Triphenylphosphine Groups Research Articles

Mitochondria-Targeted Multifunctional Nanoprodrugs by Inhibiting Metabolic Reprogramming for Combating Cisplatin-Resistant Lung Cancer.

How to address the resistance of cisplatin (CDDP) has always been a clinical challenge. The resistance mechanism of platinum-based drugs is very complex, including nuclear DNA damage repair, apoptosis escape, and tumor metabolism reprogramming. Tumor cells can switch between mitochondrial oxidative phosphorylation (OXPHOS) and glycolysis and develop resistance to chemotherapy drugs through metabolic variability. In addition, due to the lack of histone protection and a relatively weak damage repair ability, mitochondrial DNA (mtDNA) is more susceptible to damage, which in turn affects mitochondrial OXPHOS and can become a potential target for platinum-based drugs. Therefore, mitochondria, as targets of anticancer drugs, have become a hot topic in tumor resistance research. This study constructed a self-assembled nanotargeted drug delivery system LND-SS-Pt-TPP/HA-CD. β-Cyclodextrin-grafted hydronic acid (HA-CD)-encapsulated prodrug nanoparticles can target CD44 on the tumor surface and further deliver the prodrug to intracellular mitochondria through a triphenylphosphine group (TPP+). Disulfide bonds can be selectively degraded by glutathione (GSH) in mitochondria, releasing lonidamine (LND) and the cisplatin prodrug (Pt(IV)). Under the action of GSH and ascorbic acid, Pt(IV) is further reduced to cisplatin (Pt(II)). Cisplatin can cause mtDNA damage, induce mitochondrial dysfunction and mitophagy, and then affect mitochondrial OXPHOS. Meanwhile, LND can reduce the hexokinase II (HK II) level, induce destruction of mitochondria, and block energy supply by glycolysis inhibition. Ultimately, this self-assembled nano targeted delivery system can synergistically kill cisplatin-resistant lung cancer cells, which supplies an overcome cisplatin resistance choice via the disrupt mitochondria therapy.

Mitochondria-targeting nanozyme for catalytical therapy and radiotherapy with activation of cGAS-STING

BackgroundOvercoming radio-resistance and enhance radio-sensitivity to obtain desired therapeutic outcome plays an important role in treating cancer. MethodsHere we constructed a versatile enzyme-like nano-radiosensitizer MDP. MDP is composed of MnCO decorated and Ru-based nanozyme with triphenylphosphine (TPP) group coordinated on the surface. ResultsDue to the mitochondria-targeting ability of TPP and enhanced permeability and retention effect (EPR) effect of MDP, MDP accumulated in the mitochondria of tumor cells. Therefore, quantities of reactive oxygen species were produced via multiple enzyme-like properties including peroxidase (POD) and catalase (CAT) in a tumor microenvironment mimicking status. In additional, more energy of radiation ionizing was deposed in tumor site via Compton effect and secondary electron scattering by Ru element. Impressively, it was disclosed that the nanozyme can act as a cGAS-STING agonist to provoke immune response of the system, which hereby further elevated this combined therapy. ConclusionsCollectively, we fabricated a novel nanozyme with POD and CAT mimicking properties for the combination therapy of catalytical therapy, radiotherapy as well as immune therapy to eliminate cancer.

Mitochondria-Targeting Upconversion Nanoparticles@MOF for Multiple-Enhanced Photodynamic Therapy in Hypoxic Tumor.

The effect of photodynamic therapy (PDT) is severely limited by tumor hypoxia and the short half-life of reactive oxygen species (ROS). Herein, we constructed a near-infrared (NIR) light-regulated PDT nanoplatform (TPP-UCNPs@MOF-Pt) consisting of an upconversion nanoparticle (UCNP) core and porphyrin-based metal-organic framework (MOF) shell with platinum nanoparticles (PtNPs) and a mitochondria-targeting triphenylphosphine (TPP) group on the surface. TPP-UCNPs@MOF-Pt could effectively relieve the tumor hypoxia by converting intracellular H2O2 to oxygen (O2) and elevated the ROS level to enhance PDT efficacy under NIR light irradiation. In addition, the mitochondria-targeting TPP-UCNPs@MOF-Pt was localized on the mitochondria, leading to severe depolarization of the mitochondrial membrane and activation of the apoptotic pathway, further amplifying the therapeutic efficacy. In vitro and in vivo experiments demonstrated that the greatly enhanced photodynamic therapeutic efficacy of TPP-UCNPs@MOF-Pt was achieved by combining relief of tumor hypoxia with mitochondrial targeting and NIR activation. This study provides a promising strategy for construction of an MOF-based multifunctional nanoplatform to address the current limitations of PDT treatment for hypoxic tumors.

