Darstellung und eigenschaften von und reaktionen mit metallhaltigen heterocyclen XX. Darstellung,eigenschaften und kristallstruktur von λ4-thia-λ5-phospha-h2-metallabicyclo[2.2.1]heptadienen und ihre verwendung zur synthese von metallorganischen und organischen verbindungen

The novel λ⁴-thia-λ⁵-phospha-h²-manganabicyclo[2.2.1]heptadienes (OC)₃Mn[$\text{CR}{}^2\text{CR}{}^2\text{CR}{}^2\text{CR}{}^2\text{PR}{}^1{}_2\text{S}$] (R¹ = CH₃, C₆H₅; R² = CO₂CH₃, CO₂C₂H₅, CO₂C₆H₁₁) are formed by action of the activated alkynes R²C  CR² on the heterocycles [(OC)₄MnPR¹₂S]₂ via the isolable, five-membered heterometallacyclopentadienes (OC)₄$\text{MnSPR}{}^1{}_2\text{C(R}{}^2\text{)C}$(R²). The compound with R¹ = CH₃ and R² = CO₂CH₃ crystallizes in the triclinic space group P$\text{1}$ with Z = 2 and separates quantitatively the thiophene derivative $\text{CR}{}^2\text{CR}{}^2\text{CR}{}^2\text{CR}{}^2\text{S}$ under CO pressure or by reaction with (NH₄)₂Ce(NO₃)₆. The use of various acetylenes and of acetylenes with different alkyl groups yields the unsymmetric substituted manganabicycloheptadienes (OC)₃Mn[$\text{CR}{}^4\text{CR}{}^3\text{CR}{}^2\text{CR}{}^2\text{P(CH}{}_3\text{)}{}_2\text{S}$] (R² = CO₂CH₃, R³ = R⁴ = CO₂C₂H₅; R² = R⁴ = CO₂CH₃, R³ = H). With propionic acid methylester the alkyne insertion proceeds regiospecifically. With Raney nickel selective S elimination under ring contraction and formation of the λ⁴-phospha-h²-manganabicyclo[2.1.1]hexenes (OC)₃Mn[$\text{CR}{}^2\text{CR}{}^3\text{CR}{}^2\text{CR}{}^2\text{P}$R¹₂] (R¹ = CH₃: R² = R³ = CO₂CH₃, CO₂C₂H₅; R² = CO₂CH₃, R³ = H; R¹ = C₆H₅: R² = R³ = CO₂C₂H₅) occurs. (OC)₃Mn[$\text{CR}{}^2\text{CR}{}^3\text{CR}{}^2\text{CR}{}^2\text{P}$(CH₃)₂] (R² = R³ = CO₂CH₃) crystallizes in the monoclinic space group P2₁/m with Z = 2. The IR and NMR spectra of the heterocycles are discussed in detail.     

Primary radical termination in polymerization: Evaluation of the characteristic constant

Polymerization experiments with styrene in benzene at 60°, initiated by benzoyl peroxide, covering a wide range of concentration of both monomer and initiator are reported; the results cannot be explained in terms of the classical rate relationship with $\text{R}{}_{\mathrm{p}}\text{∝ [}\text{I}\text{]}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{[}\text{M}\text{]}$. Deviations were reflected in unexpected orders of monomer up to [M]^1·4 and of initiator down to [I]^0·42 when the initiator concentration is increased and monomer concentration is decreased. Based on the concept of primary radical termination, an equation, viz.

$\text{ln}\text{R}\text{p}\text{2}\text{[I][M]}{}^2\text{=}\text{ln}\text{2f}{}_{\mathrm{k}}\text{k}{}_{\mathrm{d}}\text{k}\text{p}\text{2}\text{k}{}_{\mathrm{t}}\text{?2}\text{k}{}_{\mathrm{prt}}\text{k}{}_{\mathrm{i}}\text{k}{}_{\mathrm{p}}\text{×}\text{R}{}_{\mathrm{p}}\text{[M]}{}^2$

is proposed. Semi-log plots of R_p²/[I] [M]² vs R_p/[M]² show a wide range of linearity; the characteristic constant k_prt/k_ik_p and also f_k can be obtained from the slope and intercept, respectively, k_prt, k_i and k_p are, respectively, the rate constants of primary radical termination, initiation and propagation and f_k is the efficiency of initiation, defined as the fraction of radicals which come out of the solvent cage and take part in initiation, primary radical termination and primary radical recombination. The definition of f_k is thus differentiated from the conventional efficiency of initiation. Finally, we have derived an equation which allows determination of the classical efficiency of initiation as a function of [I]/[M]² and also allows a correction of R_p in handling the above equation by taking into account the small amount of monomer consumed in initiation.     

