Ligand vs. metal basicity: Reactions of 2-(diphenylphosphanyl)anilido and 2-(diphenylphosphanyl)phenolato complexes of rhodium(I) and iridium(I) with HBF4

Article abstract of DOI:10.1515/znb-2010-0322

Treatment of [M(CO)(PPh₃)(2-Ph₂PC₆H ₄NR-κN, κP)], where M/NR = Rh/NH (1), Rh/NCH₃ (2), Ir/NH (3), and Ir/NCH₃ (4), with Et₂OHBF₄ in CH₂Cl₂ result

Full text of DOI:10.1515/znb-2010-0322

Ligand vs. Metal Basicity: Reactions of 2-(Diphenylphosphanyl)anilido
and 2-(Diphenylphosphanyl)phenolato Complexes of Rhodium(I) and
Iridium(I) with HBF4
Lutz Dahlenburga and Konrad Herbstb
a Department Chemie und Pharmazie, Universita¨t Erlangen-Nu¨rnberg, Egerlandstraße 1,
91058 Erlangen, Germany
b Haldor Topsøe A/S, Nymøllevej 55, 2800 Lyngby, Denmark
Reprint requests to Prof. Dr. Lutz Dahlenburg. Fax: +49 9131 85 27387.
E-mail: Lutz.Dahlenburg@chemie.uni-erlangen.de
Z. Naturforsch. 2010, 65b, 376 – 382; received November 14, 2009
Dedicated to Professor Rolf W. Saalfrank on the occasion of his 70th birthday
Treatment of [M(CO)(PPh3)(2-Ph2PC6H4NR-κN,κP)], where M/NR = Rh/NH (1), Rh/NCH3 (2),
Ir/NH (3), and Ir/NCH3 (4), with Et2O·HBF4 in CH2Cl2 resulted in protonation at nitrogen with for-
mation of [M(CO)(PPh3)(2-Ph2PC6H4NHR-κN,κP)]BF4 [M/NHR = Rh/NH2 (7), Rh/NHCH3 (8),
Ir/NH2 (9), Ir/NHCH3 (10)]. Similar protonation of [Rh(CO)(PPh3)(2-Ph2PC6H4O-κO,κP)] (5) in
CH2Cl2 afforded [Rh(CO)(PPh3)(2-Ph2PC6H4OH-κO,κP)]BF4 (11), but furnished [Rh(CO)(PPh3)-
(NCCH3)(2-Ph2PC6H4OH-κP)]BF4 (12) if carried out in CH3CN. [Ir(CO)(PPh3)(2-Ph2PC6H4O-
κO,κP)] (6) reacted with HBF4 by protonation at the central metal atom and oxidative ad−dition
to give [IrH(FBF3)(CO)(PPh3)(2-Ph2PC6H4O-κO,κP)] (13), the substitutionally labile BF4 lig-
and of which underwent smooth exchange with neutral donors L producing [IrH(CO)(L)(PPh3)(2-
Ph2PC6H4O-κO,κP)]BF4 with L = H2O (14), CH3CN (15) and PPh3 (16). The structures of 6 and 15
were determined by single-crystal X-ray crystallography.
Key words: P,N Ligands, P,O Ligands, Rhodium Complexes, Iridium Complexes, Protonation
Introduction
the reaction of its NH analog with HCl also re-
sulted in oxidative addition to iridium and protona-
tion at nitrogen. However, different from the con-
version of [Ir(CO)(PPh3)(2-Ph2PC6H4NH-κN,κP)]
into the stable ionic product [IrH(Cl)(CO)(PPh3)-
(2-Ph2PC6H4NH2-κN,κP)]Cl, the protonation of the
N-methylanilido ligand was followed by dissocia-
tion of the NHCH3 group from the metal, allow-
ing the chloride ion to coordinate with formation of
the covalent ring-opened product [IrHCl2(CO)(PPh3)-
(2-Ph2PC6H4NHCH3-κP)], stabilized by intramolec-
ular -N(CH3)H···Cl-Ir hydrogen bonding [2]. In con-
trast, the ring-opened compound [IrHCl2(CO)(PPh3)-
(2-Ph2PC6H4POH-κP)], resulting from combination
of the chelated phenolato complex [Ir(CO)(PPh3)-
(2-Ph2PC6H4O-κO,κP)] with HCl in chloroform be-
In previous work we have been investigating several
aspects of the coordination chemistry of bidentate 2-
(diphenylphosphanyl)phenol, -thiophenol and -aniline
ligands, both in their neutral 2-Ph2PC6H4XH (X =
O, S, NH, NCH3) and deprotonated 2-Ph2PC6H4X−
forms [1 – 5], in particular with regard to the reac-
tivity of their Ir(I) and Rh(I) complexes towards se-
lected Brønsted and Lewis acids [1, 2]. In this con-
text, the 2-(diphenylphosphanyl)anilido-substituted
iridium(I) complex [Ir(CO)(PPh3)(2-Ph2PC6H4NH-
κN,κP)] was seen to react with HCl in CHCl3 or
◦
toluene solution at −60 C by oxidative addition to
the central metal atom as well as protonation at ni-
trogen to form the ionic chelate complex [IrH(Cl)-
