Syntheses, Structural Characterizations, and Reactivity Studies of Half

Mar 31, 2015 - The syntheses and structural characterizations of the first extensive series of Group 9 (Co, Rh, and Ir) tricarbadecaboranyl half-sandw...
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Syntheses, Structural Characterizations, and Reactivity Studies of Half-Sandwich Cobalt, Rhodium, and Iridium Metallatricarbadecaboranyl Complexes Emily R. Berkeley, Ariane Perez-Gavilan,† Patrick J. Carroll, and Larry G. Sneddon* Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States S Supporting Information *

ABSTRACT: The syntheses and structural characterizations of the first extensive series of Group 9 (Co, Rh, and Ir) tricarbadecaboranyl halfsandwich complexes are reported. The carbonyl complexes 1,1-(CO)2-2Ph-closo-1,2,3,4-MC3B7H9, M = Co (1), Rh (2), and 8,8,8-(CO)3-9-Phnido-8,7,9,10-IrC3B7H9 (3) were obtained by the reactions of Li+(6-Phnido-5,6,9-C3B7H9)− with Co(CO)4I, [Rh(CO)2Cl]2, and Ir(CO)3Cl, respectively. Further reactions of 1, 2, and 3 with 1,2-bis(diphenylphosphino)ethane (dppe) yielded the 1,1-dppe-2-Ph-closo-1,2,3,4-MC3B7H9, M = Co (4), Rh (5), and 8-CO-8,8-dppe-9-Ph-nido-8,7,9,10-IrC3B7H9 (6) derivatives with their crystallographic determinations showing that 1 and 2 contain the η6-2-Ph-2,3,4-C3B7H91− ligand with the metallatricarbadecaboranyl cluster fragments having closo-octadecahedral geometries, while 3 has a slipped-cage η4-9-Ph-7,9,10C3B7H91− coordination and a nido-cluster framework. The reaction of Li+(6-Ph-nido-5,6,9-C3B7H9)− with [Rh(COD)Cl]2 and [Ir(COD)Cl]2 produced the COD coordinated complexes 1,1-COD-2-Ph-closo-1,2,3,4-MC3B7H9, M = Rh (7), Ir (8), with η6-2Ph-2,3,4-C3B7H91− ligands and closo-cluster structures. On the other hand, slipped-cage structures with η4-9-Ph-7,9,10-C3B7H91− coordination were achieved by the reactions of 1, 3, or 8 with an excess of the stronger donor tert-butyl isocyanide to give 8,8,8(CNtBu)3-9-Ph-nido-8,7,9,10-MC3B7H9, M = Co (9), Ir (10), respectively, or by the reaction of 8 with 1 equiv of tert-butyl isocyanide to give 8,8-COD-8-CNtBu-9-Ph-nido-8,7,9,10-IrC3B7H9 (11). Upon the reaction of 1 with diphenylacetylene, both carbonyls were displaced with subsequent alkyne cyclization to form the tetraphenylcyclobutadienyl complex 1,1-(η4-C4Ph4)-2Ph-closo-1,2,3,4-CoC3B7H9 (12). The crystalline tetramethylcyclobutadienyl derivative 1,1-(η4-C4Me4)-2-Ph-closo-1,2,3,4CoC3B7H9 (13) was synthesized by the reaction of Li+(6-Ph-nido-5,6,9-C3B7H9)− with (η4-C4Me4)Co(CO)2I, and its crystallographic determination confirmed the formation of a complex where a formal Co3+ ion is sandwiched between η4C4Me42− and η6-2-Ph-2,3,4-C3B7H91− ligands. In contrast to the reactions with diphenylacetylene, the reaction of 8 with 3-hexyne resulted in cage deboronation to produce 2,2-COD-10-Ph-closo-2,1,6,10-C3B6H8 (14). Neither 7 nor 8 would undergo oxidativeaddition when treated with I2. Although 11 reacted with I2 and perfluoro-1-iodohexane, oxidative-addition products were also not obtained, but instead, iodation of a cage boron occurred to produce 8,8-COD-1-CNtBu-9-Ph-11-I-nido-8,7,9,10-IrC3B7H8 (15).

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INTRODUCTION The tricarbadecaborane 6-R-nido-5,6,9-C3B7H91− anions1,2 have proven to be versatile and complementary analogues of the cyclopentadienyl ligand and have now been used to make a wide variety of metallocene-like complexes where a metal is sandwiched between two tricarbadecaboranyl cages or one cage and a cyclopentadienyl ring.2,3 A number of methods have now also been developed that allow the efficient syntheses of both B- and C-cage-functionalized metallatricarbadecaboranes.4 These metallatricarbadecaboranyl complexes have been shown to have many unique properties relative to their organometallic cousins, including increased hydrolytic and thermal stabilities, the capacity to readily change the hapticity and electron donation of the tricarbadecaboranyl ligand via cage-slippage rearrangements, and an exceptional ability to stabilize low metal oxidation states.2−5 The unique properties of the tricarbadecaboranyl ligand stimulated our interest2,5 in developing the chemistry and applications of the tricarbadecaboranyl equivalents of cyclopentadienyl half-sandwich complexes that have been shown to © 2015 American Chemical Society

bind and/or activate chemical transformations of important small molecules, such as carbon monoxide, phosphines, isocyanides, olefins, alkynes, and/or alkanes. Owing to their important uses in applications as diverse as cycloaddition and CH activation reactions, as well as their utility as starting materials for the syntheses of other organometallics, Cp/Cp*ML2 (M = Co, Rh, Ir; L = CO, PR3, olefins, etc.) complexes have proven to be one of the most important classes of half-sandwich complexes.6 In this paper, we report the syntheses and structural properties of the first extensive series of their tricarbadecaboranyl half-sandwich counterparts.

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RESULTS AND DISCUSSION Carbonyl Complexes. THF solutions of 1,1-(CO)2-2-Phcloso-1,2,3,4-MC3B7H9, M = Co (1), Rh (2), were generated by Received: February 18, 2015 Published: March 31, 2015 1396

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Organometallics the reactions of Li+(6-Ph-nido-5,6,9-C3B7H9)− with Co(CO)4I and [Rh(CO)2Cl]2, respectively (eq 1). The 11B NMR spectra of both complexes showed patterns, with seven resonances between 20 and −35 ppm (Supporting Information, Figures S1 and S2), characteristic of metal-coordinated η6-2-Ph-2,3,4-C3B7H91− ligands.2−4

placed (eq 3) to give the 1,1-dppe-2-Ph-closo-1,2,3,4-MC3B7H9, M = Co (4), Rh (5), complexes.

