Polyazolyl chelate chemistry. 6.1 Bidentate coordination of HB(pz)3 (pz = pyrazol-1-yl) to ruthenium and osmium: Crystal structure of [RuH(CO)(PPh3)2{κ2-HB(pz)3}]

Article abstract of DOI:10.1021/om970991y

[RuHCl(CO)(PPh₃)₃], [Ru(SnPh₃)Cl(CO)(PPh₃)₂], or [RuH(CO)(NCMe)₂(PPh₃)₂]BF₄ reacts with K[HB(pz)₃] (pz = pyrazol-1-yl) to provide [RuH(CO)(PPh

Full text of DOI:10.1021/om970991y

1552
Organometallics 1998, 17, 1552-1557
P olya zolyl Ch ela te Ch em istr y. 6.1 Bid en ta te
Coor d in a tion of HB(p z)3 (p z ) P yr a zol-1-yl) to
Ru th en iu m a n d Osm iu m : Cr ysta l Str u ctu r e of
[Ru H(CO)(P P h 3)2{K2-HB(p z)3}]
Ian D. Burns, Anthony F. Hill,*,2 Andrew J . P. White, David J . Williams, and
J ames D. E. T. Wilton-Ely
Department of Chemistry, Imperial College of Science, Technology and Medicine,
London SW7 2AY, U.K.
Received November 13, 1997
[RuHCl(CO)(PPh3)3], [Ru(SnPh3)Cl(CO)(PPh3)2], or [RuH(CO)(NCMe)2(PPh3)2]BF4 reacts
with K[HB(pz)3] (pz ) pyrazol-1-yl) to provide [RuH(CO)(PPh3)2{η2-HB(pz)3}], thermolysis
of which proceeds via loss of phosphine and formation of [RuH(CO)(PPh3){η3-HB(pz)3}]. The
thiocarbonyl analogue [RuH(CS)(PPh3)2{η2-HB(pz)3}] is obtained from [RuHCl(CS)(PPh3)3]
and K[HB(pz)3], thermolysis of which provides [RuH(CS)(PPh3){η3-HB(pz)3}]. In chloroform,
this species provides [RuCl(CS)(PPh3){η3-HB(pz)3}]. [RuH(CS)(PPh3)2{η2-H2B(bta)2}] (bta
) benzotriazolyl) results from the reaction of [RuHCl(CS)(PPh3)3] with K[H2B(bta)2]. The
hydride-bridged dinuclear complex [RuCu(µ-H)(CO)(PPh3)2{η3-HB(pz)3}]PF6 results in high
yield from the reaction of [RuH(CO)(PPh3)2{η2-HB(pz)3}], with [Cu(NCMe)4]BF4. [Os(C6H5)-
(CO)(PPh3)2{η2-HB(pz)3}] (from [Os(C6H5)Cl(CO)(PPh3)2] and K[HB(pz)3]) converts on heating
to [Os(C6H5)(CO)(PPh3){η3-HB(pz)3}].
In tr od u ction
and the thermolysis of these compounds to provide the
conventional η3 complexes [MH(CO)(PiPr3){η3-HB(pz)3}],8
which are analogues of the complexes [RuH(CO)(PR3)-
{η3-HB(pz)3}] (R ) Ph,9 Cy10) described previously.
These observations have prompted us to report results
from our ongoing study which further illustrate biden-
tate coordination of the HB(pz)3 ligand within group 8,
We have recently been concerned with the develop-
ment of poly(azolyl)borate chemistry within group 8.1,3
The chemistry of such ligands is rich for group 6 metals
and to a lesser extent for those in groups 7 and 9.4 In
contrast, group 8, the birthplace of η5-cyclopentadienyl
chemistry, has seen comparatively little of the notionally
related hydrotris(pyrazol-1-yl)borate ligand (Chart 1)4
until recently.3,5 The tendency for this ligand to adopt
a facially tridentate coordination mode is very strong,
and reduced denticity is usually only observed in cases
where it is disfavored by the electronic nature of the
metal, e.g., d8-ML4 square-planar geometry.6 A par-
ticularly elegant illustration of this situation has been
provided by Connelly, who showed that the bidentate
coordination of the HB(pzMe2-3,5)3 scorpionate in
[Rh(CO)(PPh3){η2-HB(pzMe2-3,5)3}] could be closed by
a one-electron-oxidation process which removed the
stabilizing effect associated with the d8 square-planar
geometry.7
(5) (a) Bruce, M. I.; Sharrocks, D. N.; Stone, F. G. A. J . Organomet.
Chem. 1971, 31, 269. Bruce, M. I.; Iqbal, M. Z.; Stone, F. G. A. J . Chem.
Soc. A 1971, 2820. (b) Albers, M. O.; Robinson, D. J .; Shaver, A.;
Singleton, E.; Organometallics 1986, 5, 2199. Albers, M. O.; Crosby,
S. F. A.; Liles, D. C.; Robinson, D. J .; Shaver, A.; Singleton, E.
Organometallics 1987, 6, 2015. Albers, M. O.; Oosthuisen, H. E.;
Robinson, D. J .; Shaver, A.; Singleton, E. J . Organomet. Chem. 1985,
282, C49. Steyn, M. M. d. V.; Singleton, E.; Hietkamp, S.; Liles, D. C.
J . Chem. Soc., Dalton Trans. 1990, 2991. (c) Restivo, R. J .; Ferguson,
G.; O’Sullivan, D. J .; Lalor, F. J . Inorg. Chem. 1975, 14, 3046. Restivo,
R. J .; Ferguson, G. J . Chem. Soc., Chem. Commun. 1973, 847.
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McNair, A. M.; Boyd, D. C.; Mann, K. R. Organometallics 1986, 5, 303.
(e) Hiraki, K.; Ochi, N.; Kitamura, T.; Sasada, Y.; Shinoda, S., Bull.
Chem. Soc. J pn. 1982, 55, 2356. (f) Llobet, A.; Hodgson, D. J .; Meyer,
T. Inorg. Chem. 1990, 29, 3760. (g) LaPointe, A. M.; Schrock, R. R.;
Davis, W. M. J . Am. Chem. Soc. 1995, 117, 4802. LaPointe, A. M.;
Schrock, R. R. Organometallics 1993, 12, 3379. (h) Gemel, C.; Trimmel,
G.; Slugovc, C.; Kremel, S.; Mereiter, K.; Schmid, R.; Kirchner, K.
