New PC(sp3)P pincer complexes of platinum and palladium

Carbometalated Complexes Possessing Tripodal Pseudo-C3-Symmetric Triptycene-Based Ligands

“…For example, for Pd­(P 3 T2)­Cl , the observed Cl1–Pd1–C1 angle is 176.6° and for P1–Pd1–P2, P2–Pd1–P3, and P1–Pd1–P3 the angles range from 118.6 to 122.8°. As expected, the Pd–Cl bond in Pd­(P 3 T2)­Cl is slightly longer than the corresponding bond in the previously reported anthracene-based two-dimensional pincer complexes owing to a stronger trans influence exerted by the sp 3 -hybridized carbon. , …”

Fluoride Anion Complexation by a Triptycene‐Based Distiborane: Taking Advantage of a Weak but Observable C−H⋅⋅⋅F Interaction

“…Examples of such systems include diboranes in which the two boron atoms are connected by an ortho-phenylene (A) [4] or a1 ,8-naphthalenediyl (B) [5] backbone.G iven the increasing interest that the chemistry of group 15 Lewis acids is drawing, [6] af ew groups including ours, [7] have started to investigate bidentate Lewis acids bearing two pnictogen atoms in the + Vstate [8] as in the case of C, [9] abis(phosphonium) derivative which has been used to catalyze hydrodefluorination reactions.R ealizing that the separation between the Lewis acidic sites impacts the chelating properties of these systems,i to ccurred to us that the use of inherently bulkier pentavalent group 15 centers may benefit from scaffolds which offer al arger separation. [7a] While this neutral Lewis acid proved to be sufficiently potent to chelate fluoride anions in water, we observed that the chelated anion in [D-m 2 -F] À is forced into proximity of the Lewis basic, electron-rich oxygen site.B ecause this situation may reduce the overall anion affinity of the receptor through repulsive forces,wehave now decided to focus on abackbone which does not present such acentral Lewis basic site.These considerations have led us to consider use of the 1,8-triptycenediyl backbone which has received ag reat deal of attention in the context of bis(phosphine) chemistry, [10] but has,t oo ur knowledge,n ever been used for the construction of bidentate Lewis acids.T his backbone was chosen for two reasons.F irst, its roof-shaped barrelene core projects the Lewis acidic site away from the bridgehead atom, thus lessening the occurrence of possible repulsions.Second, bearing in mind that C À H···F bonds have been previously observed (E), [11] it occurred to us that the triptycene bridgehead CÀHg roup oriented toward the binding pocket could augment anion binding.H erein, we report the first triptycene-based bidentate Lewis acid. [7a] While this neutral Lewis acid proved to be sufficiently potent to chelate fluoride anions in water, we observed that the chelated anion in [D-m 2 -F] À is forced into proximity of the Lewis basic, electron-rich oxygen site.B ecause this situation may reduce the overall anion affinity of the receptor through repulsive forces,wehave now decided to focus on abackbone which does not present such acentral Lewis basic site.These considerations have led us to consider use of the 1,8-triptycenediyl backbone which has received ag reat deal of attention in the context of bis(phosphine) chemistry, [10] but has,t oo ur knowledge,n ever been used for the construction of bidentate Lewis acids.T his backbone was chosen for two reasons.F irst, its roof-shaped barrelene core projects the Lewis acidic site away from the bridgehead atom, thus lessening the occurrence of possible repulsions.Second, bearing in mind that C À H···F bonds have been previously observed (E), [11] it occurred to us that the triptycene bridgehead CÀHg roup oriented toward the binding pocket could augment anion binding.H erein, we report the first triptycene-based bidentate Lewis acid.…”

“…With this in mind, we recently targeted D,adistiborane based on the 4,5dimethylxanthenediyl backbone. [7a] While this neutral Lewis acid proved to be sufficiently potent to chelate fluoride anions in water, we observed that the chelated anion in [D-m 2 -F] À is forced into proximity of the Lewis basic, electron-rich oxygen site.B ecause this situation may reduce the overall anion affinity of the receptor through repulsive forces,wehave now decided to focus on abackbone which does not present such acentral Lewis basic site.These considerations have led us to consider use of the 1,8-triptycenediyl backbone which has received ag reat deal of attention in the context of bis(phosphine) chemistry, [10] but has,t oo ur knowledge,n ever been used for the construction of bidentate Lewis acids.T his backbone was chosen for two reasons.F irst, its roof-shaped barrelene core projects the Lewis acidic site away from the bridgehead atom, thus lessening the occurrence of possible repulsions.Second, bearing in mind that C À H···F bonds have been previously observed (E), [11] it occurred to us that the triptycene bridgehead CÀHg roup oriented toward the binding pocket could augment anion binding.H erein, we report the first triptycene-based bidentate Lewis acid. We also demonstrate that the bridgehead C À Hu nit directed toward the anion binding pocket acts as ahydrogen-bond donor and thus play afavorable role in the binding of the anionic guest.…”

Cationic Two-Coordinate Complexes of Pd(I) and Pt(I) Have Longer Metal-Ligand Bonds Than Their Neutral Counterparts

“…In square-planar Pd(II) complexes where acetonitrile is cis to two phosphines, the Pd-N distances are ca. 2.08-2.12 Å when acetonitrile is trans to a strongly transinfluencing ligand (hydride, alkyl, or aryl) [48][49][50][51] and ca. 1.98-2.00 Å when it is trans to a weakly trans-influencing carboxylate.…”