DALTON FULL PAPER J. Chem. Soc., Dalton Trans., 1999, 155–159 155 Synthesis, structure and redox behaviour of facial [ReIIIL(PPh3)Cl3] and its stereoretentive conversion to [ReIVL9(PPh3)Cl3] via metal promoted aldimine æÆ amide oxidation (L 5 pyridine-2-aldimine; L9 5 pyridine-2-carboxamide) Sibaprasad Bhattacharyya, Sangeeta Banerjee, Bimal Kumar Dirghangi, Mahua Menon and Animesh Chakravorty * Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Calcutta 700 032, India Received 11th August 1998, Accepted 29th October 1998 The reaction of mer-[ReIIIL(OPPh3)Cl3] 2 with PPh3 in benzene has aVorded bluish violet fac-[ReIIIL(PPh3)Cl3] 1, where L is the SchiV base of pyridine-2-carbaldehyde and the substituted aniline p-XC6H4NH2 (X = H, Me, OMe or Cl).Geometrical preferences are rationalized in terms of the electronic nature of the ligands OPPh3 (s- and p-donor), PPh3 (s-donor and p-acceptor) and L (s-donor and p-acceptor).The cyclic voltammetric E1/2 values of 1 lie near 0.6 V (ReIV–ReIII) and 20.6 V (ReIII–ReII). Electrooxidation of 1 at 1.0 V vs. SCE in wet acetonitrile aVords yellow fac-[ReIVL9(PPh3)Cl3] 3 which is also obtainable via oxidation by dilute nitric acid (L9 is a monoanionic pyridine-2- carboxamide). Complex 3 displays ReIV–ReIII and ReV–ReIV couples near 20.2 V and 1.4 V respectively reflecting superior stabilization of the rhenium(IV) state by the amide ligand. The X-ray structures of two representative complexes of type 1 and 3 have revealed the presence of severely distorted and facially configured RePN2Cl3 coordination spheres.The average Re–Cl distance is lower by 0.06 Å in 3 due to contraction of the metal radius upon oxidation. The Re–P length is however larger by 0.1 Å in 3 signifying a weakening of Re–P back-bonding. The rhenium chemistry of SchiV bases of pyridine-2- carbaldehyde is under scrutiny in this laboratory. Facile oxygen-atom-transfer, metal-mediated ligand oxidation and stabilization of unusual rhenium moieties are among the notable features that have so far been documented.1–6 In this work we disclose a spontaneous geometrical transformation associated with ligand substitution. The reaction has aVorded a family of pyridine-2-aldimine chelates of trivalent rhenium incorporating phosphine coordination.The species are redox active and undergo facile aldimineæÆ amide oxidation. The structure and properties of the present complexes and their oxidized derivatives are described.Results and discussion Synthesis of fac-[ReL(PPh3)Cl3] 1 Four pyridine-2-aldimine ligands (L1–L4; general abbreviation is L), diVering in the X substituent have been utilized. The complexes have facial geometry (see below) and are formed upon reacting the meridional phosphine oxide complexes of type [ReL(OPPh3)Cl3] 2,1–3 with PPh3, in boiling benzene, N N H Re X Cl Cl Cl PPh3 N N H Re X Cl Cl OPPh3 Cl 1d [ReL4(PPh3)Cl3] (X = Cl) 1c [ReL3(PPh3)Cl3] (X = OMe) 1b [ReL2(PPh3)Cl3] (X = Me) 1a [ReL1(PPh3)Cl3] (X = H) 2 [ReL(OPPh3)Cl3] III III equation (1). The reaction