Synthesis of homoleptic tris(organo-chelate)iridium(III) complexes by spontaneous ortho-metallation of electronrich olefin-derived N,N′-diarylcarbene ligands and the X-ray structures of fac-[Ir{CN(C6H4Me-p) (CH2)2NC6H3Me-p}3] and mer-Ir{CN(C6H4Me-p)(CH2)2NC6H3Me-p}2 {CN(C6H4Me-p)(CH2)2NC6H4Me-p}Cl (a product of HCl cleavage)

Treatment of [{Ir(COD)(μ-Cl)}₂] with excess of the electron-rich olefin [$\text{CN(Ar)(CH}{}_2\text{)}{}_2\text{N}$Ar]₂ (abbreviated as (L^Ar)₂, Ar = C₆H₄Me-p or C₆H₄OMe-p) affords the ortho-metallated tricycle [$\text{Ir(L}{}^{\mathrm{A}}\text{r}$)₃], which for Ar = C₆H₄Me-p (Ia) with HCL yields [$\text{Ir(L}{}^{\mathrm{A}}\text{r}$)₂(L^Ar)]Cl (IV); X-ray data show that in IV there is an unexpectedly close Ir?C(o-aryl) contact (2;52(1) Å) involving the “free” L^Ar which compares with an IrC(o-aryl) distance of 2.09(3) Å in Ia or 2.07(3) Å in the ortho-metallated L^Ar ligand of complex IV.     

Peroxo salts as initiators of vinyl polymerization—2. Kinetics of polymerization of acrylic acid and sodium-acrylate by peroxodisulphate in aqueous solution—effect of pH and Ag+ catalysis

Results on the rate of polymerization of acrylic acid by S₂O^2?₈ ion in alkaline and acid conditions are presented. R_p depended upon $\text{[S}{}_2\text{O}{}^{\mathrm{2?}}{}_8\text{]}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and $\text{[monomer]}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ both in acid and alkaline solutions. The influence of ionic strength, the effect of pH on R_p and the catalytic effect of Ag⁺ and Cu²⁺ on the system have been discussed. Suitable mechanisms are proposed.     

Electronic conductivity in nonstoichiometric cerium dioxide

The electrical conductivity of sintered specimens of nonstoichiometric CeO_2?x was measured as a function of temperature (750–1500°C) and oxygen pressure (1–10^?22 atm). The isothermal compositional dependence of the electrical conductivity of CeO_2?x was determined by combining recently obtained thermodynamic data, x = x(P_O2, T), with the conductivity data. The compositional and temperature dependence of the electrical conductivity may be represented by the expression

$\text{σ=410[x]e}{}^{\mathrm{<mtext>?(0.158+x)</mtext><mtext>kT</mtext>}}\text{(}\text{ohm cm}\text{)}{}^{\mathrm{?1}}$

over the temperature range 750–1500°C and from x = 0.001 to x = 0.1.This expression was rationalized in terms of the following simple relations for (a) the electron carrier concentration

$\text{n}{}_{\mathrm{ce}}\text{′}{}_{\mathrm{ce}}\text{=}\text{8x}\text{a}{}_0{}^3$

where n_Ce′Ce is the number of Ce′_Ce per cm³ and a₀ is the lattice parameter and (b) the electron mobility

$\text{μ=5.2(10}{}^{\mathrm{?2}}\text{)e}{}^{\mathrm{<mtext>?(0.158+x)</mtext><mtext>kT</mtext>}}\text{(}\text{cm}{}^2\text{/}\text{V sec}\text{)}$

.     