The 11B and 1H NMR spectra for 4 and 5 (Supporting Information, Figures S4, S5, S7, and S8) were similar to those of 1 and 2, again supporting η6-coordination of the tricarbadecaboranyl cage. The room-temperature 31P{1H} NMR spectrum of 4 exhibited two resonances (78.7 and 62.3 ppm) (Supporting Information, Figure S6), indicating that the two dppe phosphorus atoms were in different environments, while that of 5 showed only one doublet (57.5 ppm, J103Rh‑P = 165 Hz). However, when the spectrum of 5 was recorded at −53 °C, the expected two doublet peaks emerged (57.3 ppm, J103Rh‑P = 160 Hz and 57.9 ppm, J103Rh‑P = 174 Hz) (Supporting Information, Figure S9), thus supporting a fluxional rearrangement of the dppe at higher temperatures. The crystallographically determined structures of 4 and 5, shown in Figure 1, confirmed that, consistent with their expected 24 skeletal electron counts, the cage frameworks in these complexes adopt closo-octadecahedral structures with the metal coordinated to the six-membered (C2−B5−B6−C3−B7−C4) puckered face of the cage. In both compounds, the closest metal−cage interactions are with the C2 and C3 carbons that are puckered out of the face toward the metals, with much longer distances to the C4−B5−B6−B7 atoms. The Co−C2 and Co−C3 distances (1.9773(18) and 1.965(2) Å) in 4 are significantly shorter than those found in commo-Co-(1-Co-2Me-2,3,5-C3B7H9)2 (2.068(2), 1.990(3), 2.070(2), 1.981(2) Å),3b which is consistent with enhanced Co−C2 and Co−C3 bonding in 4 as a result of the electron-donating dppe group. The Co−P1 and Co−P2 distances (2.1812(5) and 2.1580(6) Å) in 4 and the Rh−P1 and Rh−P2 distances (2.2322(5) and 2.2851(5) Å) in 5 are significantly longer than the Co−P (2.1093(7) and 2.1077(7) Å) and Rh−P (2.2036(12) and 2.2063(13) Å) distances in Cp*Co(dppe)13 and (2-menthyl-4,7-dimethylindenyl)Rh(dppe),14 respectively, again consistent with the more electron-withdrawing tricarbadecaboranyl cages of 4 and 5 reducing metal back-bonding to their dppe ligands. The metal to (C4−B5−B6−B7)centroid distances in 4 (1.5899(2) Å) and 5 (1.8992(1) Å) are significantly shorter than the cobalt to Cp* centroid (1.705 Å) and rhodium to indenyl-ring centroid (1.9782(19) Å) distances found in Cp*Co(dppe)13 and (2menthyl-4,7-dimethyl-indenyl)Rh(dppe).14 In 4, the cobalt sits reasonably centered over the cage with a dihedral angle of only 4.8(5)° between the C2−Co1−C3 and C2−B8−B9−C3 planes. However, in 5, this dihedral angle has increased to 17.8(3)° as a result of the rhodium being somewhat shifted toward the B5−B6 edge (Rh−B5, 2.261(2) Å, Rh−B6, 2.343(2) Å) of the cage with lengthened distances to C4 and B7 (2.722(3) and 2.608(4) Å). As a result of the reduced rhodium bonding interactions with C4 and B7, the C2−C4, C4−B7, and B7−C3 (1.483(3), 1.751(5), and 1.562(5) Å) distances in 5 are shortened relative to those of 4 (1.511(3), 1.774(3), and 1.589(3) Å). The relative metal positions in 4 and 5 may be related to the different twist angles between the dppe and cage

When Li+(6-Ph-nido-5,6,9-C3B7H9)− was reacted with Ir(CO)3Cl, the expected 1,1-(CO)2-2-Ph-closo-1,2,3,4-IrC3B7H9 was not formed, but instead, 8,8,8-(CO)3-9-Ph-nido-8,7,9,10IrC3B7H9 (3) was produced (eq 2).

Consistent with the (CO)3Ir unit providing 4 skeletal-electron donation to the cage, the 11B spectrum of 3, with six peaks between 0.0 and −17.0 ppm and a high-field resonance near −35 ppm (Supporting Information, Figure S3), indicated a slipped η49-Ph-7,9,10-C 3 B7 H 9 1− ligand and a nido cluster framework.2,3d,e,h,j,5 Likewise, the 3 1H NMR spectrum showed two midfield cage-CH resonances (4.23 and 3.06 ppm) characteristic2,3d,e,h,j,5 of a nido-type structure, rather than the high-field (C4−H, 0.0−3.0 ppm)/low-field (C3−H, 5.0−6.0 ppm) pattern typically observed in closo-complexes2−4 with η6-2-Ph-2,3,4C3B7H91− ligands. Consistent with the relative CO stretches of 1,1,1-(CO)3-2Ph-closo-1,2,3,4-MnC3B7H9 (2051, 2002, and 1964 cm−1)5a versus both CpMn(CO)3 (2027 and 1944 cm−1) and Cp*Mn(CO)3 (2004 and 1910 cm−1),7 the CO stretching frequencies of 1 (2056, 2053 cm−1), 2 (2084, 2011 cm−1), and 3 (2081, 2028 cm−1) were higher than those of the corresponding η5-Cp and η5Cp* carbonyl complexes: CpM(CO)2, M = Co, 2023, 1957 cm−1;8 Rh, 2051, 1994 cm−1;9 Ir, 2043, 1976 cm−1;10 Cp*M(CO)2, M = Co, 1999, 1934 cm−1;9 Rh, 2034, 1966 cm−1;10 Ir, 2020, 1951 cm−1.11 This trend illustrates the stronger electron-withdrawing properties of the η6- and η4-tricarbadecaboranyl1− ligands compared to Cp and Cp* that reduce metal back-bonding to the carbonyl π* orbitals, with the resulting weaker M−C bonds in 1, 2, and 3 making their carbonyl ligands more labile than in their cyclopentadienyl counterparts. The lability of the 1 and 2 carbonyls prevented complete characterization of these complexes, since rapid decomposition resulted upon solvent removal.12 However, as discussed in the following sections, their carbonyls were readily substituted in solution to yield stable half-sandwich complexes that could be crystallographically characterized. Dppe Complexes. When 1 or 2 were reacted with diphenylphosphinoethane (dppe), their carbonyls were dis1397

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ance in the IR of a new CO stretch associated with this intermediate, which was found at a lower frequency (2050 cm−1) than that of the highest frequency stretch of 2 (2084 and 2011 cm−1), further suggested an 8-CO-8,8-dppe-9-Ph-nido-8,7,9,10RhC3B7H9 structure where the electron-donating dppe coordinated before the second CO was displaced. Such an associative substitution pathway was previously demonstrated for the carbonyl substitution reactions of 1,1,1-(CO)3-2-Ph-closo1,2,3,4-MC3B7H9 (M = Mn, Re), which gave 1,1-(CO)2-1-L-2Ph-closo-1,2,3,4-MC3B7H9 products via slipped-cage 8,8,8(CO)3-8-L-9-Ph-nido-8,7,9,10-MC3B7H9 intermediates (L = CNtBu, PMe3, or PPh3).5a Attempts to isolate an 8-CO-8,8dppe-9-Ph-nido-8,7,9,10-RhC3B7H9 intermediate during the synthesis of 5 led to complete conversion to 5 upon workup. However, as discussed below, strong evidence in support of the proposed structure of this intermediate was obtained by the synthesis and characterization of its iridium analogue. Thus, it was found that, when 3 was reacted with dppe, only two carbonyls were displaced to give 8-CO-8,8-dppe-9-Ph-nido8,7,9,10-IrC3B7H9 (6) (eq 4).

The 11B and 1H NMR spectra observed for 6 (Supporting Information, Figures S11, S12) were again characteristic of a nido-cage framework. Like 5, the 31P{1H} NMR spectrum of 6 showed only one peak (17.3 ppm) at room temperature (Supporting Information, Figure S13), indicating a fluxional dppe rearrangement. Again, consistent with the stronger σ donor properties of dppe, which enhances iridium to CO back-bonding, the IR spectrum of 6 exhibited a single CO stretch at a lower frequency (2013 cm−1) than those of 3 (2081 and 2028 cm−1). The crystallographically determined structure of 6 (Figure 2) confirmed both the retention of one CO and a slipped-cage framework where the iridium is η4-coordinated to the C7−B3− B4−C9 face of the cage. 6 is thus a structural analogue of the proposed 8-CO-8,8-dppe-2-Ph-nido-8,7,9,10-RhC3B7H9 intermediate observed during the reaction leading to 5. The remaining iridium attached carbonyl group in 5 lies in the same plane as the five-membered open face of the nidoiridatricarbadecaboranyl fragment and extends outward from the cage. We have previously described3h,j,5a how the facile ability of the tricarbadecaboranyl ligand to slip between η6 and η4 coordinations, with a resulting decrease in its electron donation to the metal from 6 to 4 electrons, is analogous to that of the Cp η5 to η3 ring-slippage process that has been proposed to occur in the associative substitution reactions of some metallacyclopentadienyl15 complexes. Cage-slippage to allow the metal to coordinate to either the C7−B3−B4−C9 or the C9−C10− B11−C7 faces of the tricarbadecaboranyl cage should be possible. However, carbon atoms have been shown to prefer low-coordinate positions on the open faces of clusters,16 so the favored slip that occurs in metallatricarbadecaboranyl complexes results in the metal becoming η4-coordinated to the C7−B3− B4−C9 face, thereby generating a five-membered M8−C7− B11−C10−C9 open face containing all three cage carbons. From

