Palladium(ii) complexes supported by PBP and POCOP pincer ligands: a comparison of their structure, properties and catalytic activity.

A Pd(ii) chloride complex supported by a Yamashita-Nozaki PBP pincer ligand, [C6H4-1,2-(NCH2PtBu2)2B]PdCl (1a), was synthesized. The structure, properties and catalytic activity of complex 1a were compared with those of the corresponding POCOP pincer complex [C6H3-2,6-(OPtBu2)2]PdCl (2a). It was found that the Pd centre in complex 1a is more electron rich and easier to be oxidized than that in complex 2a; complex 1a is a much better catalyst for Suzuki-Miyaura cross-coupling reactions than complex 2a. Starting from complexes 1a and 2a, two series of Pd(ii) pincer complexes bearing a SH, BH4, N[combining low line]CS, N[combining low line]CSe or N3 covalent ligand, [C6H4-1,2-(NCH2PtBu2)2B]PdY (Y = SH, 1b; BH4; 1c; N[combining low line]CS, 1d; N[combining low line]CSe, 1e; and N3, 1f) and [C6H3-2,6-(OPtBu2)2]PdY (Y = SH, 2b; BH4, 2c; N[combining low line]CS, 2d; N[combining low line]CSe, 2e; and N3, 2f), were synthesized and fully characterized. Single crystal X-ray diffraction analysis indicated that the Pd centre is less tightly chelated in PBP pincer complexes. The strong σ-donor ability of the PBP pincer ligand has little influence on the structure of the covalent ligand possessing both σ-donor and π-acceptor properties. However, the stretching vibrational frequencies of N[combining low line]CS, N[combining low line]CSe and N3 ligands and the coordination mode of the BH4 ligand are significantly different in these two types of palladium pincer complexes.

Combination of the CYP2C19 metabolizer and the GRACE risk score better predicts the long-term major adverse cardiac events in acute coronary syndrome undergoing percutaneous coronary intervention.

INTRODUCTION: Both Global Registry of Acute Coronary Events (GRACE) risk score and CYP2C19 metabolizer status can independently predict major adverse cardiac events (MACEs) in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI). We investigated whether their combination could better predict MACE occurrence in patients with ACS undergoing PCI. MATERIALS AND METHODS: This retrospective cohort study included 548 consecutive patients with ACS undergoing PCI. A cumulative MACE curve was calculated using the Kaplan-Meier method. Multivariate Cox regression was used to identify MACE predictors. The predictive value of GRACE risk score alone and CYP2C19 metabolizer status was estimated by the area under the receiver operating characteristic curve (AUC), net reclassification improvement (NRI), and integrated discrimination improvement (IDI). RESULTS: In a median of 28.58 months, 17 patients (3%) were lost to follow-up, and 62 (11.3%) experienced MACEs. Multivariate Cox regression analysis showed that both GRACE score and CYP2C19 metabolizer status were independent MACE predictors (hazard ratio 1.019, 95% CI 1.011-1.027, p < 0.001; hazard ratio 2.383, 95% CI 1.601-3.547, p < 0.001, respectively). Kaplan-Meier analysis showed that CYP2C19 PM increased the MACE risk (log rank test = 10.848, p = 0.004). The GRACE score adjustment by CYP2C19 metabolizer status enhanced the predictive value (AUC increased from 0.682 for GRACE score alone to 0.731 for GRACE score plus CYP2C19 metabolizer). This result was further verified by IDI and NRI. CONCLUSIONS: CYP2C19 metabolizer status and GRACE score are readily available predictive approaches for MACEs, and their combination derives a more accurate long-term MACE prediction in clopidogrel-treated patients with ACS undergoing PCI.

The Reactivity of Mercapto Groups against Boron Hydrides in Pincer Ligated Nickel Mercapto Complexes.