Etude comparative des structures type K4NiF4 et pérovskite par la méthode des invariants

The study of K₂NiF₄ and perovskite structure type by the “method of invariants” leads to the relationship: $\text{(A-X)}{}_9\text{2}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{? (A-X)}{}_{12}\text{=}\text{constant}$, where (A-X)₉ and (A-X)₁₂ are the invariant values associated with cation A in coordination number 9 and 12. In the case where A = K⁺ and X = F^?, we propose the relationship:

$\text{(K}{}^{\mathrm{+}}\text{?F)}{}_{\mathrm{R}}\text{= 2.832 R}{}^{\mathrm{<mtext>1</mtext><mtext>11.4</mtext>}}$

where R is the coordination number.     

Anomaly in dispersion intermolecular potential produced by intense radation field

It is predicted that a gap of 2μE/3^{$\text{1}\text{2}$} appears in the dispersion potential for a pair of ground-state (identical) atoms, or molecules, at distance R such that ?δ + (4π?₀)^?1($\text{μ}{}^2\text{3}\text{R}{}^3$)(1 ? 3 cos²θ) = 0, where μ is the electric dipole moment, E is the field strength of an intense radiation field and θ is the angle between the polarization direction of the field and R. The detuning term Δ is ω₀?ω where ω₀ is the transition frequency of the atom or molecule, and ω is that of the field. The gap is of the order of 10¹¹ Hz when the intensity of the radiation field is a few $\text{MW}\text{cm}{}^2$.     

Effect of benzophenone on the H2O2-induced photopolymerization of methyl methacrylate

Benzophenone (BP) in low concentrations (<0.001 mol 1^?1) produces a rate enhancing effect in the H₂O₂-induced bulk photopolymerization of MMA. R_p is proportional to [H₂O₂]^0.4 and [BP]^0.4, and $\text{k}{}_{\mathrm{p}}{}^2\text{k}{}_1$ at 30° is 1.00 × 10^?2 1.mol^?1 sec^?1. In diluted systems, different solvents produce different kinetic effects, reaction order with respect to monomer being negative for IPA and THF as solvent, positive but <1.0 for benzene and chloroform, 1.2 for acetonitrile, CCl₄ and t-butanol and 1.8 for DMA. The variable solvent effect is attributed to modification of the initiation process by the various solvents to different extents. Kinetic analysis of data for bulk photopolymerization gives evidence for primary radical termination and degradative initiator transfer.     

Thermophysical properties of the intermetallic Mn3MN perovskites III. Heat capacity of the solid solution Mn3.2Ga0.8N

The heat capacity of the solid solution Mn_3.2Ga_0.8N was measured between 5 to 330 K by adiabatic calorimetry. A sharp anomaly with first-order character was detected at T_A = (160.5±0.5) K, corresponding to a magnetic rearrangement and a lattice expansion. No sharp anomaly was observed at T_c ≈ 260 K where the magnetic ordering takes place; instead, a smooth shoulder was detected. The thermodynamic functions at 298.15 K are $\text{C}{}_{\mathrm{<mtext>p,</mtext><mtext>m</mtext>}}\text{R}\text{= 15.16}$, $\text{S}{}_{\mathrm{m}}{}^{\mathrm{o}}\text{R}\text{= 18.57}$, $\text{{H}{}_{\mathrm{m}}{}^{\mathrm{o}}\text{(T)?H}{}_{\mathrm{m}}{}^{\mathrm{o}}\text{(0)}}\text{R}\text{= 2896}\text{K}$, $\text{?{G}{}_{\mathrm{m}}{}^{\mathrm{o}}\text{(T)?H}{}_{\mathrm{m}}{}^{\mathrm{o}}\text{(0)}}\text{RT}\text{= 8.85}$. At low temperatures the coefficient for the linear electronic contribution to the heat capacity was derived: γ = (0.031±0.003) J·K^?2·mol^?1. Moreover, the different contributions to the heat capacity were obtained and the electronic origin of the phase transitions was established.     

Gas phase oxidative-addition reactions of alkyl radicals at complexed cobalt(II) centres

Negative chemical ionisation mass spectrometry is used as a probe to identify reactions between hydrocarbon radicals and cornplexed cobalt(II) centres in the gas phase. Methane NCI mass spectra of a series of cobalt(II) complexes containing O₄, O₂N₂ and N₄ donor atom sets are characterised by adduct ions of the form [M + C_nH_2n+1]^? at m/z values above the molecular ion, [M]^?. Formation of such ionic species has been rationalised in terms of a one-electron oxidative-addition mechanism involving attack by hydrocarbon plasma-derived alkyl radicals at the metal centre prior to electron capture: Co^IIL_n + R^? → RCo^IIIL_n$\text{e}{}^{\mathrm{?}}$ [Co^IL_n]^?. The competing resonance electron attachment reaction: Co^IIL_n$\text{e}{}^{\mathrm{?}}$ also occurs within the ion source.     

