To design a molecule with highly reactive, ambiphilic P III cationic center, a pincer-type ligand bearing two ortho-carborane (oCb) "arms" and a neutral central pyridine donor (2) was chosen (Fig. ) . We envisioned that 2 would provide the necessary rigidity and robustness to structurally constrain the P III cationic center, the pyridine donor would stabilize this cationic center, while the strongly electron-withdrawing oCb "arms" would make this P III -center highly electrophilic (low-lying LUMO). Thus, 2 was doubly deprotonated by n BuLi and reacted with excess of PCl3 producing chlorophosphine 1-Cl (Fig. ). Colorless crystals of 1-Cl were obtained from a mixture of CH2Cl2/n-hexane (10:1) and its molecular structure was determined by X-ray crystallography (Fig. ). In an attempt to obtain the desired 1 + , 1-Cl was reacted with AgOTf (1 equiv.), however instead of a separated [1 + ][OTf] ion pair, 1-OTf was obtained (Fig. ). 1-OTf was crystallized from CH2Cl2 at room temperature and its molecular structure was determined using X-ray crystallography (Fig. ). The 31 P NMR chemical shift of 1-OTf at δ = 36.0 ppm resembles the chemical shift of 1-Cl (δ = 33.8 ppm), indicating that despite the trans effect from the pyridine donor, no dissociation to 1 + and TfO -occurs in solution at room temperature on the NMR timescale. This points to the highly electrophilic P III -center in 1-OTf. To obtain a noncoordinated, "free" 1 + cation, the chloride in 1-Cl was abstracted by [Et3Si][B(C6F5)4], giving the desired [1 + ][B(C6F5)4] (Fig. ). [1 + ][B(C6F5)4] was crystallized from CHCl3 as light yellow crystals and its molecular structure was determined by X-ray crystallography (Fig. ). [1 + ][B(C6F5)4] is a separated ion pair both in solid and solution with a low-field signal in 31 P NMR at δ = 132.2 ppm. The P-center in 1 + is pyramidalized and strongly deviated from a local C3v symmetry, which is typical to trigonal pyramidal σ 3 P centers, with bond angles around phosphorus atom being ∠C1-P1-C2 = 124.1°, ∠C1-P1-N1 and ∠N1-P1-C2 = 87.2°. Thus, ligand 2 enforces a distorted trigonal pyramidal geometry of P1 center in 1 + with a Cs local symmetry, which could also be described as a cis-divacant pseudo trigonal bipyramid in which C1 and C2 atoms of the oCb units are at the equatorial positions and the central N1 is at the axial one. The electronic structure of 1 + was further studied by DFT calculations performed at BP86(D3)/def2-TZVP level of theory . The optimized geometry of 1 + is in good agreement with the experimentally obtained structure (Fig. ). The MOs analysis of the calculated 1 + reveals that the HOMO is primarily located on the P-center, while the LUMO is located on the P-center with the expected delocalization into the pyridine 𝜋-system. The HOMO-LUMO energy gap of 2.8 eV suggests a highly reactive nature of the P-center in 1 + (Fig. ). The natural bond orbital (NBO) analysis shows that the lone pair (LP) at P-center (occupancy of 1.85 e) resides on an sp 0.87 hybrid with a dominant s character. The natural population analysis (NPA) exhibits charges of -0.47 and +1.26 on N-and P-centers, respectively. An electron occupancy of N1-P1 bond of 1.53 e was calculated, with the bonding coefficients significantly polarized towards the N1 center (92.76% and 7.24% on N1 and P1 respectively). The calculated Wiberg bond index (WBI) value for N1-P1 bond is 0.6419. The nature of N-P bond in 1 + was also analyzed by Baders quantum theory of atoms in molecules (QTAIM) . A positive Laplacian (∇ 2 ρ(rBCP) = 0.075159) and low magnitude of electron density (ρ = 0.136520) at the bond critical point (BCP) of the N-P bond in 1 + indicate the donor acceptor interactions between these two atoms (Fig. ). Considering all these factors, the nature of 1 + can be most accurately described as a pyridine-supported phosphenium cation. The low HOMO-LUMO gap in 1 + suggests a high reactivity of this P III -center, which encouraged us to check its reactivity with H2. Thus, a J-Young NMR tube containing CH2Cl2 solution of 1 + was pressurized with H2 (4 atm) and the reaction was left at r.t. while the reaction progress was monitored by multinuclear NMR spectroscopy. After ~7 days, the formation of 1 + -H2, the formal oxidative addition product of the H-H bond to the P III cationic center in 1 + (Fig. ), could be observed by the 31 P NMR as a triplet at δ = -42.66 ppm with 1 J(PH) of 504 Hz (Fig. ). The corresponding doublet with same coupling constant was measured by 1 H NMR at δ = 7.35 ppm ( 1 J(PH) = 504 Hz). To the best of our knowledge, 1 + is the first compound with a single P III -center that is capable of splitting H-H bond in a formal oxidative addition reaction. The reaction time could be significantly reduced (~48 h) by heating the reaction to 60 °C, however, the outcome was not as clean. 1 + -H2 was precipitated from CH2Cl2/n-hexane solution (1:3) as an offwhite powder, however, multiple attempts to obtain crystals suitable for a single crystal X-ray diffraction failed.