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A P-stereogenic linear tetraphosphine tetraoxide, (R,R)- or (S,S)-dpmppm(=O) 4 , was synthesized to prepare C 2 dinuclear M(hfa) 3 complexes (M=Eu, Tb, Y) as the first example of lanthanide(III) complexes with P-chiral multidentate phosphine oxides. The mononuclear M(hfa) 3 complexes (M=Eu, Y) with a P-chiral diphosphine dioxide, tpdpb(=O) 2 , were also prepared, and comparison of their photophysical properties for the Eu III complexes revealed that significant chiral induction from the P-chiral centers arises on the achiral M(hfa) 3 units through intramolecular π-π stacking constraint in the dinuclear system., (© 2021 Wiley-VCH GmbH.)

Reactions of Pd 8 strings supported by meso-Ph 2 PCH 2 P(Ph)CH 2 P(Ph)CH 2 PPh 2 (meso-dpmppm) ligands, [Pd 8 (meso-dpmppm) 4 (L) 2 ] 4+ (L=CH 3 CN (1), XylNC (2)) with C 60 resulted in the exclusive formation of unprecedented metal-chain-wired C 60 bucky balls, [{Pd 4 (meso-dpmppm) 2 (L)} 2 (C 60 )] 4+ (L=CH 3 CN (11), XylNC (12)), in which a C 60 fullerene is trapped in the central Pd-Pd junction, as unambiguously established by spectroscopic, X-ray crystallographic, and theoretical techniques. The similar reaction of Pd 8 strings supported by rac-dpmppm, [Pd 8 (rac-dpmppm) 4 (CH 3 CN) 2 ] 4+ (3) also afforded a racemic mixture of [{Pd 4 ((R*,R*)-dpmppm) 2 (CH 3 CN)} 2 (C 60 )] 4+ (13) without scrambling the Pd 4 fragments with (R,R)- and (S,S)-dpmppm ligands. Consequently, those of enantiopure chiral Pd 8 strings, [Pd 8 ((R*,R*)-dpmppm) 4 (CH 3 CN) 2 ] 4+ , certainly afforded chiral bucky balls of [{Pd 4 ((R*,R*)-dpmppm) 2 (CH 3 CN)} 2 (C 60 )] 4+ (13 RR and 13 SS ), that exhibit mirror-image circular dichroism spectra. The reactions of 1 and 2 were also applied for trapping a C 70 fullerene to give 2 : 1 adducts of [{Pd 4 (meso-dpmppm) 2 (L)} 2 (C 70 )] 4+ (L=CH 3 CN (21), XylNC (22)). These results provide useful information for creating a platform to develop dimensionally and chirality controlled metal-carbon nanocomposite materials., (© 2021 Wiley-VCH GmbH.)

A series of the octapalladium chains supported by meso-Ph 2 PCH 2 P(Ph)CH 2 P(Ph)CH 2 PPh 2 (meso-dpmppm) ligands, [Pd 8 (meso-dpmppm) 4 (L) 2 ](BF 4 ) 4 (L=none (1), solvents: CH 3 CN (2 a), dmf (2 b), dmso (2 c), RN≡C: R=Xyl (3 a), Mes (3 b), Dip (3 c), t Bu (3 d), Cy (3 e), CH 3 (CH 2 ) 7 (3 f), CH 3 (CH 2 ) 11 (3 g), CH 3 (CH 2 ) 17 (3 h)) and [Pd 8 (meso-dpmppm) 4 (X) 2 ](BF 4 ) 2 (X=Cl (4 a), N 3 (4 b), CN (4 c), SCN (4 d)), were synthesized by using 2 a as a stable good precursor, and characterized by spectroscopic (IR, 1 H and 31 P NMR, UV-vis-NIR, ESI-MS) measurements