Importance of pre pump arterial pres sure monitoring in hemodialysis patients

Pre-pump arterial pressure (PreAP) is monitored to avoid generating excessive negative pressure. National Kidney Foundation K/DOQI clinical practice guidelines for vascular access recommend that PreAP should not fall below-250 mmHg because excessive negative PreAP can lead to a decrease in the delivery of blood flow, inadequate dialysis, and hemolysis. Nonetheless, these recommendations are consistently disregarded in clinical practice and pressure sensors are often removed from the dialysis circuit.Thus far,delivered blood flow has been reported to decrease at values more negative than -150 mmHg of PreAP. These values have been analyzed by an ultrasonic flowmeter and not directly measured. Furthermore, no known group has evaluated whether PreAP-induced hemolysis occurs at a particular threshold. Therefore, the aim of this study was to clarify the importance of PreAP in the prediction of inadequate dialysis and hemolysis. By using different diameter needles, human blood samples from healthy volunteers were circulated in a closed dialysis circuit. The relationship between PreAP and delivered blood flow or PreAP and hemolysis was investigated. We also investigated the optimal value for PreAP using several empirical monitoring methods, such as a pressure pillow. Our investigation indicated that PreAP is a critical factor in the determination of delivered blood flow and hemolysis,both of which occured at pressure values more negative than -150 mmHg. With the exception of direct pressure monitoring, commonly used monitoring methods for PreAP were determined to be ineffective. We propose that the use of a vacuum monitor would permit regular measurement of PreAP

Cyclic Trinuclear Rh₂M Complexes (M = Rh, Pt, Pd, Ni) Supported by <i>meso</i>-1,3-Bis[(diphenylphosphinomethyl)phenylphosphino]propane

Reaction of [MCl₂(cod)] (M = Pd, Pt) with a tetraphosphine, <i>meso</i>-1,3-bis­[(diphenylphosphinomethyl)­phenylphosphino]­propane (dpmppp), afforded the mononuclear complexes [MCl₂(dpmppp)] (M = Pd (<b>3a</b>), Pt (<b>3b</b>)), in which the dpmppp ligand coordinated to the M ion by two inner phosphorus atoms to form a six-membered chelate ring with two outer phosphines uncoordinated. The pendant outer phosphines readily reacted with [RhCl­(CO)₂]₂ to give the cationic heterotrinuclear complexes [MRh₂(μ-Cl)₃(μ-dpmppp)­(CO)₂]­X (X = [RhCl₂(CO)₂], M = Pd (<b>4a</b>), Pt (<b>4b</b>); X = PF₆, M = Pd (<b>5a</b>), Pt (<b>5b</b>)). The nickel analogue [NiRh₂(μ-Cl)₃(μ-dpmppp)­(CO)₂]­PF₆ (<b>5c</b>) was also prepared. A neutral homotrinuclear Rh₃ complex, [Rh₃(μ-Cl)₃(μ-dpmppp)­(CO)₂] (<b>6</b>), was synthesized by the reaction of [RhCl­(CO)₂]₂ with dpmppp and was further reacted with HgX₂ (X = Cl, Br, I) to afford the Rh₃Hg tetranuclear complexes [Rh₃(HgX)­(μ-Cl)₂(μ-X)­(μ-dpmppp)­(CO)₂]­PF₆ (X = Cl (<b>7a</b>), Br (<b>7b</b>), I (<b>7c</b>)), where the Rh₃(μ-Cl)₂(μ-X) cores act as tridentate ligands to form three donor–acceptor Rh→Hg interactions. The two CO ligands of <b>7a</b>–<b>c</b> were replaced by XylNC to yield [Rh₃(HgX)­(μ-Cl)₂(μ-X)­(μ-dpmppp)­(XylNC)₂]­PF₆ (X = Cl (<b>8a</b>), Br (<b>8b</b>), I (<b>8c</b>)). The isocyanides had an appreciable influence on the three Rh→Hg interactions, which was monitored by the ²<i>J</i>_HgP values observed in the ³¹P­{¹H} NMR spectra and discussed on the basis of DFT calculations. Complex <b>6</b> also reacted with CuCl and HBF₄ to give [Rh₃(CuCl)­(μ-Cl)₃(μ-dpmppp)­(CO)₂] (<b>9</b>) and [Rh₃(μ₃-H)­(μ-Cl)₃(μ-dpmppp)­(CO)₂]­BF₄ (<b>10</b>), respectively. These results suggested that the new tetraphosphine dpmppm proved quite useful in constructing fine-tunable heterometallic frameworks

