Synthesis of Heavy Cyclodipnictadiphosphanes [ClE (Î¼-P-Ter)] 2 [E= P

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Synthesis of Heavy Cyclodipnictadiphosphanes [ClE(μ-P-Ter)]2 [E = P, As, Sb, or Bi; Ter = 2,6-bis(2,4,6-trimethylphenyl)phenyl] Alexander Hinz,† Axel Schulz,*,‡,§ and Alexander Villinger‡ †

Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K. Institut für Chemie, Abteilung Anorganische Chemie, Universität Rostock, Albert-Einstein-Straße 3a, 18059 Rostock, Germany § Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Abteilung Materialdesign, Albert-Einstein-Straße 29a, 18059 Rostock, Germany ‡

S Supporting Information *

ABSTRACT: A complete series of terphenyl-substituted 1,3-dichloro-1,3-dipnicta-2,4-diphosphanes {[ClE(μ-P-Ter)]2, where E = P, As, Sb, or Bi and Ter = 2,6-bis(2,4,6-trimethylphenyl)phenyl} was prepared and fully characterized. While the heavy derivatives with E = Sb or Bi can be accessed via conversion of silylated phosphanes with amino-dichloropnictanes and subsequent elimination of TerNH2, the lighter congeners could be prepared only by a metathesis reaction of [ClBi(μ-P-Ter)]2 with PCl3 and AsCl3. Spectroscopic and structural data indicate the existence of cis and trans isomers of [ClP(μ-P-Ter)]2 in contrast to all heavier derivatives, for which only the trans isomer was obtained.

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INTRODUCTION Small inorganic ring systems have attracted the interest of researchers for decades. The undiminished interest in this class of compounds is reflected in an excellent review article by Rivard et al.1 Structural features, reactivity, and bonding modes of small ring systems appeal for both theoretical and practical reasons. Our work is focused on group 15 element heterocycles. Among these cyclodiphosphadiazanes are best known, as there are numerous examples and their chemistry has been explored well.2,3 However, reports of four-membered all pnictogen rings composed without nitrogen as a ring atom are scarce. Several studies of cyclotetraphosphanes have been conducted,4,5 but 1,3-dihalo-tetraphosphanes could not be accessed until recently. Wiberg et al. reported on [ClP(μ-P-SitBu3)]2 in 2002, but it could not be isolated (Scheme 1).6 Later, Lerner et al. were

Scheme 2. Selected Bicyclic Tetraphosphanes and Heavier Homologues {R = Mes*, ArDipp, or Ter; R′ = Ga(HC[C(Me)N(2,6-iPrC6H3)2]NMe2)}

Scheme 1. Known 1,3-Dihalo-1,3-dipnicta-2,4-diphosphanes

activation of white phosphorus by a “dithallene”, [ArDipp-Tl]2 [ArDipp = 2,6-bis(2,6-diisopropylphenyl)phenyl],14 and bulky lithiated aryl moieties, Mes*Li or TerLi [Ter = 2,6-bis(2,4,6trimethylphenyl)phenyl], respecitvely.15 The heavier congeners, such as cyclodiarsadiphosphanes, are found even more infrequently;16−18 e.g., Power et al. reported on the structure of the corresponding [1.1.0]bicycle [As(μ-PMes*)]2 and the heavier congener [Sb(μ-P-Mes*)]2 (Scheme 2).19 Futhermore, [1.1.0]bicyclic tetraarsane bearing tert-butyl substituents had already been generated by Baudler et al.,20 while the [1.1.0]bicyclic tetrastibane was published only recently by S. Schulz et al. featuring a bulky gallyl substituent.21 The halogenated four-membered heterocycles of the type [ClE(μ-P-Ter)]2 were hitherto unknown for E = As, Sb, or Bi

able to isolate and fully characterize [IP(μ-P-SitBu3)]2.7 Just recently, [ClP(μ-P-Mes*)]2 [Mes* = 2,4,6-tri(tert-butyl)phenyl] could be isolated and utilized for further reactions by our group.8,9 Frequently observed cyclic group 15 species are [1.1.0]bicyclic systems (Scheme 2),10 featuring either a symmetric or an asymmetric substitution pattern as shown by means of NMR spectroscopy6,11 and diffraction methods.12,13 Interestingly, the most recent reports of [1.1.0]bicyclic tetraphosphanes from the groups of Power and Lammertsma were the result of the © XXXX American Chemical Society

Received: February 3, 2016

A

DOI: 10.1021/acs.inorgchem.6b00218 Inorg. Chem. XXXX, XXX, XXX−XXX

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Inorganic Chemistry and had not been isolated for E = P. Herein, we report on their synthesis and full characterization to close this gap in main group chemistry. [ClE(μ-P-Ter)]2 compounds stabilized by a bulky terphenyl substituent can be versatile starting materials for numerous important reactions, e.g., reduction, halide abstraction, or halide addition, leading to the formation of biradicaloids, cations, and radical cations.

Scheme 3. Reaction of Amino-dichlorophosphane 1P with Silylated Phosphane 2

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RESULTS To generate the desired [ClE(μ-P-Ter)]2 (E = P, As, Sb, or Bi) compounds, we followed two strategies of E−P bond formation: (i) the reaction of aminopnictanes with silylated phosphanes as depicted in Schemes 3−5 and (ii) the metathesis reaction of heavy [ClE(μ-P-Ter)]2 (E = Sb or Bi) with PCl3 or AsCl3 (Scheme 6). Synthesis and Reactivity of Amino-phosphino-chloropnictanes R(H)N-E(Cl)-P(H)R. Terphenylamino-dichloropnictanes 1E [E = P, As, Sb, or Bi (Schemes 3−5)] were readily obtained in good yields (>75−95%) by adding a solution of ECl3 in diethyl ether to a solution of TerNHLi in diethyl ether.22,23 Silylated terphenylphosphane (2, TerPHSiMe3) was afforded by reaction of TerPH2 with nBuLi in THF and quenching of in situ-generated TerPHLi with Me3SiCl (80% yield). With 1E and 2 in hand, it was now possible to study the elimination of Me3SiCl with simultaneous E−P bond formation (Schemes 3−5) upon combining both compounds, resulting in the formation of chloro-amino-phosphino-pnictanes, Ter(H)NE(Cl)-P(H)Ter (3E). Species 3E always occurred as a mixture of two diastereomers, arising from the fact that both E and P atoms represent chiral centers. These diastereomers can easily be distinguished by means of NMR spectroscopy. Selected characteristic NMR data are given in Table 1. Aided by DFT