Organometallics 1996, 15, 3998. Gemel, C.; Wiede, P.; Mereiter, K.;
Sapunov, V. N.; Schmid, R.; Kirchner, K. J . Chem. Soc., Dalton Trans.
1996, 4071. Trimmel, G.; Slugovc, C.; Wiede, P.; Mereiter, K.; Sapunov,
V. N.; Schmid, R.; Kirchner, K. Inorg. Chem. 1997, 36, 1076. (i)
Corrochano, A. E.; J alo´n, F. A.; Otero, A.; Kubici, M. M.; Richard, P.
Organometallics 1977, 16, 145. (j) Chan, W.-C.; Lau, C.-P.; Chen, Y.-
Z.; Fang, Y.-Q.; Ng, S.-M.; J ia, G. Organometallics 1997, 16, 34. Chen,
Y.-Z.; Chan, W.-C.; Lau, C.-P.; Chu, H.-S.; Lee, H. L.; J ia, G.
Organometallics 1997, 16, 1241. (k) Freedman, D. A.; Gill, T. P.;
Blough, A. M.; Koefod, R. S.; Mann, K. R. Inorg. Chem. 1997, 36, 95.
(6) (a) Ir(I): Ghosh, C. K.; Rogers, D. P. S.; Graham, W. A. G. J .
Chem. Soc., Chem. Commun. 1988, 1511. Ghosh, C. K.; Graham, W.
A. G. J . Am. Chem. Soc. 1987, 109, 4726. (b) Pt(II), Pd(II): Byers, P.
K.; Canty, A. J .; Honeyman, R. T. Adv. Organomet. Chem. 1992, 34,
1.
Very recently, Esteruelas has discussed the formation
of complexes formulated as [MH(CO)(PiPr3)2{η2-HB-
(pz)3}] (M ) Ru, Os) on the basis of spectroscopic data
(1) For part
5 see: Anderson, S.; Harman, A.; Hill, A. F. J .
Organomet. Chem. 1995, 498, 251.
(2) E-mail: a.hill@ic.ac.uk.
(3) (a) Anderson, S.; Hill, A. F.; Slawin, A. M. Z.; Williams, D. J . J .
Chem. Soc., Chem. Commun. 1993, 266. (b) Alcock, N. W.; Burns, I.
D.; Claire, K. S.; Hill, A. F. Inorg. Chem. 1992, 31, 2906. (c) Cartwright,
J .; Harman, A.: Hill, A. F. J . Organomet. Chem. 1990, 396, C31. (d)
Hill, A. F. J . Organomet. Chem. 1990, 395, C35. (e) Alcock, N. W.; Hill,
A. F.; Melling, R. P. Organometallics 1991, 10, 3898.
(4) (a) Trofimenko, S. Prog. Inorg. Chem. 1986, 34, 115. (b) Trofi-
menko, S. Chem. Rev. 1972, 72, 497. (c) Niedenzu, K.; Trofimenko, S.
Top. Curr. Chem. 1986, 131, 1. Trofimenko, S. Chem. Rev. 1993, 93,
943. (e) Kitajima, N.; Tolman, W. B. Prog. Inorg. Chem. 1995, 43, 419.
(7) Connelly, N. C.; Emslie, D. J . H.; Metz, B.; Orpen, A. G.; Quayle,
M. J . J . Chem. Soc., Chem. Commun. 1996, 2289.
S0276-7333(97)00991-6 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 03/24/1998

Polyazolyl Chelate Chemistry
Organometallics, Vol. 17, No. 8, 1998 1553
Ch a r t 1. η5-Cyclop en ta d ien yl a n d η3- a n d
η2-Hyd r otr is(p yr a zolyl)bor a te Coor d in a tion
mmol) and K[HB(pz)3] (0.34 g, 1.33 mmol) in dichloromethane
(30 mL) was stirred for 20 h and the mixture filtered through
diatomaceous earth. The filtrate was freed of volatiles, and
the residue was crystallized from a mixture of dichloromethane
and ethanol. Yield: 0.73 g (66%). (b) [RuHCl(CO)(PPh3)3]
(0.50 g, 0.53 mmol) and K[HB(pz)3] (0.15 g, 0.60 mmol) were
dissolved in dichloromethane (20 mL) and stirred for 20 h. A
further quantity of dichloromethane (20 mL) was added and
contaminants removed by filtration through diatomaceous
earth. Ethanol (30 mL) was then added and the solvent
volume reduced by rotary evaporation, resulting in crystal-
lization of the colorless product. This was isolated by filtration
and washed with ethanol (20 mL) and petroleum ether (20 mL)
and dried in vacuo. Yield: 0.36 g (79%). IR (CH2Cl2): 2361,
2341 [ν(BH)], 1975 [ν(RuH)], 1931 [ν(CO)] cm-1. IR (Nujol):
2330, 2405 [ν(BH)], 1982 [ν(RuH)], 1926 [ν(CO)], 1586, 1571,
1299, 1286, 1127, 1120, 1054, 1038, 984, 955, 920, 876, 844
including crystallographic confirmation for one example.
Furthermore, we show that the pendance of one pyra-
zolyl group may be exploited in bridge-assisted metal-
metal bond formation.
cm-1
.
NMR (CDCl3, 25 °C): 1H, δ -11.73 [dd, 1 H, RuH,
2J (PH) ) 19.2, 23.8 Hz], 3.8 [s(br), 1 H, BH], 5.23, 5.84, 6.16,
[t × 3, 3 × 1 H, H4(pz), J (HH) ≈ 2.0 Hz], 6.41, 6.51, 6.83, 6.90
[d × 4, 4 × 1 H, H3,5(pz), J (HH) ≈ 2.0 Hz], 7.09-7.32 ppm [m,
31 H, C6H5 and obscured H3,5(pz)], 7.80 [d, 1 H, C3,5(pz)] ppm;
13C{1H}, δ 205.2 [t, RuCO, 2J (PC) ) 16.1 Hz], 146.9, 144.8,
141.7 [C3(pz)], 136.1, 135.3, 135.0 [C5(pz)], 134.0-127.9 [C6H5],
105.4 (2 C), 104.1 (1 C) [C4(pz)] ppm; 31P{1H}: 47.6, 42.3 ppm
[AB, 2J (AB) ) 301.8 Hz]. F AB-MS: m/z (%) 869 (4) [M]+, 840
(2) [M - CO - H]+, 801 (80) [M - pz]+, 691 (74) [Ru(pz)-
(PPh3)2]+, 655 (17) [M - HB(pz)3]+, 625 (23) [Ru(PPh3)2]+, 605
(36) [M - H - PPh3]+, 576 (10) [M - CO - H - PPh3]+, 537
(50) [M - pz - PPh3]+, 363 (68) [RuPPh3]+, 263 (100) [HPPh3]+.