(CO)(PPh3)(2-Ph2PC6H4NH2-κN,κP)]Cl, containing
one of its NH groups hydrogen-bonded to Ir-
Cl [2]. Treatment of the N-methylanilido compound
[Ir(CO)(PPh3)(2-Ph2PC6H4NCH3-κN,κP)] with hy-
drogen chloride under the conditions chosen for
◦
tween −60 and +20 C proved to be stable only in
the presence of excess hydrogen chloride but other-
wise was transformed by elimination of HCl and
ring closure into [IrH(Cl)(CO)(PPh3)(2-Ph2PC6H4O-
κO,κP)] [1]. With the aim of weighing the O- and N-
c
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L. Dahlenburg – K. Herbst · Ligand vs. Metal Basicity
377
basicities of 2-(diphenylphosphanyl)anilidoand -phen- groups manifest themselves by single and, respec-
olato ligands against those displayed by coordinatively tively, split ν(NH) absorptions around 3200 cm−1 as
unsaturated metal centers, we have extended our pre- well as by proton resonances observed as broad signals
vious studies to the reactivity of the rhodium and irid- at δ ca. 5.0 and 5.5 for the two aniline complexes 7
ium chelate complexes [M(CO)(PPh3)(2-Ph2PC6H4X- and 9, and at δ ca. 4.3 and 5.1 for their N-methylated
κP,κX)] (X = NH, NHCH3, O) towards Brønsted acids homologs 8 and 10. P,N-chelation in the [M(CO)-
which, different from HCl, possess non-coordinating (PPh3)(2-Ph2PC6H4NHR-κN,κP)]+ cations is evident
or, at best, weakly coordination anions, e. g., HBF4.
from the pronounced downfield shifts [6] of their Ph2P
1
31P{ H} resonances (δ ca. 47 for M = Rh; δ ca. 44
Results and Discussion
for M = Ir), which are approximately 66 – 69 ppm at
lower field than those of the free 2-Ph2PC6H4NHR
ligands (δ ca. −22) and thus closely resemble the
31P shift values observed for the two deprotonated
P,N bidentates in the respective [M(CO)(PPh3)(2-
Ph2PC6H4NR-κN,κP)] precursors (δ ca. 49 for M =
Rh; δ ca. 38 for M = Ir) [2]. Coupling constants 2JP,P
of 280 to 285 Hz indicate the PPh3 and Ph2P donors to
be coordinated in mutual trans position [7].
Rhodium complex 5 similarly underwent proto-
nation of its anionic 2-Ph2PC6H4O− ligand when
combined in CH2Cl2 with ethereal HBF4 in 1 : 1
stoichiometry. Both the P,O-chelated identity and the
trans-P-Rh-P geometry of the resulting ionic prod-
Treatment of CH2Cl2 solutions of the 16e
chelate complexes [M(CO)(PPh3)(2-Ph2PC6H4NR-
κN,κP)] [2], where M/NR = Rh/NH (1), Rh/NCH3
(2), Ir/NH (3), and Ir/NCH3 (4), with one molar
equivalent of HBF4 (54 % in diethyl ether) resulted
in smooth protonation of the amide functions to form
the corresponding tetrafluoroborate salts [M(CO)-
(PPh3)(2-Ph2PC6H4NHR-κN,κP)]BF4 (Scheme 1,
7 – 10). When allowed to interact with one additional
equivalent of HBF4, none of the four d8 complexes 7 –
10 underwent any clean further transformation such
as, e. g., protonation at rhodium or iridium with or
without decoordination of the NH2 and NHCH3
donors. Instead, intractable mixtures of products were
obtained.
In the infrared spectra, the moderately air-stable
yellow complex salts 7 – 10 exhibit a single carbonyl
stretch band in the 1980– 2010 cm−1 region, each
positioned ca. 50 cm−1 at higher wavenumbers than
those of the neutral starting compounds 1 – 4 [2],
along with a very strong absorption between 1050
and 1070 cm−1 arising from the triply degenerate
ν(BF) vibration of the anion. The NHCH3 and NH2
uct,
[Rh(CO)(PPh3)(2-Ph2PC6H4OH-κO,κP)]BF4
(11), have been established by IR and 31P-NMR
spectroscopy as outlined above for 7 – 10: ν(BF) =
1098, ν(CO) = 2000 cm−1; δ(Ph2P) = 43.6, JP,P
=
2
284.4 Hz. The presence of the phenolic OH group was
evident from a broad 1H resonance at δ = 10.1.