Figure 1. Crystallographically determined structures of 4 (top) and 5 (bottom). Selected distances (Å) and angles (deg): 4, Co1−P1, 2.1812(5); Co1−P2, 2.1580(6); Co1−C2, 1.9773(18); Co1−C3, 1.965(2); Co1−C4, 2.254(2); Co1−B5, 2.197(2); Co1−B6, 2.227(2); Co1−B7, 2.246(2); Co1−(C4−B5−B6−B7) centroid , 1.5899(2); C2−C4, 1.511(3); C2−B5, 1.587(3); B5−B6, 1.865(3); B6−C3, 1.567(3); C3−B7, 1.589(3); B7−C4, 1.774(3); C2−Co1−C3, 113.93(8); C2−Co1−P1, 120.17(6); C3−Co1−P1, 104.27(6); C2− Co1−P2, 106.33(6); C3−Co1−P2, 123.83(6); P1−Co1−P2, 86.35(2). 5, Rh1−P1, 2.2322(5); Rh1−P2, 2.2851(5); Rh1−C2, 2.107(2); Rh1− C3, 2.135(2); Rh1−C4, 2.722(3); Rh1−B5, 2.261(2); Rh1−B6, 2.343(3); Rh1−B7, 2.608(4); Rh1−(C4−B5−B6−B7) centroid , 1.8992(1); C2−C4, 1.483(3); C2−B5, 1.606(4); B5−B6, 1.883(4); B6−C3, 1.536(4); C3−B7, 1.562(5); B7−C4, 1.751(5); C2−Rh1−C3, 96.17(10); C2−Rh1−P1, 101.59(6); C3−Rh1−P1, 149.57(10); C2− Rh1−P2, 141.04(8); C3−Rh1−P2, 98.53(7); P1−Rh1−P2, 82.921(19).

ligands in the two complexes that result in different steric interactions. In both complexes, the dppe is twisted away from the C2 and C3 cage carbons. In 4, the angle between the P1−M− P2 and the C2−M−C3 planes is 76.66(3)°, situating the phosphorus atoms in sterically favorable positions above the B5− B6 and C4−B7 edges, but the corresponding angle in 5 is only 49.51(5)°. In this configuration, P2 of the dppe is almost directly over B7. The NMR and IR data collected during the course of the reaction to produce 5 suggested the initial formation of an intermediate complex, with the new high field (−34.7 ppm) resonance that appeared in the 11B NMR spectra (Supporting Information, Figure S10) characteristic2,3d,e,h,j,5 of a structure with a slipped-cage nido-framework. The simultaneous appear1398

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Figure 2. Crystallographically determined structure of 6. Selected distances (Å) and angles (deg): Ir8−C44, 1.891(7); O1−C44, 1.136(9); Ir8−P1, 2.3689(18); Ir8−P2, 2.3479(18); Ir8−C9, 2.196(7); Ir8−C7, 2.177(7); Ir8−B4, 2.238(8); Ir8−B3, 2.237(8); Ir8−(C7−B3−B4−C9)centroid, 1.6053(2); Ir8−C10, 3.145(7); Ir8−B11, 3.178(7); C9−C10, 1.553(9); C9−B4, 1.733(10); B4−B3, 1.876(12); B3−C7, 1.699(11); C7−B11, 1.603(11); B11−C10, 1.626(11); C9− Ir8−C7, 81.7(3); C9−Ir8−P1, 101.14(18); C7−Ir8−P1, 100.8(2); C9−Ir8−P2, 172.72(19); C7−Ir8−P2, 92.5(2); P2−Ir8−P1, 84.25(6); O1−C44−Ir8, 176.6(7); C44−Ir8−P1, 94.7(2); C44−Ir8−P2, 89.4(2).

a cage skeletal electron-counting viewpoint, the metallatricarbadecaboranyl fragment in 6 has the nido geometry, based on an icosahedron missing one vertex, that is expected for an 11-vertex deltahedron containing 26 skeletal electrons. The intracage distances in 6 are similar to those in previously reported halfsandwich nido-cage structures,5a such as 8-CNtBu-8,8,8-(CO)39-Ph-nido-8,7,9,10-MC3B7H9 (M = Mn, Re). COD Complexes. When Li+(6-Ph-nido-5,6,9-C3B7H9)− was reacted with [Rh(COD)Cl]2 and [Ir(COD)Cl]2, the 1,1-COD2-Ph-closo-1,2,3,4-MC3B7H9, M = Rh (7), Ir (8), complexes were produced (eq 5) as crystalline solids in 60% and 49% yields, respectively. The 11B and 1H NMR spectra (Supporting Information, Figures S14−S17) and crystallographically determined structures (Figure 3) for these complexes confirmed closocage structures with η6-coordinated cages and bidentate COD ligands.

Figure 3. Crystallographically determined structures of 7 (top) and 8 (bottom). Selected distances (Å) and angles (deg): 7, Rh1−C18, 2.179(2); Rh1−C19, 2.152(2); Rh1−C22, 2.209(2); Rh1−C23, 2.195(2); Rh1−(C18−C19−C22−C23)centroid, 1.5245(1); C18−C19, 1.387(4); C22−C23, 1.382(4); Rh1−C2, 2.166(2); Rh1−C3, 2.097(2); Rh1−C4, 2.805(2); Rh1−B5, 2.314(3); Rh1−B6, 2.363(3); Rh1−B7, 2.731(3); C2−C4, 1.498(3); C2−B5, 1.611(3); B5−B6, 1.892(4); B6− C3, 1.585(4); C3−B7, 1.571(3); B7−C4, 1.721(4); Rh1−(C4−B5− B6−B7)centroid, 1.9598(2); C2−Rh1−C3, 92.45(9); C18−Rh1−C19, 37.34(9); C22−Rh1−C23, 36.57(9). 8, Ir1−C18, 2.144(3); Ir1−C19, 2.145(3); Ir1−C22, 2.149(3); Ir1−C23, 2.151(3); Ir1−(C18−C19− C22−C23)centroid, 1.49196(6); C18−C19, 1.415(4); C22−C23, 1.413(4); Ir1−C2, 2.144(3); Ir1−C3, 2.076(3); Ir1−C4, 2.624(3); Ir1−B5, 2.351(3); Ir1−B6, 2.405(3); Ir1−B7, 2.541(3); C2−C4, 1.510(4); C2−B5, 1.619(4); B5−B6, 1.885(5); B6−C3, 1.593(5); C3−B7, 1.595(4); C7−B4, 1.746(4); Ir1−(C4−B5−B6−B7)centroid, 1.89331(6); C2−Ir1−C3, 98.72(10); C18−Ir1−C19, 38.53(11); C22− Ir1−C23, 38.35(11).

Rather than the twisted configurations found for 4 and 5, in both 7 and 8, the metal-coordinated CC groups of the COD ligands are situated above the C2 and C3 cage carbons. The metals in both compounds are again slightly shifted toward the B5−B6 edge with dihedral angles of 21.3(2)° and 12.4(3)°, respectively, between their C2−B8−B9−C3 and C2−M−C3 planes. As a result, although the C18−C19−C22−C23 plane is

perpendicular to the C2−M−C3 plane in both 7 and 8, it is tilted (7, 68.23(7)°; 8, 80.12(7)°), relative to the plane passing through the cage C2−B8−B9−C3 plane. The rhodium to (C4−B5−B6−B7)centroid (1.9598(2) Å) and Rh−C2 and Rh−C3 (2.166(2) and 2.047(2) Å) distances in 7 are significantly longer than those values observed for the dppe 1399

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Organometallics complex 5 (1.8992(1), 2.107(2), and 2.135(2) Å), consistent with the weaker electron-donating properties of COD versus dppe. Likewise, the metal to COD-carbon distances in 7 (2.1838aver Å) and 8 (2.1473aver Å) are longer and the metalcoordinated COD CC bonds are shorter (7, 1.382(4) and 1.387(4) Å; 8, 1.415(4) and 1.413(4) Å) than those found in CpRh(COD) (2.1148aver, 1.420(10) and 1.409(11) Å)17 and Cp’Ir(COD) (Cp’ = MeC5H4),18 (2.114(13)aver, 1.430(8), and 1.435(8) Å), reflecting the expected lower metal back-bonding to COD in 7 and 8. Isocyanide Complexes. The reactions of 1 and 3 with an excess of the strong donor tert-butyl isocyanide produced 8,8,8(CNtBu)3-9-Ph-nido-8,7,9,10-MC3B7H9, M = Co (9), Ir (10), in 62% and 75% yields, respectively (eqs 6 and 7).