and X-ray crystallographic analyses (for 1, 2 a, b, 3 a, b, e, f, 4 a-d). On the basis of DFT calculations on the X-ray determined structure of 2 b ([2b-Pd 8 ] 4+ ) and the optimized models [Pd 8 (meso-Ph 2 PCH 2 P(H)CH 2 P(H)CH 2 PH 2 ) 4 (CH 3 CN) 2 ] 4+ ([Pd 8 Ph 8 ] 4+ ) and [Pd 8 (meso-H 2 PCH 2 P(H)CH 2 P(H)CH 2 PH 2 ) 4 (CH 3 CN) 2 ] 4+ ([Pd 8 H 8 ] 4+ ), with and without empirically calculating dispersion force stabilization energy (B3LYP-D3, B3LYP), the formation energy between the two Pd 4 fragments is assumed to involve mainly noncovalent interactions (ca. -70 kcal/mol) with four sets of interligand C-H/π interactions and Pd⋅⋅⋅Pd metallophilic one, while electron shared covalent interactions are almost canceled out within the Pd 8 chain. All the compounds isolated are stable in solution and exhibit characteristic absorption at ∼900 nm, which is assignable to a spin allowed HOMO to LUMO transition, and shows temperature dependent intensity change with variable absorption coefficients presumably due to coupling with some thermal vibrations. The structures and electronic states of the Pd 8 chains are found finely tunable by varying the terminal capping ligands. In particular, theoretical calculations elucidated that the HOMO-LUMO energy gap is systematically related to the central Pd-Pd distance (2.7319(6)-2.7575(6) Å) by two ways with neutral ligands L (1, 2, 3) and with anionic ligands X (4), which are reflected on the NIR absorption energy of 867-954 nm. The isocyanide terminated Pd 8 complexes (3) further reacted with excess of RNC (6 eq) to afford the Pd 4 complexes, [Pd 4 (meso-dpmppm) 2 (RNC) 2 ](BF 4 ) 2 (13), and the cyclic voltammograms of 2 a (L=CH 3 CN), 3, and 13 (R=Xyl, Mes, t Bu, Cy) demonstrated wide range redox behaviors from 2{Pd 4 } 4+ to 2{Pd 4 } 0 through 2{Pd 4 } 2+ ↔{Pd 8 } 4+ , {Pd 8 } 3+ , and {Pd 8 } 2+ strings. The oxidized complexes, [Pd 4 (meso-dpmppm) 2 (RNC) 3 ](BF 4 ) 4 (16), were characterized by X-ray analyses, and the two-electron reduced chain of [Pd 8 (meso-dpmppm) 4 ](BF 4 ) 2 (7) was analyzed by spectroscopic and electrochemical techniques and DFT calculations. Reactions of 2 a with 1 equiv. of aromatic linear bisisocyanide (BI) in CH 2 Cl 2 deposited insoluble coordination polymers, {[Pd 8 (meso-dpmppm) 4 (BI)](BF 4 ) 4 } n (5), and interestingly, they were soluble in acetonitrile, 31 P{ 1 H} and 1 H DOSY NMR spectra as well as SAXS curves suggesting that the coordination polymers may exist in acetonitrile as dynamically 1D self-assembled coordination polymers comprising ca. 50 units of the Pd 8 rod averaged within the timescale., (© 2021 Wiley-VCH GmbH.)