Dissociation of the OH function from the metal
atom with formation of [Rh(CO)(PPh3)(NCCH3)(2-
Ph2PC6H4OH-κP)]BF4 (12) was observed when the
reaction between 5 and an equimolar quantity of
Et2O·HBF4 was conducted in acetonitrile as a strongly
donating solvent rather than in dichloromethane,which
has only poor coordinating abilities [8 – 11]. The over-
all geometry of the cation [Rh(CO)(PPh3)(NCCH3)-
(2-Ph2PC6H4OH-κP)]+ shown in Scheme 1 was con-
1
firmed by spectral data. In particular, the 31P{ H}-
NMR spectrum revealed very similar chemical shifts
for the two trans-positioned phosphorus nuclei (δ =
25.3 and 31.5; 2JP,P = 292.2 Hz), which proves the 2-
Ph2PC6H4OH ligand to be bonded in a monodentate
fashion.
Whereas the phenolato rhodium complex 5 re-
acted with HBF4 in different solvents by protona-
tion at oxygen to give 11 or 12, the very same reac-
tion of the phenolato iridium(I) compound [Ir(CO)-
(PPh3)(2-Ph2PC6H4O-κO,κP)] (6) afforded the hy-
drido complex [IrH(FBF3)(CO)(PPh3)(2-Ph2PC6H4O-
Scheme 1.
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378
L. Dahlenburg – K. Herbst · Ligand vs. Metal Basicity
κO,κP)] (13) by oxidative addition of the acid. The
outcome of this reaction, which parallels the oxida-
tive addition of HBF4 to trans-[IrCl(CO)(PPh3)2] [12],
clearly shows the metal basicity of 6 to surpass that of
the 2-Ph2PC6H4O− chelate ligand. In agreement with
the assignment of 13 as an iridium(III) complex con-
−
taining a coordinated BF4 ion of C3v symmetry, the
IR-active triply degenerate ν(BF) vibration of the free
anion is now seen to be split into two components ab-
sorbing at 924 and 1125 cm−1 (F2 → A1 + E). Co-
ordination of the hydride cis to two mutually trans-
positioned P-donors and trans to Ir-FBF3 follows from
Fig. 1. Molecular structure of [IrH(CO)(NCCH3)(PPh3)(2-
1
both the 31P{ H}-NMR spectrum consisting of two
Ph2PC6H4O-κO,κP)]BF4 (15) in the crystal (aryl H atoms
doublets split by 313.5 Hz and the 1H-NMR spectrum
containing a cis-P,P-coupled IrH pseudotriplet at δ =
−26.60, i. e., close to the chemical shift previously
reported as δ = −26.5 for trans-(H,F)-, trans-(P,P)-
[IrH(Cl)(FBF3)(CO)(PPh3)2] [12].
˚
omitted for clarity). Selected bond lengths (A) and angles
(deg): Ir–P(1) 2.322(2), Ir–P(2) 2.381(2), Ir–O(2) 2.053(4),
Ir–N 2.134(5), Ir–C(1) 1.831(8), Ir–H, 1.6 (calcd.); P(1)–Ir–
P(2) 169.26(6), P(1)–Ir–O(2) 84.0(1), P(1)–Ir–N 90.3(1),
P(1)–Ir–C(1) 92.7(2), P(2)–Ir–O(2) 85.9(1), P(2)–Ir–N
92.5(1), P(2)–Ir–C(1) 97.2(2), O(2)–Ir–N 86.3(2), O(2)–Ir–
C(1) 175.3(2), N–Ir–C(1) 97.1(3).
As observed for other transition metal tetraflu-
−
oroborato complexes, the BF4 ligand of 13 is
ABX-type splitting with trans- and cis-P,P couplings
substitutionally labile and is easily displaced by di-
verse hard and soft donors to produce aqua, nitrile and
phosphane derivatives such as, e. g., [IrH(CO)(OH2)-
(PPh3)(2-Ph2PC6H4O-κO,κP)]BF4 (14), [IrH(CO)-
of 291.0, 15.3, and 13.3 Hz, respectively, (ii) pseu-
1
doquartet multiplicity of the 13C{ H} carbonyl reso-
nance, and (iii) an IrH doublet of virtual triplets charac-
terized by trans-2JP,H = 148.0 Hz and |cis-2JP,H +cis-
2JPꢀ,H| = 31.8 Hz.