of mer-[ReOCl3(PPh3)2] with L also furnishes 1, equation (2), but in poorer yield.mer-[ReL(OPPh3)Cl3] 1 PPh3 æÆ fac-[ReL(PPh3)Cl3] 1 OPPh3 (1) mer-[ReOCl3(PPh3)2] 1 L æÆ fac-[ReL(PPh3)Cl3] 1 OPPh3 (2) Selected spectral and magnetic characterization data for the complexes are listed in Tables 1 and 2. The magnetic moments (ª2 mB, Table 1) are lower than the spin-only value for the t2g 4 (assuming idealised octahedral geometry) configuration which is not unusual for trivalent rhenium.7 The paramagnetically shifted 1H NMR signals of 1 have been assigned (Table 2) on the basis of signal intensity, spin–spin structure and previous work.8–10 A selected portion of the 1H NMR spectrum of 1b is displayed in Fig. 1. Structure The X-ray structure of fac-[ReL1(PPh3)Cl3] 1a has been determined. A molecular view is shown in Fig. 2 and selected bond parameters are listed in Table 3. The aldimine and phosphine ligands are facially disposed and so are the chloride ligands, forming a severely distorted octahedral RePN2Cl3 coordination sphere. The chelate ring along with the pyridine ring and Cl(2), Cl(3) atoms constitute a good plane (mean deviation 0.05 Å) to which the pendent phenyl ring makes a dihedral angle of 50.18. The X-ray structures of a few ReIII–PPh3 complexes are known.8,11,12 Only one of these has the ReCl3 moiety but in a meridional configuration.8 To the best of our knowledge 1a is the first structurally characterized PPh3 complex having facial ReCl3 disposition.The Re–P distance, 2.463(2) Å in 1a is normal.8,12156 J. Chem. Soc., Dalton Trans., 1999, 155–159 Table 1 Electronic spectral,a IR b and magnetic moment data at 298 K Compound 1a [ReL1(PPh3)Cl3] UV/VIS lmax/nm (e/dm23 mol21 cm21) 1575(260), 665(2085), 525(3250), 405(2985), 300 c(10230) IR n/cm21 320, 335, 510, 700, 1600 meff /mB 2.02 1b [ReL2(PPh3)Cl3] 1575(205), 665(2345), 525(4320), 400(2840), 300 c(10865) 315, 335, 510, 700, 1590 2.10 1c [ReL3(PPh3)Cl3] 1560(370), 670(2530), 525(3820), 400(2910), 300 c(10430) 330, 510, 710, 1595 2.15 1d [ReL4(PPh3)Cl3] 1565(350), 670(2460), 525(3360), 410(2890), 310 c(10000) 320, 500, 700, 1585 2.05 3a [ReL19(PPh3)Cl3] 430(3775), 300(7350) 320, 330, 500, 710, 1600, 1640 3.32 3b [ReL29(PPh3)Cl3] 440(2900), 300(7310) 315, 330, 510, 700, 1610, 1640 3.41 3c [ReL39(PPh3)Cl3] 440(2860), 295(6940) 335, 510, 700, 1605, 1630 3.45 3d [ReL49(PPh3)Cl3] 440(3010), 295(7185) 320, 330, 500, 700, 1610, 1630 3.38 a In dichloromethane.b In KBr disc; n(R–Cl) 310–335, n(C]] N) 1590–1600, n(PPh3) 510, 700, n(C]] O) 1600–1640 cm21. c Shoulder. Geometrical preference The striking geometrical diVerence between 1 and 2 is believed to be of electronic origin. In 1, PPh3 is a p-accepting ligand, the acceptor orbital being a mixture of 3dp and P–C s* components. 