Cobalt metallocycles: IV. Ring opening of cobaltacyclopentadienes by addition of SiH,SH,NH and CH to the diene moiety

Cobaltacyclopentadiene complexes, (η⁵-C₅H₅)(PPh₃)($\text{CoCR}{}^1\text{CR}{}^2\text{CR}{}^2\text{C}$R¹) (R¹, R² =; Ph, Me, CO₂Me), reacted with RH (RH: triethylsilane, thiocresol, dimethyl- and ethylene-thiourea, pyrrole, thiophene) to give diene complexes, (η⁵-C₅H₅)(η⁴-HCR¹CR²CR²CR¹R)Co, or uncomplexed, highly substituted butadiene derivatives, HCR¹CR²CR²CR¹R. The reaction with thiourea proceeded catalytically in the presence of excess of diphenylacetylene although turn-over of the catalyst was small.     

Electrical conductivity in strontium titanate with nonideal cationic ratio

The electrical conductivity of polycrystalline strontium titanate with ($\text{Sr}\text{Ti}\text{= 0.996, 0.99,}\text{and}\text{0.98}$ was determined for the oxygen partial pressure range of 10⁰ to 10^?22 atm and the temperature range of 850–1050°C. These data were found to be similar to that obtained for the sample with ideal cationic ratio. The observed data were proportional to the $\text{?}\text{1}\text{6}$ power of oxygen partial pressure for P_O2 < 10^?15atm, proportional to for the pressure range 10^?8–10^?15 atm, and proportional to for P_O2 > 10^?4atm. The deviation from the ideal Sr-to-Ti ratio was found to be accommodated by neutral vacancy pairs, (V″_Sr V″₀. The results indicate that the single-phase field of strontium titanate extends beyond 50.505 mole% TiO₂ at elevated temperatures.     

Übergangsmetall-Fulven-Komplexe: XXXII. Heteronukleare Zweikernkomplexe des Azulens

The molecular structure of the dinuclear complex [(η⁶-benzene)M$\text{o(μ-η}{}^6\text{: η}{}^4\text{-azulene)C}$r(CO)₃ was determined by an X-ray diffraction study. The reaction of [(η⁶-azulene)(η⁶-benzene)Mo] with [RhCI(CO)₂]₂ gives the salt [η⁶-benzene)M$\text{o(μ-η}{}^6\text{: η}{}^4\text{-azulene)R}$h(CO)₂]₊[RhCl₂(CO)₂]^?, the structure of which was also characterized by X-ray crystallography. The cation of this salt can also be synthesized from [(η⁶-azulene)(η⁶-benzene)Mo] and [Rh(CO)₂]⁺. The fluxionality of the cation was studied by temperature-dependent ¹H-NMR measurements. The complex [(η⁶-azulene)(η⁶-benzene)Mo] reacts with Fe₂(CO)₉ to give the dinuclear complex [(η⁶-benzene)M$\text{o(μ-η}{}^5\text{:}{}_3\text{-azulene)F}$e(CO)₃], as confirmed by X-ray diffraction.     

Electrical conductivity in calcium titanate

The electrical conductivity of polycrystalline CaTiO₃ was measured over the temperature range 800–1100°C while in thermodynamic equilibrium with oxygen partial pressures from 10^?22 to 10⁰ atm. The data were found to be proportional to the $\text{?}\text{1}\text{6}\text{th}$ power of the oxygen partial pressure for the oxygen pressure range 10^?16 – 10^?22 atm, proportional to for the oxygen pressure range 10^?8 – 10^?15 atm, and proportional to for the oxygen pressure range greater than 10^?4 atm. The region of linearity where the electrical conductivity varies as $\text{?}\text{1}\text{4}\text{th}$ power of P_O2 increased as the temperature was decreased. The observed data are consistent with the presence of small amounts of acceptor impurities in CaTiO₃. The band-gap energy (extrapolated to zero temperature) was estimated to be 3.46 eV.     