weeks in boiling benzene, there was still starting material left. In contrast, in dichloromethane after 12 h, ∼50% conversion was observed. As dominant species we identified 3P [(R,S) isomer, +134.5 (JPH = 18 Hz, JPH = 10 Hz), −52.5 (1JPP = 192 Hz, 1JPH = 203 Hz, 2JPH = 10.4 Hz); (R,R) isomer +131.5 (JPH = 21 Hz, JPH = 10 Hz), −27.1 (1JPP = 250 Hz, 1JPH = 223 Hz, 2JPH = 10.4 Hz)] besides several other side products, e.g., the aminodiphosphene Ter−PP−N(H)−Ter [+480.2, +306.5 ppm; 1 JPP = 546 Hz, 2JPH = 10.4 Hz; cf. Ter−PP−Mes*, +526.2, 455.5 ppm; 1JPP = 572 Hz; Mes*N(H)PPMes*, +316.2, +450.0 ppm, 1JPP = 532 Hz, 2JPH = 8.4 Hz]26−28 and TerPH2 (−147.1 ppm). Because no pure product could be isolated from the reaction mixtures, this reaction pathway was not further pursued (vide infra metathesis reaction). In the case of the heavier homologue 1As, in the reaction with 2 in dichloromethane, initially 3As was formed in high yields (according to NMR data) and could be isolated as pale yellowish crystalline material in good yields [70% (Scheme 4 Scheme 4. Reaction of Amino-dichloroarsane 1As with Silylated Phosphane 2

Table 1. Selected NMR Spectroscopic Data of 3E (J in hertz, δ in parts per million)a δ[31P] b

(R,R)-3P (R,S)-3P (R,R)-3As (R,S)-3As (R,R)-3Sb (R,S)-3Sb (R,R)-3Bi (R,S)-3Bi

−27.1 −52.5 −34.1 −47.6 −62.7 −79.0 −41.6 −64.6

(244, 216) (198, 198) (218) (198) (209) (194) (199) (184)

δ[1H] (PH) 3.91 3.81 3.84 3.28 4.11 3.27 3.76 −d

(216, 18) (202, 19) (215) (196) (211) (190) (200)

δ[1H] (NH) 4.88 (8.5, 7.2) 4.68 (8.7, 3.8) 4.81 (1.9) 4.63 (2.8) 4.97c 4.88c 5.34c −d

and Figure 1)]. In solution, both the (R,S) and (R,R) isomers were detected according to NMR data (cf. Table 1). Treatment of a solution of 3As with a base such as Et3N led to an orange solution, in which Ter−PAs−N(H)−Ter was the dominant species according to 31P NMR data (singlet at +412.4 ppm). After 24 h, the solution became discolored and the formation of several other compounds, among them 5As (see section 2.8 of the Supporting Information), was observed; however, only TerNH2 and [(TerNH)2AsCl] could be isolated. In benzene, the reaction of 1As with 2 was very slow. However, upon heating or with a prolonged reaction time in solution, [1.1.0]bicyclic 4As was formed and could be isolated in moderate yield [47% (Figure 1)]. For 4As, one resonance was observed in the 31P NMR spectrum (−142.8 ppm), indicating either a rigid system or fast interconversion between exo-exo and endo-exo 4As, as found by Power et al. Actually, the Power group was able to isolate both isomers of exo-exo and endo-exo [P(μ-P-ArDipp)]2 but observed only one set of signals by solution 31P NMR spectroscopy.14 The 31P NMR resonances

a

JPP and JPH couplings are given in parentheses. JPP couplings in italics. Assignment of the isomers based on comparison with DFT computations. cJPH not resolved. dNot unambiguously assignable, because several other intermediary species are superimposed.

b

computations,24,25 the more high-field-shifted resonance in the 31 P NMR spectrum was assigned to the (R,S) isomer (cf. Table S5). It is worth mentioning that computations indicate that for all examples of 3E both diastereomers are very similar in energy, but the (R,S) isomer becomes more favorable in the following order: P (+3 kJ mol−1) < As (−5 kJ mol−1) < Sb (−9 kJ mol−1) < Bi (−10 kJ mol−1). Nonetheless, because the differences in energy are rather small, it is no surprise that both isomers were experimentally observed. The reactivity of 1E with 2 is strongly dependent on the chosen solvent. Reaction of 1P with 2 requires very harsh conditions to proceed at all (Scheme 3). For example, after 4 B


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Inorganic Chemistry

(Scheme 5 and Figure 2)]. Again NMR studies also confirmed the existence of both (R,S) and (R,R) species in solution (cf. Scheme 5. Reaction of Amino-dichlorostibane 1Sb with Silylated Phosphane 2

Figure 2. Molecular structure of 3Sb. Thermal ellipsoids are drawn at 50% probability (173 K). Selected bond lengths (angstroms) and angles (degrees): P−Sb 2.5429(6), Sb−N 2.031(2), Sb−Cl 2.409(1), N−Sb−Cl 97.45(6), N−Sb−P 87.53(5), Cl−Sb−P 92.86(2).

Table 1). In the vibrational spectra of 3As, two νPH vibrations could be observed (Raman, 2307, 2344 cm−1; IR, 2308, 2343 cm−1), but only one νNH mode (Raman, 3301 cm−1; IR, 3298 cm−1). The νNH vibration was shifted to a higher wavenumber in 3Sb (Raman, 3312 cm−1; IR, 3309 cm−1), while the νPH modes were found at lower wavenumbers (Raman, 2293, 2328 cm−1; IR 2295, 2330 cm−1). The formation of 5Sb starting from 3Sb can also be triggered by addition of a base; however, depending on the utilized base, different products were obtained (Scheme 5). When triethylamine was used, 5Sb could be isolated in a moderate yield (41%), while addition of stoichiometric amounts of DBU (1,8diazabicyclo[5.4.0]undec-7-ene) led to the formation of the salt [DBU-H]+[ClSb(μ-P-Ter)2SbCl2]− (6, 39% yield). Formation of [DBU-H]+ salt 6 indicates that the formation and precipitation of DBU·HCl as a driving force was not sufficient to form 5Sb but the formal addition product of both, namely 6. The 31P NMR spectra of 5Sb and 6 displayed as expected one resonance (5Sb, −38.6 ppm; 6, −47.6 ppm), which appeared at higher field compared to that of 5As (δ[31P] = 1.8 ppm). Single-crystal X-ray diffraction studies revealed puckered fourmembered rings for 5Sb and 6 (Figure 3). However, while 5Sb adopts an endo-exo conformation with respect to the two chlorine atoms, in the anion of 6 the formal [ClSb(μ-P-Ter)]2 ring features an exo-exo arrangement forced by the endo