(NCCH3)(PPh3)(2-Ph2PC6H4O-κO,κP)]BF4
and [IrH(CO)(PPh3)2(2-Ph2PC6H4O-κO,κP)]BF4
(16). While the preparation of 14 required complex 13
(15),
Complex 15 was isolated as the addition com-
to be isolated and purified prior to the BF4−/H2O pound 15·2C3H6O by crystallizing the residue of an
exchange reaction, compounds 15 and 16 were also evaporated reaction mixture of 6 and an equimo-
obtained from the in situ protonation, with HBF4, of lar quantity of Et2O·HBF4 in CH3CN from an ace-
[Ir(CO)(PPh3)(2-Ph2PC6H4O-κO,κP)] (6) either in tone/pentane solvent mixture. X-Ray crystal structure
neat acetonitrile or in CH2Cl2 in the presence of added analysis confirmed the presence of a distorted octahe-
PPh3.
dral cation in which the acetonitrile ligand is bonded
˚
trans to Ir–H (Fig. 1). The Ir–N distance, 2.134(5) A,
Notwithstanding that the aq−ua complex 14 con-
˚
is within the range of 2.10 to 2.15 A previously
tains a non-coordinated BF4 ion, the infrared
spectrum displays three BF stretch bands at 995,
1064, and 1097 cm−1, which points to symmetry
lowering from Td to C2v (F2 → A1 + B1 + B2) as
a result of O–H···F hydrogen bonding between
measured for various other cationic iridium(III) com-
plexes possessing trans-H-Ir-NCCH3 building blocks
[16 – 19]. Ir–P and Ir–O bond lengths within the five-
˚
membered chelate ring, 2.322(2) and 2.053(4) A,
−
are slightly longer than the Ir–P and Ir–O distances
the complex cation and the BF4 counterion. Such
˚
of 2.297(2) and 2.039(4) A observed for [Ir(CO)-
hydrogen bonding interactions have previously
been established, by vibrational spectroscopy and
X-ray crystallography, for several related aqua
complexes, representative examples of which are
given by [IrH(Cl)(OH2)(CO)(PPh3)2]BF4 [12],
[Cr(CCH3)(CO)3{P(CH3)3}(OH2)]BF4 [13], [(η7-
C7H7)Mo(acac)(OH2)]BF4 [14], and [Re(CO)3-
{(CH3)2NCH2CH2N(CH3)2}(OH2)]BF4 [15].
(PPh3)(2-Ph2PC6H4O-κO,κP)] (6), the crystal struc-
ture of which has been determined for comparison
(Fig. 2).
Molecule 6 displays the expected four-coordinate
planar coordination geometry about the central
metal atom as evidenced from the sum of the
four interligand cis angles, 360.2◦. Metal-to-ligand
The geometry of the cation 16+ has been con- bond lengths and valence angles at the central
cluded from its NMR features displaying (i) 31P{ H} metal atom reveal a close relation to [Rh(CO)-
1
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L. Dahlenburg – K. Herbst · Ligand vs. Metal Basicity
379
the metal basicity of both Rh(I) and Ir(I), whereas
the ligand basicity of the 2-Ph2PC6H4O− chelate
is superior to that of the central metal atom of
[M(CO)(PPh3)(2-Ph2PC6H4O-κO,κP)] for M = Rh,
but inferior for M = Ir.
Experimental Section
All manipulations were performed under nitrogen using
standard Schlenk techniques. Solvents were distilled from
the appropriate drying agents prior to use. – IR: Mattson Po-
laris – NMR: Bruker DPX 300 (300.1 MHz for 1H, 75.5 MHz
for 13C, and 121.5 MHz for 31P) with SiMe4 as internal or
H3PO4 as external standards (downfield positive) at ambi-
ent temperature (“m” = deceptively simple multiplet). Com-
plexes [M(CO)(PPh3)(2-Ph2PC6H4NR-κN,κP)] [M = Rh:
R = H (1), CH3 (2); M = Ir: R = H (3), CH3 (4)] and [M(CO)-
(PPh3)(2-Ph2PC6H4O-κO,κP] [M = Rh (5), Ir (6)] were pre-
pared as previously described [1, 2].
Fig. 2. Molecular structure of [Ir(CO)(PPh3)(2-Ph2PC6H4O-
κO,κP] (6) in the crystal (H atoms omitted for clar-
˚
ity). Selected bond lengths (A) and angles (deg): Ir–P(1)
2.336(2), Ir–P(2) 2.297(2), Ir–O(1) 2.039(4), Ir–C(37)
1.785(8); P(1)–Ir–P(2) 167.27(7), P(1)–Ir–O(1) 85.2(1),
P(1)–Ir–C(37) 96.0(2), P(2)–Ir–O(1) 82.6(1), P(2)–Ir–C(37)
96.4(2), O(1)–Ir–C(37) 177.1(3).
