A diphenylformamidinate-bridged terpyridineplatinum(II) dimer

The compound μ-N,N' -diphenylformamidinatobis[ 2,2',2"-terpyridineplatinum(II)] perchlorate mono hydrate (1) is formed by reaction of diphenylformamidine and [Pt(tpy)Cl]Cl (tpy = terpyridine) in the presence of excess base. The two platinum centers are bridged by a single diphenylformamidinato ligand with the remaining coordination geometry completed by the terpyridine group. The platinum-platinum separation is 3.049 (1) Å

Spectroscopic and structural properties of binuclear platinum-terpyridine complexes

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Electronic spectra and photophysics of platinum(II) complexes with α-diimine ligands. Mixed complexes with halide ligands

Emission properties have been studied for a series of compounds of the formula (L_2)PtC1_2, where L_2 is N,N,N',N'-tetramethylethylenediamine, 2,2'-bipyridine (bpy), 4,4'-Me_2bpy, 5,5'-Me_2bpy, 4,4'-(t-Bu)_2bpy, 3,3'-(CH_3OCO)_2bpy, and 1,10-phenanthroline, and also for the compound Pt(bpy)I_2. Most of them exhibit orange to red luminescence from a triplet ligand-field (^3LF) state, both as solids and in glassy solution. These emissions are very broad (fwhm 2300-3400 cm^(-1) at 10 K) and structureless and are strongly Stokes-shifted from absorption. The two exceptions are the solid "red" form of Pt(bpy)Cl_2, which exhibits a relatively narrow (fwhm 1050 cm^(-1) at 10 K), vibronically structured (Δν ~ 1500 cm^-1)) red emission, and Pt(3,3'-(CH_3OCO)_2bpy)Cl_2, which exhibits a broad (fwhm 2500 cm^(-1) at 10 K) but structured (Δν ~1300 cm^(-1)) orange emission. Both of these emissions are assigned to triplet metal-to-ligand charge-transfer (^3MLCT) excited states. For the former compound, a linear-chain structure has destabilized a dσ*(d_(z^2)) level, yielding a dσ* → π*(bpy) state as the lowest energy excited state, while for the latter, the strongly electron-withdrawing substituents have stabilized a bpy π* level, yielding a dσ* → π*(bpy) state as the lowest energy excited state. The relative energies of the various types of excited states, including ligand 3_(ππ*) states, are discussed in detail. The crystal structures of Pt(5,5'-Me_2bpy)Cl_2 (monoclinic Cc, Z = 4, a = 13.413(7) Å, b = 9.063(4) Å, c = 12.261(9) Å, 0 = 121.71(6)') and Pt(3,3'-(CH_3OCO)_2bpy)Cl_2 (triclinic P1, Z = 2, a = 7.288(2) Å, b = 9.932(3) Å, c = 11.881(5) Å, α = 98.04(3)°, β = 103.56(3)°, γ = 106.54(3)°) are reported

Electronic Spectroscopy of Chloro(terpyridine)platinum(II)