Figure 1. Molecular structure of 3As (123 K, top) and 4As (173 K, middle along with the disordered core, bottom). Thermal ellipsoids are drawn at 50% probability. Selected bond lengths (angstroms) and angles (degrees): 3As, P−As 2.3574(5), As−N 1.838(2), As−Cl 2.2479(6), N−As−Cl 100.40(5), N−As−P 89.97(5); 4As, As1−P2 2.340(3), As1−P1 2.354(3), As1−As2 2.431(3), As2−P2 2.309(2), As2−P1 2.314(3), P2−As1 P1 78.44(9), P2−As2−P1 79.89(8).

of 4As was found to be high-field-shifted compared to the known [As(μ-P-Mes*)]2 [−98.4 ppm (Scheme 2)] for which no endo-exo isomer is known. The molecular structure of 4As [fold angle of 96.39(8)°, As−As distance of 2.467(3) Å, averaged P−As distance of 2.34 Å] compares well to the known structure of [As(μ-P-Mes*)]2 (e.g., fold angle of 94.6°, averaged P−As distance of 2.35 Å).19 However, the transannular As−As bond length in 4As [As−As distance of 2.467(3) Å] is considerably longer than that in [As(μ-PMes*)]2 [As−As distance of 2.383(1) Å; cf. ∑rcov(As−As) = 2.42 Å]29 due to stronger Pauli repulsion between the two terphenyl substituents.30 In the reaction of amino-dichloro-stibane 1Sb with the silyated phosphane 2, amino-phosphino-chloro-stibane 3Sb was obtained as yellow crystalline material from benzene as well as from dichloromethane solutions after 2 h in good yields [51% C


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Inorganic Chemistry

Scheme 6. Reaction of Amino-dichlorobismuthane 1Bi with Silylated Phosphane 2

The molecular structure of 5Bi and 5Bi·BiCl3 revealed a puckered four-membered heterocycle with one Cl atom in endo and the other one in exo position. The Bi−P bond lengths within the ring system amount to 2.633 and 2.635 Å (averaged values), respectively, in accord with Bi−P single bonds [cf. ∑rcov(Bi−P) = 2.62 Å].29 Von Hänisch et al. published a series of cage compounds bearing Bi−P−Bi units, all displaying Bi−P distances in the range of 2.62−2.66 Å.18,33 Interestingly, the Bi3−P adduct bonds [Bi3−Cl2, 3.051(2) Å; Bi3−P1, 3.083(2) Å] in 5Bi·BiCl3 are significantly shorter than the sum of the van der Waals radii [cf. ∑rvdW(Bi···P) = 3.87 Å]34 but longer than the sum of the covalent radii for a single bond [cf. ∑rcov(Bi−P) = 2.62 Å].29 The same holds true for the Bi3−Cl2 interaction [3.051(2) Å (Figure 4)], which is considerably longer than all the other classical Bi−Cl bonds within the [ClSb(μ-NTer)]2 and BiCl3 fragments [Figure 4; 5Bi·BiCl3, Bi−Cl distances between 2.488(2) and 2.647(2) Å; cf. 5Bi, 2.5724(8) and 2.5405(8) Å]. Thus, the coordination around the Bi3 atom of the BiCl3 Lewis acid is best described as [3+3] or a strongly distorted octahedral geometry [cf. Cl5−Bi3−Cl2, 148.61(5)°; Cl4−Bi3−P1, 167.51(6)°; Cl3−Bi3−P2, 162.40(5)°]. Metathesis Reactions of Dichloro-dipnicta-diphosphanes. To gain access to 5P and 5As, a metathesis reaction starting from the heavier congeners 5Sb and 5Bi with PCl3 and AsCl3, respectively, was investigated (Scheme 7).31,35 Indeed, metathesis was possible in both cases; however, the driving force of precipitating BiCl3 when employing 5Bi greatly increases the reaction rate. Already after 5 min at ambient temperature, 5Bi was fully converted. In the 31P NMR spectrum, 5P was observed as a mixture of cis (A2B2 spin system; +13.3, +99.9 ppm; |1JPP| = 198 Hz) and trans isomers (A2MX spin system; −2.4, +82.7, +120.0 ppm; |JAM| = 208 Hz, | JAX| = 213 Hz, |JMX| = 16 Hz), in good agreement with the previously reported values.8 After 1 h, 74% of the targeted compound 5P was present in the reaction mixture (Figure 5, top spectra), besides 7% [1.1.0]bicyclic tetraphosphane [P(μ-PTer)]2, 4% TerPCl2, 14% intermediary species, which can be assigned as TerP(PCl2)ECl2, and 1% byproduct TerP(PCl2)Cl [these and all following assignments are based on comparison of the observed NMR data and computed values only (cf. Table S7)]. Prolonged stirring did not increase the yield of 5P but caused an increase in the amount of bicyclic tetraphosphane and even more side products such as TerPHCl (Figure 5, top spectrum). In contrast, the reaction of 5Sb with PCl3 to 5P proceeded considerably slower. Despite the fact that 5Sb was also consumed very fast and could not be observed in the mixture

Figure 3. Molecular structure of 5Sb (top) and 6 (bottom, without the [DBU-H]+ counterion). Thermal ellipsoids are drawn at 50% probability (123 K). Selected bond lengths (angstroms) and angles (degrees): 5Sb, Sb1−Cl1 2.4441(6), Sb1−P2 2.5228(6), Sb1−P1 2.5294(6), Sb2−Cl2 2.4100(6), Sb2−P2 2.5415(6), Sb2−P1 2.5521(5), P2−Sb1−P1 77.94(2), Sb1−P1−Sb2 85.91(2); 6, Sb1− Cl2 2.5415(6), Sb1−P1 2.5503(6), Sb1−P2 2.5538(6), Sb1−Cl3 2.8131(6), Sb2−Cl1 2.4816(6), Sb2−Cl3 3.0362(7), Sb2−P2 2.5433(6), Sb2−P1 2.5542(6), P1−Sb1−P2 83.71(2), Sb1−P1−Sb2 84.31(2), Cl2−Sb1−Cl3 173.30(2).