(PPh3)(2-Ph2PC6H4O-κO,κP)] and [Ir(CO)(PPh3)(2-
Ph2PC6H4NHCH3-κN,κP)], the structures of which
have been reported previously [1, 2].
[Rh(CO)(PPh )(2-Ph PC H NH -κN,κP)]BF (7)
3
2
6
4
2
4
A solution of 100 mg (0.15 mmol) of 1 in 10 mL of
CH2Cl2 was treated with 21 µL of HBF4 (54 % in diethyl
ether; 0.15 mmol) and stirred for 1 h at r. t. Evaporation
of all volatiles left a pale-yellow oil which was triturated
with pentane to give 103 mg (90 %) of 7 as yellow micro-
crystals. – IR (KBr): ν = 3218/3120 (NH2), 2004 (CO),
Concluding Remarks
A comparative investigation of the reaction of
HBF4 with Vaska-type 2-(diphenylphosphanyl)anilido
complexes of rhodium(I) and iridium(I), [M(CO)-
(PPh3)(2-Ph2PC6H4NR-κN,κP)] (R = H, CH3),
has shown that, irrespective of the nature of the
central metal atom, protonation occurs at nitrogen
to form ionic 2-(diphenylphosphanyl)aniline deriva-
tives [M(CO)(PPh3)(2-Ph2PC6H4NHR-κN,κP)]BF4.
The 2-(diphenylphosphanyl)phenolato precursors
[Rh(CO)(PPh3)(2-Ph2PC6H4O-κO,κP)] and [Ir(CO)-
(PPh3)(2-Ph2PC6H4O-κO,κP)] displayed divergent
reactivity towards HBF4: the rhodium(I) compound,
dissolved in CH2Cl2 or CH3CN, was protonated
by the acid at the phenolato function producing
1
1067 (BF4) cm−1. – H NMR (CDCl3): δ = 4.97 (br, 2 H,
1
NH2), 7.5 (m, 29 H, aryl H). – 13C{ H} NMR (CDCl3):
2
3
δ = 147.8 (dd, JP,C = 23.1 Hz, JP,C = 5.3 Hz, phenylene
C-1), 190.0 (“dt”, 1JRh,C = 70.8 Hz, |cis-2JP,C +cis-2JP ,C|=
ꢀ
31.0 Hz, CO). – 31P{ H} NMR (CDCl3): δ = 31.0 (dd,
1
1JRh,P = 126.5 Hz, trans-2JP,P = 285.3 Hz, PPh3), 47.1 (dd,
1JRh,P = 123.9 Hz, Ph2P). – C37H31BF4NOP2Rh (757.32):
calcd. C 58.68, H 4.13, N 1.85; found C 58.86, H 4.09,
N 1.54.
Similar procedures were used for the preparation of com-
plexes 8 – 10.
[Rh(CO)(PPh )(2-Ph PC H NHCH -κN,κP)]BF (8)
3
2
6
4
3
4
[Rh(CO)(PPh3)(2-Ph2PC6H4OH-κO,κP)]BF4
and
From 140 mg (0.21 mmol) of 2 and 28 µL of 54 %
ethereal HBF4 (0.21 mmol) in 10 mL of CH2Cl2. – Yield:
140 mg (86 %). – IR (KBr): ν = 3244 (NH), 1996 (CO),
[Rh(CO)(PPh3)(NCCH3)(2-Ph2PC6H4OH-κP)]BF4,
respectively. In marked contrast, the iridium(I)
complex underwent protonation at the central metal
atom with formation of hydridoiridium(III) products,
[IrH(FBF3)(CO)(PPh3)(2-Ph2PC6H4O-κO,κP)] and
[IrH(CO)(L)(PPh3)(2-Ph2PC6H4O-κO,κP)]BF4 (L =
H2O, CH3CN, PPh3), under all conditions studied.
In conclusion, it has been demonstrated that the
Brønsted basicity towards HBF4 of the anionic anilido
chelate ligands of the 16e complexes [M(CO)(PPh3)-
1057 (BF4) cm−1. – 1H NMR (CDCl3): δ = 2.15 (d, 3JH,H
=
6.0 Hz, 3 H, CH3), 4.33 (br, 1 H, NH), 7.6 (m, 29 H, aryl
1
H). – 13C{ H} NMR (CDCl3): δ = 45.4 (s, CH3), 154.7
(dd, 2JP,C = 22.0 Hz, 3JP,C = 3.5 Hz, phenylene C-1), 189.9
1
(“dt”, JRh,C = 69.7 Hz, |cis-2JP,C + cis-2JP ,C|= 32.4 Hz,
ꢀ
CO). – 31P{ H} NMR (CDCl3): δ = 31.1 (dd, JRh,P
=
=
1
1
128.8 Hz, trans-2JP,P = 280.1 Hz, PPh3), 44.2 (dd, JRh,P
1
126.4 Hz, Ph2P). – C38H33BF4NOP2Rh (771.34): calcd.
(2-Ph2PC6H4NR-κN,κP)] (R = H, CH3) exceeds C 59.17, H 4.31, N 1.82; found C 59.16, H 4.33, N 1.79.