Anal. Found: C, 62.2; H, 5.0; N, 9.4. Calcd for
Exp er im en ta l Section
Gen er a l Com m en ts. All manipulations were carried out
under aerobic ambient conditions using solvents as received
from commercial sources unless otherwise indicated (proce-
dures for 6 and 7). None of the new compounds showed
marked air sensitivity during workup or subsequent spectro-
scopic characterization. The salts K[HB(pz)3],11 [Cu(NCMe)4]-
PF6,12 and [RuH(CO)(NCMe)2(PPh3)2]BF413 and the complexes
[RuHCl(CO)(PPh3)3]14 and [RuHCl(CS)(PPh3)3]15 were pre-
pared according to published procedures. The complex [Ru-
(SnPh3)Cl(CO)(PPh3)2] was prepared from triphenylvinylstan-
nane and [RuHCl(CO)(PPh3)3] according to the method described
by Roper for the analogous complex [Ru(SnMe3)Cl(CO)-
(PPh3)2].16 1H, 13C{1H}, and 31P{1H} NMR spectra were
recorded with a J EOL J NM EX270 NMR spectrometer and
calibrated against internal SiMe4 (1H), internal CDCl3 (13C),
or external H3PO4 (31P) reference. In many cases the signals
due to H3,5(pz) and C3,5(pz) could not be unequivocally assigned.
“tv” refers to virtual triplet resonances characteristic of trans-
bis(phosphine) complexes, with apparent coupling constants.
2J (PAPB) values are as observed and are not corrected for “roof”
effects. Infrared spectra were recorded both as dichlo-
romethane solutions and Nujol mulls using Perkin-Elmer
1720-X or Mattson Series 1 FT-IR spectrometers. Character-
istic “fingerprint” bands for PPh3 are omitted. FAB-mass
spectrometry was carried out using an Autospec Q instrument
with 3-nitrobenzyl alcohol as a matrix. Compositional assign-
ments are based on simulation of isotopic distributions; “M”
refers to the molecular ion with the exception of the salt 7, for
which it refers to the cationic complex. Elemental analysis
was carried out by the Imperial College Microanalytical
Service. In the case of partial solvates, the stoichiometry was
C
46H41BN6OP2Ru‚0.33CH2Cl2: C, 62.0; H, 4.7; N, 9.4.
P r ep a r a t ion of [R u H(CS)(P P h 3)2{η2-HB(p z)3}] (1b ).
[RuHCl(CS)(PPh3)3] (0.20 g, 0.21 mmol) and K[HB(pz)3] (0.05
g, 0.20 mmol) were dissolved in dichloromethane (20 mL), and
the mixture was stirred for 24 h. A further quantity of
dichloromethane (20 mL) was added and the precipitate of KCl
removed by filtration through diatomaceous earth. Ethanol
(30 mL) was then added to the filtrate and the solvent volume
reduced (rotary evaporator), causing crystallization of the off-
white product which was isolated by filtration, washed with
petroleum ether (20 mL) and dried in vacuo. Yield: 0.10 g
(78%). IR (CH2Cl2): 2435 [ν(BH)], 1982 [ν(RuH)] cm-1
. IR
(Nujol): 2440, 2420, [ν(BH)], 1983 [ν(RuH)], 1920, 1586, 1572,
1385, 1299, 1262 [ν(CS)], 1224, 1216, 1206, 1129, 1118, 1055,
1038, 983, 954, 918, 884, 877, 849, 838 cm-1. NMR (CDCl3,
25 °C): 1H, δ -9.23 [t, 1 H, RuH, 2J (PH) ) 21.8 Hz], 3.7 [s(br),
1 H, BH], 5.18, 5.88, 6.04 [s × 3, 3 × 1 H, H4(pz)], 6.29, 6.48,
6.85, 7.03 [s × 4, 4 × 1 H, H3,5(pz)], 7.14-7.34 [m, 31 H, C6H5
and obscured H3,5(pz)], 7.74 [d, 1 H, H3,5(pz), 3J (HH) ) 2.0 Hz]
ppm; 13C{1H}, δ 304.0 [t, RuCS, 2J (PC) ) 17.0 Hz], 146.3,
143.9, 141.5 [C3(pz)], 136.2, 135.5, 135.0 [C5(pz)], 134.5-127.8
[C6H5], 105.5 (2 C), 104.0 (1 C)[C4(pz)] ppm; 31P{1H}, 45.2, 41.4
ppm [AB, 2J (AB) ) 301.8 Hz]. FAB-MS: m/z (%) 885 (1) [M]+,
817 (62) [M - pz]+, 707 (40) [M(pz)(PPh3)2]+, 671 (12) [M -
{HB(pz)3}]+, 621 (25) [M - PPh3]+, 554 (50) [Ru(pz)(PPh3)]+,
407 (28) [M - {HB(pz)3} - PPh3]+. Anal. Found: C, 60.9; H,
4.8; N, 8.7. Calcd for C46H41BN6P2RuS‚0.33CH2Cl2: C, 61.0;
H, 4.6; N, 9.2.
P r epar ation of [Ru H(CS)(P P h 3){η3-HB(pz)3}] (2b). [Ru-
H(CS)(PPh3)2{η2-HB(pz)3}] (1b; 0.20 g, 0.23 mmol) was stirred
in benzene (10 mL) for 3 days. Ethanol (20 mL) was then
added, and crystals were obtained by slow concentration.