Synthesis and Properties of Bipolar Ladder-Like Polysiloxane with Carbazole and Triphenylphosphine Oxygen Groups.

In this study, a series of ladder-like polysiloxanes are synthesized by introducing double-chain Si-O-Si polymer as the backbone and the carbazole and triphenylphosphine oxide with high triplet energy as side groups. The ladder-like structures of polysiloxanes are achieved through a controlled polymerization method that involves the monomer self-assembly and subsequent surface-restricted solid-phase in situ condensation through freeze-drying. The introduction of siloxane improves thermal stability of the polymers and inhibits the conjugation of the polymers between the side groups, leading to an increase in the triplet energy level. Therefore, all these polymers perform higher triplet energy levels than phosphorescent emitter (FIrpic). The cyclic voltammetry measurements demonstrate that the bipolar polymer exhibits a high highest occupied molecular orbital (HOMO) value of -5.32eV, which is consistent with the work function of ITO/PEDOT:PSS, consequently facilitating hole injection. Furthermore, the incorporation of triphenylphosphine oxide promotes electron injection. Molecular simulations reveal that the frontier orbital distributions of the bipolar polymer are located on the carbazole and triphenylphosphine groups, respectively, which facilitate the transport of electrons and holes.

Mitochondrial-targeting Mn3O4/UIO-TPP nanozyme scavenge ROS to restore mitochondrial function for osteoarthritis therapy.

Excessive reactive oxygen species (ROS)-induced mitochondrial damage has impact on osteoarthritis (OA). Nanozyme mimics as natural enzyme alternatives to scavenge excessive ROS has offered a promising strategy for OA therapy. Herein, we reported a novel mitochondrial-targeting Mn3O4/UIO-TPP nanozyme using metal-organic frameworks with loaded Mn3O4 as the enzyme-like active core combining mitochondria-targeting triphenylphosphine (TPP) groups to serve as ROS scavengers for therapy of OA. With sequential catalysis of superoxide dismutase-like, catalase (CAT)-like, and hydroxyl radical (·OH) scavenging potentials, the nanozyme can target mitochondria by crossing subcellular barriers to effectively eliminate ROS to restore mitochondrial function and inhibit inflammation and chondrocyte apoptosis. It also has favorable biocompatibility and biosafety. Based on anterior cruciate ligament transection-induced OA joint models, this mitochondrial-targeting nanozyme effectively mitigated the inflammatory response with the Pelletier score reduction of 49.9% after 8-week therapy. This study offers a prospective approach to the design of nanomedicines for ROS-related diseases.

Dual Promotion of Phosphorus Groups for Ultralong Room Temperature Phosphorescence with High Efficiency

AbstractOrganic room temperature phosphorescence (RTP) materials have drawn wide attention due to their dynamic phosphorescence performance under ambient conditions. However, most of the pure organic RTP materials show low phosphorescence efficiency and short lifetime because of their weak spin–orbit coupling and fast nonradiative decay process. Introducing halogen heavy atoms can effectively improve the efficiency, while the lifetime would be shortened obviously. Thus, there is still a great challenge especially for developing halogen heavy atom free organic RTP materials, with simultaneously enhanced phosphorescence efficiency and lifetime. Herein, it is demonstrated that triphenylphosphine group possesses a strong n‐electron donating character and adopts a rigid tetrahedral configuration, which are in favor of accelerating intersystem crossing process and suppressing the nonradiative decay process, respectively. Benefited from the dual promotion of triphenylphosphine group, the obtained compound named CzPhP shows a decent phosphorescence efficiency of 14.36% and a prolonged lifetime of 340 ms. Another three pentavalent phosphine‐bearing analogs synthesized, i.e., CzPhPO, CzPhPS, and CzPhPSe, also present different conformational aggregations and good RTP performance. The diversity of the RTP performance of these compounds affords a potential application in anticounterfeiting and data encryption.