13 The L ligand is also p-accepting due to the a-diimine Fig. 1 A part of the proton NMR spectrum of fac-[ReL2(PPh3)Cl3] 1b in CDCl3 solution; o-H, m-H and p-H refer respectively to ortho, meta and para protons of PPh3. Table 2 1H NMR data in CDCl3 d o-H(d) m-H(t) p-H(t) 1-H(d) 2-H(t) 3-H(t) 4-H(d) 6-H(s) 8,12-H(d) 9,11-H(d) 10-H(t) CH3(s) 1a 13.80 8.96 8.73 25.70 211.40 5.23 5.00 246.00 21.35 11.85(t) 7.70 — 1b 13.70 8.96 8.74 24.80 211.00 5.27 4.60 247.60 20.9 11.44 — 3.64 1d 13.50 8.90 8.76 26.70 211.90 5.29 4.70 243.60 21.00 11.62 —— Tetramethylsilane was used as internal standard; s = singlet, d = doublet, t = triplet. function (–N]] C–C]] N–).2,14 Trivalent rhenium is prone to backbonding. 15 Assuming idealised octahedral geometry this bonding has t2g(Re) æÆ p(P) and t2g(Re) æÆ p*(L) components in 1. Back-bonding is maximized when the acceptor ligands are facially disposed so that competition between ligands for identical metal orbitals is minimal.Fig. 2 A view of [ReL1(PPh3)Cl3] 1a; the atoms are represented by their 30% thermal probability ellipsoids. Table 3 Selected bond lengths (Å) and angles (8) for complexes 1a and 3d Re–N(1) Re–N(2) Re–Cl(1) Re–Cl(2) Re–Cl(3) Re–P N(1)–C(5) N(2)–C(6) C(5)–C(6) O(1)–C(6) N(2)–Re–N(1) N(2)–Re–Cl(2) N(1)–Re–Cl(2) N(2)–Re–Cl(1) N(2)–Re–Cl(3) N(1)–Re–Cl(1) N(1)–Re–Cl(3) Cl(2)–Re–Cl(3) Cl(2)–Re–Cl(1) Cl(3)–Re–Cl(1) N(2)–Re–P N(1)–Re–P Cl(2)–Re–P Cl(1)–Re–P Cl(3)–Re–P C(5)–N(1)–Re C(6)–N(2)–Re N(1)–C(5)–C(6) O(1)–C(6)–N(2) 1a 2.103(5) 2.083(5) 2.407(2) 2.350(2) 2.379(2) 2.463(2) 1.371(8) 1.309(8) 1.408(9) — 75.9(2) 99.5(2) 174.1(2) 87.0(2) 167.0(2) 86.3(2) 91.3(2) 93.18(7) 89.74(7) 90.46(8) 93.7(2) 97.0(2) 86.97(7) 176.70(6) 89.55(7) 115.8(4) 116.6(5) 113.5(6) — 3d 2.123(7) 2.061(7) 2.331(3) 2.300(3) 2.345(3) 2.549(3) 1.336(12) 1.349(12) 1.524(13) 1.217(11) 78.2(3) 95.1(2) 173.2(2) 90.2(2) 170.1(2) 86.0(2) 92.0(2) 94.77(11) 94.42(11) 90.53(11) 93.7(2) 90.7(2) 89.37(10) 174.29(9) 84.89(10) 114.5(6) 118.2(6) 116.3(8) 127.1(9)J.Chem. Soc., Dalton Trans., 1999, 155–159 157 The meridional geometry is expected to be favoured by steric as well as electrostatic factors. In the case of 1 these advantages are more than oVset by the superior back-bonding of the facial configuration. This does not apply to [ReL(OPPh3)Cl3] since OPPh3 is purely a donor in both s and p senses. Hence its geometry is logically meridional.It is instructive to compare the metal–ligand bond distances of 1a with those of mer- [ReL2(OPPh3)Cl3].2 The average Re–Cl length of two complexes are nearly equal (2.37–2.38 Å). However the Re–N lengths in 1a are ca. 0.06 Å longer than those in the phosphine oxide complex where L2 alone is available for back-bonding [t2g(Re) æÆ p*(L2)]. The geometrical selectivity in 1 and 2 is strong and exclusive. In no case have isomers been observed. It is noteworthy that [ReL(O)Cl3] 3 and [ReL(NAr)Cl3] 5,6 are meridional, the O and NAr ligands being pure donors like OPPh3.Upon reacting 1 with aromatic amines (ArNH2) in benzene solution in air, facile and quantitative transformation to mer-[ReL(NAr)Cl3] occurs. This reaction ( fac æÆ mer) represents a reversal of the geometrical change (mer æÆ fac) characterizing the reaction of equation (1). Metal redox: formation