The electronic spectrum of [Pt(tpy)Cl]^+ (tpy = 2,2':6',2"-terpyridine) is influenced dramatically by intermolecular stacking interactions in solution and in the solid state. The crystal structure of [Pt(tpy)Cl]ClO_4 (monoclinic, P2_1/c (No. 14); a = 7.085(2), b = 17.064(5), c = 26.905(8) Å; β = 90.0(1) °; Z = 8) consists of discrete Pt_2 units (Pt-Pt = 3.269(1) Å) arranged along an infinite tpy-π stack (spacing ~ 3.35 Å). Variable-temperature and concentration studies of the absorption and emission spectra of [Pt(tpy)Cl]^+ suggest that similar metal-metal and ligand-ligand interactions persist in the solution phase. The high concentration, low-temperature emission spectrum (5:5:1 ethanol:methanol:DMF) reveals a 740-nm band indicative of M-M oligomerization, a 650-nm band attributable to tpy π-π interactions, and a 470-nm band characteristic of mononuclear [Pt(tpy)Cl]^+ π-π* emission. Concentration-dependent absorption spectra were fit to a "two-dimer" model, yielding equilibrium constants for the formation of Pt-Pt-, and tpy-tpy-bound dimers of 1.3(1) x 10^3 and 1.0(1) x 10^3 M^(-1), respectively, in 0.1 M aqueous NaCl. The low temperature solid-state luminescence of [Pt(tpy)Cl]^+ is assigned to a ^3(MMLCT) (MMLCT = metal-metal-to-ligand charge transfer) transition. The energy of this band is highly dependent on the counterion (PF_6^-, ClO_4^- , C1^-, CF_3SO_3^-), in line with the different colors of these various salts. In contrast, the room-temperature solid-state emission spectra are more difficult to interpret. While the red perchlorate salt exhibits a relatively narrow emission band at 725 nm (red-shifted from the 77-K maximum at 695 nm), consistent with a 3(MMLCT) transition, the orange (Cl^-, ClO_4^-, CF_3SO_3^-) and yellow (PF6^-) salts have extremely broad room-temperature emission bands that all appear at nearly the same energy (λ_(max) ~ 640 nm). We assign this luminescence to an eximeric intraligand transition resulting from π- π interactions and propose that the temperature dependent emissions from the orange and yellow solid materials originate from multiple electronic states

Electronic spectra and photophysics of platinum(II) complexes with α-diimine ligands. Mixed complexes with halide ligands

Emission properties have been studied for a series of compounds of the formula (L_2)PtC1_2, where L_2 is N,N,N',N'-tetramethylethylenediamine, 2,2'-bipyridine (bpy), 4,4'-Me_2bpy, 5,5'-Me_2bpy, 4,4'-(t-Bu)_2bpy, 3,3'-(CH_3OCO)_2bpy, and 1,10-phenanthroline, and also for the compound Pt(bpy)I_2. Most of them exhibit orange to red luminescence from a triplet ligand-field (^3LF) state, both as solids and in glassy solution. These emissions are very broad (fwhm 2300-3400 cm^(-1) at 10 K) and structureless and are strongly Stokes-shifted from absorption. The two exceptions are the solid "red" form of Pt(bpy)Cl_2, which exhibits a relatively narrow (fwhm 1050 cm^(-1) at 10 K), vibronically structured (Δν ~ 1500 cm^-1)) red emission, and Pt(3,3'-(CH_3OCO)_2bpy)Cl_2, which exhibits a broad (fwhm 2500 cm^(-1) at 10 K) but structured (Δν ~1300 cm^(-1)) orange emission. Both of these emissions are assigned to triplet metal-to-ligand charge-transfer (^3MLCT) excited states. For the former compound, a linear-chain structure has destabilized a dσ*(d_(z^2)) level, yielding a dσ* → π*(bpy) state as the lowest energy excited state, while for the latter, the strongly electron-withdrawing substituents have stabilized a bpy π* level, yielding a dσ* → π*(bpy) state as the lowest energy excited state. The relative energies of the various types of excited states, including ligand 3_(ππ*) states, are discussed in detail. The crystal structures of Pt(5,5'-Me_2bpy)Cl_2 (monoclinic Cc, Z = 4, a = 13.413(7) Å, b = 9.063(4) Å, c = 12.261(9) Å, 0 = 121.71(6)') and Pt(3,3'-(CH_3OCO)_2bpy)Cl_2 (triclinic P1, Z = 2, a = 7.288(2) Å, b = 9.932(3) Å, c = 11.881(5) Å, α = 98.04(3)°, β = 103.56(3)°, γ = 106.54(3)°) are reported