By using a linear tetraphosphine, meso-bis[(diphenylphosphinomethyl)phenylphosphino]methane (dpmppm), nona- and hexadecanuclear copper hydride clusters, [Cu 9 H 7 (μ-dpmppm) 3 ]X 2 (X=Cl (1 a), Br (1 b), I (1 c), PF 6 (1 d)) and [Cu 16 H 14 (μ-dpmppm) 4 ]X 2 (X 2 =I 2 (2 c), (4/3) PF 6 ⋅(2/3) OH (2 d)) were synthesized and characterized. They form copper-hydride cages of apex-truncated supertetrahedral {Cu 9 H 7 } 2+ and square-face-capped cuboctahedral {Cu 16 H 14 } 2+ structures. The hydride positions were estimated by DFT calculations to be facially dispersed around the copper frameworks. A kinetically controlled synthesis gave an unsymmetrical Cu 8 H 6 cluster, [Cu 8 H 6 (μ-dpmppm) 3 ] 2+ (3), which readily reacted with CO 2 to afford linear Cu 4 complexes with formate bridges, leading to an unprecedented hydrogenation of CO 2 into formate catalyzed by {Cu 4 (μ-dpmppm) 2 } platform. The results demonstrate that new motifs of copper hydride clusters could be established by the tetraphosphine ligands, and the structures influence their reactivity., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new linear tetraphosphine containing a PNP phosphazane bridge, rac-bis[(diphenylphosphinomethyl)phenylphosphino]phenylamine (rac-dpmppan), was synthesized and utilized to support a series of Pd/Pt mixed metal tetranuclear chains, [Pd 4-n Pt n (μ-rac-dpmppan) 2 (XylNC) 2 ](PF 6 ) 2 (XylNC=xylyl isocyanide; n=0: Pd 4 (1), 1: PtPd 3 (2), 2: PtPd 2 Pt (3), 2: Pt 2 Pd 2 (4), 3: Pt 2 PdPt (5)), in which the number and positions of additional Pt atoms were successfully controlled depending on the respective synthetic procedures using transformations from 1 to 3 through 2 and from 4 to 5 by redox-coupled exchange reactions. The 31 P{ 1 H} NMR and ESI mass spectra and X-ray diffraction analyses revealed almost identical tetranuclear structures, with slight contraction of metal-metal bonds according to incorporation of Pt atoms. The electronic absorption spectra of 1-5 exhibited characteristic bands at 635-510 nm with an energy propensity depending on the number and positions of Pt centres, which were assigned to HOMO (dσ*σσ*) to LUMO (dσ*σ*σ*) transition by theoretical calculations. The present results demonstrated that the electronic structures of Pd/Pt mixed-metal tetranuclear complexes are finely tuned as orbital-overlapping alloyed metal chains by atomically precise Pt incorporation in the Pd 4 chain., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A copper hydride cluster [Cu 8 (μ-H) 6 (μ-dppm) 5 ](PF 6 ) 2 (dppm=bis(diphenylphosphino)methane) was prepared from reaction of [CuH(PPh 3 )] 6 with dppm in the presence of [Cu(CH 3 CN) 4 ]PF 6 and exhibited fluxional behaviors in solution where the hydrides and the phosphines are scrambling around the trans-bicapped octahedral Cu 8 framework. The Cu 8 H 6 complex showed facile reactivity with CO 2 (1 atm, RT) to afford a tricopper complex, [Cu 3 (μ-H)(μ-O 2 CH)(μ-dppm) 3 ]PF 6 , which could be developed to unprecedented hydrosilylation of CO 2 catalyzed by multinuclear CuH species under mild conditions., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A heterobimetallic PtPd 3 complex supported by three bridging diphenylsilylene ligands, [Pt{Pd(dmpe)} 3 (μ 3 -SiPh 2 ) 3 ] (1, dmpe=1,2-bis(dimethylphosphino)ethane), has been synthesized from mononuclear Pd and Pt complexes. The hexagonal core composed of Pt, Pd, and Si atoms is slightly larger than that of the tetrapalladium complex, [Pd{Pd(dmpe)} 3 (μ 3 -SiPh 2 ) 3 ] (2). Reaction of PhSiH 3 with complex 1 in the presence and absence