bridging Cl− ion. The endo-Sb1−Cl1 bond [2.4441(6) Å] in 5Sb is only slightly longer than the exo-Sb2−Cl2 bond [2.4100(6) Å], but both are much shorter than the exo Sb− Cl distances in 6 [Sb2−Cl1, 2.4816(6) Å; Sb1−Cl2, 2.5415(6) Å], which might be attributed mainly to the larger coordination number in 6. As expected, the bridging chloride in 6 (Cl3) features Sb−Cl distances [2.8131(6) Å, 3.0362(7) Å; cf. ∑rcov(Sb−Cl) = 2.39 Å]29 considerably longer than any of the other Sb−Cl bonds of 5Sb or 6 that fall well within the range of those of known compounds, e.g., [ClSb(μ-NTer)]2 [2.4321(4) Å] or 3Sb [2.409(1) Å (Figure 2)].31All Sb−P bond lengths in 5Sb and 6 are almost identical (averaged values of 2.54 and 2.55 Å, respectively) and in the range of a typical single bond {2.49−2.56 Å in [Sb4(PSiMe2Thex)4] and [Sb2(PSiPh2tBu)4], where Thex = CMe2iPr;32 cf. ∑rcov(Sb−P) = 2.39 Å}.29 In contrast to the lighter congeners, 3Bi had a fleeting existence because it was detected only as a transient intermediate in the NMR spectra (Scheme 6). Its decomposition/transformation was essentially complete after 1 h in solution; however, depending on the solvent, different products could be isolated. When the reaction was conducted in dichloromethane, 5Bi was afforded in moderate yields (43%), while the reaction in benzene yielded the adduct 5Bi·BiCl3, which could be isolated after recrystallization from dichloromethane in rather low yields (21%). As found for 5Sb, crystalline 5Bi was composed exclusively of the trans isomer, which was reflected in the existence of only one 31P NMR resonance for both species, as well (5Bi, −21.6 ppm; 5Bi·BiCl3, −8.4 ppm; cf. 5Sb, −38.6 ppm). D


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Inorganic Chemistry

Figure 5. 31P NMR spectra of the metathesis reaction mixtures of 5E (E = Sb or Bi) with PCl3. Proposed intermediates and products: [ClE(μ-P-Ter)2PCl] (green), TerP(PCl2)ECl2 (gray), TerP(PCl2)Cl (orange), TerPCl2 (yellow), trans-5P (light blue), cis-5P (dark blue), and TerPHCl (red). Omitted signals in the top three spectra: [P(μ-PTer)]2 (triplets at −322.3 and −171.3 ppm; JPP = 182 Hz).

methathesis reactions. Ter−PE−Cl can easily add PCl3 to form Ter−P(ECl2)PCl2, from which ECl3 can be eliminated, affording Ter−PP−Cl as a short-lived intermediate. Finally, thermodynamically favored dimerization leads to the formation of 5P. However, no detailed investigations regarding the mechanism were conducted, and it will be the subject of future studies. As mentioned above, a major drawback of this synthetic approach is the formation of [1.1.0]bicyclic [P(μ-P-Ter)]2 (4P) as a side product. As reported previously by Power et al., [P(μP-ArDipp)]2, for 4P only one set of signals was observed, even though endo-exo and exo-exo isomers can exist. From the mixture of 4P and 5P, crystallization of 5P was difficult, even though the yield was high according to 31P NMR data, and thus, the isolated yield of 21% for cis-5P (Figure 6) was rather poor and the trans isomer could not be isolated. However, the metathesis route represents the first feasible synthetic approach to [ClP(μ-P-Ter)]2 (5P), because the “classic” route via TerPH2 and PCl3 and the base-induced elimination of HCl afforded another isomer of Ter2P4Cl2 [TerP3(Cl)P(Cl)Ter].8 By thermal rearrangement of TerP3(Cl)P(Cl)Ter, only spectroscopic evidence of the formation of 5P could be obtained. The metathesis reaction of 5Bi with AsCl3 proceeded similarly fast. After 1 h, 85% of the target compound 5As was observed in solution (δ[31P] = +1.8 ppm); nonetheless, crystallization was a limiting factor for the isolation of 5As, leading to a poor isolated yield (17%). It is interesting to note that only one signal for 5As was observed in the 31P NMR spectrum, in accordance with the presence of one isomer in solution. X-ray structure elucidation of 5E (E = P or As) revealed the typical puckered four-membered heterocycle; however, in the case of 5P, the cis (exo-exo) isomer was found, while for 5As, the trans (endo-exo) isomer was found. cis-5P exhibits P−P distances in the expected range for covalent P−P single bonds [2.227(1)−2.236(1) Å; cf. ∑rcov(P−P) = 2.22 Å].29 The P2As2 scaffold in 5As features slightly shorter P−As bonds [2.3346(7)−2.3520(7) Å], in accord with those found in [(Me3Si)2C(H)As(μ-PSi(iPr)Ph)2]2 [cf. 2.353(1), 2.373(1) Å].18

Figure 4. Molecular structure of 5Bi (top) and 5Bi·BiCl3 (bottom). Thermal ellipsoids are drawn at 50% probability (123 K). Selected bond lengths (angstroms) and angles (degrees): 5Bi, Bi1−Cl1 2.5724(8), Bi1−P2 2.6098(8), Bi1−P1 2.6253(7), Bi1−Bi2 3.5857(2), Bi2−Cl2 2.5405(8), Bi2−P1 2.6408(7), Bi2−P2 2.6564(7), P2−Bi1−P1 77.08(2), Bi1−P1−Bi2 85.83(2); 5Bi·BiCl3, Bi1−P1 2.622(2), Bi1−P2 2.633(2), Bi1−Cl1 2.647(2), Bi1−Bi2 3.5974(4), Bi2−P2 2.642(2), Bi2−P1 2.643(2), Bi2−Cl2 2.646(2), Bi3−Cl3 2.488(2), Bi3−Cl4 2.505(2), Bi3−Cl5 2.565(2), Bi3−Cl2 3.051(2), Bi3−P1 3.083(2), P1−Bi1−P2 80.71(5), Bi1−P1−Bi2 86.20(4), Cl5−Bi3−Cl2 148.61(5), Cl4−Bi3−P1 167.51(6), Cl3− Bi3−P2 162.40(5).

Scheme 7. Metathesis Reactions of 5E with PCl3 and AsCl3

after 1 h (Figure 5, bottom spectra), the dominant resonances were assigned to [ClP(μ-P-Ter)2SbCl]2 (83%; +214, −23.7 ppm; 1JPP = 250 Hz) and TerP(PCl2)SbCl2 (13%; +198.7, −19.0 ppm; 1JPP = 260 Hz), besides only miniscule amounts of other side products (1% TerPHCl, 3% TerPCl2). Even after 24 h at ambient temperature, only 47% of 5P had been formed, while the majority was still at the state of intermediates, among them [ClP(μ-P-Ter)2SbCl]2 (31%) and TerP(PCl2)SbCl2 (5%). Furthermore, the side products TerPHCl (6%), Ter2P4 (6%), TerP(PCl2)Cl (1%), and TerPCl2 (4%) were already present in these mixtures (Figure 5, bottom spectra). The rather large number of intermediates observed by 31P NMR spectroscopy (Figure 5) led to the assumption that these metathesis reactions proceed via a stepwise exchange of [ECl] by [PCl]/[AsCl] moieties. Presumably, dissociation of 5E into monomeric Ter−PE−Cl is one of the key steps in these E


Inorganic Chemistry

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CONCLUSION In summary, amino-phosphino-chloropnictanes (3E) could be synthesized by reaction of amino-dichloropnictanes with silylated phosphanes. Exploiting TerNH2 as a leaving group from amino-phosphino-chloropnictanes (3E) allowed the synthesis of the whole 5E series for E = P, As, Sb, or Bi. The heavier species, 5Sb and 5Bi, could be isolated directly after elimination of the amine. In contrast, for the lighter congeners 5P and 5As, a metathesis reaction starting from 5Bi was utilized. While for 5P both cis and trans isomers were observed, for all heavier congeners only the trans isomer could be detected, in accord with computational data. Formal addition of chloride ion to 5Sb afforded an unprecedented anionic species in 6, which is a plausible intermediate in cis−trans isomerization processes of the investigated dichloro-1,3-dipnicta-2,4-diphosphanes [ClE(μ-P-Ter)]2. These dihalogenated cyclodipnicta2,4-diphosphane derivatives can be the basis for systematic investigations of cationic, anionic, reduced, or oxidized derivatives of the P2E2 heterocycles.