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L. Dahlenburg – K. Herbst · Ligand vs. Metal Basicity
1
1
[Ir(CO)(PPh )(2-Ph PC H NH -κN,κP)]BF (9)
CO). – 31P{ H} NMR (CDCl3): δ = 25.3 (dd, JRh,P
=
=
3
2
6
4
2
4
121.2 Hz, trans-2JP,P = 292.2 Hz, PPh3), 31.5 (dd, JRh,P
121.2 Hz, Ph2P). – C39H33BF4NO2P2Rh (799.34): calcd.
C 58.60, H 4.16, N 1.75; found C 59.06, H 4.62, N 1.56.
1
From 150 mg (0.20 mmol) of 3 and 27 µL of 54 % ethe-
real HBF4 (0.21 mmol) in 10 mL of CH2Cl2. – Yield: 145 mg
(86 %). – IR (KBr): ν = 3244/3176 (NH2), 1980 (CO), 1069
(BF4) cm−1. – 1H NMR (CDCl3): δ = 5.45 (br, 2 H, NH2),
[IrH(FBF )(CO)(PPh )(2-Ph PC H O-κO,κP)] (13)
1
7.5 (m, 29 H, aryl H). – 13C{ H} NMR (CDCl3): δ = 147.5
3
3
2
6 4
(dd, 2JP,C = 21.0 Hz, 3JP,C = 6.3 Hz, phenylene C-1), 175.1
A mixture of 180 mg (0.24 mmol) of 6 and 33 µL of 54 %
ethereal HBF4 (0.24 mmol) in 10 mL of CH2Cl2 was stirred
for 1 h at r. t. Evaporation of the solvent followed by treat-
ment of the residue with pentane left 195 mg (96 %) of 13
as a pale-yellow solid. – IR (KBr): ν = 2054 (CO), 1125/924
(FBF3) cm−1. – 1H NMR (CDCl3): δ = −26.60 (“t” (br),
1 H, IrH), 6.8, 7.2 (both m, 2 H each, C6H4), 7.6 (m, 25 H,
1
(“t”, |cis-2JP,C +cis-2JP ,C| = 20.8 Hz, CO). – 31P{ H} NMR
ꢀ
(CDCl3): δ = 28.1 (PPh3), 42.6 (Ph2P); both d, trans-2JP,P
=
283.1 Hz. – C37H31BF4IrNOP2 (846.63): calcd. C 52.49,
H 3.69, N 1.65; found C 51.69, H 3.81, N 1.51.
[Ir(CO)(PPh )(2-Ph PC H NHCH -κN,κP)]BF (10)
3
2
6
4
3
4
C6H5). – 31P{ H} NMR (CDCl3): δ = 14.6 (PPh3), 36.6
1
From 130 mg (0.18 mmol) of 4 and 24 µL of 54 %
ethereal HBF4 (0.18 mmol) in 10 mL of CH2Cl2. – Yield:
140 mg (96 %). – IR (KBr): ν = 3227 (NH), 1987 (CO),
(Ph2P); both d, trans-2JP,P = 313.5 Hz. – C37H30BF4IrO2P2
(847.62): calcd. C 52.43, H 3.57; found C 52.53, H 3.80.
1057 (BF4) cm−1. – 1H NMR (CDCl3): δ = 2.20 (d, 3JH,H
=
[IrH(CO)(OH )(PPh )(2-Ph PC H O-κO,κP)]BF (14)
5.8 Hz, 3 H, CH3), 5.07 (br, 1 H, NH), 7.7 (m, 29 H, aryl
2
3
2
6
4
4
1
H). – 13C{ H} NMR (CDCl3): δ = 47.1 (s, CH3), 155.7
A solution of 140 mg (0.17 mmol) of 13 in 10 mL of
CH2Cl2 was treated with 3 µL of water. Stirring the mixture
for 1 h at r. t. followed by evaporation to dryness afforded
143 mg (99 %) of compound 14 as a pale-yellow solid which
was washed with pentane and dried. – IR (KBr): ν = 3408
(OH), 2276 (IrH), 2045 (CO), 1097/1064/995 (BF4) cm−1. –
(dd, 2JP,C = 20.4 Hz, 3JP,C = 2.0 Hz, phenylene C-1), 174.3
1
(“t”, |cis-2JP,C +cis-2JP ,C| = 21.2 Hz, CO). – 31P{ H} NMR
ꢀ
(CDCl3): δ = 28.6 (PPh3), 40.0 (Ph2P); both d, trans-2JP,P
281.2 Hz. – C38H33BF4IrNOP2 (860.66): calcd. C 53.03,
=
H 3.86, N 1.63; found C 52.73, H 4.03, N 1.13.