of [ReL9(PPh3)Cl3] 3 The fac-[ReL(PPh3)Cl3] complexes are electroactive in dichloromethane solution displaying two quasi-reversible one-electron responses in the range 20.5 to 0.7 V vs.SCE. Reduction potential data are listed in Table 4. The responses are assigned to the ReIV–ReIII (E1/2 ª 0.6 V) and ReIII–ReII (E1/2 ª 20.6 V) couples. In 2 the ReIV–ReIII couple occurs at ca. 0.3 V.3 Thus the trivalent state of rhenium is more diYcult to oxidize in 1 than in 2. This is consistent with the presence of phosphine back-bonding in 1. The red oxidized complex [ReIVL(PPh3)Cl3]1 11 can be generated in solution by coulometric oxidation of 1 in dry acetonitrile at 1.0 V.It reacts spontaneously with added water aVording the amide complex fac-[ReIVL9(PPh3)Cl3] 3, equation (3). The facial geometry is conserved in the conversion of 3 [ReIVL(PPh3)Cl3]1 1 H2O æÆ fac-[ReIVL9(PPh3)Cl3] 1 2 fac-[ReIIIL(PPh3)Cl3] 1 3H1 (3) 1 æÆ 3, vide infra. When coulometry is performed in moist acetonitrile the regenerated fac-[ReIIIL(PPh3)Cl3] complex, equation (3), is reoxidized and in this manner the whole of 1 is finally converted to 3.The total coulomb count at full conversion corresponds to the transfer of three electrons. From the electrolytic solution 3 can be isolated in excellent yields. These findings encouraged us to explore the chemical oxidation of 1 to 3. Aqueous nitric acid and hydrogen peroxide were indeed found to be very eVective. The most convenient synthesis of 3 is based on aqueous nitric acid oxidation of 1 in acetonitrile solution.Aldimine æÆ amide conversion in oxidizing aqueous environments has previously been observed 2 in the cases of 2 Table 4 Cyclic voltammetric formal potential a at 298 K Compound 1a 1b 1c 1d 3a 3b 3c 3d E2� 1 /V (DEp/mV) 20.60(100), 0.65(80) 20.61(100), 0.62(80) 20.64(100), 0.58(80) 20.59(100), 0.68(80) 20.10(80), 1.28(80) 20.15(80), 1.19(80) 20.18(80), 1.10(80) 20.06(80), 1.35(80) a Solvent, dichloromethane; scan rate, 50 mV s21; E2� 1 = 1/2 (Epa 1 Epc) where Epa and Epc are anodic and cathodic peak potentials respectively; DEp = Epc 2 Epa.Reference electrode, SCE. The concerned couples are 1–12 (ReIII–ReII), 11–1 (ReIV–ReIII), 3–32 (ReIV–ReIII), 31–3 (ReV–ReIV). and mer-[ReL(NAr)Cl3].5,6 Rate studies on 23 and on a ruthenium system 16 have demonstrated that the reaction proceeds by the addition of a molecule of water to the aldimine function polarized by metal oxidation. In the present case the oxidized metal is rhenium(IV) as in 11.Rapid oxidation of the corresponding water adduct 4 via induced transfer to two electrons 17 associated with proton dissociation, can aVord 3. Spectral and magnetic data for fac-[ReIVL9(PPh3)Cl3] 3 are listed in Table 1. The magnetic moments are lower 3 than the t2g 3 (assuming idealised octahedral geometry) spin-only value. Two strong amide stretches occur in the range 1600–1640 cm21. In dichloromethane solution 3 displays two quasi-reversible cyclic voltammetric responses in the range of 20.2 to 1.4 V corresponding