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Figure 6. Molecular structures of 5P and 5As. Thermal ellipsoids are drawn at 50% probability (123 K). Selected bond lengths (angstroms) and angles (degrees): 5P, Cl1−P2 2.072(1), Cl2−P4 2.079(1), P1− C1 1.852(3), P1−P2 2.227(1), P1−P4 2.230(1), P2−P3 2.231(1), P3−P4 2.236(1), P2−P1−P4 84.15(4), P1−P2−P3 84.53(4); 5As, P1−As1 2.3346(7), P1−As2 2.3498(7), P2−As1 2.3367(7), P2−As2 2.3520(7), As1−Cl1 2.2681(8), As2−Cl2 2.2208(7), As1−P1−As2 84.23(2), P1−As1−P2 78.93(2).

EXPERIMENTAL SECTION

All manipulations were conducted under oxygen- and moisture-free conditions under argon using standard Schlenk or drybox techniques. 31 1 P{ H}, 13C{1H}, and 1H NMR spectra were recorded on BRUKER AVANCE 250, AVANCE 300, and AVANCE 500 spectrometers, respectively. The 1H and 13C NMR chemical shifts were referenced to the solvent signals.5 The 31P NMR chemical shifts are referenced to H3PO4 (85%). For CHN analysis, an Analysator Flash EA 1112 system from Thermo Quest was used. For IR, a Nicolet 380 FT-IR instrument with a Smart Orbit ATR module was used. For Raman experiments, a LabRAM HR 800 Horiba Jobin YVON system equipped with a High Stability BX40 Microscope (focus of 1 μm) or an Olympus Mplan 50× NA 0.70 lens was used, and the laser was variable and was chosen prior to the measurement. For DSC, a DSC 823e instrument from MettlerToledo (heating rate of 5 °C/min) was used. For MS, a Finnigan MAT 95-XP instrument from Thermo Electron was used. X-ray Structure Determination. X-ray quality crystals of all compounds were selected in a Fomblin YR-1800 perfluoroether (Alfa Aesar) at ambient temperatures. The samples were cooled to 123(2) K during measurement. The data were collected on a Bruker Apex Kappa-II CCD diffractometer or on a Bruker-Nonius Apex X8 CCD diffractometer using graphite monochromated Mo Kα radiation (λ = 0.71073). The structures were determined by direct methods (SHELXS-2013) and refined by full-matrix least-squares procedures (SHELXL-2013). Semiempirical absorption corrections were applied (SADABS). All non-hydrogen atoms were refined anisotropically, and hydrogen atoms were included in the refinement at calculated positions using a riding model. Additional information can be found in the Supporting Information. Synthesis of 3As. Colorless TerPH(SiMe3) (200 mg, 0.478 mmol) and colorless TerNHAsCl2 (226 mg, 0.476 mmol) were combined as solids. Then, 10 mL of dichloromethane was added, and the solution was stirred for 2 h. Afterward, the solution was concentrated to incipient crystallization (1 mL) and stored at 4 °C overnight, affording pale yellowish crystals of 3As. The supernatant was removed via syringe, and the crystals were dried in vacuo (261 mg, 0.333 mmol, 70%): mp 94 °C dec. Elemental analysis for C48H52NPAsCl found (calcd): C 73.00 (73.51), H 6.60 (6.68), N 1.49 (1.79). For the (R,R) isomer: 1H NMR (298 K, C6D6, 250.1 MHz) δ 4.29 (d, JPH = 216 Hz), 5.19 (d, JPH = 2.1 Hz); 31P NMR (298 K, C6D6, 121.5 MHz) δ −32.7 (d, JPH = 218 Hz). For the (R,S) isomer: 1H NMR (298 K, C6D6, 250.1 MHz) δ 3.59 (d, JPH = 193 Hz), 5.01 (d, JPH = 3.6 Hz); 31P NMR (298 K, C6D6, 121.5 MHz) δ −47.7 (d, JPH = 193 Hz); IR (ATR) 2343 (w), 3297 (w) cm−1; Raman (632 nm) 2306 (4), 2343 (23), 3300 (11) cm−1. Synthesis of 4As. Colorless TerPH(SiMe3) (191 mg, 0.457 mmol) and colorless TerNHAsCl2 (217 mg, 0.458 mmol) were

The potential energy surface of 5E was studied by means of DFT computations.24,25 The trans isomer of all considered species 5E is energetically favored over the cis isomer (cf. Table S6). The difference between the isomers increases in the following order: P (0.2 kJ mol−1) < As (11 kJ mol−1) < Sb (23 kJ mol−1) < Bi (27 kJ mol−1). Because the cis isomer of 5P was observed, it is likely that it can be formed for the heavier congeners, as well. Provided the activation barrier is sufficiently low, rapid interconversion from the cis to trans isomer could explain the observation of only one isomer of 5As, 5Sb, and 5Bi. Possibly, the reaction occurs via ionic intermediates like the [ClSb(μ-P-Ter)SbCl2]− anion in compound 6, and subsequent addition and elimination of Cl− could be the key step. Let us have a closer look at the bonding situation of the intriguing 5Bi·BiCl3, which can be regarded as a donor− acceptor complex between [ClBi(μ-P-Ter)]2 and BiCl3. This donor−acceptor bond exhibits only a small covalent character, as indicated by the Wiberg bond indices (WBI) of the P−Bi bonds of 0.18 and 0.20, respectively. In contrast, the P−Bi bonds within the [ClBi(μ-P-Ter)]2 ring display WBIs between 0.89 and 0.91 (0.91 and 0.97 in 5Bi), in accord with the experimental structural data indicating single bonds. Finally, NBO analyses of model compound [DBU-H]+[ClSb(μ-P-Ph)2SbCl2]− [6Ph, terphenyl substituted with phenyl (see Figure 3)] revealed that the negative charge of the anion is delocalized over the whole molecule. While in 5Sb the P2Sb2Cl2 core bears an overall charge of +0.51 e, the central P2Sb2Cl3 core of 6 carries a charge of −0.36 e (Clbridge, −0.65 e; P, +0.01 e; Sb, +0.69 e; Clring, −0.55 e). Upon formal addition of Cl− to [ClSb(μ-P-Ter)]2, the WBI of the Sb−Cl bonds decreases from 0.70 and 0.76 to 0.60 for both exo Sb−Cl bonds. The WBI of the bridging Cl− ion (endo position) amounts to 0.24, indicating a strong electrostatic rather than covalent interaction. F


