Molecular structure of hexakis(methyl isocyanide)dipalladium(I) bis(hexafluorophosphate) hemiacetone, [Pd2(CNMe)6](PF6)2.1/2Me2CO.  Palladium(I) dimer

In relation to the known complexes Pd2(CNMe)6 2+ and Pd2(CN-t-Bu)4Cl2, Pd2(tmb)2Cl2 (tmb = 2,5-dimethyl-2‘,5‘-diisocyanohexane) and Pd3(dppm)3CO2+ (dppm = ((C6H5)2P)2CH2), respectively, the ground and lowest energy triplet excited state geometries of the model compounds Pd2(CNMe)4Cl2 and Pd2(CN(CH2)4NC)2Cl2, and Pd3(PH3)6CO2+ have been optimized using density functional theory. The computations for ground state structures are in excellent agreement with the X-ray data. In the excited states, bond lengthening (due to the change in Pd−Pd bond order 0 → 1) is predicted. In the bridged species, Pd2(CN(CH2)4NC)2Cl2, the computations reveal that twisting of the dihedral angle must occur in order to account for the large change in Pd−Pd distance. Finally, the Pd−Pd bond lengthening for the Pd3(dppm)3CO2+ cluster in the 3A2 excited state is predicted to be ∼0.19 Å relative to the ground state. This value has also been confirmed by an analysis of the emission band using Heller's time-dependent theory.

Section: Resultsmentioning

confidence: 99%

Geometry Optimizations of the Ground and Excited Triplet State Structures of the Low-Valent Metal−Metal Bonded Isocyanide and Carbonyl Di- and Trinuclear Palladium Complexes Using Density Functional Theory

Provencher

Harvey

1996

“…(15) Taylor, N. 7) 26 (3)* N( 2) 191 (11) 4701 ( 7) 3518 ( 7) 23 (3)* N(3) 6662 ( 11) 4446 ( 7) 2371 ( 7) 22 (3)* N(4) 1984 ( 11) 612 ( 7) 5647 ( 7) 22 (3)* C(l) -265 (9) 6322 (9) 26 (2) C( 9) 6641 ( 17) 2640 (11) 9844 (10) 42 (5)* a Asterisks denote cases where the equivalent isotropic U value is defined as one-third of the trace of the orghogonalized Uy tensor.…”

Section: Introductionmentioning

confidence: 99%

Bridged or nonbridged structures for dinuclear metal complexes. The case of tetrakis(methyl isocyanide)dipalladium(I) iodide: an unbridged compound

Rutherford¹,

Olmstead²,

Balch³

1984

The structure of (CH3NC)4Pd21z has been determined by X-ray diffraction. Molecules of the type (RNC),Pd2X2 were originally assigned a halide-bridged structure largely on the basis of infrared data. (CH3NC)4PdzIz crystallizes in the space group Pi with cell dimensions (determined at 140 K) of a = 7.188 (2) A, b = 10.933 (2) A, c = 12.803 (4) A, a = 80.58 (2)O, j3 = 75.45 (2)', y = 81.22 (2)O, Z = 2, and V = 954.3 (4) A3. The structure was refined to a conventional R value of 0.039 from 2489 significant reflections. It has an unbridged structure with a linear I-Pd-Pd-I unit and two terminal isocyanide ligands on each palladium. The Pd-Pd and average Pd-I distances are 2.533 (1) and 2.698 (1) A. The low-energy metal-halogen stretching vibrations, which caused the original structure misidentification, are discussed in the context of other compounds with linear X-M-M-X units.C C(6

“…Gen. Crystallogr. 9) 6026 ( 7) 35 (7) 0( 13) 3426 ( 14) 925 ( 10) 6503 ( 8) 44 ( 8) 0( 14) 2317 ( 14) 1312 ( 11) 6402 ( 8) 52 ( 9) 0( 15)…”

Section: Resultsunclassified

“…2001 ( 12) 1994 ( 11) 5823 ( 9) 51 ( 9) 0( 16) 2825 (12) 2275 ( 9) 5344 ( 7) 35 (7) 0( 21) 6423 (10) 1784 ( 8) 5247 ( 6) 24 ( 6) C( 22) 6988 ( 12) 1080 ( 9) 4898 ( 7) 32 ( 6) 0( 23) 8069 ( 14) 719 ( 10) 5281 ( 8) 49 ( 8) 0( 24) 8576 ( 13) 1073 ( 11) 6025 ( 8) 47 ( 8) 0(25) 7974 ( 13) 1772 ( 10) 6367 ( 7) 39 ( 7) 0( 26) 6910 ( 12) 2128 ( 9) 5990 ( 7) 35 ( 7) 0(31) 4570 ( 12) 1643 ( 8) 3861 ( 6) 30 ( 6) 0(32) 5274 ( 12) 1803 ( 9) 3277 ( 7) 36 ( 7) C( 33) 4973 ( 13) 1382 ( 10) 2533 ( 7) 42 ( 7) 0(34) 4007 ( 15) 806 ( 10) 2402 ( 8) 48 ( 8) 0( 35) 3303 ( 13) 631 (…”

Section: Resultsunclassified

“…However, the O-(l)-W-0(2) bond angle (175. 7 (3)°) is certainly not indicative of a very strong metal-metal attraction, since under these circumstances the axial ligands are normally pushed away from the metal-metal vector.12 The W=Ot bond distance is sensitive to, and influences, the ligand trans to it. In this case Ph3PO is the (12) Sattelberger, A. P.; Wilson, R. B.; Huffman, J. C. Inorg.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

An oxotungsten(V) dimer with unusual stereochemistry: synthesis and structure of anti-bis(.mu.-isobutylthiolato)bis[oxodichloro(triphenylphosphine oxide)tungsten(V)], 1

Ball¹,

Boorman²,

Richardson³

1986

Figure 2. HOMO and LUMO levels for the W(dcq)"(mpic)4_" series.thylpicolinate ligands, the ligand ir* levels are high enough in energy that the MLCT transition energy values vary more than the E°' values. Smith and Schultz12 had found only a small variation in the charge-transfer transitions of their S-donor complexes relative to the electrochemical potentials. However, their systems possess charge-transfer levels of the ligand-to-metal type rather than the metal-to-ligand variety; thus the LUMO and HOMO level changes appear to parallel each other in the S-donor species, unlike the present ones in which they move apart.Acknowledgment. Partial support of this research by the Office of Naval Research is gratefully acknowledged. The help of Drs. Debra Rolison, David Venezky, and Marian Stankovich during various aspects of this study are also acknowledged with grateful appreciation.