[c]phenanthrene ( 1 ) has been used to prepare complexes of the type [PtL( 1 )] (L ? C₂H₄, CH₂?CH? CO₂Me, PhC?CPh, MeC?CMe, MeO₂CC?CCO₂Me, (i-Pr)O₂CC?CCO₂(i-Pr), Ph₃P and CO). It is shown that these complexes are less labile than the corresponding species [PtL(Ph₃P)₂]. The preparation of complexes trans-[PtX(R)(1)] by oxidative addition of RX (RX ? PhCH₂Br and Mel) to [Pt(C₂H₄)(1)] is described. The isolation of [PtO₂(CH₃)₂CO(1)] is also reported.     

Neue Benzylkomplexe der Lanthanoiden. Darstellung und Kristallstrukturen von [(C5Me5)2Y(CH2C6H5)(thf)], [(C5Me5)2Sm(CH2C6H5)2K(thf)2]∞ und [(C5Me5)Gd(CH2C6H5)2(thf)]

New Benzyl Complexes of the Lanthanides. Synthesis and Crystal Structures of [(C₅Me₅)₂Y(CH₂C₆H₅)(thf)], [(C₅Me₅)₂Sm(CH₂C₆H₅)₂K(thf)₂]_∞, and [(C₅Me₅)Gd(CH₂C₆H₅)₂(thf)] YBr₃ reacts with potassium benzyl and [K(C₅Me₅)] in THF to give KBr and the monobenzyl compound [(C₅Me₅)₂ · Y(CH₂C₆H₅)(thf)] 1 . The analogous reaction with SmBr₃ in THF leads to the polymeric product [(C₅Me₅)₂Sm(CH₂C₆H₅)₂ ∞ K(thf)₂]_∞ 2 , with GdBr₃ to [(C₅Me₅)Gd(CH₂C₆H₅)₂(thf)] 3 . The structures of 1–3 were determined by X-ray single crystal structure analysis:

• Space group P1 , Z = 2, a = 851.2(4) pm, b = 952.7(4) pm, c = 1858.6(8) pm, α = 79.90(4)°, β = 77.35(4)°, γ = 73.30(3)°.
• Space group P1 , Z = 2, a = 903.3(2) pm, b = 1375.9(3) pm, c = 1801.1(4) pm, α = 100.92(3)°, β = 100.77°, γ = 98.25(3)°.
• Space group P2₁/n, Z = 8, a = 1458.2(5) pm, b = 927.8(3) pm, c = 3792.9(15) pm, β = 96.83(3)°.

     

Synthesis and characterization of cobalt(II), nickel(II) and copper(II) perchlorate complexes with bis [(diphenylphosphinyl)methyl] phenylphosphine oxide,bis [(disphenylphosphinyl)methyl]ethyl phosphinate,and bis [(diphenylphosphinyl)methyl] phosphinic acid

The synthesis and characterization of cobalt(II), nickel(II) and copper(II) perchlorate complexes containing bis [(diphenylphosphinyl)methyl] [phenylphosphine oxide (RPPH), bis [(diphenylphosphinyl)methyl] ethyl phosphinate (RPOEt), and bis [(diphenylphosphinyl)methyl] phosphinic acid (RPOH) have been studied. The substituent at the central phosphorus atom of the ligand is responsible for the types of complexes formed. The new complexes [M(RPPh)₂(ClO₄)₂.nH₂O, [M(RPPh)₃](ClO₄)₂.4H₂O, [M(RPOEt)₂](ClO₄)₂.2H₂O, and [M(RPOH)₃] (ClO₄)₂.nH₂O are characterized as high spin and most of them have an octahedral or distorted octahedral geometry [M = Co(II), Ni(II), or Cu(II); n = 2?5]. The coordination of two P = O groups from one ligand to the metal has been proposed for most of the complexes formed. The coordination of all three P = O groups has been assumed for complexes [M(RPPh)₂](ClO₄)₂.nH₂O and [M(RPOEt)₂](ClO₄)₂.2H₂O.     

Investigation on Optical and Biological Properties of 2-(4-Dimethylaminophenyl)benzothiazole Based Cycloplatinated Complexes

The optical and biological properties of 2-(4-dimethylaminophenyl)benzothiazole cycloplatinated complexes featuring bioactive ligands ([{Pt(Me₂N-pbt)(C₆F₅)}L] [L=Me₂N-pbtH 1 , p-dpbH (4-(diphenylphosphino)benzoic acid) 2 , o-dpbH (2-(diphenylphosphino)benzoic acid) 3 ), [Pt(Me₂N-pbt)(o-dpb)] 4 , [{Pt(Me₂N-pbt)(C₆F₅)}₂(μ-PR_nP)] [PR₄P=O(CH₂CH₂OC(O)C₆H₄PPh₂)₂ 5 , PR₁₂P=O{(CH₂CH₂O)₃C(O)C₆H₄PPh₂}₂ 6 ] are presented. Complexes 1 – 6 display ¹ILCT and metal-perturbed ³ILCT dual emissions. The ratio between both bands is excitation dependent, accomplishing warm-white emissions for 2 , 5 and 6 . The phosphorescent emission is lost in aerated solutions owing to photoinduced electron transfer to ³O₂ and the formation of ¹O₂, as confirmed in complexes 2 and 4 . They also exhibit photoinduced phosphorescence enhancement in non-degassed DMSO due to local oxidation of DMSO by sensitized ¹O₂, which causes a local degassing. Me₂N-pbtH and the complexes specifically accumulate in the Golgi apparatus, although only 2 , 3 and 6 were active against A549 and HeLa cancer cell lines, 6 being highly selective in respect to nontumoral cells. The potential photodynamic property of these complexes was demonstrated with complex 4 .     