Article

Inorganic Chemistry combined as solids. Then, 10 mL of benzene was added, and the solution was stirred for 48 h. According to NMR reaction monitoring, no significant reaction occurred. Afterward, the solution was boiled for 12 h, affording a yellowish solution, which was concentrated to incipient crystallization and stored at ambient temperature overnight. Colorless crystals were deposited. The mother liquor was removed via syringe, and the crystals were dried in vacuo (91 mg, 0.108 mmol, 47%): mp 212 °C dec; 1H NMR (298 K, C6D6, 250.1 MHz) δ 2.04 (s, 24 H, o-CH3), 2.37 (s, 12 H, p-CH3), 6.70 (d, 4 H, m-CH), 6.90 (s, 8 H, m-CHMes), 6.94 (dd, 2 H, p-CH, JHH = 7.2 Hz, JHH = 7.9 Hz); 31P NMR (298 K, C6D6, 121.5 MHz) δ −142.8 (s). Elemental analysis for C48H50P2As2 found (calcd): C 68.42 (68.74), H 5.95 (6.01), N 0.04 (0.00). Synthesis of 3Sb. Colorless TerPH(SiMe3) (168 mg, 0.402 mmol) and yellow TerNHSbCl2 (206 mg, 0.395 mmol) were combined as solids. Then, 10 mL of dichloromethane was added, and the solution was stirred for 2 h, retaining its yellow color in the process. Afterward, the solution was concentrated to incipient crystallization (1 mL) and stored at 4 °C overnight, affording pale yellowish crystals of 3Sb. The supernatant was removed via syringe, and the crystals were dried in vacuo (249 mg, 0.300 mmol, 76%): mp 129 °C dec. Elemental analysis for C48H52NPSbCl found (calcd): C 68.99 (69.37), H 6.21 (6.31), N 1.39 (1.69). For the (R,R) isomer: 1H NMR (298 K, C6D6, 250.1 MHz) δ 4.11 (d, JPH = 211 Hz), 4.97 (s); 31 P NMR (298 K, C6D6, 121.5 MHz) δ −62.7 (d, JPH = 213 Hz). For the (R,S) isomer: 1H NMR (298 K, C6D6, 250.1 MHz) δ 3.38 (d, JPH = 189 Hz), 4.88 (s); 31P NMR (298 K, C6D6, 121.5 MHz) δ −78.6 (d, JPH = 187 Hz); IR (ATR) 2325 (vw), 2350 (vw), 3309 (vw) cm−1; Raman (632 nm) 2310 (2), 2326 (20), 3308 (12) cm−1. Synthesis of 5Sb. A yellowish solution of 3Sb (331 mg, 0.398) in benzene (10 mL) was treated with NEt3 (0.2 mL, excess) at ambient temperature and stirred for 3 h. The color of the solution slightly intensified during the reaction but remained yellow. Volatiles were removed in vacuo, and the yellowish residue was redissolved in benzene (20 mL). The solution was filtered through a porous sintered glass disc (porosity G4), and the filtrate was concentrated to incipient crystallization. After storage at ambient temperature for 48 h, yellow crystals of 5Sb were obtained. The supernatant was removed via syringe, and the crystals were dried in vacuo (82 mg, 0.082 mmol, 41%): mp 245 °C dec; 1H NMR (298 K, C6D6, 250.1 MHz) δ 2.16 (s, 24 H, o-CH3), 2.34 (s, 12 H, p-CH3), 6.84 (s, 8 H, m-CHMes), 6.85 (d, 4 H, JHH = 7.2 Hz), 7.02 (dd, 2 H, p-CH, JHH = 6.9 Hz, JHH = 7.8 Hz); 31 P NMR (298 K, C6D6, 121.5 MHz) δ −38.6 (s). Elemental analysis for C48H50P2Sb2Cl2 found (calcd): C 57.15 (57.46), H 4.99 (5.02), N 0.09 (0.00). Synthesis of 6. A yellowish solution of 3Sb (250 mg, 0.480 mmol) in 5 mL of benzene was treated with DBU (74 mg, 0.486 mmol) at ambient temperature and stirred for 3 h. The color of the solution remained yellowish. The solution was concentrated to incipient crystallization (3 mL). After storage at ambient temperature for 48 h, pale yellow needle-shaped crystals of 6 were obtained. The supernatant was removed via syringe, and the crystals were dried in vacuo (149 mg, 0.124 mmol, 39%): mp 86 °C dec; 1H NMR (298 K, C6D6, 250.1 MHz) δ 0.98 (m, 2 H, DBU), 1.20 (m, 2 H, DBU), 1.35 (m, 2 H, DBU), 1.44 (m, 2 H, DBU), 2.31 (m, 2 H, DBU), 2.37 (s, 24 H, o-CH3), 2.43 (s, 12 H, p-CH3), 2.49 (m, 2 H, DBU), 2.55 (m, 2 H, DBU), 3.25 (m, 2 H, DBU), 6.95 (s, 8 H, m-CHMes), 6.97 (d, 4 H, JHH = 7.2 Hz), 7.10 (dd, 2 H, p-CH, JHH = 6.8 Hz, JHH = 8.1 Hz); 31P NMR (298 K, C6D6, 121.5 MHz) δ −47.6 (s). Elemental analysis for C57H67N2P2Sb2Cl3 found (calcd): C 56.99 (57.43), H 5.86 (5.67), N 2.56 (2.35). Synthesis of 5Bi. Colorless TerPH(SiMe3) (271 mg, 0.647 mmol) and red TerNHBiCl2 (395 mg, 0.650 mmol) were combined as solids. Then, 10 mL of dichloromethane was added, and the solution was stirred for 2 h. Immediately after addition, the solution darkened and became nearly black. Afterward, the solution was filtered through a porous sintered glass disc (porosity G4), and the filtrate was concentrated to incipient crystallization (3 mL) and stored at 4 °C overnight, affording black block-shaped crystals of 5Bi. The supernatant was removed via syringe, and the crystals were dried in vacuo