Design and synthesis of TPP+-Mitomycin C conjugate with reduced toxicity

Mitomycin C (MMC) is a class of alkylating anticancer drug, which non-specifically interacts with nuclear DNA and cross-links guanine and cytosine of DNA, thereby affecting DNA replication and synthesis. However, toxic effects largely impeded MMC’s clinical applications. In this study, triphenylphosphine groups (TPP+) were attached to MMC via the active aziridine amine with the aim to reduce its toxicity. MTT assay suggested that 5 possessed a good anticancer activity (IC50 = 1.09 μM, A549) with negligible effects on human normal cells (IC50 > 20 μM, L02 and HUVEC), while MMC exhibited IC50 values of less than 2.5 μM on the tested human normal cells. Dose range-finding experiments suggested that 5 had little effect on the body weight and tissues in mouse at a dose of 20 mg/kg, indicating significantly reduced toxicity as compared to MMC (LD50 < 2.5 mg/kg). Collectively, these data suggested that TPP+ group could be an effective vector to reduce toxicity of MMC.

Molecularly engineered AIEgens with enhanced quantum and singlet-oxygen yield for mitochondria-targeted imaging and photodynamic therapy.

Luminogens characteristic of aggregation-induced emission (AIEgens) have been extensively exploited for the development of imaging-guided photodynamic therapeutic (PDT) agents. However, intramolecular rotation of donor–acceptor (D–A) type AIEgens favors non-radiative decay of photonic energy which results in unsatisfactory fluorescence quantum and singlet oxygen yields. To address this issue, we developed several molecularly engineered AIEgens with partially “locked” molecular structures enhancing both fluorescence emission and the production of triplet excitons. A triphenylphosphine group was introduced to form a D–A conjugate, improving water solubility and the capacity for mitochondrial localization of the resulting probes. Experimental and theoretical analyses suggest that the much higher quantum and singlet oxygen yield of a structurally “significantly-locked” probe (LOCK-2) than its “partially locked” (LOCK-1) and “unlocked” equivalent (LOCK-0) is a result of suppressed AIE and twisted intramolecular charge transfer. LOCK-2 was also used for the mitochondrial-targeting, fluorescence image-guided PDT of liver cancer cells.

Synthesis, characterization, theoretical, and antimicrobial studies of indenoquinoxalin-based ligands and their reactions with CuBr(PPh3)3

A series of three ligands were derived from the condensation of indeno[1,2-b]quinoxalin-11-one and hydrazines (L1 from hydrazine, L2 from phenylhydrazine and L3 from thiosemicarbazide). The three ligands were stirred with CuBr(PPh3)3 in dichloromethane; no reaction was observed except in the case of L3, providing a complex with the formula CuBr(PPh3)2(κS-L3) (Cu-L3). Crystal structure of the complex revealed that the central copper atom in the molecule is coordinated to two triphenylphosphine groups, a bromine atom and to the indeno[1,2-b]quinoxalin-11-ylidenecarbothioamidohydrazide (L3) ligand via S atom; forming a distorted tetrahedral geometry around it. In general, Cu-L3 complex has shorter Cu-P bond lengths compared to the parent complex which suggest less steric hindrance in Cu-L3. None of the three ligands were able to use the nitrogen atoms as donating atoms due to their highly engagement in hydrogen-bonding as observed in the crystal structure of Cu-L3 as well as the theoretical calculations. Moreover, theoretical calculation indicated that Cu-N interactions were weak with long distances beyond the typical bonding distances. Antimicrobial screening against a range of strains showed selective inhabitations of indeno[1,2-b]quinoxalin-11-one, L1 and L3 against S. aureus strain. Moreover, the introduction of the copper fragment to L3 did not cause any significant improvements to the antimicrobial properties of L3.

Mitochondria-Targeted BODIPY Nanoparticles for Enhanced Photothermal and Photoacoustic Imaging In Vivo

Short-wavelength absorption and emission (<600 nm), hydrophobicity, and low selectivity have greatly restricted the biomedical applications of BODIPY. Herein, a series of mitochondria-targeted BODIPY nanoparticles with a cationic triphenylphosphine (TPP) group (Mito-BDP1-5 NPs) bearing different lengths of ethylene glycol (0-4 units), along with HO-BDP5 without a cationic TPP group for comparison, have been rationally designed and prepared to investigate the interplay between their structures and the related properties. Our studies found that Mito-BDP1-4 NPs showed a tendency of aggregation and precipitation while Mito-BDP5 NPs could be stable in aqueous solutions. Compared with HO-BDP5, tailor-made Mito-BDP5 possessed a high photothermal conversion efficiency (PCE) of 76.6 vs 9.0% and exhibited the highest photoinduced cytotoxicity. Upon NIR irradiation, the temperature induced by Mito-BDP5 NPs increased rapidly from room temperature to 76.0 °C in vitro and 50.0 °C at the tumor site in vivo within 5 min. Furthermore, effective mitochondrial imaging in vitro, photothermal imaging (PTI), and photoacoustic imaging (PAI) in vivo were achieved. In this paper, we developed tailor-made photothermal agents for targeting mitochondria and enhancing the PTI and PAI performances, which could be potentially applied in clinical precision theranostics.