The 11B and 1H NMR spectra of 9 and 10 were both characteristic of η4-9-Ph-7,9,10-C3B7H91− coordinated cages (Supporting Information, Figures S18−S20). The crystallographically determined structures of 9 and 10 shown in Figure 4 confirmed η4-cage coordination with the cages having the nidocage frameworks expected for 26 skeletal electrons. In both complexes, two of the metal-coordinated isocyanide groups extend away from the nido-metallatricarbadecaboranyl fragment such that they are approximately trans to the C7 and C9 cage carbons, with the third isocyanide then pointing above the fivemembered open face. Consistent with both their crystallographically determined structures and the three tBu resonances observed in their 1H NMR spectra, 9 and 10 each exhibited three CN stretches in their IR spectra. Compared to carbon monoxide, isocyanides are generally considered to be stronger σ-donors but weaker πacceptors, and depending upon the relative importance of these two bonding components, isocyanide complexes can exhibit CN stretching frequencies either above or below the value for a free isocyanide.19 Consistent with strong isocyanide σ-donation, one of the CN stretching frequencies observed for 9 (2186, 2128, 2026 cm−1) was higher than that of free tBuNC (2137 cm−1),20 as was previously observed5a for the 8-CNtBu-8,8,8-(CO)3-9-Phnido-8,7,9,10-MC3B7H9 complexes, M = Mn (2187 cm−1); M = Re (2178 cm−1). The stretching frequencies for 9 were higher than those of complexes such as CpCo(CNtBu)2, CpCo(C2H4)(CNtBu), and CpCo(CO)(CNtBu).21 Likewise, the three cobalt to isocyanide-carbon distances in 9 (Co−C18, Co−C24, and Co−C30 (1.8616(15), 1.8907(15), and 1.8670(16) Å) are all substantially longer than those found in CpCo(CNtBu)(CS3)

Figure 4. Crystallographically determined structures of 9 (top) and 10 (bottom). Selected distances (Å) and angles (deg): 9, Co8−C18, 1.8616(15); C18−N19, 1.152(2); N19−C20, 1.456(2); Co8−C24, 1.8907(15); C24−N25, 1.154(2); N25−C26, 1.461(2); Co8−C30, 1.8670(16); C30−N31, 1.148(2); N31−C32, 1.4615(19); Co8− (C24−C18−C30)centroid, 0.9569(2); Co8−C9, 2.0486(14); Co8−C7, 2.0449(15); Co8−B4, 2.1052(18); Co8−B3, 2.1224(17); Co8−(C7− B3−B4−C9)centroid, 1.4454(2); Co8−C10, 2.966(2); Co8−B11, 2.992(2); C9−C10, 1.530(2); C9−B4, 1.658(2); B4−B3, 1.827(2); B3−C7, 1.642(2); C7−B11, 1.592(2); C9−Co8−C7, 87.17(6); C18− Co8−C30, 87.72(7); C18−Co8−C24, 100.27(6); C24−Co8−C30, 100.13(6), Co8−C18−N19, 178.58(14); Co8−C24−N25, 172.48(14); Co8−C30−N31, 174.99(14); C18−N19−C20, 176.28(16); C24− N25−C26, 171.15(15); C30−N31−C32, 170.72(16). 10, Ir8−C18, 1.978(2); C18−N19, 1.145(3); N19−C20, 1.460(3); Ir8−C24, 2.006(2); C24−N25, 1.149(3); N25−C26, 1.463(3); Ir8−C30, 1.978(2); C30−N31, 1.148(3); N31−C32, 1.458(3); Ir8−C9, 2.1393(19); Ir8−C7, 2.142(2); Ir8−B4, 2.213(2); Ir8−B3, 2.229(2); Ir8−(C7−B3−B4−C9)centroid, 1.55721(7); Ir8−C10, 3.084(2); Ir8− B11, 3.116(2); C9−C10, 1.545(3); C9−B4, 1.722(3); B4−B3, 1.867(3); B3−C7, 1.689(3); C7−B11, 1.613(3); B11−C10, 1.617(3); C9−Ir8−C7, 83.52(8); C18−Ir8−C24, 92.79(8); C18−Ir8−C30, 90.11(8); C24−Ir8−C30, 93.21(8); Ir8−C18−N19, 178.99(19); Ir8− C24−N25, 177.77(19); Ir8−C30−N31, 176.91(19), C18−N19−C20, 177.0(2); C24−N25−C26, 172.3(2); C30−N31−C32, 174.2(2).

(Co−C, 1.827(8) Å),22 indicating less back-bonding and more C−N triple bond character in 9, as would be expected given the 1400

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Organometallics stronger electron-withdrawing character of the tricarbadecaboranyl versus Cp. The Ir−(C7−B3−B4−C9)centroid distance in 10 (1.55721(7) Å) is significantly shorter than that observed for 6 (1.6053(2) Å), again reflecting the stronger donating properties of the three isocyanide ligands relative to the CO and dppe ligands in 6. Two of the IR CN stretches of 10 (2199, 2158, 2064 cm−1) were higher than that of free tBuNC, again indicating strong isocyanide σ-donation, with the highest frequency stretch similar to that observed for Cp*Ir(CNtBu)(mnt) (mnt = maleonitriledithiolate).23 When 8 was reacted with 3 equiv of tert-butyl isocyanide at 60 °C, displacement of the COD was also found to result in the formation of 10 (eq 8). Again, consistent with an associative substitution pathway for this reaction, when only 1 equiv of tertbutyl isocyanide was reacted with 8, isocyanide coordination without COD dissociation was observed to form 8,8-COD-8CNtBu-9-Ph-nido-8,7,9,10-IrC3B7H9 (11) in 74% yield (eq 9) with a nido-cage structure indicated by the patterns observed in both its 11B (Supporting Information, Figure S21) and 1H NMR (Supporting Information, Figure S22) spectra and a single CN stretch at 2189 cm−1.

Figure 5. Crystallographically determined structure of 11. Selected distances (Å) and angles (deg): Ir8−C26, 2.013(7); C26−N27, 1.163(10); N27−C28, 1.476(10); Ir8−C18, 2.215(7); Ir8−C19, 2.205(8); Ir8−C22, 2.234(8); Ir8−C23, 2.247(8); Ir8−(C18−C19− C22−C23)centroid, 1.5805(2); C18−C19, 1.374(12); C22−C23, 1.395(11); Ir8−C9, 2.142(6); Ir8−C7, 2.136(6); Ir8−B4, 2.250(8); Ir8−B3, 2.270(9); Ir8−C10, 3.071(7); Ir8−B11, 3.126(9); C9−C10, 1.532(9); C9−B4, 1.669(10); B4−B3, 1.854(11); B3−C7, 1.638(12); C10−B11, 1.638(11); B11−C7, 1.641(11); Ir8−(C7−B3−B4− C9) centroid , 1.5832(2); C9−Ir8−C7, 82.8(2); Ir8−C26−N27, 177.3(7); C18−Ir8−C19, 36.2(3); C22−Ir8−C23, 36.3(3); C26− N27−C28, 178.3(8).

X-ray analysis confirmed the nido structure shown in Figure 5 for 11. The remaining isocyanide is pointed above the fivemembered open face of the cage with the iridium slipped to the η4-coordination site over C7−B3−B4−C9. The coordinated CC groups of the COD are located trans to the C9 and C7 cage carbons and approximately bisect the C7−Ir8−C9 plane. The Ir1−(C7−B3−B4−C9)centroid distance is shorter in 11 (1.5832(2) Å) than that in 6 (1.6053(2) Å), but longer than that found in 10 (1.55721(7) Å), again consistent with the relative electron-donating abilities of the other ligands in these complexes. As shown by eq 9, when a pure sample of 11 was heated at 60 °C in either hexane or toluene for 16 h, it converted to a mixture of 8 and 10. Alkyne Reactions. Many examples of (η4-C4Ar4)CoCp sandwich complexes have been prepared through the reaction of CpCoL2 complexes with alkynes.24 Likewise, when 1 was reacted with diphenylacetylene at 60 °C for 5 days, both carbonyls were displaced with subsequent alkyne cyclization to form the oily red 1,1-(η4-C4Ph4)-2-Ph-closo-1,2,3,4-CoC3B7H9 (12) (eq 10) product.