These were isolated by filtration, washed with petroleum ether
(10 mL), and dried in vacuo. The off-white product can be
purified by column chromatography (silica gel, benzene elu-
ant). Yield: 0.12 g (85%). IR (CH2Cl2): 2480 [ν(BH)], 1981
[ν(RuH)] cm-1. IR (Nujol): 2472 [ν(BH)], 1979 [ν(RuH)], 1931,
1498, 1405, 1393, 1308, 1269 [ν(CS)], 1212, 1115, 1046, 979,
955, 922, 882, 847, 813 cm-1. NMR (C6D6, 25 °C): 1H δ -8.96
[d, 1 H, RuH, 2J (PH) ) 28.4 Hz], 3.5 [s(br), 1 H, BH], 5.38,
1
confirmed by H NMR integration.
P r ep a r a tion of [Ru H(CO)(P P h 3)2{η2-HB(p z)3}] (1a ). (a)
A suspension of [RuH(CO)(NCMe)2(PPh3)2]BF4 (1.00 g, 1.22
(8) Bohanna, C.; Esteruelas, M. A.; Go´mez, A. V.; Lo´pez, A. M.;
Martine´z, M.-P. Organometallics 1997, 16, 4464.
(9) Sun, N.-Y.; Simpson, S. J . J . Organomet. Chem. 1992, 434, 341.
(10) Halcrow, M. A.; Chaudret, B.; Trofimenko, S. J . Chem. Soc.,
Chem. Commun. 1993, 465.
(11) Trofimenko, S. J . Am. Chem. Soc. 1967, 89, 3170.
(12) Kubas, G. J . Inorg. Synth. 1990, 28, 68.
(13) Cavit, B. E.; Grundy, K. R.; Roper, W. R. J . Chem. Soc., Chem.
Commun. 1972, 60.
(14) Laing, K. R.; Roper, W. R. J . Chem. Soc. A 1970, 2149.
(15) Brothers, P. J .; Roper, W. R. J . Organomet. Chem. 1983, 258,
73.
(16) Craig, P. R.; Flower, K. R.; Roper, W. R.; Wright, L. J . Inorg.
Chim. Acta 1995, 240, 385. Clark, G. R.; Flower, K. R.; Roper, W. R.;
Wright, L. J . Organometallics 1993, 12, 259. Clark, G. R.; Flower, K.
R.; Roper, W. R.; Wright, L. J . Organometallics 1993, 12, 3810.

1554 Organometallics, Vol. 17, No. 8, 1998
Burns et al.
5.77, 5.80 [t × 3, 3 × 1 H, H4(pz), 3J (HH) ) 2.0 Hz], 6.37, 7.25,
[m ) t + d, 2 H, H4(pz) + H3,5(pz)], 6.3-7.3 [m, 38 H, C6H5
+
3
7.30, 7.47 [d × 4, 4 × 1 H, H3,5(pz), J (HH) ) 2.0 Hz], 6.58-
3H3,5(pz)], 7.39, 7.84 [d × 2, 1 H × 2, H3,5(pz)] ppm; 31P{1H},
7.54 [m, 31 H, C6H5 obscured H3,5(pz)], 8.27 [s, 1 H, H3,5(pz)]
ppm; 13C{1H}, δ 305.1 [d, RuCS, 2J (PC) ) 19.6 Hz], 144.4,
143.7, 143.0 [C3(pz)], 134.9, 134.5, 134.4, 134.0, 129.7, 127.8,
127.7, 127.3 [C5(pz) and C6H5 unequivocal assignments not
made], 105.3, 105.2, 104.5 [C4(pz)] ppm; 31P{1H}, 62.4 ppm.
FAB-MS: m/z (%) 621 (65) [M]+, 577 (24) [M - CS - H]+, 553
(51) [M - pz]+, 509 (3) [M - H - pz - CS]+, 485 (7) [M -
2pz]+, 407 (14) [M - HB(pz)3]+, 363 (10) [M - H - HB(pz)3 -
CS]+. Anal. Found: C, 54.7; H, 4.2; N, 12.7. Calcd for
2.34, -2.62 ppm [AB, J (AB) ) 301.8 Hz]. FAB-MS: m/z (%)
2
1034 (23) [M]+, 967 (23) [M - pz]+, 956 (3) [M - HPh]+, 889
(2) [M - HPh - pz]+, 772 (100) [M - PPh3]+. Anal. Found:
C, 59.2; H, 3.6; N, 7.4. Calcd for C52H45BN6OOsP2‚0.25CH2-
Cl2: C, 59.5; H, 4.4; N, 8.0.
P r ep a r a tion of [Os(C6H5)(CO)(P P h 3){η3-HB(p z)3}] (6).
[Os(C6H5)(CO)(PPh3)2{η2-HB(pz)3}] (5; 0.07 g, 0.07 mmol) was
dissolved in dry, degassed toluene (30 mL). The mixture was
heated under reflux for 4 h. All solvent was removed under
reduced pressure (rotary evaporation) and a small amount of
ethanol (5 mL) added. Ultrasonic trituration provided a
colorless product, which was washed with hexane (20 mL) and
dried. Yield: 0.05 g (96%). The product can be recrystallized
from a mixture of dichloromethane and ethanol. IR (CH2Cl2):
C
28H26BN6PRuS: C, 54.1; H, 4.2; N, 13.5.
P r ep a r a tion of [Ru Cl(CS)(P P h 3){η3-HB(p z)3}] (3). [Ru-
H(CS)(PPh3){η3-HB(pz)3}] (2b; 0.20 g, 0.23 mmol) was heated
under reflux in chloroform (10 mL) for 5 h. Ethanol (20 mL)
was then added and crystals obtained by slow concentration.
The bright yellow product was purified by column chromatog-
raphy (silica gel, 1:4 hexane/dichloromethane eluant). The
first fraction to elute contained the desired product, which was
crystallized from dichloromethane and ethanol. Yield: 0.10
g (67%). IR (CH2Cl2): 2489 [ν(BH)] cm-1. IR (Nujol): 2516 [ν-
(BH)], 1509, 1499, 1392, 1310, 1290 [ν(CS)], 1221, 1210, 1190,
1112, 1049, 1028, 986, 925, 892, 856 cm-1. NMR (CDCl3, 25
°C): 1H, δ 4.6 [s(br), 1 H, BH], 5.79 [t, 2 H, H4(pz), 3J (HH) not
resolved], 6.19 [t, 1 H, H4(pz), 3J (HH) not resolved], 6.29, 6.58
2487 [ν(BH)], 1922 [ν(CO)] cm-1
1914 [ν(CO)], 1569, 1307, 1214, 1116, 1049, 985, 923, 890 cm-1
. IR (Nujol): 2478 [ν(CO)],
.