to the couples ReIV–ReIII (E1/2 ª 20.2 V) and ReV– ReIV (E1/2 ª 1.4 V) (Table 4).Thus the ReIV–ReIII couple moves to lower potential by ~700 mV in going from 1 to 3 reflecting the ease of ReIII–ReIV oxidation upon amide binding. The facial geometry of 3 has been proven by structure determination of [ReL49(PPh3)Cl3] 3d (Fig. 3, Table 3). As in 1a the chelate ring, the pyridine ring and Cl(2), Cl(3) atoms are coplanar (mean deviation 0.02 Å).The pendant aryl ring makes a dihedral angle of 68.98 (50.18 in 1a) to the plane. The amide group C(5)C(6)O(1)N(2) is nearly perfectly planar. Contraction of the metal radius upon oxidation causes a ca. 0.06 Å decrease in average Re–Cl distances between 1a and 3d. For comparison we note that between a similar phosphine Fig. 3 A view of [ReL49(PPh3)Cl3] 3d; the atoms are represented by their 30% thermal probability ellipsoids. N N Re X Cl Cl Cl PPh3 O 3d [ReL4'(PPh3)Cl3] (X = Cl) 3c [ReL3'(PPh3)Cl3] (X = OMe) 3b [ReL2'(PPh3)Cl3] (X = Me) 3a [ReL1'(PPh3)Cl3] (X = H) IV N N Re X Cl Cl Cl PPh3 HO H H 4 + IV158 J.Chem. Soc., Dalton Trans., 1999, 155–159 oxide pair both the Re–Cl and Re–OPPh3 (no back-bonding) bonds contract.2 In contrast the Re–P length increases by 0.1 Å between 1a and 3d. This is primarily attributed to the weakening of Re–P back-bonding upon metal oxidation. The residual interaction is, however suYcient to sustain facial geometry in 3 which fails to isomerise even on prolonged boiling in toluene.Conclusion The fac-[ReIIIL(PPh3)Cl3] 1 family having a facially configured RePN2Cl3 coordination sphere has been synthesized via ligand displacement from mer-[ReIIIL(OPPh3)Cl3] 2. The facial geometry of 1 is a result of the optimization of Re–PPh3 and Re–L back-bonding. The electrochemical and chemical oxidation of 1 is stereoretentive and has furnished fac-[ReIVL9(PPh3)Cl3] 3 in which the rhenium(IV) state is stabilized by amide bonding.The Re–P back-bonding and bond length orders are respectively 1 > 3 and 1 < 3. Experimental Materials [ReL(OPPh3)Cl3],3 [ReOCl3(PPh3)2] 18 and pyridine-2-aldimine 19 were prepared by reported methods. The purification and drying of dichloromethane and acetonitrile for synthesis as well as for electrochemical work were done as described.20 Toluene and benzene were distilled over sodium before use.All other chemicals and solvents were of reagent grade and used as received. Physical measurements Spectra were recorded with the following equipment: electronic spectra, Hitachi 330 spectrophotometer; infrared spectra (KBr disc, 4000–300 cm21), Perkin-Elmer 783 spectrophotometer, proton NMR spectra were recorded on a Bruker FT 300 MHz spectrometer. Electrochemical measurements were done by using a PAR model 370-4 electrochemistry system as described.13b All experiments were performed at a platinum working electrode under a dinitrogen atmosphere, the supporting electrolyte being tetraethylammonium perchlorate.The potentials are referenced to the saturated calomel electrode (SCE) and are uncorrected