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Synthesis of Transition Metal Complexes Supported by Mixed Donor PSiP' Bis-Phosphino Silyl Pincer Ligands
No full textIn an effort to explore new metal mediated reactivity and further the versatility of metal pincer chemistry, research in the Turculet group has targeted the synthesis of novel bis(phosphino)silyl PSiP pincer complexes. Given the profound influence that ligand design can have on the reactivity of the ensuing metal complexes, pincer ligands that feature a mixed neutral donor set have emerged as an intriguing ligand class that offers enhanced control over the steric and electronic features of a metal pincer complex. In this context the synthesis and reactivity of metal complexes supported by unsymmetrical PSiP’ ligation was pursued.
In this work three novel PSiP’ ligands were synthesized: (Cy-PSiP’-Ph)H, (Ph-PSiP*-iPr)H and (Cy-PSiP*-iPr)H. Group 10 complexes of the type (Cy-PSiP’-Ph)MX (M = Pt, Pd, Ni; X = Cl, Me, Ph) were prepared. The Pd and Ni chloride complexes were structurally characterized and found to exhibit approximate square planar coordination geometry in the solid state, with the silyl donor coordinated trans to the chloride ligand. The Me derivatives proved to be surprisingly unreactive with hydrosilanes, which is unlike the related Cy-PSiP analogues previously reported by the Turculet group. Amido complexes of the type (Cy-PSiP’-Ph)M(NHR) (M = Pt, Ni; R = H, Ph) and (Cy-PSiP’-Ph)Pd(NH2) were also synthesized. While the latter complexes proved to be quite stable, related complexes of the type (Cy-PSiP’-Ph)Pd(NHR) (R = Ph, tBu) underwent facile rearrangement processes involving Si-C (sp2) bond cleavage in the ligand backbone. Such processes have previously been reported for related (Cy-PSiP)MX (M = Ni, Pd; X = alkyl, amido) species. Group 10 complexes supported by alternative PSiP’ ligands including (Ph-PSiP*-iPr)PtCl and (Cy-PSiP*-iPr)MCl (M = Pt, Ni) were also synthesized. The complex (Cy-PSiP*-iPr)PdCl was structurally characterized and found to exist as a dimeric species in the solid state, with the CH2PiPr2 ligand arms bridging between Pd centers. Solution NMR data suggests that in some cases, κ3-coordination of Ph-PSiP*-iPr and Cy-PSiP*-iPr is achieved.
Finally preliminary studies revealed that Group 8 and 9 complexes supported by such PSiP’ ligands are synthetically viable
Heterologous protein secretion in Lactobacilli with modified pSIP vectors.
Get PDFWe describe new variants of the modular pSIP-vectors for inducible gene expression and protein secretion in lactobacilli. The basic functionality of the pSIP system was tested in Lactobacillus strains representing 14 species using pSIP411, which harbors the broad-host-range Lactococcus lactis SH71rep replicon and a β-glucuronidase encoding reporter gene. In 10 species, the inducible gene expression system was functional. Based on these results, three pSIP vectors with different signal peptides were modified by replacing their narrow-host-range L. plantarum 256rep replicon with SH71rep and transformed into strains of five different species of Lactobacillus. All recombinant strains secreted the target protein NucA, albeit with varying production levels and secretion efficiencies. The Lp_3050 derived signal peptide generally resulted in the highest levels of secreted NucA. These modified pSIP vectors are useful tools for engineering a wide variety of Lactobacillus species
UMP, PSIP muafakat perkasakan agenda kesukarelawanan
Get PDFBagi melahirkan graduan yang memiliki keseimbangan yang
holistik meliputi aspek jasmani, emosi, rohani dan intelek,
Universiti Malaysia Pahang (UMP) mengorak langkah menjalinkan hubungan dengan rakan strategiknya, Persekutuan Seruan Islam Perak (PSIP) pada 29 Jun 2010 yang lalu
Understanding the Solution and Solid-State Structures of Pd and Pt PSiP Pincer-Supported Hydrides
No full textThe PSiP pincer-supported complex
(<sup>Cy</sup>PSiP)PdH [<sup>Cy</sup>PSiP = Si(Me)(2-PCy<sub>2</sub>-C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>] has been implicated as
a crucial intermediate in carboxylation of both allenes and boranes.