NMR (CDCl3, 25 °C): 1H, δ 4.5 [s(br), 1 H, BH], 5.88, 5.89,
6.00 [t × 3, 1 H × 3, H4(pz)], 6.60-7.34 [23 H, C6H5 + 3H3,5
-
(pz)], 7.58, 7.65, 7.71 [d × 3, 1 H × 3, H3,5(pz)] ppm; 31P{1H},
10.8 ppm. FAB-MS: m/z (%) 722 (100) [M]+, 695 (16) [M -
Ph]+, 664 (6) [M - Ph - CO]+, 510 (4) [M - PPh3]+.
P r ep a r a tion of [Ru Cu (µ-H)(CO)(P P h 3)2{η3-HB(p z)3}]-
P F 6 (7). [RuH(CO)(PPh3)2{η2-HB(pz)3}] (1a ; 0.20 g, 0.23
mmol) and [Cu(NCMe)4]PF6 (0.09 g, 0.24 mmol) were placed
in a Schlenk tube under nitrogen. Freshly degassed dichlo-
romethane (10 mL) was then added and the mixture stirred
under nitrogen for 12 h. Subsequent addition of ethanol (20
mL) and slow concentration provided off-white crystals, which
were isolated by filtration, washed with light petroleum ether
(20 mL), and dried in vacuo. Yield: 0.15 g (60%). IR (CH2-
Cl2): 2492 [ν(BH)], 1967 (br) [ν(CO)]/[ν(Ru-H-Cu)] cm-1. IR
(Nujol): 2480 [ν(BH)], 1955 [ν(CO)], 1932 [ν(Ru-H-Cu)], 1309,
1213, 1119, 1050, 926, 921, 837 [PF6] cm-1. NMR (CDCl3, 25
°C) 1H: δ -12.78 [s(br), 1 H, RuCuH, J (PH) not resolved], 4.6
3
[d × 2, 2 × 1 H, H3,5(pz), J (HH) ) 2.0 Hz], 7.26, 7.38, 7.63 [d
3
× 3, 3 × 1 H, H3,5(pz), J (HH) ) 2.0 Hz], 7.28-7.60 [m, 15 H,
3
C6H5], 8.03 [d, 1 H, H3,5(pz), J (HH) ) 2.0 Hz] ppm; 13C{1H},
2
δ 307.9 [d, RuCS, J (PC) ) 17.8 Hz], 144.6, 143.5, 142.4 [C3-
(pz)], 136.6, 135.2, 131.8 [C5(pz)], 134.7, 131.1, 130.2, 128.1
[C6H5], 106.0 (2 C), 105.5 (1 C) [C4(pz)] ppm; 31P{1H}, 38.6 ppm.
FAB-MS: m/z (%) 656 (62) [M]+, 621 (67) [M - Cl]+, 589 (3)
[M - pz]+, 576 (3) [M - Cl - CS]+, 553 (7) [M - Cl - pz]+,
407 (6) [M - Cl - HB(pz)3]+, 359 (6) [M - Cl - PPh3]+. Anal.
Found: C, 50.7; H, 3.8; N, 12.8. Calcd for C28H25BClN6PRuS:
C, 51.3; H, 3.8; N, 12.8.
P r ep a r a tion of [Ru H(CS)(P P h 3)2{η2-H2B(bta )2}] (4).
[RuHCl(CS)(PPh3)3] (0.15 g, 0.16 mmol) was dissolved in
dichloromethane (10 mL) and a solution of K[H2B(bta)2] (0.05
g, 0.17 mmol) in acetone (2 mL) added. The reaction mixture
was stirred for 30 min, followed by the removal of volatiles
under reduced pressure. The crude product was dissolved in
dichloromethane (15 mL) and the solution filtered through
diatomaceous earth. Ethanol (20 cm3) was added to the filtrate
and the solvent volume reduced at low pressure until precipi-
tation was complete. The pale green-yellow product was
filtered, washed with ethanol (10 mL) and hexane (10 mL),
and dried in vacuo. Yield: 0.12 g (84%). IR (Nujol): 2431,
3
[s(br), 1 H, BH], 5.83, 5.96 [t × 2, 3 H, H4(pz), J (HH) ) 2.0
Hz], 6.75 [s, 2 H, H3,5(pz)], 7.03-7.56 [m, 32 H, C6H5 and
obscured H3,5(pz), 7.73, 7.76 [s × 2, 2 H, H3,5(pz)] ppm. 31P-
{1H}, 51.9, 3.4 ppm. FAB-MS: m/z (%) 931 (26) [M]+, 669 (30)
[M - PPh3]+, 640 (22) [M - CO - PPh3]+, 605 (100) [M -
CuPPh3]+, 577 (32) [M - CO - CuPPh3]+, 538 (45) [M - pz -
CuPPh3]+, 363 (21) [M - H - CO - {HB(pz)3} - CuPPh3]+.
Anal. Found: C, 49.0; H, 3.5; N, 10.1. Calcd for C46H41
-
BCuF6N6OP3Ru‚CH2Cl2: C, 48.6; H, 3.7; N, 7.2.
Cr ysta l Da ta for [Ru H(CO)(P P h 3)2{η2-HB(p z)3}] (1a ):
46H41BN6OP2Ru, Mr ) 867.7, monoclinic, space group P21/c
C
(No. 14), a ) 10.247(2) Å, b ) 16.765(2) Å, c ) 24.172(2) Å, â
) 98.52(2)°, V ) 4106.8(8) Å3, Z ) 4, Dc ) 1.40 g cm-3, µ(Mo
KR) ) 5.0 cm-1, F(000) ) 1784. A pale brown prismatic block
of dimensions 0.47 × 0.43 × 0.27 mm was used. A total of
7237 independent reflections were measured on a Siemens P4/
PC diffractometer with graphite-monochromated Mo KR ra-
diation using ω scans. The structure was solved by direct
methods, and all non-hydrogen atoms were refined anisotro-
pically using full-matrix least squares based on F to give R )
0.034, Rw ) 0.036 for 5691 independent observed reflections
(|Fo| > 4σ(|Fo|), 2θ e 45°) and 518 parameters. The Ru-H
hydrogen atom was located from a ∆F map and refined
isotropically. Atomic coordinates, bond lengths and angles,
and thermal parameters have been deposited at the Cambridge
Crystallographic Data Centre (CCDC). Selected bond lengths
and angles are given in Table 1.