As discussed later, comparable reactions of 8 with 2-hexyne only led to cage fragmentation products. However, it was found that the crystalline tetramethylcyclobutadienyl (Cb*) derivative 1,1-(η4-C4Me4)-2-Ph-1,2,3,4-CoC3B7H9 (13) could be synthesized by a different synthetic route25 (eq 11) involving the reaction of Li+(6-Ph-nido-5,6,9-C3B7H9)− with (η4-C4Me4)Co(CO)2I. The 11B NMR spectra of 12 and 13 (Supporting Information, Figure S23) were nearly identical with typical closo spectral patterns. Their 1H NMR spectra showed, in addition to the resonances of the Ph and Me substituents of their η4cyclobutadienyl ligands, the upfield and low-field cage-CH resonances expected for a closo-cage framework (Supporting Information, Figure S24).2,3 The crystallographically determined structure of 13 (Figure 6) confirmed the formation of a complex where a formal Co3+ ion is sandwiched between η4-C4Me42− and η6-2-Ph-2,3,4-C3B7H91− ligands. 1401

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Organometallics

similar to the spectra of 2-Cp-10-Ph-closo-2,1,6,10-MC3B6H8 (M = Ru, Fe). The crystallographic determination shown in Figure 7

Figure 6. Crystallographically determined structure of 13. Selected distances (Å) and angles (deg): Co1−C18, 2.0017(19); Co1−C19, 2.025(2); Co1−C20, 2.0236(19); Co1−C21, 2.002(2); Co1− Cb*centroid, 1.7310(2); C18−C19, 1.453(3); C19−C20, 1.448(3); C20−C21, 1.457(3); C21−C18, 1.452(3); Co1−C2, 1.978(2); Co1− C3, 1.947(2); Co1−C4, 2.259(2); Co1−B5, 2.221(2); Co1−B6, 2.243(3); Co1−B7, 2.269(2); Co1−(C4−B5−B6−B7) centroid , 1.6113(2); C2−C4, 1.504(3); C2−B5, 1.584(3); B5−B6, 1.857(4); B6−C3, 1.575(4); C3−B7, 1.569(3); B7−C4, 1.754(3); C3−Co1−C2, 111.63(9); C12−C2−Co1, 126.76(14); C18−C19−C20, 90.34(16); C19−C20−C21, 89.85(16); C20−C21−C18, 89.99(16); C21−C18− C19, 89.82(16).

Figure 7. Crystallographically determined structure of 14. Selected distances (Å) and angles (deg): Ir2−C17, 2.168(9); Ir2−C18, 2.161(9); Ir2−C21, 2.214(10); Ir2−C22, 2.201(9); Ir2−(C17−C18−C21− C22)centroid, 1.5185(3); C17−C18, 1.428(14); C21−C22, 1.364(15); Ir2−C1, 2.067(9); Ir2−B3, 2.325(11); Ir2−C6, 2.074(8); Ir2−B7, 2.198(10); Ir2−B5, 2.411(11); C17−Ir2−C18, 38.5(4); C21−Ir2− C22, 36.0(4).

confirmed a closo-bicapped square antiprism cage geometry, with two of the cage carbons (C1 and C10) in the low-coordinate capping positions and the third carbon (C6) situated in a fivecoordinate site adjacent to the metal. The intracage distances of 14 are similar to those found in 2-Cp-10-Ph-closo-2,1,6,10RuC3B6H8 with the exception that the C6−B7 distance in 14 (2.355 Å) is substantially longer than that of 2-Cp-10-Ph-closo2,1,6,10-RuC3B6H8 (1.777(3) Å). The COD group is tilted away from the C1 cage carbon, with a 73.2(3)° angle between the plane of the COD coordinated carbons (C17−C18−C21−C22) of 14 and the cage Ir2−B8−B9 cage plane. This tilt leads to different bonding interactions for the two COD olefin units. Thus, in contrast to 8, where the two COD CC bond lengths are similar, in 14, C17−C18 (1.428(14) Å) is much longer than C21−C22 (1.364(15) Å) and the Ir−C21 and Ir−C22 distances are longer (2.214(10) and 2.201(9) Å) than Ir−C17 and Ir−C18 (2.168(9) and 2.161(9) Å), indicating less Ir back-bonding to the C21C22 group situated directly across from the C1 cage carbon. Fluoride induced deboronation of the 1-Cp-2-Ph-closo-1,2,3,4MC3B6H8 (M = Ru, Fe) complexes was proposed27 to initially occur by nucleophilic attack at the electropositive boron (B8) located between C2 and C4, followed by rearrangement of the Ph−C group to the four-coordinate cage position away from the metal-bonding face. As indicated by the arrows in eq 12, a similar pathway involving attack by the alkyne at the positive B8 boron of 8, followed by deboronation and cage rearrangement, could lead to the formation of 14. Attempted Oxidative-Addition Reactions. Many Group 9 CpML2 complexes have been shown to undergo oxidativeaddition reactions with, for example, iodine28 and/or perfluoroalkyl iodides.28a,29 Likewise, the larger cage 1,1-(COD)12-tBuNH-1,2,4,12-MC3B8H10 tricarbollide complexes have

The internal bond angles at the Cb* ring carbons are all 90°, and the C−C ring distances are statistically equivalent (1.453(3)aver Å). The Co1−Cb*centroid distance (1.7310(2) Å) in 13 is significantly longer than those found in either (η4C4Me4)Co(η5-indenyl)25 (1.683(4) Å) or the larger cage tricarbollide complexes,26 1-(η4-C4Me4)-1,2,3,4-CoC3B8H11 (Co-Cb*, 1.696 Å) and 1-(η4-C4Me4)-12-tBuNH-1,2,4,12CoC3B8H10 (Co-Cb*, 1.703 Å), indicating, consistent with a bonding competition with the strongly electron-withdrawing tricarbadecaboranyl ligand, less back-bonding from the cobalt to the Cb* ligand in 13. Likewise, the Co−(C4−B5−B6−B7)centroid distance (1.6113(2) Å) in 13 is longer than that of 4 (1.5899(2) Å), further suggesting significant bonding competition between the cyclobutadienyl and tricarbadecaboranyl ligands. When 8 was stirred with 2 equiv of 3-hexyne at room temperature for 5 h, hexyne coordination was not observed, but instead, cage deboronation resulted to produce 2,2-COD-10-Phcloso-2,1,6,10-C3B6H8 (14) in 72% yield (eq 12).

Deboronation of the isoelectronic 1-Cp-2-Ph-closo-1,2,3,4MC3B7H9 (M = Ru, Fe) complexes by tetrabutylammonium fluoride to form 2-Cp-10-Ph-closo-2,1,6,10-MC3B6H8 (M = Ru, Fe) has previously been observed.27 The 11B NMR spectra of 14 (Supporting Information, Figure S25) showed only six resonances, indicating the loss of one cage boron and was 1402

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Organometallics been shown to readily oxidatively add Br2 or I2 with loss of COD to produce [(tBuNH-C3B8H10)MX2]2 products.30 Unfortunately, but in keeping with the well-established ability of the tricarbadecaboranyl ligand to stabilize low metal oxidation states,3i,j,5 neither 7 nor 8 reacted with I2. Although 11 reacted with I2 at room temperature and with perfluoro-1-iodohexane under UV irradiation, oxidative-addition products were also not obtained, but instead, 8,8-COD-8-CN tBu-9-Ph-11-I-nido8,7,9,10-IrC3B7H8 (15) was formed (eq 13).