Trifluoromethyl substitution enhances photoinduced activity against breast cancer cells but reduces ligand exchange in Ru(ii) complex.

A series of five ruthenium complexes containing triphenyl phosphine groups known to enhance both cellular penetration and photoinduced ligand exchange, cis-[Ru(bpy)2(P(p-R-Ph)3)(CH3CN)]2+, where bpy = 2,2′-bipyridine and P(p-R-Ph)3 represent para-substituted triphenylphosphine ligands with R = –OCH3 (1), –CH3 (2) –H (3), –F (4), and –CF3 (5), were synthesized and characterized. The photolysis of 1–5 in water with visible light (λirr ≥ 395 nm) results in the substitution of the coordinated acetonitrile with a solvent molecule, generating the corresponding aqua complex as the single photoproduct. A 3-fold variation in quantum yield was measured with 400 nm irradiation, Φ400, where 1 is the most efficient with a Φ400 = 0.076(2), and 5 the least photoactive complex, with Φ400 = 0.026(2). This trend is unexpected based on the red-shifted metal-to-ligand charge transfer (MLCT) absorption of 1 as compared to that of 5, but can be correlated to the substituent Hammett para parameters and pKa values of the ancillary phosphine ligands. Complexes 1–5 are not toxic towards the triple negative breast cancer cell line MDA-MB-231 in the dark, but 3 and 5 are >4.2 and >19-fold more cytotoxic upon irradiation with blue light, respectively. A number of experiments point to apoptosis, and not to necrosis or necroptosis, as the mechanism of cell death by 5 upon irradiation. These findings provide a foundation for understanding the role of phosphine ligands on photoinduced ligand substitution and show the enhancement afforded by –CF3 groups on photochemotherapy, which will aid the future design of photocages for photochemotherapeutic drug delivery.

Heterobifunctional PEG-grafted black phosphorus quantum dots: “Three-in-One” nano-platforms for mitochondria-targeted photothermal cancer therapy

Black phosphorus (BP) nano-materials, especially BP quantum dots (BPQDs), performs outstanding photothermal antitumor effects, excellent biocompatibility and biodegradability. However, there are several challenges to overcome before offering real benefits, such as poor stability, poor dispersibility as well as difficulty in tailoring other functions. Here, a “three-in-one” mitochondria-targeted BP nano-platform, called as BPQD-PEG-TPP, was designed. In this nano-platform, BPQDs were covalently grafted with a heterobifunctional PEG, in which one end was an aryl diazo group capable of reacting with BPQDs to form a covalent bond and the other end was a mitochondria-targeted triphenylphosphine (TPP) group. In addition to its excellent near-infrared photothermal properties, BPQD-PEG-TPP had much enhanced stability and dispersibility under physiological conditions, efficient mitochondria targeting and promoted ROS production through a photothermal effect. Both in vitro and in vivo experiments demonstrated that BPQD-PEG-TPP performed much superior photothermal cytotoxicity than BPQDs and BPQD-PEG as the mitochondria targeted PTT. Thus this “three-in-one” nanoplatform fabricated through polymer grafting, with excellent stability, dispersibility and negligible side effects, might be a promising strategy for mitochondria-targeted photothermal cancer therapy.

Platinum Atoms Dispersed in Single-chain Polymer Nanoparticles

The intramolecular cross-linking of single polymer chains can form single-chain nanoparticles (SCNPs), which have many applications. In this study, styrenic copolymers with pendent triphenylphosphine as the coordination site for platinum ions (Pt(II)) and benzocyclobutene as the latent reactive groups are synthesized. Triphenylphosphine groups in the chains can coordinate Pt(II) and aid slight single-chain folding in dilute solution. The intramolecular cross-linking caused by the ring-open reaction of benzocyclobutene completes the single-chain collapse and forms stable SCNPs in dilute solution. Pt(II) embedded in SCNPs can be further reduced to platinum atoms (Pt(0)). Pt(0) steadily and atomically dispersed in SCNPs exhibits better catalytic properties than normal polymer carried platinum particles do for the reduction of p-nitrophenol to p-aminophenol.