Cyclic Trinuclear Rh₂M Complexes (M = Rh, Pt, Pd, Ni) Supported by <i>meso</i>-1,3-Bis[(diphenylphosphinomethyl)phenylphosphino]propane

Reaction of [MCl₂(cod)] (M = Pd, Pt) with a tetraphosphine, <i>meso</i>-1,3-bis­[(diphenylphosphinomethyl)­phenylphosphino]­propane (dpmppp), afforded the mononuclear complexes [MCl₂(dpmppp)] (M = Pd (<b>3a</b>), Pt (<b>3b</b>)), in which the dpmppp ligand coordinated to the M ion by two inner phosphorus atoms to form a six-membered chelate ring with two outer phosphines uncoordinated. The pendant outer phosphines readily reacted with [RhCl­(CO)₂]₂ to give the cationic heterotrinuclear complexes [MRh₂(μ-Cl)₃(μ-dpmppp)­(CO)₂]­X (X = [RhCl₂(CO)₂], M = Pd (<b>4a</b>), Pt (<b>4b</b>); X = PF₆, M = Pd (<b>5a</b>), Pt (<b>5b</b>)). The nickel analogue [NiRh₂(μ-Cl)₃(μ-dpmppp)­(CO)₂]­PF₆ (<b>5c</b>) was also prepared. A neutral homotrinuclear Rh₃ complex, [Rh₃(μ-Cl)₃(μ-dpmppp)­(CO)₂] (<b>6</b>), was synthesized by the reaction of [RhCl­(CO)₂]₂ with dpmppp and was further reacted with HgX₂ (X = Cl, Br, I) to afford the Rh₃Hg tetranuclear complexes [Rh₃(HgX)­(μ-Cl)₂(μ-X)­(μ-dpmppp)­(CO)₂]­PF₆ (X = Cl (<b>7a</b>), Br (<b>7b</b>), I (<b>7c</b>)), where the Rh₃(μ-Cl)₂(μ-X) cores act as tridentate ligands to form three donor–acceptor Rh→Hg interactions. The two CO ligands of <b>7a</b>–<b>c</b> were replaced by XylNC to yield [Rh₃(HgX)­(μ-Cl)₂(μ-X)­(μ-dpmppp)­(XylNC)₂]­PF₆ (X = Cl (<b>8a</b>), Br (<b>8b</b>), I (<b>8c</b>)). The isocyanides had an appreciable influence on the three Rh→Hg interactions, which was monitored by the ²<i>J</i>_HgP values observed in the ³¹P­{¹H} NMR spectra and discussed on the basis of DFT calculations. Complex <b>6</b> also reacted with CuCl and HBF₄ to give [Rh₃(CuCl)­(μ-Cl)₃(μ-dpmppp)­(CO)₂] (<b>9</b>) and [Rh₃(μ₃-H)­(μ-Cl)₃(μ-dpmppp)­(CO)₂]­BF₄ (<b>10</b>), respectively. These results suggested that the new tetraphosphine dpmppm proved quite useful in constructing fine-tunable heterometallic frameworks

Stepwise Expansion of Pd Chains from Binuclear Palladium(I) Complexes Supported by Tetraphosphine Ligands

