Single-crystal X-ray and neutron diffraction studies of an. eta. sup 2 -dihydrogen transition-metal complex: trans-(Fe(. eta. sup 2 -H sub 2 )(H)(PPh sub 2 CH sub 2 CH sub 2 PPh sub 2 ) sub 2 )BPh sub 4

Journal Article · Wed Nov 22 00:00:00 EST 1989 · Journal of the American Chemical Society; (USA)

DOI:https://doi.org/10.1021/ja00206a009· OSTI ID:6973450

Ricci, J S ^[1]; Koetzle, T F ^[2]; Bautista, M T; Hofstede, T M; Morris, R H; Sawyer, J F ^[3]

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1. Univ. of Southern Maine, Portland (USA) Brookhaven National Lab., Upton, NY (USA)
2. Brookhaven National Lab., Upton, NY (USA)
3. Univ. of Toronto, Ontario (Canada)

The H-H distance in the {eta}{sup 2}H{sub 2} ligand in (Fe({eta}{sup 2}-H{sub 2})H(dppe){sub 2})BPh{sub 4}, 1 BPh{sub 4}, dppe = PPh{sub 2}CH{sub 2}CH{sub 2}PPh{sub 2}, is 0.816 (16) {angstrom} as determined by neutron diffraction on a crystal of volume 2.62 mm{sup 3} at 20 K: 1-BPh{sub 4} is monoclinic, space group C2/c, a = 16.999 (7) {angstrom}, b = 16.171 (2) {angstrom}, c = 22.114 (5) {angstrom}, {beta} = 102.52 (2){degree}, U = 5,934.4 (2) {angstrom}{sup 3}, and D{sub c} = 1.315 g cm{sup {minus}3} for Z = 4; R(F) = 0.071, R(F{sup 2}) = 0.110, R{sub w}(F{sup 2}) = 0.113 for 4,116 reflections with I {>=} 3{sigma}(I). The H-H separation is 0.87 (3) {angstrom} as determined by X-ray diffraction at 298 K: monoclinic, C2/c, a = 17.327 (3) {angstrom}, b = 16.407 (4) {angstrom}, c = 22.224 (3) {angstrom}, {beta} = 102.87 (1){degree}, U = 6,159.2 (1) {angstrom}{sup 3}, and D{sub c} = 1.267 g cm{sup {minus}3} for Z = 4; R(F) = 0.038, R{sub w}(F) = 0.034, for 3,673 reflections (I {>=} 3{sigma}(I)). These {eta}{sup 2}-H{sub 2} distances agree with the X-ray value of 0.89 (11) {angstrom} reported for the tetrafluoroborate salt, 1-BF{sub 4}. As was found for 1-BF{sub 4}, 1-BPh{sub 4} contains an {eta}{sup 2}-H{sub 2} ligand that is symmetrically side-on bonded to the iron and trans to the terminal hydride such that the Fe has a distorted octahedral configuration. These diffraction studies serve to calibrate H-H distances obtained by the T{sub 1} NMR method for dihydrogen complexes in solution where the H{sub 2} ligand is suggested to be rapidly spinning. The H-H distance is the same as that in W({eta}{sup 2}-H{sub 2})(CO){sub 3}(P(i-Pr){sub 3}){sub 2} despite the fact that the tungsten complex has a more labile H{sub 2} ligand. The terminal hydride-iron distance of 1.535 (12) {angstrom} as determined by neutron diffraction is shorter than the distances to the dihydrogen ligand (H-Fe = 1.616 (10) {angstrom}).

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6973450
• Journal Information: Journal of the American Chemical Society; (USA), Vol. 111:24; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
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PHYSICAL AND ANALYTICAL CHEMISTRY
TRANSITION ELEMENT COMPLEXES
CRYSTAL STRUCTURE
DATA ANALYSIS
EXPERIMENTAL DATA
MEASURING INSTRUMENTS
MEASURING METHODS
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NEUTRON DIFFRACTION
ORGANOMETALLIC COMPOUNDS
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360102* - Metals & Alloys- Structure & Phase Studies
400201 - Chemical & Physicochemical Properties