A Bis(pyrazolyl)(bipyridyl)platinum Complex

(4,4' -Dimethyl-2,2'-bipyridyl)bis(3,5-dimethylpyrazolium) platinum(II) 0.5-tetrahydrofuran solvate monohydrate, [Pt(C_5H_7N_2MC_(12)H_(12)-N2)].0.5C_4H_80.H_2O, M_r = 623.65, monoclinic, P2_1/n, ɑ = 8.625 (2), b = 20.593 (8), c = 14.451(4) Å, β = 90.32 (2)°, v = 2566.7 (14) Å^3, Z = 4, D_x = 1.61 g cm^(-3), λ(Mo Kɑ)= 0.71073 Å, μ = 55.50 cm^(-1), F(000) = 1232, room temperature, R = 0.0387 for 2874 reflections with F_o^2 > 3σ(F_o^2). The square-planar Pt complex has normal Pt-N(bipyridyl) bonds [2.009 (8) Å] and slightly short Pt-N(pyrazolyl) bonds [1.983 (7) Å]. The ligand molecules have normal distances and angles; the planes of the pyrazolyl ligands are twisted by about 60° to the bipyridyl-Pt plane, with the closest contacts between the pyrazolyls being -3.3 Å (Cl4···N5 and C19···N3)

Electronic Spectroscopy of Chloro(terpyridine)platinum(II)

The electronic spectrum of [Pt(tpy)Cl]^+ (tpy = 2,2':6',2"-terpyridine) is influenced dramatically by intermolecular stacking interactions in solution and in the solid state. The crystal structure of [Pt(tpy)Cl]ClO_4 (monoclinic, P2_1/c (No. 14); a = 7.085(2), b = 17.064(5), c = 26.905(8) Å; β = 90.0(1) °; Z = 8) consists of discrete Pt_2 units (Pt-Pt = 3.269(1) Å) arranged along an infinite tpy-π stack (spacing ~ 3.35 Å). Variable-temperature and concentration studies of the absorption and emission spectra of [Pt(tpy)Cl]^+ suggest that similar metal-metal and ligand-ligand interactions persist in the solution phase. The high concentration, low-temperature emission spectrum (5:5:1 ethanol:methanol:DMF) reveals a 740-nm band indicative of M-M oligomerization, a 650-nm band attributable to tpy π-π interactions, and a 470-nm band characteristic of mononuclear [Pt(tpy)Cl]^+ π-π* emission. Concentration-dependent absorption spectra were fit to a "two-dimer" model, yielding equilibrium constants for the formation of Pt-Pt-, and tpy-tpy-bound dimers of 1.3(1) x 10^3 and 1.0(1) x 10^3 M^(-1), respectively, in 0.1 M aqueous NaCl. The low temperature solid-state luminescence of [Pt(tpy)Cl]^+ is assigned to a ^3(MMLCT) (MMLCT = metal-metal-to-ligand charge transfer) transition. The energy of this band is highly dependent on the counterion (PF_6^-, ClO_4^- , C1^-, CF_3SO_3^-), in line with the different colors of these various salts. In contrast, the room-temperature solid-state emission spectra are more difficult to interpret. While the red perchlorate salt exhibits a relatively narrow emission band at 725 nm (red-shifted from the 77-K maximum at 695 nm), consistent with a 3(MMLCT) transition, the orange (Cl^-, ClO_4^-, CF_3SO_3^-) and yellow (PF6^-) salts have extremely broad room-temperature emission bands that all appear at nearly the same energy (λ_(max) ~ 640 nm). We assign this luminescence to an eximeric intraligand transition resulting from π- π interactions and propose that the temperature dependent emissions from the orange and yellow solid materials originate from multiple electronic states

Structures of [M_2(dimen)_4](Y)_2 (M = Rh, Ir; dimen = 1,8-Diisocyanomenthane; Y = PF_6, Tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, B(C_6H_5)_4) Crystals Featuring an Exceptionally Wide Range of Metal−Metal Distances and Dihedral Twist Angles

The binuclear complexes [M_2(dimen)_4](Y)_2 (M = Rh, Ir; dimen = 1,8-diisocyanomenthane; Y = PF_6, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate), and B(C_6H_5)_4) have face-to-face structures with M−M distances between 3.60 and 4.48 Å, and square-planar unit twist angles between 0 and 17.2°. Ligand flexing and out-of-plane bending of the metal centers accommodate M−M distances longer than 3.9 Å; addition of a torsional deformation produces a twisted conformation for shorter M−M distances (<3.9 Å). Spectroscopic data indicate that there are two or more deformational isomers of Ir_2(dimen)_4^(2+) in solution