Reaction of [Pd₂(XylNC)₆]­X₂ (X = PF₆, BF₄) with a linear tetraphosphine, <i>meso</i>-bis­[(diphenylphosphinomethyl)­phenylphosphino]­methane (dpmppm), afforded binuclear Pd^I complexes, [Pd₂(μ-dpmppm)₂]­X₂ ([<b>2</b>]­X₂), through an asymmetric dipalladium complex, [Pd₂(μ-dpmppm)­(XylNC)₃]²⁺ ([<b>1</b>]²⁺). Complex [<b>2</b>]²⁺ readily reacted with [Pd⁰(dba)₂] (2 equiv) and an excess of isocyanide, RNC (R = 2,6-xylyl (Xyl), <i>tert</i>-butyl (^<i>t</i>Bu)), to generate an equilibrium mixture of [Pd₄(μ-dpmppm)₂(RNC)₂]²⁺ ([<b>3</b>′]²⁺) + RNC ⇄ [Pd₄(μ-dpmppm)₂(RNC)₃]²⁺ ([<b>3</b>]²⁺), from which [Pd₄(μ-dpmppm)₂(XylNC)₃]²⁺ ([<b>3a</b>]²⁺) and [Pd₄(μ-dpmppm)₂(^<i>t</i>BuNC)₂]²⁺ ([<b>3b</b>′]²⁺) were isolated. Variable-temperature UV–vis and ³¹P­{¹H} and ¹H NMR spectroscopic studies on the equilibrium mixtures demonstrated that the tetrapalladium complexes are quite fluxional in the solution state: the symmetric Pd₄ complex [<b>3b</b>′]²⁺ predominantly existed at higher temperatures (>0 °C), and the equilibrium shifted to the asymmetric Pd₄ complex [<b>3b</b>]²⁺ at a low temperature (∼−30 °C). The binding constants were determined by UV–vis titration at 20 °C and revealed that XylNC is of higher affinity to the Pd₄ core than ^<i>t</i>BuNC. In addition, both isocyanides exhibited higher affinity to the electron deficient [Pd₄(μ-dpmppmF₂)₂(RNC)₂]²⁺ ([<b>3F</b>′]²⁺) than to [Pd₄(μ-dpmppm)₂(RNC)₂]²⁺ ([<b>3</b>′]²⁺) (dpmppmF₂ = <i>meso</i>-bis­[{di­(3,5-difluorophenyl)­phosphinomethyl}­phenylphosphino]­methane). When [<b>2</b>]­X₂ was treated with [Pd⁰(dba)₂] (2 equiv) in the absence of RNC in acetonitrile, linearly ordered octapalladium chains, [Pd₈(μ-dpmppm)₄(CH₃CN)₂]­X₄ ([<b>4</b>]­X₄: X = PF₆, BF₄), were generated through a coupling of two {Pd₄(μ-dpmppm)₂}²⁺ fragments. Complex [<b>2</b>]²⁺ was also proven to be a good precursor for Pd₂M₂ mixed-metal complexes, yielding [Pd₂Cl­(Cp*MCl) (Cp*MCl₂)­(μ-dpmppm)₂]²⁺ (M = Rh ([<b>5</b>]²⁺), Ir ([<b>6</b>]²⁺), and [Au₂Pd₂Cl₂(dpmppm–H)₂]²⁺ ([<b>7</b>]²⁺) by treatment with [Cp*MCl₂]₂ and [AuCl­(PPh₃)], respectively. Complex [<b>7</b>]²⁺ contains an unprecedented PC­(sp³)P pincer ligand with a PCPCPCP backbone, dpmppm–H of deprotonated dpmppm. The present results demonstrated that the binuclear Pd^I complex [<b>2</b>]²⁺ was a quite useful starting material to extend the palladium chains and to construct Pd-involved heteromultinuclear systems

Stepwise Expansion of Pd Chains from Binuclear Palladium(I) Complexes Supported by Tetraphosphine Ligands