Influence of the introduction of a triphenylphosphine group on the anticancer activity of a copper complex

Aiming at obtaining new copper complexes with good cytotoxicity against cancer cells, triphenylphosphine (TPP) was introduced to obtain insight into the influence of the co-ligands. In this paper, two copper complexes, Cu(2-pbmq)(CH3OH)Br2 (1) and [Cu(2-pbmq)(TPP)Br]2 (2) were designed, synthesized, and characterized by X-ray crystallography, 2-((2-(pyrazin-2-yl)-1H-benzo[d]imidazol-1-yl)methyl))quinolone (2-pbmq), to investigate the influence of the TPP group on the anticancer activity of the metal complex. Although the presence of the TPP group diminished the intensity of the interaction properties of the complex with DNA, the in vitro anticancer activity and cellular uptake of the TPP-containing complex were markedly superior to those of its TPP-lacking counterpart. Detailed studies on the more potently cytotoxic complex 2 revealed that it accumulated in nucleus, arrested the cell cycle at the G0-G1 phase, causing mitochondrial dysfunction, involving the potential simultaneous mitochondrial membrane collapse, cellular ATP level depletion, and Ca2+ leakage, eventually inducing cell apoptosis. In summary, the introduction of a TPP group enhances the biological activity and cytotoxicity of the complex.

Novel soluble and thermally stable polyimides derived from 4-(4-diphenylphosphino)phenyl-2,6-bis(4-aminophenyl)pyridine and various aromatic dianhydrides

4-(4-Diphenylphosphino)phenyl-2,6-bis(4-aminophenyl)pyridine, as a novel aromatic diamine, was synthesized from 4-(diphenylphosphino)benzaldehyde and 4-nitroacetophenone through two-step, Chichibabin and reduction reaction successively. A series of aromatic polyimides containing pyridine and triphenylphosphine groups were prepared from this diamine with five dianhydrides via a conventional two-step thermal imidization procedure. These resulting polyimides were amorphous and showed good solubility in common polar solvents, such as N-methyl-2-pyrrolidone and N,N-dimethylacetamide. They exhibited outstanding thermal stability with glass transition temperature of 288–380 °C, 5% weight loss temperature of 521–583, and more than 60% residue at 800 °C under nitrogen. They also showed excellent flame retardancy with limited oxygen index value of 40–45. Tough and flexible polymer films had good mechanical properties with tensile strength of 69.1–128.6 MPa, tensile modulus of 1.7–2.1 GPa, and elongation at break of 7.2–25.7%, as well as high optical transparency with the UV cutoff wavelength in the 390–410 nm range.

Photostable Ratiometric Two-Photon Fluorescent Probe for Visualizing Hydrogen Polysulfide in Mitochondria and Its Application.

Hydrogen polysulfide (H2Sn) has currently attracted much research interest because it not only plays an important physiological function in many biological and health-related events, but also is considered as a newfound potent signal transducer. Small-molecule-based ratiometric fluorescent probes have advantages in sensitivity and biodetection, but such approaches that are intentionally developed for H2Sn detection and expected to be mitochondria-accessible are still lacking. In this work, because of the triphenylphosphine group introduced into the molecular scaffold of the naphthalimide derivative, Mito-NRT-HP was successfully applied to visualize intracellular H2Sn in mitochondria with excellent aqueous solubility, super photobleaching resistance, favorable cellular membrane permeability, and good biocompatibility. This one- and two-photon fluorescent probe with high selectivity and sensitivity (limit of detection, LOD = 0.01 μM) evinced a 70-fold enhancement of the fluorescence ratio (I546nm/I478nm) in the presence of H2Sn over other reactive sulfur species (RSS). The experimental results also give Mito-NRT-HP the potential for mapping the H2Sn distribution in mitochondria and evaluating the H2Sn roles in more biological processes, and they demonstrated the practical application possibility of Mito-NRT-HP in the early diagnosis of lipopolysaccharide-induced (LPS-induced) acute organ injury.