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CONCLUSIONS

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EXPERIMENTAL SECTION

The syntheses and structural characterizations of the first extensive series of Group 9 tricarbadecaboranyl half-sandwich complexes, 1,1-L2-2-Ph-closo-1,2,3,4-MC3B7H9 and 8,8,8-L3-9Ph-nido-8,7,9,10-MC3B7H9, have been achieved. The structural and reactivity studies of these complexes demonstrated that, compared to their cyclopentadienyl counterparts, the tricarbadecaboranyl ligands (1) exhibit strong electron-withdrawing properties that reduce metal back-bonding to other π-accepting ligands, thereby increasing the lability of these ligands; (2) readily form either η6- or η4-coordination geometries that allow a metal to bind a variable number of ligands without violating the 18-electron count at the metal; and (3) show an increased ability to stabilize lower metal oxidation states. These unique properties are complementary to their Cp/Cp* counterparts and provide an opportunity to tune the electronic and reactivity properties of new classes of half-sandwich complexes.

The 11B and 1H NMR spectra (Supporting Information, Figures S27 and S28) of 15 were similar to those of 11 with the exception that the doublet resonance at −16.4 ppm in the spectrum of 11 was replaced by a −20.0 ppm singlet, thus indicating iodide substitution at one boron in 15. The crystallographic determination shown in Figure 8 confirmed

General Procedures. Unless otherwise noted, all reactions and manipulations were performed in dry glassware under nitrogen atmospheres using the high-vacuum or inert-atmosphere techniques described by Shriver.31 Materials. Solutions of the Li+(6-Ph-nido-5,6,9-C3B7H9)− salt were prepared as previously reported.1,2 (η4-C4Me4)Co(CO)2I was prepared as reported in the literature.25 Co2(CO)8, [Rh(CO)2Cl]2, [Rh(COD)Cl]2, [Ir(COD)Cl]2 (COD = cyclooctadiene, C8H12), Ir(CO)3Cl (Strem), I2, HCl·Et2O, 1,2-bis(diphenylphosphino)ethane (dppe), diphenylacetylene, and tert-butyl isocyanide (Aldrich) were used as received. The reaction solvents, toluene, tetrahydrofuran (THF), hexanes, dichloromethane, and benzene, were all from Fisher and dried using appropriate drying agents. When used for workup, hexanes, pentane, and dichloromethane (Fisher) were used as received. The NMR solvents, C6D6 (D, 99.5%), CDCl3 (D, 99.9%), and CD2Cl2 (D, 99.9%) (Cambridge Isotope), were used as received. Physical Measurements. 1H NMR at 400.1 MHz, 11B NMR at 128.4 MHz, and 31P NMR at 161.9 MHz were carried out on a Bruker DMX 400 spectrometer. All 11B NMR chemical shifts are referenced to external BF3·OEt2 (0.00 ppm) with a negative sign, indicating an upfield shift. All 1H chemical shifts were measured relative to residual protons in the lock solvents and are referenced to (CH3)4Si (0.00 ppm). All 31P NMR chemical shifts are referenced to external H3PO4 (0.00 ppm). NMR spectra are shown in the Supporting Information. High- (HRMS) and low-resolution mass spectra using negative chemical ionization (NCI) or electrospray ionization (ESI) techniques were recorded on a Micromass Autospec or a Waters GC-TOF Premier Spectrometer, respectively. Infrared spectra were recorded on a PerkinElmer Spectrum 100 FT-IR spectrometer using KBr pellets or NaCl plates. Silica gel (230−400 mesh, Fisher) was used for chromatography. Elemental analyses were performed at the Microanalytical Laboratory, University of California, Berkeley. Melting points were obtained on a standard melting point apparatus and are uncorrected. 1,1-(CO)2-2-Ph-closo-1,2,3,4-CoC3B7H9 (1). As described in the literature,32 a toluene (5 mL) solution of Co(CO)4I was prepared by the room temperature, stirred reaction of Co2(CO)8 (417 mg, 1.22 mmol) with I2 (381 mg, 1.50 mmol) in the dark for 2 h. A THF solution of Li+(6-Ph-nido-5,6,9-C3B7H9)− (2.4 mL of a 1 M solution, ∼2.4 mmol) was added to the solution, and the mixture stirred in the dark overnight for 14 h. The resulting red solution was chromatographed using a hexanes eluent to give 1 as a moisture-, air-, and light-sensitive compound. Full characterization of 1 could not be obtained since it rapidly decomposed upon solvent removal. 1: red; 11B NMR (128.4 MHz, C6H14) ppm (int, mult, J = Hz) 5.5 (1, d, 167), −1.5 (1, d, 164), −11.3 (1, d, 165), −14.1 (1, d, 160), −27.5 (1, d, 149), −29.6 (1, d, 167), −32.5 (1, d, 169). IR (solution, NaCl plates, cm−1): 2056 (s), 2053 (s) (CO stretches).

Figure 8. Crystallographically determined structure of 15. Selected distances (Å) and angles (deg): Ir8−C26, 1.995(5); C26−N27, 1.155(7); Ir8−C18, 2.240(6); Ir8−C19, 2.230(5); Ir8−C22, 2.256(5); Ir8−C23, 2.250(6); Ir8−(C18−C19−C22−C23)centroid, 1.5993(2); C18−C19, 1.406(9); C22−C23, 1.381(8); Ir8−C9, 2.143(6); Ir8−C7, 2.148(5); Ir8−B4, 2.250(6); Ir8−B3, 2.270(6); Ir8−(C7−B3−B4−C9)centroid, 1.5728(2); Ir8−C10, 3.063(5); Ir8−B11, 3.075(7); B11−I1, 2.186(6); Ir8−C26−N27, 177.3(5); C9−Ir8−C7, 84.1(2); C18−Ir8−C19, 36.7(2); C22−Ir8−C23, 35.7(2).

substitution at the B11 boron on the open face of the cage with a B−I distance (2.186(6) Å) similar to that found in 1-Cp-2-Ph-6I-closo-1,2,3,4-MC3B7H8 (M = Fe (2.187(3) Å), Ru (2.194(3) Å)).4b,e The remaining bond distances and angles of 15 were similar to those of 11. 1403