At this stage, however, there is uncertainty regarding the exact structure
of (<sup>Cy</sup>PSiP)PdH, especially in solution. Previously, both
a Pd(II) structure with a terminal Pd hydride and a Pd(0) structure
featuring an η<sup>2</sup>-silane have been proposed. In this
contribution, a range of techniques were used to establish that (<sup>Cy</sup>PSiP)PdH and the related Pt species, (<sup>Cy</sup>PSiP)PtH,
are true M(II) hydrides in both the solid state and solution. The
single-crystal X-ray structures of (<sup>Cy</sup>PSiP)MH (M = Pd and
Pt) and the related species (<sup>iPr</sup>PSiP)PdH [<sup>iPr</sup>PSiP = Si(Me)(2-P<sup>i</sup>Pr<sub>2</sub>-C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>] are in agreement with the presence of a terminal metal
hydride, and the exact geometry of (<sup>Cy</sup>PSiP)PtH was confirmed
using neutron diffraction. The <sup>1</sup>H and <sup>29</sup>Si{<sup>1</sup>H}NMR chemical shifts of (<sup>Cy</sup>PSiP)MH (M = Pd and
Pt) are consistent with a structure containing a terminal hydride,
especially when compared to the chemical shifts of related pincer-supported
complexes. In fact, in this work, two general trends relating to the <sup>1</sup>H NMR chemical shifts of group 10 pincer-supported terminal
hydrides were elucidated: (i) the hydride shift moves downfield from
Ni to Pd to Pt and (ii) the hydride shift moves downfield with more <i>trans</i>-influencing pincer central donors. DFT calculations
indicate that structures containing a M(II) hydride are lower in energy
than the corresponding η<sup>2</sup>-silane isomers. Furthermore,
the calculated NMR chemical shifts of the M(II) hydrides using a relativistic
four-component methodology incorporating all significant scalar and
spin–orbit corrections are consistent with those observed experimentally.
Finally, in situ X-ray absorption spectroscopy (XAS) was used to provide
further support that (<sup>Cy</sup>PSiP)MH exist as M(II) hydrides
in solution
Synthesis and Reactivity of Silyl Iron, Cobalt, and Nickel Complexes Bearing a [PSiP]-Pincer Ligand via Si–H Bond Activation
No full textThe
synthesis and characterization of a series of Ni, Co, and Fe
complexes bearing a tridentate bis(phosphino)silyl ligand (κ3-(2-Ph2PC6H4)2SiMeH, [PSiP]-H, 1) are reported. 1 reacted
with Ni(PMe3)4 to afford the mononuclear nickel(0)
complex [η2(Si–H)-PSiP]Ni(PMe3)
(2). The halogeno nickel complexes [PSiP]Ni(X)(PMe3) (X = Cl (3), Br (4), I (5)) were synthesized in the reactions of 2 with Me3SiCl or MeHSiCl2, EtBr, and
MeI. Complex 2 underwent ligand substitution of PMe3 by CO to give [η2(Si–H)-PSiP]Ni(CO)
(6). Complex 3 reacted with NaOMe to deliver
[PSiP]Ni(OMe)(PMe3) (7) through anionic ligand
substitution, while the neutral ligand replacement of PMe3 by CO in 3 afforded the rare hexacoordinate 20-electron
nickel(II) complex [PSiP]Ni(Cl)(CO)2 (8).
Unexpectedly, reaction of 1 with NiMe2(PMe3)3 produced the tetracoordinate nickel(0) complex
[Me2PSiP]2Ni (9). The complex [Me2PSiP]Ni(CO)2 (10) was acquired from 9 after the substitution of one [PSiP] ligand by two carbonyl
ligands. 1 reacted with Co(PMe3)4 or CoCl(PMe3)3 to afford the hydrido cobalt(II)
complex [PSiP]CoH(PMe3) (11) or hydrido cobalt(III)
complex [PSiP]Co(H)(Cl)(PMe3) (13). Complex 12, [PSiP]Co(H)(I)(PMe3), could be obtained from
the reaction of MeI with 11 or 13. Treatment
of 13 with 1 equiv of MeLi or n-BuMgBr
in THF resulted in the clean formation of cobalt(I) complex [PSiP]Co(PMe3)2 (14) via reductive elimination.
The simple anhydrous inorganic salt NiCl2 or CoCl2 could also react with 1 in the presence of PMe3 to form the corresponding silyl complexes 3 and
[PSiP]Co(Cl)(PMe3) (15) via Si–H bond
cleavage. 1 reacted with Fe(PMe3)4 to form the hexacoordinate octahedral hydrido iron(II) complex [PSiP]Fe(H)(PMe3)2 (16). The molecular structures
of complexes 2–5, 10, 12, 13, 15, and 16 were determined by X-ray single crystal diffraction. 16 has excellent catalytic reactivity for the reduction of aldehydes
and ketones
Synthesis and Reactivity of Silyl Iron, Cobalt, and Nickel Complexes Bearing a [PSiP]-Pincer Ligand via Si–H Bond Activation
No full textThe
synthesis and characterization of a series of Ni, Co, and Fe
complexes bearing a tridentate bis(phosphino)silyl ligand (κ3-(2-Ph2PC6H4)2SiMeH, [PSiP]-H, 1) are reported. 1 reacted
with Ni(PMe3)4 to afford the mononuclear nickel(0)
complex [η2(Si–H)-PSiP]Ni(PMe3)
(2). The halogeno nickel complexes [PSiP]Ni(X)(PMe3) (X = Cl (3), Br (4), I (5)) were synthesized in the reactions of 2 with Me3SiCl or MeHSiCl2, EtBr, and
MeI. Complex 2 underwent ligand substitution of PMe3 by CO to give [η2(Si–H)-PSiP]Ni(CO)
(6). Complex 3 reacted with NaOMe to deliver
[PSiP]Ni(OMe)(PMe3) (7) through anionic ligand
substitution, while the neutral ligand replacement of PMe3 by CO in 3 afforded the rare hexacoordinate 20-electron
nickel(II) complex [PSiP]Ni(Cl)(CO)2 (8).