for the junction contribution. Magnetic susceptibilities were measured on a PAR-155 vibrating sample magnetometer. Microanalyses were done by using a Perkin-Elmer 240C elemental analyser. Syntheses fac-[ReIIIL(PPh3)Cl3] 1. The complexes were prepared by the same general methods. Details are given for 1b (L = L2).To a pink solution of mer-[ReL2(OPPh3)C(100 mg, 0.14 mmol) in dry benzene (15 cm3), PPh3 (200 mg, 0.75 mmol) was added and the mixture was heated to reflux under pure nitrogen for 1 h aVording a violet solution which yielded crystalline fac- [ReL2(PPh3)Cl3] (20 mg) upon cooling to room temperature. The complex was collected by filtration and the filtrate was stripped of solvent. The residue was dissolved in a small volume of CH2Cl2 and subjected to chromatography on a silica gel column prepared in benzene.Upon elution with benzene– acetonitrile (25 : 1, 15 : 1 and 10 : 1) mer-[ReL2(OPPh3)Cl3] (18 mg), mer-[ReL2(NC6H4Me)Cl3] (7 mg) and fac-[ReL2(PPh3)Cl3] (28 mg) were successively isolated. The total yield of bluish violet fac-[ReL2(PPh3)Cl3] is 48 mg, 50%. The complex was also synthesized starting from a solution of [ReOCl3(PPh3)2] (100 mg, 0.12 mmol) in dry benzene (15 cm3) containing L2 (29 mg, 0.15 mmol).The mixture was heated to reflux under pure nitrogen for 1 h. The violet solution was stripped of solvent and the residue subjected to chromatography as described above. The yield of fac-[ReL2(PPh3)Cl3] was 37 mg, 40% (Found: C, 48.95; H, 3.25; N, 3.70. Calc. for C30H25Cl3N2PRe 1a: C, 48.87; H, 3.39; N, 3.80. Found: C, 48.68; H, 3.51; N, 3.61. Calc. for C31H27Cl3N2PRe 1b: C, 49.56; H, 3.60; N, 3.73. Found: C, 48.40; H, 3.35; N, 3.50. Calc. for C31H27Cl3N2OPRe 1c: C, 48.52; H, 3.52; N, 3.65.Found: C, 47.00; H, 3.25; N, 3.50. Calc. for C30H24Cl4N2PRe 1d: C, 46.69; H, 3.11; N, 3.63%). fac-[ReIVL9(PPh3)Cl3] 3. The same general methods were used for all the complexes. The case of 3b (L9 = L29) is detailed below. A solution of fac-[ReIIIL2(PPh3)Cl3] (20 mg, 0.027 mmol) in wet acetonitrile (20 cm3) containing tetraethylammonium perchlorate (25 mg, 0.11 mmol) was electrolyzed exhaustively under nitrogen at 1.0 V vs. SCE.The bluish violet solution changed to red and finally to yellow. The coulomb count corresponded to the transfer of three electrons, equation (4) fac-[ReIIIL(PPh3)Cl3] æÆ fac-[ReIVL9(PPh3)Cl3] 1 3H1 1 3e2 (4) (observed count, 7.25; calculated count for one electron, 2.45). The electrolyzed solution was stripped of the solvent and the residue was washed thoroughly with hot water and then dried over P4O10, yielding pure yellow fac-[ReL29(PPh3)Cl3]. The yield was 14 mg, 72%. Chemical synthesis of the complex was achieved by oxidation of fac-[ReL2(PPh3)Cl3] (50 mg, 0.067 mmol) in acetonitrile (20 cm3) by aqueous HNO3 (0.5 M, 0.5 cm3).The mixture was stirred for 1 h at room temperature aVording a yellow solution [hydrogen peroxide (0.5 cm3, 30%) requires 12 h stirring in an ice bath]. The solvent was removed and the residue washed and dried as