1H NMR (CDCl3): δ = −21.57 (“t”, |cis-2JP,H +cis-2JP ,H| =
ꢀ
[Rh(CO)(PPh )(2-Ph PC H OH-κO,κP)]BF (11)
3
2
6
4
4
22.2 Hz, 1 H, IrH), 3.5 (br, 2 H, H2O), 6.5, 7.0 (both m,
2 H each, C6H4), 7.3 (m, 25 H, C6H5). – 31P{ H} NMR
1
160 mg (0.24 mmol) of 5 and 33 µL of 54 % ethereal
HBF4 (0.24 mmol) were combined in 10 mL of CH2Cl2.
Stirring at ambient conditions and subsequent work-up as de-
scribed for compound 7 afforded 169 mg (91 %) of 11 as yel-
low crystals. – Yield: 165 mg (91%). – IR (KBr): ν = 2000
(CO), 1098 (BF4) cm−1. – 1H NMR (CDCl3): δ = 7.1−7.6
(CDCl3): δ = 13.4 (PPh3), 35.3 (Ph2P); both d, trans-2JP,P
=
314.0 Hz. – C37H32BF4IrO3P2 (865.63): calcd. C 51.34,
H 3.73; found C 51.12, H 3.69.
[IrH(CO)(NCCH )(PPh )(2-Ph PC H O-κO,κP)]BF
4
3
3
2
6
4
1
(m, 29 H, aryl H), 10.1 (br, 1 H, OH). – 13C{ H} NMR
(15)
2
3
(CDCl3): δ = 161.2 (dd, JP,1C = 18.0 Hz, JP,C = 3.6 Hz,
phenylene C-1), 188.6 (“dt”, JRh,C = 82.1 Hz, |cis-2JP,C
+
This compound was obtained from equimolar quantities
of 6 and 54 % ethereal HBF4 in acetonitrile using a proce-
dure similar to the one outlined above for the rhodium com-
plex 12. The oily residue remaining after evaporation of the
solvent was re-dissolved in acetone. Addition of pentane re-
sulted in the gradual deposition of some off-white cystals
which were identified as the acetone solvate 15·2C3H6O by
X-ray structure analysis.
cis-2JP ,C| = 32.2 Hz, CO). – 31P{ H} NMR (CDCl3): δ =
1
ꢀ
28.0 (dd, 1JRh,P = 125.9 Hz, trans-2JP,P = 284.4 Hz, PPh3),
1
43.6 (dd, JRh,P = 118.1 Hz, Ph2P). – C37H30BF4O2P2Rh
(758.30): calcd. C 58.61, H 3.99; found C 57.58, H 3.87.
[Rh(CO)(PPh )(NCCH )(2-Ph PC H OH-κP)]BF (12)
3
3
2
6
4
4
Treatment of a suspension of 160 mg (0.24 mmol) of 5
in 10 mL of acetonitrile with 33 µL of 54 % ethereal HBF4
(0.24 mmol) gave a clear solution which was stirred for 1 h
at ambient conditions. Removal of the volatiles left the prod-
[IrH(CO)(PPh ) (2-Ph PC H O-κO,κP)]BF (16)
3 2
2
6
4
4
Addition of 100 µL of 54 % ethereal HBF4 (0.73 mmol)
uct as a bright-yellow solid which was washed with pen- and 83 mg (0.32 mmol) of PPh3 to 240 mg (0.17 mmol)
tane and dried under vacuum. – Yield: 188 mg (98 %). – of 6, dissolved in 10 mL of CH2Cl2, produced a colorless
IR (KBr): ν = 3394 (OH), 2296 (CN), 1999 (CO), 1094 solution which was stirred at ambient conditions for 1 h and
(BF4) cm−1. – 1H NMR (CDCl3): δ = 1.98 (s, 3 H, CH3), 2.6 then evaporated. Complex 16 was left as an off-white residue
1
(br, 1 H, OH), 7.0 – 8.1 (m, 29 H, aryl H). – 13C{ H} NMR which was washed with pentane and dried. – Yield: 355 mg
(CDCl3): δ = 1.6 (s, CH3), 120.6 (s, CN), 188.0 (unresolved, (quantitative). – IR (KBr): ν = 2127 (IrH), 2040 (CO), 1092
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L. Dahlenburg – K. Herbst · Ligand vs. Metal Basicity
381
1
◦
3
(BF4) cm−1. – H NMR (CDCl3): δ = −9.01 (“dt”, trans- c = 20.903(5) A, β = 94.71(4) , V = 3103(3) A , Z = 4,
˚
˚