2421 [ν(BH)], 1282 [ν(CS)], 1209, 1146, 1077, 970, 870 cm-1
NMR (CDCl3, 25 °C): 1H, δ -9.26 [t, 1 H, RuH, J (PH) ) 20.2
Hz], 3.7 [s(v br), 2 H, BH2], 6.94-7.82 [m, 38 H, C6H5
.
+
C6H4N3] ppm; 13C{1H}, 305.2 [t, RuCS, J (PC) ) 16.1 Hz], 134.0
[s(br), C2,6(C6H5)], 132.5 [tv, C1(C6H5), J (PC) ) 21.5 Hz], 129.4
[s, C4(C6H5)], 127.4 [C3,5(C6H5)], 146.3, 146.1, 138.4, 138.2,
125.9, 125.8 [1 C × 6, bta], 122.9, 117.8, 112.5 [2 C(br) × 3,
bta] ppm. 31P{1H}, 43.5 ppm. FAB-MS: m/z (%) 919 (4) [M]+,
671 (8) [M - H2B(bta)2]+, 657 (1) [M - PPh3]+, 625 (0.3) [Ru-
(PPh3)2]+, 407 (3) [M - PPh3 - H2B(bta)2]+, 263 (100) [HP-
Ph3]+. Anal. Found: C, 63.9; H, 4.5; N, 8.9. Calcd for
C
49H41BN6P2RuS: C, 64.0; H, 4.5; N, 9.1%.
P r ep a r a tion of [Os(C6H5)(CO)(P P h 3)2{η2-HB(p z)3}] (5).
[Os(C6H5)Cl(CO)(PPh3)2] (0.25 g, 0.29 mmol) was stirred with
K[HB(pz)3] (0.08 g, 0.32 mmol) in dichloromethane (20 mL)
for 1 h. Propan-2-ol (20 mL) was added and the solvent volume
reduced until precipitation of the colorless product was com-
plete. The solid was washed with ethanol and hexane and
dried. Yield: 0.17 g (57%). The product can be recrystallized
from a mixture of dichloromethane and ethanol. IR (CH2Cl2):
Resu lts a n d Discu ssion
The preparation of [RuH(CO)(PPh3){HB(pz)3}] from
K[HB(pz)3] and [RuHCl(CO)(PPh3)3] under forcing con-
ditions (refluxing toluene) has been reported9 (Scheme
1). The extreme conditions reportedly required contrast
2478 [ν(BH)], 1920 [ν(CO)] cm-1
. IR (Nujol): 2476 [ν(BH)],
1920 [ν(CO)], 1569, 1297, 1130, 1058, 952, 877 cm-1
. NMR
(CDCl3, 25 °C): 1H, δ 5.67, 5.76 [t × 2, 1 H × 2, H4(pz)], 6.23

Polyazolyl Chelate Chemistry
Organometallics, Vol. 17, No. 8, 1998 1555
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for th e Com p lex
[Ru H(CO)(P P h 3)2{η2-HB(p z)3}] (1a )
Bond Lengths
Ru-H(1a)
Ru-C(17)
Ru-N(6)
1.494(35)
1.827(3)
2.141(2)
1.150(4)
Ru-N(1)
Ru-P(38)
Ru-P(19)
2.196(2)
2.363(1)
2.378(1)
C(17)-O(18)
Interbond Angles
H(1A)-Ru-N(6)
N(1)-Ru-P(19)
N(1)-Ru-P(38)
N(1)-Ru-N(6)
H(1A)-Ru-P(19)
N(6)-Ru-P(38)
Ru-N(1)-N(2)
84.5(13) H(1a)-Ru-C(17)
90.8(13)
89.6(1)
96.7(1)
88.0(1)
91.3(13) N(6)-Ru-P(19)
94.6(1)
C(17)-Ru-P(19)
C(17)-Ru-P(38)
N(1)-Ru-C(17)
90.0(1)
86.6(1)
96.7(1)
88.2(1)
126.2(2)
111.5(3)
Ru-N(6)-N(7)
124.7(2)
N(2)-B(11)-N(7)
N(2)-B(11)-N(12) 108.6(2)
N(7)-B(11)-N(12) 108.4(3)
F igu r e 1. Molecular geometry of [RuH(CO)(PPh3)2{η2-HB-
(pz)3}] (1a ). Phenyl groups are omitted for clarity.
Sch em e 1. Syn th esis of η3- a n d
η2-Hyd r otr is(p yr a zolyl)bor a te Ca r bon yl Com p lexes
of Ru th en iu m
The reaction of [RuH(CO)(NCMe)2(PPh3)2]BF4 with
K[HB(pz)3] at room temperature provides a complex for-
mulated as [RuH(CO)(PPh3)2{κ2-HB(pz)3}] (1a ) (Scheme
1) on the basis of spectroscopic data and a single-crystal
X-ray diffraction study (Figure 1, and Table 1, vide
infra). The complex may also be prepared via the reac-
tion of [RuHCl(CO)(PPh3)3] with K[HB(pz)3] (CH2Cl2,
25 °C). Somewhat surprisingly, the reaction of [Ru-
(SnPh3)Cl(CO)(PPh3)2] with K[HB(pz)3] in a mixture of
dichloromethane and ethanol also provides good yields
of 1a . This latter result is unusual in that the precursor
stannyl complex may be recrystallized unchanged from
the same solvent mixture, suggesting that alcoholysis
of the ruthenium stannyl bond occurs after coordination
of the HB(pz)3 ligand, although we have not yet detected
any intermediates in this process.
The gross formulation of 1a follows from spectroscopic
data (Experimental Section), which are comparable to
those for Esteruelas’ complex [RuH(CO)(PiPr3)2{η2-HB-
(pz)3}]8 and [RuH(CO)(PPh3)2{κ2-H2B(bta)2}].18 Final
confirmation of the formulation is given by the ther-
molysis of the complex in refluxing toluene to provide
[RuH(CO)(PPh3){κ3-HB(pz)3}] (2a ) and PPh3. The η2
derivative 1a is however quite stable under mild con-
ditions: crystals used for the X-ray diffraction study
were grown over a five-day period at room temperature.