of Ph 2 SiH 2 results in the formation of a tetranuclear complex with silyl and hydride ligands at the Pt center, [PtH(SiPh 2 H){Pd(dmpe)} 3 (μ 3 -SiHPh) 3 ] (3), and an octanuclear complex, [{Pt{Pd(dmpe)} 3 (μ 3 -SiHPh) 3 } 2 (κ 2 -dmpe)] (5), respectively. Both M-Si (M=Pt, Pd) bond lengths and the 29 Si NMR chemical shifts of 1 and 2 are located between those of mononuclear late transition-metal complexes with a silylene ligand and complexes with donor-stabilized silylene ligands. CuI and AgI adducts of 1 and 2, formulated as [M(μ-M'I){Pd(dmpe)} 3 (μ 3 -SiPh 2 ) 3 ] (M=Pt, Pd; M'=Cu, Ag), undergo elimination of CuI (AgI) and regenerate the tetrametallic complexes upon heating or addition of a chelating diphosphine. Elimination of AgI from 2-AgI occurs more rapidly than elimination of CuI from 2-CuI, as determined from the results of kinetics experiments., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

By using a chiral tetraphosphine, rac-bis[(diphenylphosphinomethyl)phenylphosphino]methane (rac-dpmppm), linear octapalladium chains were synthesized as discrete molecules of [Pd 8 (μ-rac-dpmppm) 4 L 2 ](BF 4 ) 4 (L=CH 3 CN, dmf, XylNC), [Pd 8 (μ-rac-dpmppm) 4 ](BF 4 ) 4 , and [Pd 8 (μ-rac-dpmppm) 4 (Cl) 2 ](BF 4 ) 2 , which are stable in the solution states and characterized by spectroscopic and crystallographic methods to reveal the octapalladium chains supported by homochiral four tetraphosphines. Variable-temperature NMR studies for a 1:1 mixture of [Pd 8 (μ-rac-dpmppm) 4 (dmf) 2 ](BF 4 ) 4 and [Pd 8 (μ-meso-dpmppm) 4 (dmf) 2 ]-(BF 4 ) 4 in [D 7 ]DMF revealed that the Pd 8 chains were dissociated at higher temperature (T≈140 °C) into the Pd 4 units of {Pd 4 (μ-rac-dpmppm) 2 } 2+ and {Pd 4 (μ-meso-dpmppm) 2 } 2+ , and they were thermodynamically self-aligned to restore the Pd 8 chains at lower temperature (T<60 °C), through perfect chiral self-recognition between the stereogenic tetrapalladium units., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new linear hexaphosphine, rac-cis,cis,trans-bis{[(diphenylphosphinomethyl)phenylphosphinomethyl]phenylphosphino}methane (P6), was synthesized and isolated as a pure isomer, confirmed by transforming to the corresponding phosphine sulfide. The methylene-bridged linear hexaphosphine readily organized flexible gold(I) and silver(I) hexanuclear chains, [M6(μ-P6)2]X6 (X6 = (OTf)6, M = Au (1), Ag (2); X6 = Cl2(PF6)4, M = Au (3)). The hexaphosphine also supported a tetrasilver(I) complex [Ag4(μ-P6)2](OTf)4 (4), which was readily transformed by treatment with AgOTf into 3, revealing a drastic alternation of the two P6 arrangement. The hexagold(I) chains exhibited a considerably red-shifted absorption (∼410 nm) and emission (540-580 nm) to (1) [5dσ*→6pσ] and from (3) [5dσ*→6pσ] excited states of the metal centers, respectively. The new linear hexaphosphine could be a useful tool to construct linear metal clusters as subnano building blocks., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A linear tetraphosphine, meso-bis[(diphenylphosphinomethyl)phenylphosphino]methane (dpmppm) was used to synthesize linear octapalladium-extended metal atom chains as discrete molecules of [Pd8(μ-dpmppm)4](BF4)4 (1) and [Pd8(μ-dpmppm)4L2](BF4)4 (L=2,6-xylyl isocyanide (XylNC; 2), acetonitrile (3), and N,N-dimethylformamide (dmf; 4)), which are stable in the solution states and show interesting temperature-dependent photochemical properties in the near IR region. Variable temperature NMR studies demonstrated that at higher temperature T≈140 °C the Pd8 chains were dissociated into Pd4 fragments, which