Kristallstrukturen,Schwingungsspektren und Normalkoordinatenanalysen der stereoisomeren Trifluorotrichloroplatinate(IV), fac-[(C5H5N)2CH2][PtF3Cl3] · 0,5(CH3)2CO und mer-[(C5H5N)2CH2][PtF3Cl3]

Crystal Structures, Vibrational Spectra, and Normal Coordinate Analyses of the Stereoisomeric Trifluorotrichloroplatinates(IV), fac-[(C₅H₅N)₂CH₂][PtF₃Cl₃] · 0.5(CH₃)₂CO and mer-[(C₅H₅N)₂CH₂][PtF₃Cl₃] The geometric isomers fac- und mer-[PtF₃Cl₃]^2? have been isolated by ion exchange chromatography on diethylaminoethyl cellulose. The doubly charged complex anions form stable AB-type salts with the dication dipyridiniomethane, [(C₅H₅N)₂CH₂]²⁺. The X-ray structure determination on single crystals of fac-[(C₅H₅N)₂CH₂][PtF₃Cl₃] · 0,5(CH₃)₂CO ( 1 ) (triclinic, space group P1 with a = 8.468(3), b = 8.847(2), c = 12.1260(10) Å, α = 79.986(12), β = 79.009(12), γ = 69.20(3)°, Z = 2) and mer-[(C₅H₅N)₂CH₂][PtF₃Cl₃] ( 2 ) (monoclinic, space group P2₁/n with a = 9.620(2), b = 14.031(4), c = 10.435(3) Å, β = 97.54(2)°, Z = 4) reveals the perfect ordering of the anion sublattice. Due to the stronger trans influence of Cl compared to F in asymmetric axes $ {\rm F}^. $? Pt? Cl′ the Pt? $ {\rm F}^. $ distance is lengthened by 1.8%, the Pt? Cl′ distance is shortened by 1.2% in comparison with symmetrically coordinated axes. Correspondingly, the vibrational spectra exhibit shifts of the Pt$ {\rm F}^. $ streching vibrations by 8% to lower, and of the PtCl′ streching vibrations by 12% to higher frequencies. Normal coordinate analyses performed on the basis of the X-ray data result in valence force constants for weakened Pt? $ {\rm F}^. $ bonds to be 14% lower, for the strengthened Pt? Cl′ bonds to be 20% higher than in symmetric axes, respectively. Generally the trans influence in fluorochloroplatinates(IV) on the bond lengths is very low with 1–2%, it results in considerable shifts of the stretching vibrations by 8–12% and reveals the strongest effect on the valence force constants with 14–20%.     

Oxidative addition of different electrophiles with rhodium(I) carbonyl complexes of unsymmetrical phosphine–phosphine monoselenide ligands

Dimeric chlorobridge complex [Rh(CO)₂Cl]₂ reacts with two equivalents of a series of unsymmetrical phosphine–phosphine monoselenide ligands, Ph₂P(CH₂)_nP(Se)Ph₂ {n = 1( a ), 2( b ), 3( c ), 4( d )}to form chelate complex [Rh(CO)Cl(P∩Se)] ( 1a ) {P∩Se = η²‐(P,Se) coordinated} and non‐chelate complexes [Rh(CO)₂Cl(P～Se)] ( 1b–d ) {P～Se = η¹‐(P) coordinated}. The complexes 1 undergo oxidative addition reactions with different electrophiles such as CH₃I, C₂H₅I, C₆H₅CH₂Cl and I₂ to produce Rh(III) complexes of the type [Rh(COR)ClX(P∩Se)] {where R = ? C₂H₅ ( 2a ), X = I; R = ? CH₂C₆H₅ ( 3a ), X = Cl}, [Rh(CO)ClI₂(P∩Se)] ( 4a ), [Rh(CO)(COCH₃)ClI(P～Se)] ( 5b–d ), [Rh(CO)(COH₅)ClI‐(P～Se)] ( 6b–d ), [Rh(CO)(COCH₂C₆H₅)Cl₂(P～Se)] ( 7b–d ) and [Rh(CO)ClI₂(P～Se)] ( 8b–d ). The kinetic study of the oxidative addition (OA) reactions of the complexes 1 with CH₃I and C₂H₅I reveals a single stage kinetics. The rate of OA of the complexes varies with the length of the ligand backbone and follows the order 1a > 1b > 1c > 1d . The CH₃I reacts with the different complexes at a rate 10–100 times faster than the C₂H₅I. The catalytic activity of complexes 1b–d for carbonylation of methanol is evaluated and a higher turnover number (TON) is obtained compared with that of the well‐known commercial species [Rh(CO)₂I₂]^?. Copyright © 2006 John Wiley & Sons, Ltd.     