Several pincer ligated nickel mercapto complexes, [2,6-(R2 PCH2 )2 C6 H3 ]NiSH (R=tBu, 1 a; iPr, 1 b), [2,6-(R2 PO)2 C6 H3 ]NiSH (R=tBu, 2 a; iPr, 2 b) and [4-MeOCO-2,6-(tBu2 PO)2 C6 H2 ]NiSH (3 a), were synthesized and fully characterized. The reactivity of the mercapto groups against boron hydrides and organic bases was investigated. It was found that the mercapto groups are difficult to be deprotonated by boron hydrides or organic bases. The treatment of complex 2 a or 2 b with an excess amount of catecholborane (HBcat) afforded the corresponding pincer ligated nickel borohydride complexes and the HBcat degradation product. The treatment of complex 1 a, 2 a or 2 b with an excess amount of BH3 ⋅THF produced the corresponding nickel borohydride species and the S-bridged triborane species THF⋅BH2 -µ2 -S(B2 H5 ) (5). No reactions between these complexes and organic bases were observed. DFT calculations were carried out to understand this reactivity and get mechanistic insights into the reactions.

Short- and long-term prognostic value of hyponatremia in patients with acute coronary syndrome: A systematic review and meta-analysis.

Hyponatremia is relevant to heart failure, liver cirrhosis and stroke, but the prognostic value of serum sodium levels in patients with acute coronary syndrome are still unclear. So we did a systematic review and meta-analysis to assess the prognostic value of hyponatremia on adverse events in patients after ACS. We systematically searched PubMed, Embase and Cochrane Library to find literatures which studied the prognostic value of hyponatremia in patients with ACS. Our main endpoints were the all-cause mortality and heart failure in the short- and long-term. Of 369 identified studies, 20 studies were included in our analysis. Compared with the normal natrium, hyponatremia was significantly associated with the increased risks of all-cause mortality within 30 days (RR: 2.18; 95%CI: 1.96-2.42) and during the follow-ups (HR: 1.74; 95%CI: 1.56-1.942). For the second endpoint of short- and long-term heart failure, the pooled effect sizes in hyponatremia patients were 1.72(95%CI: 1.38-2.14) and 1.69(95%CI: 1.12-2.55) respectively. In conclusion, hyponatremia has a significant prognostic value for short- and long-term adverse event in patients after ACS, the dynamic monitoring of serum sodium levels may could help physicians to identify high risk ACS patients and to stratify risk for optimal management.

A reaction of [2,6-(tBu2PO)2C6H3]NiSCH2Ph with BH3·THF: borane mediated C-S bond cleavage.

C-S bond activation of thiophenols and mercaptans is of great importance but has rarely been reported. In this paper we report the C-S bond cleavage of the thiolato ligand of [2,6-(tBu2PO)2C6H3]NiSCH2Ph (1) mediated by BH3·THF. The treatment of 1 with an excess amount of BH3·THF in THF at room temperature afforded the borohydride complex [2,6-(tBu2PO)2C6H3]Ni(η2-BH4) (2) as the only product. The reaction of 1 with 2 equiv. of BH3·THF in THF at room temperature for 48 h produced the hydride complex [2,6-(tBu2PO)2C6H3]NiH (3) and the mercapto complex [2,6-(tBu2PO)2C6H3]NiSH (5). As a new complex, 5 was also independently synthesized by a salt metathesis reaction of the corresponding chloride complex with NaSH and fully characterized by multinuclear NMR, FTIR, HRMS, X-ray crystallography and elemental analysis. A possible mechanism for the formation of 5 was proposed. It was supposed that 5 formed through BH3 mediated C-S bond cleavage of the thiolato ligand of 1. The result would initiate further studies on the transition metal catalyzed borane mediated C-S bond activation of mercaptans.

Hydroboration of CO2 catalyzed by bis(phosphinite) pincer ligated nickel thiolate complexes.

We report the hydroboration of CO2 with catecholborane catalyzed by a series of bis(phosphinite) pincer ligated nickel thiolate complexes. Turnover frequencies (TOFs) up to 2400 h-1 were achieved at room temperature under an atmospheric pressure of CO2. This represents the highest TOF value known to date for the reduction of CO2 to the methoxide level under mild conditions.

Highly efficient reduction of carbon dioxide with a borane catalyzed by bis(phosphinite) pincer ligated palladium thiolate complexes.

Highly efficient catalytic reduction of CO2 with catecholborane has been developed by using bis(phosphinite) pincer ligated palladium thiolate complexes. Turnover frequencies up to 1780 h-1 have been achieved at room temperature under an atmospheric pressure of CO2. These thiolate complexes represent the most efficient homogeneous catalysts known to date for the reduction of CO2 to methanol under mild conditions.