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Understanding factors that influence the volatility of lanthanide complexes remains an important goal for applications such as gas-phase f-metal separations and the synthesis of lanthanide-containing thin films. Lanthanide complexes often exhibit volatility differences that depend on the ability of ligands to saturate the lanthanide coordination sphere and attenuate intermolecular bonding in the solid state. This can make it difficult to assess how electronic factors associated with differing ligand substituents influence volatility. Here we describe the synthesis, structures, and thermal properties of a series of volatile lanthanide complexes (Ln = Nd, Er, and Yb) containing N4O3 ligands decorated with different alkyl and fluoroalkyl substituents (CF3, CF2CF2CF3, Me, and tBu). These ligands completely enveloped the tested lanthanides to form monomeric complexes with 7-coordinate distorted capped octahedral coordination geometries, as determined using single-crystal X-ray diffraction. Thermogravimetric analysis and bulk sublimation studies show how metal encapsulation affords complexes with the same volatility regardless of metal size, even with lanthanide ions with significantly different radii such as Nd3+ and Yb3+. Most notably, the results show that increasing ligand fluorination, a strategy often used to increase the volatility of metal complexes, is not always beneficial and can significantly attenuate the volatility of lanthanide complexes depending on location with respect to other substituents in the ligand framework. A pair-wise model based on density functional theory shows that the net intermolecular interactions in the unit cell can still be stronger when fluorination is present. In other words, even if individual interactions between neighboring molecules are weaker, the total number of interactions in the solid arising from the nature of crystal packing is equally important to consider. [ABSTRACT FROM AUTHOR]

Here we report P K‐edge X‐ray absorption spectroscopy (XAS), density functional theory (DFT), and time‐dependent density functional theory (TDDFT) studies of [R2P(CH2)nPR2]PdCl2, where R = phenyl or cyclohexyl and n = 1–3. P K‐edge XAS data were collected on room temperature CH2Cl2 solutions of [Ph2P(CH2)nPPh2]PdCl2, where n = 1 (dppm; 1), 2 (dppe; 2), or 3 (dppp; 3) to determine if solid‐state variations in covalent Pd–P bonding reported previously (Inorg. Chem. 2015, 54, 5646) were present in solution. A flow cell was used to overcome challenges associated with photon‐induced decomposition, which often occurs rapidly in solution during ligand K‐edge XAS data collection at room temperature. While the solid‐state data for 2 revealed a 10 % increase in P 1s→Pd‐P σ* transition intensity compared to 1 and 3, no statistical difference in Pd–P covalency was observed for 1–3 in solution. In contrast, solid‐state P K‐edge XAS data collected on [Cy2P(CH2)nPCy2]PdCl2, where n = 1 (dcpm; 4), 2 (dcpe; 5), or 3 (dcpp; 6), matched the trend in P 1s→Pd–P σ* transition intensity for solids of 1–3 despite exchanging the phenyl substituents for cyclohexyl. DFT and TDDFT calculations conducted on 4–6 corroborated the experimental data. Collectively, the solid‐state XAS and DFT results suggest that changes in the diphosphine backbone have the same relative effect on Pd–P σ covalency regardless of the substituents attached to phosphorus. [ABSTRACT FROM AUTHOR]

Phosphorus K-edge X-ray absorption spectroscopy (XAS) is a highly effective experimental method for investigating metal-phosphorus bonding and electronic structure. Here, we provide a comprehensive review of P K-edge XAS studies of transition metal complexes and show how they were used to investigate a wide range of chemical phenomena, including covalent metal-ligand bonding, redox non-innocence in ligands, molecular magnetism, and luminescence. Limitations of the technique are discussed along with opportunities for future work. [ABSTRACT FROM AUTHOR]

Here we report a convenient synthesis of new diphosphoramidite ligands derived from 1,8,10,9-triazaboradecalin (TBD) and describe their complexes with group 10 metals. [Display omitted] Here we report a convenient synthesis of new diphosphoramidite ligands derived from 1,8,10,9-triazaboradecalin (TBD) and describe their complexes with group 10 metals. Treating the chlorinated and structurally characterized ligand precursor ClTBDPhos (L1) with four equivalents of HOR (R = C 3 H 7 or C 3 HF 6) in the presence of NEt 3 yielded the diphosphoramidite ligands iPrOTBDPhos (L2) and F-iPrOTBDPhos (L3) in good yields. L2 and L3 were used to prepare a variety of Ni, Pd, and Pt complexes with chloride and 1,2-benzenedithiolate ligands so their structures and spectroscopic properties could be compared to similar complexes with methoxy-substituted MeOTBDPhos such as (MeOTBDPhos)PdCl 2 , which is reported here for the first time. Single-crystal XRD studies on the (ROTBDPhos)PtCl 2 complexes revealed that increasing the size of alkoxy substituents from MeO to i PrO to F- i PrO decreases the P-M-P bite angle from 97.47(3)° in (MeOTBDPhos)PtCl 2 to 93.98(4)° in (F-iPrOTBDPhos)PtCl 2. Similar changes were observed in the dithiolate complexes (iPrOTBDPhos)Pt(S 2 C 6 H 4) and (F-iPrOTBDPhos)Pt(S 2 C 6 H 4), and the structural studies revealed longer Pt-P bond distances compared to the dichloride complexes that correlated to ca. 1000 Hz decrease in their 195Pt-31P coupling constants. No significant changes were observed in the ligand bond distances in complexes containing the methoxy and isoproxy-substituted ligands, but complexes with fluorinated F-iPrOTBDPhos revealed subtle, but significant differences in their P-N, P-O, and B-N distances that reflect substituent-induced electronic changes in the ligand. Overall, this work establishes a more convenient synthetic entry into the chemistry of alkoxy-substituted TBDPhos ligands for ongoing studies with these and related transition metal complexes. [ABSTRACT FROM AUTHOR]