The complex is indefinitely stable in the solid state.
Th ioca r bon yl Com p lexes. Given the facile forma-
tion of [RuH(CS)(PPh3)([9]aneS3)]Cl from the reaction
of [RuHCl(CS)(PPh3)3] with 1,4,7-trithiacyclononane,17
the synthesis of the complex [RuH(CS)(PPh3){HB(pz)3}]
(2b) was attempted. Treating a dichloromethane solu-
tion of [RuHCl(CS)(PPh3)3] with K[HB(pz)3] leads to the
rapid formation of [RuH(CS)(PPh3)2{η2-HB(pz)3}] (1b)
in good yield (Scheme 2). The spectroscopic data for 1b
differ only slightly from those for 1a , primarily in those
features associated with the thiocarbonyl ligand (13C
with those for the formation of the related complexes
[RuH(CA)(PPh3){[9]aneS3}]+ at room temperature.17
Similarly, K[H2B(bta)2] (bta ) benzotriazolyl) and [NMe4]-
[B3H8] react with [RuHCl(CO)(PPh3)3] or [RuH(CO)-
(NCMe)2(PPh3)2]ClO4 to provide [RuH(CO)(PPh3)2{κ2-
H2B(bta)2}]18 and [RuH(η2-B3H8)(CO)(PPh3)2],19 respec-
tively, also at room temperature. Furthermore, the or-
ganometallic complexes [Ru(R)Cl(CO)(PPh3)2] (R ) aryl,
vinyl) react rapidly with K[HB(pz)3] at room tem-
perature to provide the complexes [Ru(R)(CO)(PPh3)-
{HB(pz)3}].3d
2
NMR: 304.5 ppm [t, J (PC) ) 17.0 Hz]; ν(CS) ) 1262
cm-1). Stirring a solution of 1b at room temperature
in dichloromethane or benzene leads to the formation
of the thiocarbonyl analogue of 2a , viz., [RuH(CS)(PPh3)-
{η3-HB(pz)3}] (2b). Although this transformation is
slow (3 days), it is noteworthy that it ensues under
ambient temperatures while the carbonyl analogue 1a
requires refluxing toluene for conversion to 2a . Spec-
troscopic data for 2b are comparable to those for 2a and
(17) Cannadine, J .; Hector, A.; Hill, A. F. Organometallics 1992, 11,
2323.
(18) Cartwright, J .; Hill, A. F. J . Organomet. Chem. 1992, 429, 229.
(19) Burns, I. D.; Hill, A. F.; Thompsett, A. R.; Alcock, N. W.; Claire,
K. J . Organomet. Chem. 1992, 425, C8.

1556 Organometallics, Vol. 17, No. 8, 1998
Burns et al.
Sch em e 2. Syn th esis of η3- a n d
η2-P oly(a zolyl)bor a te Th ioca r bon yl Com p lexes of
Ru th en iu m
Sch em e 3. Syn th esis of η3- a n d
η2-Hyd r otr is(p yr a zolyl)bor a te P h en yl Com p lexes
of Osm iu m
have shown that the dihydrobis(benzotriazolyl)borate
ligand readily coordinates to ruthenium, rhodium, and
iridium.1,3c,18 The reaction of [RuHCl(CS)(PPh3)3] with
K[H2B(bta)2] (bta ) benzotriazolyl) readily provides the
complex [RuH(CS)(PPh3)2{η2-H2B(bta)2}] (4), spectro-
scopic data for which are comparable to those for 1b
and the carbonyl analogue [RuH(CO)(PPh3)2{η2-H2B-
2
(bta)2}].18 (13C NMR, 305.2 ppm [t, J (PC) ) 16.1 Hz];
ν(CS) 1282 cm-1). While the boat conformation of the
H2B(bta)2 ligand would in principle render the two
phosphines chemically inequivalent in a static structure,
inversion of the metallacycle must be rapid on the NMR
time scale. This is also suggested by the triplet multi-
plicity of the hydride resonance apparent in the 1H NMR
unremarkable, other than to confirm that both the
2
thiocarbonyl (13C, 305.1 ppm, d, J (PC) ) 19.6 Hz; IR,
1269 cm-1) and the hydride ligand (1H, δ -8.96, d,
2J (PH) ) 28.4 Hz) have retained their integrity. Heat-
ing 2b in refluxing chloroform leads to hydride/chloride
metathesis and formation of [RuCl(CS)(PPh3){HB(pz)3}]
(3). Although the reaction of [RuCl2(CS)(OH2)(PPh3)2]
with [9]aneS3 provides [RuCl(CS)(PPh3)([9]aneS3)]Cl,
this same precursor does not react cleanly with K[HB-
(pz)3] to provide 3. Rather, the major product is the
pyrazole complex [RuCl2(CS)(Hpz)(PPh3)2], resulting
from cleavage of the HB(pz)3 ligand.
The cis disposition of thiocarbonyl and hydride ligands
raises the question of migratory insertion of these two
ligands. Roper has illustrated that such processes are
quite facile in the chemistry of osmium thiocarbonyls.20
The complexes 1b and 2b therefore appear ideally con-
structed for such a coupling. Both the thermal conver-
sion of 1b to 2b and the photolysis of 2b lead to blue-
green side products; however, these have not yet been
obtained in sufficiently large amounts for complete
characterization (13C NMR, analysis), although these
almost certainly involve thioformyl groups, given the
absence of characteristic terminal thiocarbonyl infrared
absorptions.
2
spectrum of 4 (-9.26 ppm, J (PH) ) 20.2 Hz) and the
singlet 31P NMR resonance (43.5 ppm).