Reaction of [Pd₂(XylNC)₆]­X₂ (X = PF₆, BF₄) with a linear tetraphosphine, <i>meso</i>-bis­[(diphenylphosphinomethyl)­phenylphosphino]­methane (dpmppm), afforded binuclear Pd^I complexes, [Pd₂(μ-dpmppm)₂]­X₂ ([<b>2</b>]­X₂), through an asymmetric dipalladium complex, [Pd₂(μ-dpmppm)­(XylNC)₃]²⁺ ([<b>1</b>]²⁺). Complex [<b>2</b>]²⁺ readily reacted with [Pd⁰(dba)₂] (2 equiv) and an excess of isocyanide, RNC (R = 2,6-xylyl (Xyl), <i>tert</i>-butyl (^<i>t</i>Bu)), to generate an equilibrium mixture of [Pd₄(μ-dpmppm)₂(RNC)₂]²⁺ ([<b>3</b>′]²⁺) + RNC ⇄ [Pd₄(μ-dpmppm)₂(RNC)₃]²⁺ ([<b>3</b>]²⁺), from which [Pd₄(μ-dpmppm)₂(XylNC)₃]²⁺ ([<b>3a</b>]²⁺) and [Pd₄(μ-dpmppm)₂(^<i>t</i>BuNC)₂]²⁺ ([<b>3b</b>′]²⁺) were isolated. Variable-temperature UV–vis and ³¹P­{¹H} and ¹H NMR spectroscopic studies on the equilibrium mixtures demonstrated that the tetrapalladium complexes are quite fluxional in the solution state: the symmetric Pd₄ complex [<b>3b</b>′]²⁺ predominantly existed at higher temperatures (>0 °C), and the equilibrium shifted to the asymmetric Pd₄ complex [<b>3b</b>]²⁺ at a low temperature (∼−30 °C). The binding constants were determined by UV–vis titration at 20 °C and revealed that XylNC is of higher affinity to the Pd₄ core than ^<i>t</i>BuNC. In addition, both isocyanides exhibited higher affinity to the electron deficient [Pd₄(μ-dpmppmF₂)₂(RNC)₂]²⁺ ([<b>3F</b>′]²⁺) than to [Pd₄(μ-dpmppm)₂(RNC)₂]²⁺ ([<b>3</b>′]²⁺) (dpmppmF₂ = <i>meso</i>-bis­[{di­(3,5-difluorophenyl)­phosphinomethyl}­phenylphosphino]­methane). When [<b>2</b>]­X₂ was treated with [Pd⁰(dba)₂] (2 equiv) in the absence of RNC in acetonitrile, linearly ordered octapalladium chains, [Pd₈(μ-dpmppm)₄(CH₃CN)₂]­X₄ ([<b>4</b>]­X₄: X = PF₆, BF₄), were generated through a coupling of two {Pd₄(μ-dpmppm)₂}²⁺ fragments. Complex [<b>2</b>]²⁺ was also proven to be a good precursor for Pd₂M₂ mixed-metal complexes, yielding [Pd₂Cl­(Cp*MCl) (Cp*MCl₂)­(μ-dpmppm)₂]²⁺ (M = Rh ([<b>5</b>]²⁺), Ir ([<b>6</b>]²⁺), and [Au₂Pd₂Cl₂(dpmppm–H)₂]²⁺ ([<b>7</b>]²⁺) by treatment with [Cp*MCl₂]₂ and [AuCl­(PPh₃)], respectively. Complex [<b>7</b>]²⁺ contains an unprecedented PC­(sp³)P pincer ligand with a PCPCPCP backbone, dpmppm–H of deprotonated dpmppm. The present results demonstrated that the binuclear Pd^I complex [<b>2</b>]²⁺ was a quite useful starting material to extend the palladium chains and to construct Pd-involved heteromultinuclear systems

Heterotrinuclear Complexes with Palladium, Rhodium, and Iridium Ions Assembled by Conformational Switching of a Tetraphosphine Ligand around a Palladium Center

Reaction of [PdCl₂(cod)] with a tetraphosphine, <i>meso</i>-bis­[((diphenylphosphino)­methyl)­phenylphosphino]­methane (dpmppm), afforded the mononuclear Pd^II complexes [PdCl­(dpmppm-κ³)]­X (X = Cl (<b>1a</b>), PF₆ (<b>1b</b>)); the pincer-type dpmppm ligand coordinates to the Pd atom with two outer and one inner phosphorus atom to form fused six- and four-membered chelate rings. The remaining inner phosphine is uncoordinated and readily reacts with [Cp*MCl₂]₂ to give the heterodimetallic complexes [PdCl­(Cp*MCl₂)­(μ-dpmppm-κ³,κ¹)]­X (X = Cl, M = Rh (<b>21a</b>), Ir (<b>21b</b>); X = PF₆, M = Rh (<b>23a</b>), Ir (<b>23b</b>)). Attachment of the second metal fragment to the uncoordinated phosphine caused a crucial conformational change of the six-membered chelate ring from a stable chair conformation to a twist-boat structure, which concomitantly destabilizes the four-membered ring for its opening reactions. Complexes <b>21</b> (X = Cl) were converted to [PdCl₂(Cp*MCl₂)­(dpmppmO)], in which the terminal P atom is dissociated and oxidized as Ph₂P­(O)­CH₂P­(Ph)­CH₂P­(Ph)­CH₂PPh₂ (dpmppmO), and in the presence of another 1 equiv of [Cp*M′Cl₂]₂, complexes <b>21</b> were readily transformed into the heterotrinuclear complexes [PdCl₂(Cp*M′Cl₂)­(Cp*MCl₂)­(μ-dpmppm-κ²,κ¹,κ¹)] (M = M′ = Rh (<b>31a</b>), Ir, (<b>31b</b>); M = Ir, M′ = Rh (<b>31c</b>)), where the third metal M′ is trapped by the terminal P atom with its four-membered-ring opening. Complexes <b>23</b> also reacted with another 1 equiv of [Cp*M′Cl₂]₂ to afford the heterotrinuclear complexes [PdCl­(μ-Cl)­(Cp*M′Cl)­(Cp*MCl₂)­(μ-dpmppm-κ²,κ¹,κ¹)]­PF₆ (M = M′ = Rh (<b>32a</b>), Ir, (<b>32b</b>); M = Ir, M′ = Rh (<b>32c</b>), M = Rh, M′ = Ir (<b>32d</b>)); the additional metal M′ is ligated by the terminal phosphine and is further connected to the Pd atom via a chloride bridge, resulting in a rather electron-deficient M′ center on the basis of cyclic voltammetry. These results exhibited that the addition of a bulky metal fragment to the uncoordinated phosphine of <b>1</b> brings about a conformational switch around the Pd center to promote the ring-opening reaction of the four-membered chelate ring, which leads to an incorporation of the third metal fragment to construct heterotrinuclear structures