(165 mg, 0.140 mmol, 43%). Spectroscopic evidence of the formation of 3Bi could be obtained only in an NMR experiment, because it is a transient species. For the 3Bi (R,R) isomer: 1H NMR (298 K, CD2Cl2, 250.1 MHz) δ 3.76 (d, JPH = 200 Hz), 6.08 (s); 31P NMR (298 K, CD2Cl2, 121.5 MHz) δ −41.6 (d, JPH = 213 Hz). For the 3Bi (R,S) isomer: 1H NMR (298 K, CD2Cl2, 250.1 MHz) δ 3.38 (d, JPH = 189 Hz), 4.88 (s); 31P NMR (298 K, CD2Cl2, 121.5 MHz) δ −64.6 (d, JPH = 187 Hz). For 5Bi: mp 231 °C dec; 1H NMR (298 K, C6D6, 250.1 MHz) δ 2.17 (s, Δν1/2 = 2 Hz, 24 H, o-CH3), 2.34 (s, 12 H, p-CH3), 6.78 (dd, 2 H, p-CH, JHH = 7.1 Hz, JHH = 8.0 Hz), 6.84 (s, 8 H, mCHMes), 7.02 (d, 4 H, JHH = 7.6 Hz); 31P NMR (298 K, C6D6, 121.5 MHz) δ −21.8 (s, Δν1/2 = 910 Hz). Elemental analysis for C48H50P2Bi2Cl2 found (calcd): C 48.90 (48.95), H 4.31 (4.28), N 0.11 (0.00). Synthesis of 5Bi·BiCl3. Colorless TerPH(SiMe3) (251 mg, 0.600 mmol) and red TerNHBiCl2 (369 mg, 0.607 mmol) were combined as solids. Then, 10 mL of benzene was added, and the solution was stirred for 2 h. Immediately after addition, the solution darkened and became nearly black. Afterward, the solution was filtered through a porous sintered glass disc (porosity G4) padded with Celite (Kieselguhr), and the filtrate was concentrated to incipient crystallization (3 mL) and stored at ambient temperature for 3 days, affording black rod-shaped crystals of 5Bi·BiCl3. The supernatant was removed via syringe, and the crystals were dried in vacuo (96 mg, 0.064 mmol, 21%): mp 270 °C dec; 1H NMR (298 K, C6D6, 250.1 MHz) δ 2.17 (s, Δν1/2 = 9 Hz, 24 H, o-CH3), 2.31 (s, 12 H, p-CH3), 6.79 (dd, 2 H, p-CH, JHH = 7.0 Hz, JHH = 8.1 Hz), 6.84 (s, 8 H, mCHMes), 6.94 (d, 4 H, JHH = 7.2 Hz); 31P NMR (298 K, C6D6, 121.5 MHz) δ −8.4 (s, Δν1/2 = 335 Hz); 31P NMR (193 K, C7D8, 121.5 MHz) δ −12.0 (s, Δν1/2 = 45 Hz). Elemental analysis for C48H50P2Bi3Cl5 found (calcd): C 38.66 (38.61), H 3.47 (3.38), N 0.01 (0.00). Synthesis of 5P. On a preparative scale, to a suspension of 5Bi (275 mg, 0.234 mmol) in 5 mL of benzene was added PCl3 (0.1 mL) via syringe at ambient temperature. The solution was stirred for 1 h, until all the black solid was dissolved. In the process, the solution turned yellow and became turbid. The solution was filtered through a porous sintered glass disc (porosity G4) padded with Celite (Kieselguhr). The filtrate was then concentrated, affording a yellowish oil and an organic solution phase. Phases were separated, and volatiles were removed in vacuo. The oil was treated with 5 mL of n-hexane, causing a colorless solid to precipitate. The hexane was removed via syringe and the solid dried in vacuo. Of both fractions, crystals of cis5P could be grown by prolonged storage of saturated solutions in dichloromethane at 4 °C. The mother liquor was removed via syringe, and the crystals were dried in vacuo (41 mg, 0.050 mmol, 21%): mp 218 °C dec; 1H NMR (298 K, C6D6, 250.1 MHz) δ 2.13 (s, 12 H, oCH3), 2.15 (s, 12 H, o-CH3), 2.20 (s, 12 H, o-CH3), 2.30 (s, 6 H, pCH3, cis), 2.34 (s, 12 H, p-CH3, trans), 6.78 (s, 4 H, m-CHMes, cis), 6.83 (s, 8 H, m-CHMes, trans), 6.75 (d, 2 H, 3JHH = 7.3 Hz, m-CH, cis), 6.82 (d, 4 H, 3JHH = 7.2 Hz, m-CH, trans), 7.01 (t, 1 H, 3JHH = 7.3 Hz, p-CH, cis), 7.04 (t, 2 H, 3JHH = 7.2 Hz, p-CH, trans). For cis-5P: 31P NMR (298 K, C6D6, 121.5 MHz) δ +13.3 (t, 1JPP = 198 Hz), +99.9 (t, 1 JPP = 198 Hz). For trans-5P: 31P NMR (298 K, C6D6, 121.5 MHz) δ −2.4 (t, 1JPP = 209 Hz), +82.6 (td, 1JPP = 213 Hz, 2JPP = 20.8 Hz), +119.9 (td, 1JPP = 213 Hz, 2JPP = 15.6 Hz). Elemental analysis for C48H50P4Cl2 found (calcd): C 69.71 (70.16), H 6.01 (6.13), N 0.02 (0.00). Synthesis of 5As. On a preparative scale, to a suspension of 5Bi (490 mg, 0.416 mmol) in 10 mL of benzene was added AsCl3 (0.1 mL) via syringe at ambient temperature. The solution was exposed to ultrasonication for 30 min until all the black solid was dissolved. At the same time, a dark oily phase was formed. In the process, the solution turned yellow and became turbid. The yellow solution was filtered through a porous glass disc (porosity G4) sinter padded with Celite (Kieselguhr). The filtrate was then concentrated, affording an orange oil and an organic solution phase. Phases were separated, and volatiles were removed in vacuo. The oil was treated with 5 mL of n-hexane, causing a colorless solid to precipitate. The hexane was removed via syringe and the solid dried in vacuo. The residue was redissolved in G


Article

Inorganic Chemistry diethyl ether (50 mL), and the solution was filtered and concentrated to ∼25 mL. The solution was stored at −25 °C for 3 days, affording an amorphous crystalline precipitate. The mother liquor was removed, and the solid was dried in vacuo (92 mg of raw product). The raw product was redissolved in benzene (3 mL) and concentrated to incipient crystallization (∼0.5 mL). Storage at ambient temperature overnight afforded pale yellowish crystals of 5As. The supernatant was removed via syringe, and the crystals were dried in vacuo (68 mg, 17%): mp 281 °C dec; 1H NMR (298 K, C6D6, 250.1 MHz) δ 2.17 (s, 12 H, o-CH3), 2.18 (s, 12 H, o-CH3), 2.34 (s, 12 H, p-CH3), 6.77 (s, 4 H, m-CHMes), 6.82 (dt, 4 H, JHH = 7.5 Hz, JHP = 1.3 Hz, m-CH), 6.85 (s, 4 H, m-CHMes), 7.03 (dd, 2 H, p-CH, JHH = 7.2 Hz, JHH = 7.9 Hz); 31 P NMR (298 K, C6D6, 121.5 MHz) δ +1.8 (s). Elemental analysis for C48H50P2As2Cl2 found (calcd): C 63.21 (63.38), H 5.65 (5.54), N 0.00 (0.00).