Osm iu m Com p lexes. We have shown that the
complex [Ru(C6H4Me-4)(CO)(PPh3){η3-HB(pz)3}] forms
rapidly from the reaction of [Ru(C6H4Me-4)Cl(CO)-
(PPh3)2], with no intermediates being observed.3d,e
Reaction rates for ligand exchange reactions typically
decrease down a transition-metal triad. We have
therefore investigated the preparation of a related
osmium complex to identify any intermediates in the
coordination of the HB(pz)3 ligand which might be
related to 1. Treating a dichloromethane solution of
[Os(C6H5)Cl(CO)(PPh3)2]22 with K[HB(pz)3] results in
the smooth formation of the colorless complex [Os-
(C6H5)(CO)(PPh3)2{η2-HB(pz)3}] (5). This complex also
features bidentate coordination of the scorpionate
(Scheme 3), evident from the 31P NMR spectrum (2.34,
2
-2.62 ppm, J (PAPB) ) 301.8 Hz). Furthermore, one
of the H4(pz) resonances in the 1H NMR spectrum is
shifted downfield from the remaining two, suggesting
quite a different chemical environment for the pendant
pyrazolyl group. As with 1a and 1b, one phosphine is
labile, although refluxing toluene is required for the
complete thermolysis of 5 to provide [Os(C6H5)(CO)-
(PPh3){η3-HB(pz)3}] (6). The identity of 6 follows un-
equivocally from spectroscopic data.
Lalor has described a series of ligands related to the
pyrazolylborates but based on benzotriazole,21 and we
(20) Clark, G. R.; Collins, T. J .; Hall, D.; J ames, S. M.; Roper, W. R.
J . Organomet. Chem. 1977, 141, C5. Collins, T. J .; Roper, W. R. J .
Organomet. Chem. 1977, 139, C56. Collins, T. J .; Roper, W. R. J .
Organomet. Chem. 1977, 139, C9. Collins, T. J .; Roper, W. R. J .
Organomet. Chem. 1978, 159, 73.
(21) Lalor, F. J .; Miller, S. M.; Garvey, N. Polyhedron 1990, 9, 63.
Lalor, F. J .; Miller, S. M.; Garvey, N. J . Organomet. Chem. 1988, 356,
C57.
(22) Roper, W. R.; Wright, L. J . J . Organomet. Chem. 1977, 142,
C1. Rickard, C. E. F.; Roper, W. R.; Taylor, G. E.; Waters, J . M.; Wright,
L. J . J . Organomet. Chem. 1990, 389, 375.

Polyazolyl Chelate Chemistry
Organometallics, Vol. 17, No. 8, 1998 1557
The possibility that the pendant nature of one pyra-
zolyl group in 2a could be used for bridge-assisted
metal-metal bond formation was briefly investigated.
The reaction of 1a with [Cu(NCMe)4]PF6 resulted in a
colorless complex formulated as [RuCu(µ-H)(CO)(PPh3)2-
{κ3-HB(pz)3}] (7) being isolated (Scheme 1). A very
broad resonance in the 1H NMR spectrum at -12.78
ppm indicated the presence of a bridging hydride, al-
though appropriate infrared activity could not be un-
equivocally identified. Apart from the heptet resonance
due to the PF6 counteranion, the 31P{1H} NMR spec-
trum clearly showed two different phosphorus environ-
ments at 51.9 and 3.4 ppm. The latter, being broad, is
attributed to the phosphine attached to the copper cen-
ter, while that to lower field is assigned to the ruthenium-
bound phosphine. The presence of the hydrotris(pyra-
zol-1-yl)borate ligand was confirmed by pyrazole reso-
nances apparent in the 1H NMR spectrum (δ 5.83, 5.96,
6.75, 7.73, 7.76). The FAB mass spectrum proved most
diagnostic, clearly showing a molecular ion at m/z 931
in addition to a range of assignable fragmentations.
Unfortunately, we have been unable to obtain crystal-
lographic grade crystals to confirm the structural for-
mulation. It is noteworthy that, as already indicated
above, the conversion of 1a to 2a does not proceed under
the conditions of the formation of 7. This suggests that
the reaction proceeds by direct combination of the copper
reagent with 1a , presumably via coordination to the
pendant pyrazolyl arm, followed by rearrangement to
the final product.
ruthenium phosphorus bonds are close to collinear
(P(19)-Ru-P(38) ) 173.1(1)°), and the atoms in the
equatorial coordination sites (C(17), H(1A), N(1), N(6))
are essentially coplanar (maximum deviation 0.028 Å
by H(1A)). The features of interest center on the Ru-
(µ-pz)2BH(pz) moiety. There is the expected asymmetry
in the Ru-N bond distances, that trans to H(1A) (2.196-
(2) Å) being substantially longer than that trans to the
carbonyl ligand (2.141(2) Å). In the absence of chelation
by the N(12)-based pyrazolyl group, the six-membered
ring comprising Ru, N(6), N(7), B(11), N(2), and N(1)
has a slightly flattened boat conformation. The two
noncoordinating nitrogen atoms lie only slightly out of
the coordination plane by approximately 0.23 Å; cf. 0.91
Å for B(11). The pendant pyrazolyl ring is oriented
approximately orthogonal to the chelate ring, rotation
being hindered by the C(3) and C(8) pyrazolyl hydrogen
atoms. While this ring protrudes from the molecule
somewhat, there are no intermolecular contacts of any
note. The only (barely) noteworthy intramolecular in-
teraction involves a probably weak alignment of the
pyrazolyl ring based on N(7) with a proximal phosphine
phenyl ring (centroid-centroid separation 3.49 Å).
Ack n ow led gm en t. We are grateful to the EPSRC
(U.K.) for the award of studentships (to I.D.B. and
J .D.E.T.W.-E) and for the financial support of diffrac-
tometry facilities. We are grateful to J ohnson Matthey
Ltd for a generous loan of ruthenium salts. A.F.H.
gratefully acknowledges the award of a Senior Research
Fellowship by the Leverhulme Trust and The Royal
Society.
Discu ssion of th e Str u ctu r e of [Ru H(CO)(P P h 3)2-
{η2-HB(p z)3}] (1a ). The compound forms pale brown
prismatic blocks when crystallized by diffusion of etha-
nol into a dichloromethane solution of the complex. The
X-ray analysis confirmed the cis-bidentate coordination
of the HB(pz)3 ligand and the trans-bis(phosphine)
disposition suggested by spectroscopic data. The hy-
dride hydrogen atom was clearly located in the X-ray
study and freely refined. The coordination geometry at
ruthenium (Figure 1) is approximately octahedral. The
Su p p or tin g In for m a tion Ava ila ble: Tables of positional
parameters, intramolecular distances and angles, calculated
H coordinates, anisotropic and equivalent anistropic displace-
ment coefficients, and crystallographic procedural details (10
pages). Ordering information is given on any current mast-
head page.
OM970991Y