DOI: 10.1021/acs.organomet.5b00141 Organometallics 2015, 34, 1396−1407

Article

Organometallics 1,1-(CO)2-2-Ph-closo-1,2,3,4-RhC3B7H9 (2). A solution of Li+(6Ph-nido-5,6,9-C3B7H9)− (5 mL of a 0.35 M solution, ∼1.7 mmol) in THF was stirred with [Rh(CO)2Cl]2 (450 mg, 1.16 mmol) in the dark for 14 h at room temperature. The red solution was chromatographed using a hexanes eluent to give 2 as a moisture-, air-, and light-sensitive compound. Full characterization of 2 could not be obtained since it rapidly decomposed upon solvent removal. 2: red; 11B NMR (128.4 MHz, C6H14) ppm (int, mult, J = Hz) 10.5 (1, d, 127), 1.3 (1, d, 113), −4.9 (1, d, 145), −10.9 (1, d, 112), −12.8 (1, d, 131), −19.9 (1, d, 153), −26.6 (1, d, 145). IR (solution, NaCl plates, cm−1): 2084 (s), 2011 (s) (CO stretches). HRMS: m/z calc for 12 C111H1416O211B7103Rh1: 358.06934, found: 358.2345. 8,8,8-(CO)3-9-Ph-nido-8,7,9,10-IrC3B7H9 (3). A solution of Li+(6Ph-nido-5,6,9-C3B7H9)− (5 mL of a 0.35 M solution, ∼1.7 mmol) in THF was stirred with Ir(CO)3Cl (500 mg, 1.7 mmol) in the dark for 14 h at room temperature. The red solution was chromatographed using a hexanes eluent to give 3 as a moisture-, air-, and light-sensitive solid. 3: 40% yield (304 mg, 0.68 mmol); red/yellow; mp 180 °C; Anal. Calcd for (3 + 3THF) C24B7H38O6Ir: C, 41.75; H, 4.55; found: C, 42.14; H, 4.45; 11B NMR (128.4 MHz, CD2Cl2) ppm (int, mult, J = Hz) −1.1 (1, d, 134), −4.1 (1, d, 164), −10.3 (2, d, 151), −12.3 (1, d, 150), −16.5 (1, d, 181), −37.6 (1, d, 148); 1H{11B} NMR (400.1 MHz, CDCl3) ppm (int, assgn) 7.73−6.87 (5, Ph), 5.19 (1, BH), 4.23 (1, cage-CH), 3.83 (1, BH), 3.75 (1, BH), 3.21 (1, BH), 3.06 (1, cage-CH), 3.01 (1, BH), 2.95 (1, BH) (the remaining BH resonance was not resolvable); IR (NaCl, cm−1): 2545 (s), 2081 (s), 2028 (s), 1596 (w), 1577 (w), 1490 (w), 1456 (w), 1444 (w), 1263 (m), 1093 (w), 1076 (w), 1029 (w), 987 (m), 801 (m), 754 (m), 740 (m), 700 (m). 1,1-dppe-2-Ph-closo-1,2,3,4-CoC3B7H9 (4). A solution of 1 (∼0.5 mmol), prepared in situ via the reaction of Co(CO)4I with Li+(6-Phnido-5,6,9-C3B7H9)−, was added to a THF solution (10 mL) of 1,2bis(diphenylphosphino)ethane (dppe) (216 mg, 0.54 mmol), and the mixture stirred at 40 °C for 14 h. The solvent was vacuum-evaporated, and the resulting oil was chromatographed with a 1:1 dichloromethane/ hexanes eluent to give 4. Crystals were obtained upon slow evaporation of a pentane solution. 4: 31% yield (98.1 mg, 0.15 mmol); green; mp 275−277 °C. Anal. Calcd for C35B7H38P2Co: C, 64.16; H, 5.84; found: C, 64.01; H, 6.27; 11 B NMR (128.4 MHz, C6D6) ppm (int, mult, J = Hz) 2.3 (1, d, 161), −0.2 (1, d, br), −15.0 (1, d, br), −16.1 (1, d, 114), −28.0 (1, d, 134), −31.0 (1, d, 175), −32.5 (1, d, 156). 1H{11B} NMR (400.1 MHz, CD2Cl2) ppm (int, assgn) 7.88−6.85 (25, 5Ph), 6.36 (1, cage-CH), 3.14 (1, BH), 2.55 (1, CH2), 2.33 (2, CH2), 1.78 (1, CH2), 1.62 (1, BH), 1.26 (1, BH), 1.03 (1, cage-CH), 0.57 (1, BH), 0.28 (1, BH) (the remaining BH resonances were not resolvable); 31P{1H} NMR (161.9 MHz, C6D6) ppm (mult) 78.7 (1, s), 62.3 (1, s). IR (NaCl, cm−1): 3062 (m), 3028 (m), 2573 (s), 2551 (s), 2530 (s), 2520 (s), 2483 (s), 1594 (w), 1586 (w), 1572 (w), 1485 (m), 1432 (s), 1419 (m), 1409 (m), 1334 (w), 1322 (w), 1307 (w), 1273 (w), 1189 (w), 1095 (s), 1026 (m), 1000 (m), 975 (m), 938 (s), 873 (s), 811 (s), 746 (s), 682 (s), 678 (s), 649 (s), 530 (s), 520 (s), 489 (s), 475 (m). 1,1-dppe-2-Ph-closo-1,2,3,4-RhC3B7H9 (5). A THF solution of 2 (∼0.33 mmol), prepared in situ via the reaction of [Rh(CO)2Cl]2 with Li+(6-Ph-nido-5,6,9-C3B7H9)−, was mixed with a THF (10 mL) solution of 1,2-bis(diphenylphosphino)ethane (dppe) (133 mg, 0.33 mmol), and the mixture stirred at 40 °C for 14 h. The solvent was vacuumevaporated, and the remaining oil was chromatographed with a 1:1 dichloromethane/hexanes eluent to give 5. Crystals were obtained upon recrystallization from hot pentane. 5: 35% yield (80.7 mg, 0.12 mmol); red; mp 223−225 °C; Anal. Calcd for C35B7H38P2Rh: C, 60.12; H, 5.48; found: C, 60.20; H, 5.55; 11 B NMR (128.4 MHz, CD2Cl2) ppm (int, mult, J = Hz) 8.3 (1, d, 101), −0.1 (1, d, 170), −1.2 (1, d, 151), −10.0 (1, d, 101), −16.4 (1, d, 120), −17.4 (1, d, 114), −21.1 (1, d, 114); 1H{11B} NMR (400.1 MHz, CD2Cl2) ppm (int, assign) 7.68−6.58 (25, 5Ph), 3.54 (1, BH), 3.12 (1, cage-CH), 3.00 (1, cage-CH), 2.81 (1, BH), 2.72 (1, BH), 2.09 (4, 2CH2), 1.95 (1, BH), 1.87 (1, BH), 1.66 (1, BH), 1.49 (1, BH); 31P{1H} NMR (161.9 MHz, C6D6) ppm (int, mult, J103Rh−P = Hz) at 27 °C: 57.5 (d, 166), at −53 °C: 57.3 (1, d, 160), 57.9 (1, d, 174); IR (NaCl, cm−1): 3058 (m), 3026 (m), 2960 (m), 2925 (m), 2538 (s), 2228 (s), 1721 (w),