Addition of protic molecules to coordinated 2-pyridinecarboxaldehyde in gold(III), palladium(II), and platinum(II) complexes

The reactions of Au^III, Pt^II and Pd^II complexes with 2-pyridinecarboxaldehyde (2CHO-py) have been examined in protic (H₂O, MeOH, EtOH) and aprotic (DMF, CH₂Cl₂) solvents. Compounds in which the pyridine ligand is N-coordinated, either in the original aldehydic form or in a new form derived from addition of one or two protic molecules, have been isolated, namely: [Au(2CHO-py · H₂O)Cl₃], [Au(2CHO-py · MeOH)Cl₃], [Au(2CHO-py · 2EtOH)Cl₃], cis-[Pt(2CHO-py)₂Cl₂], trans-[Pd(2CHO-py)₂Cl₂], trans-[Pt(dmso)(2CHO-py)Cl₂], [Pt{C₅H₄N-(CH₂SMe)}Cl(2CHO-py)](ClO₄), [Pt(terpy)(2CHOpy)](ClO₄)₂, [Pt(terpy)(2CHO-py · H₂O)](ClO₄)₂ (terpy = 2,2′:6′,2′′-terpyridine). ¹H-n.m.r. experiments show that the addition of the protic molecule(s) to the Pt^II and Pd^II complexes is reversible. The effects of the nature of the metal ion and the ancillary ligands as well as of the total charge of the complexes on the relative stability of the addition products are discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Synthese und Struktur der Nitrido‐Komplexe [(n‐Bu)4N]2[{(L)Cl4Re≡N}2PtCl2] (L = THF und H2O) und [(n‐Bu)4N]2[(H2O)Cl4Re≡N‐PtCl(μ‐Cl)]2

Synthesis and Crystal Structure of the Nitrido Complexes [(n‐Bu)₄N]₂[{(L)Cl₄Re≡N}₂PtCl₂] (L = THF und H₂O) and [(n‐Bu)₄N]₂[(H₂O)Cl₄Re≡N‐PtCl(μ‐Cl)]₂ The threenuclear complex [(n‐Bu)₄N]₂[{(THF)Cl₄Re≡N}_2—PtCl₂] ( 1a ) is obtained by the reaction of [(n‐Bu)₄N][ReNCl₄] with [PtCl₂(C₆H₅CN)₂] in THF/CH₂Cl₂. It forms red crystals with the composition 1a · 2 CH₂Cl₂ crystallizing in the tetragonal space group I4₁/a with a = 3186.7(2); c = 1311.2(1) pm and Z = 8. If the reaction of the educts is carried out without THF, however under exposure to air the compound [(n‐Bu)₄N]₂[{(H₂O)Cl₄Re≡N}₂PtCl₂] ( 1b ) is obtained as red trigonal crystals with the space group R3 and a = 3628.3(3), c = 1231.4(1) pm and Z = 9. In the centrosymmetric complex anions [{(L)Cl₄Re≡N}₂PtCl₂]^2— a linear PtCl₂moiety is connected in a trans arrangement with two complex fragments [(L)Cl₄Re≡N]^— via asymmetric nitrido bridges Re≡dqN‐Pt. For Pt^II such results a square‐planar coordination PtCl₂N₂. The linear nitrido bridges are characterized by distances Re‐N = 169.5 pm and Pt‐N = 188.8 pm ( 1a ), respectively, Re‐N = 165.6 pm and Pt‐N = 194.1 pm ( 1b ). By the reaction of [(n‐Bu)₄N][ReNCl₄] with PtCl₄ in CH₂Cl₂ platinum is reduced forming the heterometallic Re^VI/Pt^II complex, [(n‐Bu)₄N]₂[(H₂O)Cl₄Re≡N‐PtCl(μ‐Cl)]₂ ( 2 ). It crystallizes in the monoclinic space group C2/c with a = 2012.9(1); b = 1109.0(2); c = 2687.4(4) pm; β = 111.65(1)° and Z = 4. In the central unit ClPt(μ‐Cl)₂PtCl of the anionic complex [(H₂O)Cl₄Re≡N‐PtCl(μ‐Cl)]₂^2— with the symmetry C₂ the coordination of the Pt atoms is completed by two nitrido bridges Re≡N‐Pt to nitrido complex fragments [(H₂O)Cl₄Re≡N] ^— forming a square‐planar arrangement for the Pt atoms. The distances in the linear nitrido bridges are Re‐N = 165.9 pm and Pt‐N = 190.1 pm.