were thermodynamically self-aligned to restore the Pd8 chains at lower temperature T<60 °C. The coldspray ionization mass spectra suggested a possibility for further aggregation of the linear tetrapalladium units., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Reactions of meso-bis[(diphenylphosphinomethyl)phenylphosphino]methane (dpmppm) with Cu(I) species in the presence of NaBH4 afforded di- and tetranuclear copper hydride complexes, [Cu2(μ-H)(μ-dpmppm)2]X (1) and [Cu4(μ-H)2(μ4-H)(μ-dpmppm)2]X (2) (X=BF4, PF6). Complex 1 undergoes facile insertion of CO2 (1 atm) at room temperature, leading to a formate-bridged dicopper complex [Cu2(μ-HCOO)(dpmppm)2]X (3). The experimental and DFT theoretical studies clearly demonstrate that CO2 insertion into the Cu2(μ-H) unit occurred with the flexible dicopper platform. Complex 2 also undergoes CO2 insertion to give a formate-bridged complex, [Cu4(μ-HCOO)3(dpmppm)2]X, during which the square Cu4 framework opened up to a linear tetranuclear chain., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A series of tetragold(I) complexes supported by tetraphosphine ligands, meso- and rac-bis[(diphenylphosphinomethyl)phenylphosphino]methane (meso- and rac-dpmppm) were synthesized and characterized to show that the tetranuclear Au(I) alignment varies depending on syn- and anti-arrangements of the two dpmppm ligands with respect to the metal chain. The structures of syn-[Au4 (meso-dpmppm)2X]X'3 (X = Cl; X' = Cl (4 a), PF6 (4 b), BF4 (4 c)) and syn-[Au4 (meso-dpmppm)2]X4 (X = PF6 (4 d), BF4 (4 e), TfO (4 f); TfO = triflate) involved a bent tetragold(I) core with a counter anion X incorporated into the bent pocket. Complexes anti-[Au4 (meso-dpmppm)2]X4 (X = PF6 (5 d), BF4 (5 e), TfO (5 f)) contain a linearly ordered Au4 string and complexes syn-[Au4 (rac-dpmppm)2X2]X'2 (X = Cl, X' = Cl (6 a), PF6 (6 b), BF4 (6 c)) and syn-[Au4 (rac-dpmppm)2]X4 (X = PF6 (6 d), BF4 (6 e), TfO (6 f)) consist of a zigzag tetragold(I) chain supported by the two syn-arranged rac-dpmppm ligands. Complexes 4 d-f, 5 d-f, and 6 d-f with non-coordinative large anions are strongly luminescent in the solid state (λmax = 475-515 nm, Φ = 0.67-0.85) and in acetonitrile (λmax = 491-520 nm, Φ = 0.33-0.97); the emission was assigned to phosphorescence from (3) [dσ*σ*σ* pσσσ] excited state of the Au4 centers on the basis of DFT calculations as well as the long lifetime (a few μs). The emission energy is predominantly determined by the HOMO and LUMO characters of the Au4 centers, which depend on the bent (4), linear (5), and zigzag (6) alignments. The strong emissions in acetonitrile were quenched by chloride anions through simultaneous dynamic and static quenching processes, in which static binding of chloride ions to the Au4 excited species should be the most effective. The present study demonstrates that the structures of linear tetranuclear gold(I) chains can be modified by utilizing the stereoisomeric tetraphosphines, meso- and rac-dpmppm, which may lead to fine tuning of the strongly luminescent properties intrinsic to the Au(I) 4 cluster centers., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A flexible building block: Flexible tetragold(I) chain complexes supported by a new single methylene-bridged tetraphosphine ligand were synthesized and further transformed into discrete linear octagold(I) {Au(8)} and cyclic hexagold(I) {Au(6)} structures by reaction with KI and NaAuCl(4), respectively (see picture, Au purple, Cl dark green, PF(6) light green, I pink). The tetragold complexes are also luminescent at room temperature.