The homolytic bond dissociation energy of the titanium neutral hydride D0(Ti–H) is determined experimentally for the first time by using guided ion beam tandem mass spectrometry to measure the kinetic energy dependence of the endothermic hydride abstraction reactions of Ti+ with methylamine, dimethylamine, and trimethylamine. From the thresholds of these reactions, the value of D0(Ti–H)=2.12±0.09 eV (48.9±2.1 kcal/mol) at 298 K is derived. Other 298 K thermodynamic values obtained are D0(Ti+–H)=8.19±0.09 eV (188.8±2.1 kcal/mol), I.E.(TiH)=6.59±0.14 eV, P.A.(Ti)=15.64±0.09 eV (360.6±2.1 kcal/mol), and ΔfH(TiH)=116.4±2.3 kcal/mol. This thermochemistry is compared with theoretical values and its relationship to hydride bond energies for the other first row transition metals is discussed.

1.
P. B. Armentrout and L. S. Sunderlin, in Transition Metal Hydrides, edited by A. Dedleu (VCH, New York, in press).
2.
R. E.
Smith
and
A. G.
Gaydon
,
J. Phys. B
4
,
797
(
1971
);
A. G.
Gaydon
,
J. Phys. B
7
,
2429
(
1974
).,
J. Phys. B
3.
J. L.
Elkind
and
P. B.
Armentrout
,
Int. J. Mass Spectrom. Ion Proc.
83
,
259
(
1988
).
4.
P. R.
Scott
and
W. G.
Richards
,
J. Phys. B
7
,
500
(
1974
).
5.
G.
Das
,
J. Chem. Phys.
74
,
5766
(
1981
).
6.
(a)
S. P.
Walch
and
C. W.
Bauschlicher
,
J. Chem. Phys.
78
,
4597
(
1983
);
(b)
D. P.
Chong
,
S. R.
Langhoff
,
C. W.
Bauschlicher
,
S. P.
Walch
, and
H.
Partridge
,
J. Chem. Phys.
85
,
2850
(
1986
); ,
J. Chem. Phys.
(c)
C. W.
Bauschlicher
,
J. Phys. Chem.
92
,
3020
(
1988
).
7.
(a)
J.
Anglada
,
P. J.
Bruna
,
S. D.
Peyerimhoff
, and
R. J.
Buenker
,
J. Mol. Struct. (Theochem.)
93
,
299
(
1983
);
(b) P. J. Bruna and J. Anglada, in Quantum Chemistry: The Challenge of Transition Metals and Coordination Chemistry, edited by A. Veillard (Reidel, Dordrecht, 1986), p. 67;
(c)
J.
Anglada
and
P. J.
Bruna
,
Mol. Phys.
69
,
281
(
1990
).
8.
U. Wedig, M. Dolg, H. Stoll, and H. Preuss, in Quantum Chemistry: The Challenge of Transition Metals and Coordination Chemistry, edited by A. Veillard (Reidel, Dordrecht, 1986), p. 79.
9.
The De value reported by these authors is converted to D00 by using ωe = 1535 cm−1, the average of thefrequencies reported in Refs.6(c) and 7(c).
10.
M. A.
Tolbert
and
J. L.
Beauchamp
,
J. Phys. Chem.
90
,
5015
(
1986
).
11.
Y.-M. Chen, D. E. Clemmer, and P. B. Armentrout (to be published).
12.
K. M.
Ervin
and
P. B.
Armentrout
,
J. Chem. Phys.
83
,
166
(
1985
).
13.
P. J.
Chantry
,
J. Chem. Phys.
55
,
2746
(
1971
).
14.
L. S.
Sunderlin
and
P. B.
Armentrout
,
J. Phys. Chem.
92
,
1209
(
1988
).
15.
L.
Sanders
,
S.
Hanton
, and
J. C.
Weisshaar
,
J. Phys. Chem.
91
,
5145
(
1987
).
16.
R. H.
Garstang
,
Mon. Not. R. Astron. Soc.
124
,
321
(
1962
);
(personal communication).
17.
N.
Aristov
and
P. B.
Armentrout
,
J. Am. Chem. Soc.
108
,
1806
(
1986
).
18.
W. J.
Chesnavich
and
M. T.
Bowers
,
J. Phys. Chem.
83
,
900
(
1979
).