Synthesis and solution properties of poly[2-methoxy-4,6-di(p,p′-isopropylidene diphenyloxy)-s-triazine] I

Poly[2-methoxy-4,6-di(p,p′-isopropylidene diphenyloxy)-s-triazine] has been synthesized by interfacial polycondensation of 2-methoxy-4,6-dichloro-s-triazine with bisphenol A. The conditions have been optimized to prepare a sample of both high solubility and molecular weight. The polymer has been fractionated by fractional precipitation and the fractions characterized by viscometry, osmometry and gel permeation chromatography. Mark-Houwink-Kuhn-Sakurada (MHKS) expressions have been developed for three solvents. The values of unperturbed dimensions $\text{(<R}{}^2\text{>}{}_0\text{/M)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, solvent-polymer interaction parameter (B and χ₁) and conformational parameter (σ) have been computed by applying the two-parameter theories of excluded volume developed by Fixman, Kurata, Stockmayer and Roig and by Flory, Fox and Schaefgen.     

Application of spin trapping technique to radical polymerization—22. N-benzoyloxyimide derivatives as photoinitiators

N-Benzoyloxyimides such as N-benzoyloxysuccinimide (NBzS) were found to act as photoinitiators for acrylonitrile (AN), methyl acrylate and methyl methacrylate. Polymerization rate (R_p) for the photopolymerization of AN with NBzS in dimethylformamide at 30° was expressed thus;

$\text{R}\text{p}\text{-}\text{k}\text{[}\text{NB}\text{Z}\text{S}\text{]}{}^{0.25}\text{[}\text{AN}{}^{1.3}$

The overall activation energy was 27.6 kJ/mol. A spin trapping study on the photolysis of NBzS revealed formation of acyl and phenyl radicals, indicating that simultaneous scissions of the NO and OCO bonds in NBzS occur under irradiation. An initiation mechanism is proposed and discussed.     

Kinetics and mechanism of the interaction of hexaaquochromium(III) with octacyanomolybdate(IV) ions

The kinetics of the interaction of hexaaquochromium(III) ion with potassium octacyanomolybdate(IV) have been studied using conductance and spectrophotometric data. The mechanism of the reaction is discussed and the effect of H⁺ ion and the ionic strength on the rate of the reaction determined. The reaction is found to be pseudo-first order with respect to potassium octacyanomolybdate(IV) and inverse first order with [H₃O⁺]. The rate of the reaction increases with increase in ionic strength and temperature. Activation parameters have been calculated using the Arrhenius equation and have the values ΔE^* = 1.3 × 10² kJ mol^?1, ΔH^* = 129 kJ mol^?1, ΔS^* = ?315 e.u., ΔF^* = 2.3 × 10² kJ and A = 1.5 × 10^?3. The mechanism proposed is based on ion-pair formation and the rate equation obtained is given by: k_obs=$\text{[}{}_{\mathrm{kK}}{}_{\mathrm{<mtext>E</mtext>}}\text{[H}{}_3\text{O}{}^{\mathrm{+}}\text{]+}\text{k′K′k}{}_{\mathrm{E}}\text{k}{}_{\mathrm{h}}\text{][Mo(CN)}{}_8{}^{\mathrm{4?}}\text{]}\text{[H}{}_3\text{O}{}^{\mathrm{+}}\text{]+}\text{k}{}_{\mathrm{<mtext>h</mtext>}}\text{+[}\text{K}{}_{\mathrm{<mtext>E</mtext>}}\text{[H}{}_3\text{O}{}^{\mathrm{+}}\text{]+}\text{K′}{}_{\mathrm{E}}\text{k}{}_{\mathrm{h}}\text{][Mo(CN)}{}_8{}^{\mathrm{4?}}\text{]}$     

Vinyl polymerization initiated by the (dimethylaniline-n-oxide)/(phenacyl bromide) system

Binary systems consisting of dimethylaniline-N-oxide (DMOA) and some α-halo-carbonyl compounds, such as phenacyl halide and α-halo-acetic acid ester, were found to induce radical polymerization of vinyl monomers. Bromo-derivatives showed higher initiating activities than chloroderivatives. The polymerization of methyl methacrylate (MMA) with DMAO and phenacyl bromide (PBr) was investigated kinetically. The polymerization rate (R_p) was expressed as follows; $\text{R}{}_{\mathrm{<mtext>p</mtext>}}\text{=}\text{k[DMAO]}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{[}\text{PBr}\text{]}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{[}\text{MMA}\text{]}$.The overall activation energy of the polymerization was calculated to be 42.7 kJ mol^?1. No noticeable chain-transfer from the polymer radical to DMAO or PBr was observed. The benzoyl radical was trapped by 2-nitroso-2-methylpropane, a spin trapping reagent, in the reaction of DMAO and PBr. The u.v. spectrum of poly (MMA) obtained suggests that the polymer contains end-groups similar to acetophenone and DMA. From the results, an initiation mechanism for the polymerization has been proposed and discussed.     