Heterotrinuclear Complexes with Palladium, Rhodium, and Iridium Ions Assembled by Conformational Switching of a Tetraphosphine Ligand around a Palladium Center

Reaction of [PdCl₂(cod)] with a tetraphosphine, <i>meso</i>-bis­[((diphenylphosphino)­methyl)­phenylphosphino]­methane (dpmppm), afforded the mononuclear Pd^II complexes [PdCl­(dpmppm-κ³)]­X (X = Cl (<b>1a</b>), PF₆ (<b>1b</b>)); the pincer-type dpmppm ligand coordinates to the Pd atom with two outer and one inner phosphorus atom to form fused six- and four-membered chelate rings. The remaining inner phosphine is uncoordinated and readily reacts with [Cp*MCl₂]₂ to give the heterodimetallic complexes [PdCl­(Cp*MCl₂)­(μ-dpmppm-κ³,κ¹)]­X (X = Cl, M = Rh (<b>21a</b>), Ir (<b>21b</b>); X = PF₆, M = Rh (<b>23a</b>), Ir (<b>23b</b>)). Attachment of the second metal fragment to the uncoordinated phosphine caused a crucial conformational change of the six-membered chelate ring from a stable chair conformation to a twist-boat structure, which concomitantly destabilizes the four-membered ring for its opening reactions. Complexes <b>21</b> (X = Cl) were converted to [PdCl₂(Cp*MCl₂)­(dpmppmO)], in which the terminal P atom is dissociated and oxidized as Ph₂P­(O)­CH₂P­(Ph)­CH₂P­(Ph)­CH₂PPh₂ (dpmppmO), and in the presence of another 1 equiv of [Cp*M′Cl₂]₂, complexes <b>21</b> were readily transformed into the heterotrinuclear complexes [PdCl₂(Cp*M′Cl₂)­(Cp*MCl₂)­(μ-dpmppm-κ²,κ¹,κ¹)] (M = M′ = Rh (<b>31a</b>), Ir, (<b>31b</b>); M = Ir, M′ = Rh (<b>31c</b>)), where the third metal M′ is trapped by the terminal P atom with its four-membered-ring opening. Complexes <b>23</b> also reacted with another 1 equiv of [Cp*M′Cl₂]₂ to afford the heterotrinuclear complexes [PdCl­(μ-Cl)­(Cp*M′Cl)­(Cp*MCl₂)­(μ-dpmppm-κ²,κ¹,κ¹)]­PF₆ (M = M′ = Rh (<b>32a</b>), Ir, (<b>32b</b>); M = Ir, M′ = Rh (<b>32c</b>), M = Rh, M′ = Ir (<b>32d</b>)); the additional metal M′ is ligated by the terminal phosphine and is further connected to the Pd atom via a chloride bridge, resulting in a rather electron-deficient M′ center on the basis of cyclic voltammetry. These results exhibited that the addition of a bulky metal fragment to the uncoordinated phosphine of <b>1</b> brings about a conformational switch around the Pd center to promote the ring-opening reaction of the four-membered chelate ring, which leads to an incorporation of the third metal fragment to construct heterotrinuclear structures