19.
L. S.
Sunderlin
,
N.
Aristov
, and
P. B.
Armentrout
,
J. Am. Chem. Soc.
109
,
78
(
1987
).
20.
P. B.
Armentrout
and
J. L.
Beauchamp
,
J. Chem. Phys.
74
,
2819
(
1981
);
P. B.
Armentrout
and
J. L.
Beauchamp
,
J. Am. Chem. Soc.
103
,
784
(
1981
).
21.
B. H.
Boo
and
P. B.
Armentrout
,
J. Am. Chem. Soc.
109
,
3549
(
1987
).
22.
Y.-M. Chen, D. E. Clemmer, and P. B. Armentrout (to be published).
23.
R. H.
Schultz
and
P. B.
Armentrout
,
J. Chem. Phys.
94
,
2262
(
1991
).
24.
S. G.
Lias
,
J. E.
Bartmess
,
J. F.
Liebman
,
J. L.
Holmes
,
R. D.
Levin
, and
W. G.
Mallard
,
J. Phys. Chem. Ref. Data
17
, Suppl.
1
(
1988
) (GIANT tables).
25.
D. E.
Clemmer
,
L. S.
Sunderlin
, and
P. B.
Armentrout
,
J. Phys. Chem.
94
,
3008
(
1990
).
26.
P. B. Armentrout, in Structure/Reactivity and Thermochemistry of Ions, edited by P. Ausloos and S. G. Lias (Reidel, Dordrecht, 1987), p. 97.
27.
P. B. Armentrout, in Advances in Gas Phase Ion Chemistry, edited by N. G. Adams and L. M. Babcock (JAI, Greenwich, Conn., to be published), Vol. 1.
28.
F. P.
Lossing
,
Y.-T.
Lam
, and
A.
Maccoll
,
Can. J. Chem.
59
,
2228
(
1981
).
29.
P. D.
Pacey
and
J. H.
Wimalasena
,
J. Phys. Chem.
88
,
5657
(
1984
);
M.
Brouard
,
P. D.
Lightfoot
, and
M. J.
Pilling
,
J. Phys. Chem.
90
,
445
(
1986
); ,
J. Phys. Chem.
J. J.
Russell
,
J. A.
Seetula
, and
D.
Gutman
,
J. Am. Chem. Soc.
110
,
3092
(
1988
);
S. S.
Parmar
and
S. W.
Benson
,
J. Am. Chem. Soc.
111
,
57
(
1989
).,
J. Am. Chem. Soc.
30.
J.
Sugar
and
C.
Corliss
,
J. Phys. Chem. Ref. Data
14
, Suppl.
2
(
1985
).
31.
To convert D2980Ti‐H to a 0 K value, we require an enthalpy difference between 0 and 298 K for Ti(s),H2, and TiH. This is known for the first two species, but not for the latter. Ignoring electronic contributions which should be relatively small, however, the difference in the 0 and 298 K bond energies is just 3kT/2 = 0.039 eV.
32.
C. W.
Bauschlicher
,
S. R.
Langhoff
,
H.
Partridge
, and
L. A.
Barnes
,
J. Chem. Phys.
91
,
2399
(
1989
).
33.
J. B.
Pedley
and
E. M.
Marshall
,
J. Phys. Chem. Ref. Data
12
,
967
(
1983
).
34.
H.
Hotop
and
W. C.
Lineberger
,
J. Phys. Chem. Ref. Data
14
, No.
3
(
1985
).
35.
The radical I.E.’s used here are calculated from the heats of formation for the neutral radicals listed in Ref. 24 (this is known well for only CH2NH2) and the revised ionic heats of formation discussed in the text. This leads to I.E.(CH2NH2) = 6.0±0.1 eV,I.E.[CH2NH(CH3)] = 5.9±0.1 eV, and I.E.[CH2N(CH3)2] = 5.7±0.1 eV.
36.
P. B.
Armentrout
and
R.
Georgiadis
,
Polyhedron
7
,
1573
(
1988
).
37.
P. B.
Armentrout
,
ACS Symp. Ser.
428
,
18
(
1990
).
38.
R. R.
Squires
,
J. Am. Chem. Soc.
107
,
4385
(
1985
).
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