Struktur und Bindung in Übergangsmetall-Fluoriden MIIMeIVF6: Neutronenbeugungs-Strukturuntersuchungen an CaSnF6, FeZrF6, und CrZrF6

Compounds M^IIMe^IVF₆ requently undergo phase transitions from the cubic ordered ReO₃ to the trigonal LiSbF₆ structure when lowering the temperature. In case of a strongly Jahn-Teller unstable cation in the M^II position additional phases may occur. Results of powder neutron-diffraction studies on CaSnF₆, FeZrF₆, and CrZrF₆ at different temperatures are reported. The high-temperature phases have the space group Fm3m; the F^? ligands are either statistically displaced from the M^IIMe^IV directions or undergo a strong thermal motion perpendicular to these directions ($\text{?M}{}^{\mathrm{<mtext>II</mtext>}}\text{}\text{FMe}{}^{\mathrm{IV}}$: 165–180°). The thermal ellipsoids of the CrF bonds are strongly indicative of a dynamical Jahn-Teller effect in addition. In the low-temperature phases of CaSnF₆ and FeZrF₆ (space group $\text{R}\text{3}$) the $\text{?M}{}^{\mathrm{<mtext>II</mtext>}}\text{}\text{FMe}{}^{\mathrm{IV}}$ is more distinctly bent (?155–160°). CrZrF₆ undergoes two reversible phase transitions, which are determined to occur at 415 ± 5 K (cubic → tetragonal, dynamic to static Jahn-Teller distortion of CrF₆ octahedra and 150 ± 10 K (tetragonal → (pseudo)monoclinic).     

Transition metalcarbon bonds: LV. Cyclometallation and other reactions of PBut2Bui and PPh2Bui with platinum(II) and palladium(II)

The new phosphine, PBu^t₂Buⁱ (L), was prepared from Bu^t₂PCl and LiBuⁱ. PPh₂Buⁱ (L′) was prepared from Ph₂PCl and LiBuⁱ. Treatment of [PtCl₂(NCBu^t)₂] with L′ gives [PtCl₂L′₂] which does not cyclometallate even on prolonged boiling in 2-methoxyethanol. In contrast, [PtCl₂(NCBu^t)₂] reacts with PBu^t₂Buⁱ in boiling 2-methoxyethanol to give the cyclometallated complex [$\text{Pt}{}_2\text{Cl}{}_2\text{(PBu}{}^{\mathrm{t}}{}_2\text{CH}{}_2\text{-CHMeCH}$₂)₂] (II, X = Cl). The corresponding bromide, iodide and acetylacetonate were prepared. With PPh₃ II (X = Cl) gives [$\text{PtCl(PBu}{}^{\mathrm{t}}{}_2\text{CH}{}_2\text{CHMeCH}$₂)(PPh₃)] which with NaBH₄ gives [$\text{PtH(PBu}{}^{\mathrm{t}}{}_2\text{CH}{}_2\text{CHMeC}$H₂)(PPh₃)]. Na₂PdCl₄ with L (2 mol equivalents) gave trans-[PdCl₂L₂], which was converted into trans-[Pd(NCS)₂-L₂] by metathesis with KSCN. Treatment of Na₂PdCl₄ with L (1 mol equivalent) gave [Pd₂Cl₄L₂], which on heating in 2-methoxyethanol gave [$\text{Pd}{}_2\text{Cl}{}_2\text{(PBu}{}^{\mathrm{t}}{}_2\text{CH}{}_2\text{-CHMeCH}$₂)₂], as a mixture of syn- and anti-isomers. The complexes trans-[PdCl₂-L′₂] and [Pd₂Cl₄L′₂] were also prepared. ¹H- and ³¹P NMR data are given.