Here we describe the synthesis, structures, and reactivity of Ru complexes containing a triaryl, redox-active S2N2 ligand derived from o-phenylenediamine and thioanisole subunits. The coordination chemistry of N,N'-bis[2-(methylthio)phenyl]-1,2-diaminobenzene [H2(MeSNNSMe)] was established by treating RuCl2(PPh3)3 with H2(MeSNNSMe) to yield {Ru[H2(MeSNNSMe)]Cl(PPh3)}Cl (1). Coordinated H2(MeSNNSMe) was sequentially deprotonated to form Ru[H(MeSNNSMe)]Cl(PPh3) (2) followed by the five-coordinate, square pyramidal complex Ru(MeSNNSMe)(PPh3) (3). Single-crystal X-ray diffraction (XRD) studies revealed that the ligand structurally rearranged around the metal at each deprotonation step to conjugate the adjacent aryl groups with the o-phenylenediamine backbone. Deprotonation of 2 with NaBH4 or treatment of 3 with BH3·tetrahydrofuran (THF) yielded Ru[(µ-H)BH2](MeSNNSMe)(PPh3) (5) with BH3 bound across a Ru-N bond in a metal-ligand cooperative fashion. The cyclic voltammogram of 3 in THF revealed three redox events consistent with one-electron oxidations and reductions of the o-phenylenediamine backbone and the metal (Ru3+/Ru2+). Reactions of 3 with CO, HBF4, and benzoic acid yielded the new complexes Ru(MeSNNSMe)(CO)(PPh3), {Ru[H(MeSNNSMe)](PPh3)(THF)}BF4, and Ru[H(MeSNNSMe)](PPh3)(PhCO2), indicating broader suitability for small molecule binding and reactivity studies. Subsequent nuclear magnetic resonance spectroscopy, infrared spectroscopy, and mass spectrometry data are reported in addition to molecular structures obtained from single-crystal XRD studies. [ABSTRACT FROM AUTHOR]

Despite the long-standing use of phosphine and diphosphine ligands in coordination chemistry and catalysis, questions remain as to their effects on metal-ligand bonding in transition metal complexes. Here we report ligand K-edge XAS, DFT, and TDDFT studies aimed at quantifying the impact of coordination geometry, diphosphine bite angle, and phosphine trans influence on covalency in M-P and M-Cl bonds. A series of four-coordinate NiCl2 and PdCl2 complexes containing PPh3 or Ph2P(CH2)nPPh2, where n = 1 (dppm), 2 (dppe), 3 (dppp), and 4 (dppb), was analyzed. The XAS data revealed that changing the coordination geometry from tetrahedral in Ni(PPh3)2Cl2 (1) to square planar in Ni(dppe)Cl2 (2) more than doubles the intensity of pre-edge features assigned to Ni-P and Ni-Cl 1s → σ* transitions. By way of comparison, varying the diphosphine in Pd(dppm)Cl2 (4), Pd(dppp)Cl2 (6), and Pd(dppb)Cl2 (7) yielded Pd-P 1s → σ* transitions with identical intensities, but a 10% increase was observed in the P K-edge XAS spectrum of Pd(dppe)Cl2 (5). A similar observation was made when comparing Ni(dppe)Cl2 (2) to Ni(dppp)Cl2 (3), and DFT and TDDFT calculations corroborated XAS results obtained for both series. Comparison of the spectroscopic and theoretical results to the diphosphine structures revealed that changes in M-P covalency were not correlated to changes in bite angles or coordination geometry. As a final measure, P and Cl K-edge XAS data were collected on trans-Pd(PPh3)2Cl2 (8) for comparison to the cis diphosphine complex Pd(dppe)Cl2 (5). Consistent with phosphine's stronger trans influence compared to chloride, a 35% decrease in the intensity of the Pd-P 1s → σ* pre-edge feature and a complementary 34% increase in Pd-Cl 1s → σ* feature was observed for 8 (trans) compared to 5 (cis). Overall, the results reveal how coordination geometry, ligand arrangement, and diphosphine structure affect covalent metal-phosphorus and metal-chloride bonding in these late transition metal complexes. [ABSTRACT FROM AUTHOR]