above, yielding fac-[ReL29(PPh3)Cl3]. The yield was 40 mg, 80% (Found: C, 47.80; H, 3.25; N, 3.60. Calc. for C30H24Cl3N2OPRe 3a: C, 47.89; H, 3.19; N, 3.73.Found: C, 48.80; H, 3.25; N, 3.50. Calc. for C31H25Cl3N2OPRe 3b: C, 48.58; H, 3.40; N, 3.66. Found: C, 47.50; H, 3.42; N, 3.45. Calc. for C31H26Cl3N2O2PRe 3c: C, 47.59; H, 3.33; N, 3.58. Found: C, 46.00; H, 2.80; N, 3.65. Calc. for C30H23Cl4N2OPRe 3d: C, 45.79; H, 2.93; N, 3.56%). Conversion of fac-[ReIIIL2(PPh3)Cl3] to mer-[ReVL2(NC6H4Me)- Cl3] A solution of fac-[ReL2(PPh3)Cl3] (50 mg, 0.067 mmol) in toluene (10 cm3) was heated to reflux for 1 h in the presence of p-toluidine (35 mg, 0.33 mmol).The violet solution was stripped of solvent and the residue was subjected to chromatography on a silica gel column using benzene–acetonitrile (15 : 1) as the eluent. The complex mer-[ReL2(NC6H4Me)Cl3] was isolated (yield 35 mg, 88%) by removing the solvent. Crystallography Dark prismatic crystals of 1a and orange prismatic crystals of 3d were grown by slow diVusion of hexane into dichloromethane solutions of the respective complexes.Cell parameters were determined by a least-squares fit of 30 machine-centered reflections (2q = 15–308). Data were collected by the w-scan technique in the range 3 < 2q < 458 for 1a and 3 < 2q < 478 for 3d on a Siemens R3m/V four-circle diVractometer with graphite-monochromated Mo-Ka radiation (l = 0.71073 Å). Two check reflections after every 198 showed no intensity reduction. All data were corrected for Lorentzpolarization and absorption.21 The metal atoms were located from Patterson maps, and the rest of the non-hydrogen atoms emerged from successive Fourier syntheses.The structures were then refined by a full-matrix least-squares procedure on F 2. All non-hydrogen atoms [except O(2) for 3d] were refined anisotropically. All hydrogen atoms were included in calculatedJ. Chem. Soc., Dalton Trans., 1999, 155–159 159 Table 5 Crystal data for [ReIII L1(PPh3)Cl3] 1a and [ReIVL49(PPh3)Cl3] 3d Complex Formula M Crystal size/mm Crystal system Space group (no.) a/Å b/Å c/Å a/8 b/8 g/8 U/Å3 Z Dc/g cm23 m(Mo-Ka)/cm21 F(000) Transmission coeYcient Total reflections Number unique reflections (Rint) Number observed reflections [I > 2s(I)] Data/restraints/parameters R1,a wR2b [I > 2s(I)] R1, wR2 (all data) Goodness of fit on F2 Maximum and mean D/s Maximum, minimum diVerence peaks/e Å23 1a C30H25Cl3N2PRe 737.04 0.5 × 0.2 × 0.15 Monoclinic P21/n (14) 11.505(6) 13.545(5) 18.720(11) — 97.66(4) — 2891(3) 4 1.693 45.58 1440 0.56/1.00 4105 3801 (0.03) 3065 3797/0/334 0.0316, 0.0680 0.0485, 0.0851 1.040 0.002/0.000 0.672, 20.849 3d C30H23Cl4N2OPRe?H2O 804.49 0.42 × 0.32 × 0.2 Triclinic P1� (2) 9.994(6) 11.617(6) 15.135(9) 76.26(4) 88.11(5) 67.40(4) 1573(2) 2 1.699 42.85 786 0.53/1.00 4733 4663 (0.051) 4054 4652/0/357 0.0506, 0.1319 0.062, 0.1554 1.153 0.002/0.000 3.087, 21.727 a R1 = S Fo| 2 |Fc /S|Fo|.b wR2 = [Sw(Fo 2 2 Fc 2)2/Sw(Fo 2)2]� �� . positions. 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