JP,H = 148.0 Hz, |cis-2JP,H + cis-2JP ,H| = 31.8 Hz, 1 H, Dcalcd = 1.63 g cm−3, µ(MoKα ) = 4.4 mm−1, F(000) =
2
ꢀ
IrH), 6.8 – 7.8 (m, 44 H, aryl H). – 13C{ H} NMR (CDCl3): 1496; 2.58◦ ≤ Θ ≤ 25.02◦, 5618 reflections collected
1
δ = 164.0 (“q”, Σ|cis-2JP,C| = 24.0 Hz, CO), 176.9 (“dt”, (−11 ≤ h ≤ +11, 0 ≤ k ≤ +17, 0 ≤ l ≤ +24), 5463 unique
JP,C = 18.9 Hz, | JP,C +3 JP ,C| = 11.8 Hz, phenylene C-1). – (Rint = 0.0381); wR(F2) = 0.0492 for all data and 379 param-
2
3
ꢀ
31P{ H} NMR (CDCl3): δ = −13.2, −0.6, 22.8 (ABX sys- eters, R(F) = 0.0349 for 2504 structure factors Fo ≥ 4σ(Fo);
1
tem, trans-2JP,P = 291.0 Hz, cis-2JP,P = 15.3 and 13.3 Hz). – weighting scheme applied: w = 1/[σ2(Fo) + (0.0094P)2],
C55H45BF4IrO2P3 (1109.91): calcd. C 59.52, H 4.09; found where P = (Fo2 + 2Fc2)/3; largest peak and hole in final
difference map: 0.871 and −0.863 e A−3. – 15·2C3H6O:
˚
C 58.90, H 3.85.
¯
C45H45BF4IrNO4P2 (1004.77); triclinic, P1, a = 9.164(6),
˚
b = 14.700(2), c = 16.515(2) A, α = 91.26(1), β =
X-Ray structure determinations
◦
3
˚
93.28(3), γ = 94.74(2) , V = 2212.7(15) A , Z = 2,
Dcalcd = 1.51 g cm−3, µ(MoKα ) = 3.1 mm−1, F(000) =
1004; 2.53◦ ≤ Θ ≤ 26.96◦, 9966 reflections collected
(−11 ≤ h ≤ +11, −18 ≤ k ≤ +18, 0 ≤ l ≤ +21),
9626 unique (Rint = 0.0284); wR(F2) = 0.1098 for all
data, 529 parameters, and 16 restraints, R(F) = 0.0493
for 7160 structure factors Fo ≥ 4σ(Fo); weighting
scheme applied: w = 1/[σ2(Fo) + (0.0512P)2], where
Single crystals of
6
(0.30 × 0.15 × 0.13 mm3)
and 15·2C3H6O (0.45 × 0.35 × 0.25 mm3) were grown
from toluene/pentane and, respectively, acetone/pentane
solvent mixtures. Diffraction measurements were made at
ambient temperature on an Enraf-Nonius CAD-4 MACH 3
diffractometer using graphite-monochromatized MoKα
˚
radiation (λ = 0.71073 A); orientation matrices and unit
P = (Fo2 +2Fc )/3; largest−p3eak and hole in final difference
CCDC 753417 (6) and CCDC 753418 (15·2C3H6O)
contain the supplementary crystallographic data for this
paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data request/cif.
2
cell parameters from the setting angles of 25 centered
medium-angle reflections; collection of the diffraction
intensities by ω scans; data empirically corrected for
˚
map: 1.746 and −1.035 e A
.
absorption using ψ scans [20] (6: Tmin = 0.349, Tmax
=
0.596; 15·2C3H6O: Tmin = 0.332, Tmax = 0.507). The
structures were solved by Direct Methods and subsequently
refined by full-matrix least-squares procedures on F2
with allowance for anisotropic thermal motion of all
non-hydrogen atoms employing the WINGX package [21]
with the programs SIR-97 [22], SHELXL-97 [23], and
ORTEP-3 [24] implemented therein. – 6: C37H29IrO2P2
(759.74); monoclinic, P21/n, a = 10.022(9), b = 14.861(4),
Acknowledgements
Support of this work by the Deutsche Forschungsgemein-
schaft (Bonn, SFB 583) is gratefully acknowledged. We are
also indebted to Mrs. S. Hoffmann for her skilful assistance.
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