CO2‐Cross‐Linked Frustrated Lewis Networks as Gas‐Regulated Dynamic Covalent Materials

AbstractThe design of structurally dynamic molecular networks can offer strategies for fabricating stimuli‐responsive adaptive materials. Herein we first report a gas‐responsive dynamic gel system based on frustrated Lewis pair (FLP) chemistry. Two trefoil‐like molecules with bulky triphenylborane and triphenylphosphine groups are synthesized as complementary Lewis acid and base with trivalent sites. They can together bind CO2 gas molecules and further form a cross‐linked network via the bonding interactions between FLPs and CO2. Such CO2‐bridged dative linkages are shown to be dynamic covalent bonds, which endow the frustrated Lewis network with adaptable behaviors and unprecedented gas‐regulated viscoelastic, mechanical, and self‐healing performance. This study is an initial attempt to apply the FLP concept in materials chemistry, but we believe that this strategy will open a promising future for gas‐sensitive smart materials.

CO2 -Cross-Linked Frustrated Lewis Networks as Gas-Regulated Dynamic Covalent Materials.

The design of structurally dynamic molecular networks can offer strategies for fabricating stimuli-responsive adaptive materials. Herein we first report a gas-responsive dynamic gel system based on frustrated Lewis pair (FLP) chemistry. Two trefoil-like molecules with bulky triphenylborane and triphenylphosphine groups are synthesized as complementary Lewis acid and base with trivalent sites. They can together bind CO2 gas molecules and further form a cross-linked network via the bonding interactions between FLPs and CO2 . Such CO2 -bridged dative linkages are shown to be dynamic covalent bonds, which endow the frustrated Lewis network with adaptable behaviors and unprecedented gas-regulated viscoelastic, mechanical, and self-healing performance. This study is an initial attempt to apply the FLP concept in materials chemistry, but we believe that this strategy will open a promising future for gas-sensitive smart materials.

Honeycomb-like Bicontinuous P-Doped Porous Polymers from Hyper-Cross-Linking of Diblock Copolymers for Heterogeneous Catalysis

This work reports a triphenylphosphine-guided hyper-cross-linking self-assembly strategy to construct honeycomb-like bicontinuous P-doped porous polymers (HBPs) based on polylactide-b-polystyrene/4-diphenylphosphinostyrene (PLA-b-P(S/DPPS)) diblock copolymers. The triphenylphosphine (PPh3) groups derived from DPPS not only play as the cross-linkable monomer with S and DPPS but also serve as the strong P ligands for binding the metal species. Subsequently, Pd nanoparticles (NPs) can be effectly encapsulated into the synthesized HBPs by a simple impregnation-reduction method. The resultant Pd@HBPs show more excellent catalytic performance for selective hydrogenations than the corresponding homogeneous catalysts and synthesized heterogeneous analogues. The great performance could be attributed to the advantage of the three-dimensionally (3D) honeycomb-like interconnected mesoporous structure, which allows the accessible catalytically active sites to be efficiently exposed toward reactants. This strategy repr...

Diminished electron density in the Vaska-type rhodium(I) complex trans-[Rh(NCBH3)(CO)(PPh3)2

Vaska-type complexes, i.e. trans-[RhX(CO)(PPh3)2] (X is a halogen or pseudohalogen), undergo a range of reactions and exhibit considerable catalytic activity. The electron density on the Rh(I) atom in these complexes plays an important role in their reactivity. Many cyanotrihydridoborate (BH3CN(-)) complexes of Group 6-8 transition metals have been synthesized and structurally characterized, an exception being the rhodium(I) complex. Carbonyl(cyanotrihydridoborato-κN)bis(triphenylphosphine-κP)rhodium(I), [Rh(NCBH3)(CO)(C18H15P)2], was prepared by the metathesis reaction of sodium cyanotrihydridoborate with trans-[RhCl(CO)(PPh3)2], and was characterized by single-crystal X-ray diffraction analysis and IR, (1)H, (13)C and (11)B NMR spectroscopy. The X-ray diffraction data indicate that the cyanotrihydridoborate ligand coordinates to the Rh(I) atom through the N atom in a trans position with respect to the carbonyl ligand; this was also confirmed by the IR and NMR data. The carbonyl stretching frequency ν(CO) and the carbonyl carbon (1)JC-Rh and (1)JC-P coupling constants of the Cipso atoms of the triphenylphosphine groups reflect the diminished electron density on the central Rh(I) atom compared to the parent trans-[RhCl(CO)(PPh3)2] complex.