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(14) Fox, A. R.; Wright, R. J.; Rivard, E.; Power, P. P. Angew. Chem., Int. Ed. 2005, 44 (47), 7729. (15) Borger, J. E.; Ehlers, A. W.; Lutz, M.; Slootweg, J. C.; Lammertsma, K. Angew. Chem. 2014, 126, 13050. (16) Weber, L.; Bungardt, D.; Boese, R.; Bläser, D. Chem. Ber. 1988, 121 (6), 1033. (17) Weber, L.; Sonnenberg, U. Chem. Ber. 1989, 122 (10), 1809. (18) von Hänisch, C.; Stahl, S. Z. Anorg. Allg. Chem. 2009, 635 (13− 14), 2230. (19) Jutzi, P.; Meyer, U.; Opiela, S.; Olmstead, M. M.; Power, P. P. Organometallics 1990, 9 (5), 1459. (20) Baudler, M.; Wietfeldt-Haltenhoff, S. Angew. Chem. 1984, 96 (5), 361. (21) Tuscher, L.; Ganesamoorthy, C.; Bläser, D.; Wölper, C.; Schulz, S. Angew. Chem. 2015, 127 (36), 10803. (22) Reiß, F.; Schulz, A.; Villinger, A.; Weding, N. Dalton Trans. 2010, 39 (41), 9962. (23) Michalik, D.; Schulz, A.; Villinger, A. Angew. Chem. 2010, 122 (41), 7737. (24) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, Ö .; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09, version C.01; Gaussian, Inc.: Wallingford, CT, 2009. (25) Computations were conducted at the PBE1PBE level of theory utilizing 6-31G(d,p) basis sets for all elements except for Sb and Bi. For these elements, pseudopotentials and a relativistic basis set were employed (Sb, ECP46MDF 4 46; Bi, ECP78MDF 4 78). (26) Smith, R. C.; Urnézǐ us, E.; Lam, K.-C.; Rheingold, A. L.; Protasiewicz, J. D. Inorg. Chem. 2002, 41 (20), 5296. (27) Niecke, E.; Kramer, B.; Nieger, M. Organometallics 1991, 10 (1), 10. (28) Mazieres, M.-R.; Rauzy, K.; Bellan, J.; Sanchez, M.; Pfisterguillouzo, G.; Senio, A. Phosphorus, Sulfur Silicon Relat. Elem. 1993, 76 (1−4), 45. (29) Pyykkö, P.; Atsumi, M. Chem. - Eur. J. 2009, 15 (46), 12770. (30) Schulz, A. Z. Anorg. Allg. Chem. 2014, 640 (11), 2183. (31) Lehmann, M.; Schulz, A.; Villinger, A. Angew. Chem. 2012, 124 (32), 8211. (32) Nikolova, D.; von Hänisch, C. Eur. J. Inorg. Chem. 2005, 2005 (2), 378. (33) von Hänisch, C.; Nikolova, D. Eur. J. Inorg. Chem. 2006, 2006 (23), 4770. (34) Mantina, M.; Chamberlin, A. C.; Valero, R.; Cramer, C. J.; Truhlar, D. G. J. Phys. Chem. A 2009, 113 (19), 5806. (35) Hinz, A.; Schulz, A.; Villinger, A. Chem. Commun. 2015, 51 (57), 11437.

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.6b00218. Additional experimental information, computational details, and absolute energies of the opimized molecules (PDF) Crystallographic data (CIF)

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS Deutsche Forschungsgesellschaft (DFG SCHU 1170/11-1) is acknowledged for financial support. The authors thank M.Sc. Jonas Bresien for setting up and maintaining Gaussian and NBO software on the cluster computer as well as for a gift of TerPH2. A.H. thanks the “Gesellschaft Deutscher Chemiker” (GDCh) for financial support.

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REFERENCES

(1) He, G.; Shynkaruk, O.; Lui, M. W.; Rivard, E. Chem. Rev. 2014, 114 (16), 7815. (2) Stahl, L. Coord. Chem. Rev. 2000, 210, 203. (3) Balakrishna, M. S.; Eisler, D. J.; Chivers, T. Chem. Soc. Rev. 2007, 36 (4), 650. (4) Jutzi, P.; Opiela, S. J. Organomet. Chem. 1992, 431 (2), C29. (5) Schrödel, H.-P.; Nöth, H.; Schmidt-Amelunxen, M.; Schoeller, W. W.; Schmidpeter, A. Chem. Ber. 1997, 130 (12), 1801. (6) Karaghiosoff, K.; Lerner, H.-W.; Wörner, A.; Wiberg, N. Z. Naturforsch. 2002, 57b, 1027. (7) Lorbach, A.; Nadj, A.; Tüllmann, S.; Dornhaus, F.; Schödel, F.; Sänger, I.; Margraf, G.; Bats, J. W.; Bolte, M.; Holthausen, M. C.; Wagner, M.; Lerner, H.-W. Inorg. Chem. 2009, 48 (3), 1005. (8) Bresien, J.; Hering, C.; Schulz, A.; Villinger, A. Chem. - Eur. J. 2014, 20, 12607. (9) Bresien, J.; Faust, K.; Schulz, A.; Villinger, A. Angew. Chem., Int. Ed. 2015, 54 (23), 6926. (10) Bresien, J.; Faust, K.; Hering-Junghans, C.; Rothe, J.; Schulz, A.; Villinger, A. Dalton Trans. 2016, 45, 1998. (11) Jutzi, P.; Meyer, U. J. Organomet. Chem. 1987, 333 (2), C18. (12) Fluck, E.; Riedel, R.; Hausen, H.-D.; Heckmann, G. Z. Anorg. Allg. Chem. 1987, 551, 85. (13) Niecke, E.; Rüger, R.; Krebs, B. Angew. Chem. 1982, 94 (7), 553. H


Synthesis of Heavy Cyclodipnictadiphosphanes [ClE (Î¼-P-Ter)] 2 [E= P

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