Unexpectedly, reaction of 1 with NiMe2(PMe3)3 produced the tetracoordinate nickel(0) complex
[Me2PSiP]2Ni (9). The complex [Me2PSiP]Ni(CO)2 (10) was acquired from 9 after the substitution of one [PSiP] ligand by two carbonyl
ligands. 1 reacted with Co(PMe3)4 or CoCl(PMe3)3 to afford the hydrido cobalt(II)
complex [PSiP]CoH(PMe3) (11) or hydrido cobalt(III)
complex [PSiP]Co(H)(Cl)(PMe3) (13). Complex 12, [PSiP]Co(H)(I)(PMe3), could be obtained from
the reaction of MeI with 11 or 13. Treatment
of 13 with 1 equiv of MeLi or n-BuMgBr
in THF resulted in the clean formation of cobalt(I) complex [PSiP]Co(PMe3)2 (14) via reductive elimination.
The simple anhydrous inorganic salt NiCl2 or CoCl2 could also react with 1 in the presence of PMe3 to form the corresponding silyl complexes 3 and
[PSiP]Co(Cl)(PMe3) (15) via Si–H bond
cleavage. 1 reacted with Fe(PMe3)4 to form the hexacoordinate octahedral hydrido iron(II) complex [PSiP]Fe(H)(PMe3)2 (16). The molecular structures
of complexes 2–5, 10, 12, 13, 15, and 16 were determined by X-ray single crystal diffraction. 16 has excellent catalytic reactivity for the reduction of aldehydes
and ketones
Circular on Public Service Internship programme (PSIP); Declaration of Internship Vacancies in MDA's for 2021-2022 Financial Year
Get PDFThis circular provides information on the Public Service Internship Programme (PSIP) and announces the declaration of internship vacancies in Ministries, Departments, and Agencies (MDAs) for the 2021-2022 Financial Year. The PSIP aims to offer opportunities for young individuals to gain practical work experience and contribute to the public sector. The circular outlines the eligibility criteria, application process, and important dates for interested candidates. It also highlights the benefits of participating in the PSIP and emphasizes the government's commitment to nurturing talent and preparing young professionals for future leadership roles in the public service
Photonic System-in-Package (pSiP) by Applying Thin Glass
No full text212215Advanced photonic System-in-Package (pSiP) technologies are proposed to enhance functionality of photonic packages featuring electrical, thermal and optical components including laser diodes, modulators, isolators, PIC, beam-splitters and micro lenses. We discuss thin glass as a suitable base material for packages made on panel level, precise glass structuring, optical waveguide integration, electrical wiring and the related high precision assembly techniques
Rhodium and Iridium Amido Complexes Supported by Silyl Pincer Ligation: Ammonia N−H Bond Activation by a [PSiP]Ir Complex
No full textRhodium and Iridium Amido Complexes Supported by Silyl Pincer Ligation: Ammonia N−H Bond Activation by a [PSiP]Ir Comple
Análisis y Aplicabilidad del protocolo PSIP
Get PDFEl presente informe analiza la funcionalidad y aplicabilidad del Protocolo de Programación y Sistema de Información (PSIP), para la conformación de manejo de metadatos como parte integral de los flujos de transporte (transport stream - TS) dentro de la televisión digital, mediante la evaluación de su aplicación para diferentes estructuras de TS en redes nacionales, con sus respectivas normas técnicas y regulatorias existentes para la prestación de este tipo de servicio y además se realiza un análisis y evaluación operacional de las principales empresa de audio y video por suscripción, esto
bajo una investigación aplicada; dando como resultado recomendar a las empresas de audio y video por suscripción, la conveniencia económica de establecer la multiplexación de Flujos de Transporte por fibra óptica, en lugar del establecimiento de múltiples cabeceras con recepción satelital y además recomendar la necesidad de establecer normas regulatorias y técnicas para la implementación de este tipo de transporte de flujos de información.This report analyzes the functionality and applicability of the Protocol of Programming and Information System (PSIP), for the conformation of metadata management as an integral part of the transport streams (transport stream - TS) within the digital television, through evaluation of your application for different structures of TS in national networks, with their existing technical and regulatory standards for the provision of such service, and also analysis and operational evaluation of the main company audio and video subscription is done, this under an applied investigation; resulting recommend
companies audio and video subscription the economic desirability of the transport stream multiplexing optical fiber, rather than the establishment of multiple headers with satellite reception and also recommend the need for regulatory standards and techniques for the implementation of this type of transport streams of information
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