1597 (w), 1573 (w), 1489 (s), 1447 (s), 1435 (s), 1413 (w), 1288 (w), 1191 (w), 1178 (w), 1161 (w), 1100 (s), 1071 (m), 1026 (m), 1000 (m), 928 (w), 880 (w), 814 (m), 758 (s), 701 (s), 548 (s), 525 (s), 512 (m), 488 (m). 8-CO-8,8-dppe-9-Ph-nido-8,7,9,10-IrC3B7H9 (6). A solution of 3 (100 mg, 0.22 mmol) and 1,2-bis(diphenylphosphino)ethane (dppe) (90 mg, 0.22 mmol) in THF (10 mL) was stirred at room temperature for 14 h. The solvent was vacuum-evaporated, and the residue was chromatographed with a 1:1 dichloromethane/hexanes eluent to give 6. Crystals were obtained upon recrystallization from hot pentane. 6: 39% yield (70 mg, 0.86 mmol); red; mp 135 °C; 11B NMR (128.4 MHz, CDCl3) ppm (int, mult, J = Hz) −8.9 (1, d, br), −13.1 (2, d, ∼108), −15.8 (2, d, ∼141), −19.0 (1, d, ∼143), −40.2 (1, d, 141). 1 H{11B} NMR (400.1 MHz, CDCl3) ppm (int, assign) 7.78−6.61 (25, 5Ph), 3.83 (1, BH), 3.66 (1, BH), 3.49 (1, cage-CH), 2.80 (1, BH), 2.73 (2, CH2), 2.32 (1, cage-CH), 2.04 (1, BH), 1.97 (4, 2CH2), 1.84 (1, BH), 0.86 (1, BH) (the remaining BH resonance was not resolvable). 31 1 P{ H} NMR (161.9 MHz, CDCl3) ppm (mult) 17.3 (s). IR (NaCl, cm−1): 3057 (m), 2964 (m), 2927 (m), 2534 (s), 2247 (w), 2013 (s), 1595 (w), 1574 (w), 1486 (m), 1435 (s), 1413 (m), 1312 (w), 1262 (s), 1191 (w). 1,1-COD-2-Ph-closo-1,2,3,4-RhC3B7H9 (7). A solution of Li+(6Ph-nido-5,6,9-C3B7H9)− (5 mL of a 0.08 M solution, ∼0.40 mmol) in THF was stirred with [Rh(COD)Cl]2 (200 mg, 0.40 mmol) in the dark for 14 h at room temperature. The dark red solution was flash chromatographed with a hexanes eluent to give 7. Crystals were obtained upon slow evaporation of a heptane solution. 7: 60% yield (100 mg, 0.24 mmol); orange/red; mp 171 °C; Anal. Calcd for C17B7H26Rh: C, 49.93; H, 6.41; found: C, 49.73; H, 6.43; HRMS: m/z calc for 12C171H2611B7103Rh1: 410.1741, found: 410.1790; 11 B NMR (128.4 MHz, CDCl3) ppm (int, mult, J = Hz) 7.8 (1, d, 151), 3.8 (1, d, 148), −4.2 (1, d, 156), −7.3 (1, d, 182), −9.8 (1, d, 157), −16.9 (1, d, 143), −20.4 (1, d, 153). 1H{11B} NMR (400.1 MHz, CDCl3) ppm (int, assign) 7.56−7.30 (5, Ph), 3.61 (1, BH), 3.52 (1, cage-CH), 3.42 (1, cage-CH), 3.26 (1, BH), 2.57 (3, 2COD-CH/1BH), 2.44 (2, COD), 2.15 (1, BH), 2.11−2.03 (8, COD), 1.96 (1, BH), 1.63 (1, BH) (the remaining BH resonance was not resolvable); IR (NaCl, cm−1): 3418 (m), 2921 (m), 2882 (m), 2834 (m), 2546 (s), 1639 (w), 1490 (w), 1446 (w), 1430 (w), 1336 (w), 1307 (w), 1263 (w), 1182 (w), 1107 (w), 1038 (w), 977 (w), 932 (w), 859 (m), 820 (w), 791 (w), 749 (m), 699 (m), 610 (m), 585 (w). 1,1-COD-2-Ph-closo-1,2,3,4-IrC3B7H9 (8). A solution of Li+(6-Phnido-5,6,9-C3B7H9)− (3.5 mL of a 0.17 M solution, ∼0.60 mmol) in THF was stirred with [Ir(COD)Cl]2 (200 mg, 0.30 mmol) in the dark for 14 h at room temperature. The dark red solution was flash chromatographed with a hexanes eluent to give 8. Crystals were obtained upon slow evaporation of a heptane solution. 8: 49% yield (146 mg, 0.29 mmol); red/orange; mp 123−126 °C; Anal. Calcd for C17B7H26Ir: C, 40.98; H, 5.26; found: C, 40.97; H, 5.08; HRMS: m/z calc for 12C171H2611B7193Ir1: 500.2315, found: 500.2332; 11 B NMR (128.4 MHz, CD2Cl2) ppm (int, mult, J = Hz) 1.5 (1, d, 151), 0.2 (1, d, 180), −7.1 (1, d, 152), −10.1 (1, d, 144), −25.0 (1, d, 169) −26.9 (1, d, 151), −28.9 (1, d, 171); 1H{11B} NMR (400.1 MHz, CD2Cl2) ppm (int, assign) 7.74−7.39 (5, Ph), 4.13 (3, 2COD-CH/ 1BH), 3.90 (1, COD), 3.53 (3, 2COD-CH/1BH), 3.21 (1, COD), 2.95 (1, cage-CH), 2.40 (1, BH), 1.89 (1, BH), 1.54 (4, COD), 1.31 (1, cageCH), 0.59 (1, BH), 0.21 (1, BH), 0.04 (1, BH); IR (NaCl, cm−1): 3085 (w), 3058 (m), 2992 (s), 2923 (s), 2840 (s), 2681 (w), 2559 (s), 2229 (w), 1948 (w), 1597 (m), 1579 (w), 1494 (m), 1474 (m), 1465 (m), 1446 (s), 1359 (w), 1327 (s), 1302 (m), 1262 (m), 1242 (m), 1204 (m), 1181 (m), 1160 (m), 1100 (m), 1076 (m), 1059 (m), 1037 (m), 1017 (s), 969 (m), 953 (s), 926 (s), 893 (m), 877 (m), 837 (m), 793 (m), 776 (m), 751 (s), 717 (s), 695 (s), 518 (m), 494 (m). 8,8,8-(CNtBu)3-9-Ph-nido-8,7,9,10-CoC3B7H9 (9). A sample of tert-butyl isocyanide (1.0 mL, 0.88 mmol) was added to a 10 mL THF solution of 1 (∼0.2 mmol), prepared in situ via the reaction of Co(CO)4I with Li+(6-Ph-5,6,9-C3B7H9)−, and the mixture stirred for 20 h at room temperature. The solvent and remaining tert-butyl isocyanide 1404

DOI: 10.1021/acs.organomet.5b00141 Organometallics 2015, 34, 1396−1407

Article

Organometallics

3033 (w), 2574 (m), 1748 (w), 1601 (m), 1573 (w), 1498 (s), 1443 (m), 1309 (w), 1261 (w), 1211 (w), 1177 (w), 1158 (w), 1094 (w), 1070 (m), 1026 (m), 971 (w), 915 (w), 801 (w), 756 (s), 689 (s), 549 (w), 536 (w), 508 (w). 1-(η4-C4Me4)-2-Ph-closo-1,2,3,4-CoC3B7H9 (13). A glyme solution of Li+(6-Ph-nido-5,6,9-C3B7H9)− (4.5 mL of a 0.08 M, ∼0.35 mmol) was added to a THF solution of (η4-C4Me4)Co(CO)2I (100 mg, 0.3 mmol), and the mixture stirred at reflux overnight. The red residue obtained upon solvent evaporation was redissolved in dichloromethane and then chromatographed using a 2:1 hexanes:dichloromethane eluent to give 13. The red solid was then washed three times with pentane, giving red crystals. 13: 37% yield (39 mg, 0.11 mmol); red; mp 152−154 °C. HRMS: m/ z calc for 12C171H2611B759Co1: 366.2018, found: 366.2025. 11B NMR (128 MHz, C6D6) ppm (int, mult, J = Hz) −2.0 (1, d, br), −2.9 (1, d, 127), −5.7 (1, d, 154), −7.6 (1, d, 145), −22.1 (1, d, 117), −22.6 (1, d, br), −25.9 (1, d, 154). 1H NMR (400.1 MHz, CD2Cl2) ppm (int, assign) 7.28−7.77 (5, Ph), 4.96 (1, cage-CH), 2.59 (1, cage-CH), 1.20 (12, 4CH3). IR (cm−1): 3331 (w), 3086 (m), 3065 (m), 3033 (m), 3019 (m), 2954 (m), 2981 (m), 2910 (m), 2603 (s), 2584 (s), 2549 (s), 2521 (s), 2348 (w), 2316 (w), 1942 (w), 1800 (w), 1597 (m), 1578 (m), 1535 (w), 1496 (m), 1454 (s), 1445 (s), 1434 (m), 1408 (m), 1016 (s), 970 (m), 935 (s), 911 (m), 861 (m), 851 (m), 817 (m), 792 (m), 742 (m), 724 (m), 690 (s), 666 (s), 621 (m), 604 (m), 536 (s), 481 (m), 466 (m). 2,2-COD-10-Ph-closo-2,1,6,10-IrC3B6H8 (14). 3-Hexyne (0.36 mL, 3.16 mmol) was added to a solution of 8 (100 mg, 0.21 mmol) in hexanes (10 mL), and the mixture was then stirred at room temperature for 20 h. The solution was frit-filtered, and the solvent was vacuum-evaporated. The red residue was chromatographed with a hexanes eluent to give 15. Crystals were obtained upon slow evaporation of a hexanes solution. 14: 72% yield (70 mg, 0.15 mmol); orange; mp 214 °C; Anal. Calcd for C17B6H25Ir: C, 41.97; H, 5.18; found: C, 41.54; H, 4.96; HRMS: m/z calc for 12C171H2511B6193Ir1: 488.2144, found: 488.2163; 11B NMR (128.4 MHz, CD2Cl2) ppm (int, mult, J = Hz) 3.3 (1, d, 171), −4.2 (1, d, 158), −9.6 (1, d, 149), −16.5 (1, d, 160), −19.1 (1, d, 158), −21.1 (1, d, 167); 1H{11B} NMR (400.1 MHz, CD2Cl2) ppm (int, assign) 7.55− 7.23 (5, Ph), 4.02 (1, cage-CH), 3.89 (1, BH), 2.69 (1, BH), 2.64 (2, COD), 2.40 (1, BH), 2.38−2.34 (2, COD), 2.19 (1, cage-CH), 2.04 (1, BH), 1.64 (1, BH), 1.40 (1, BH), 1.28 (8, COD); IR (NaCl, cm−1): 3216 (s), 2972 (m), 2056 (m), 1412 (s), 1196 (m), 1088 (m), 803 (w), 719 (w), 639 (w). 8,8-COD-8-CNtBu-9-Ph-11-I-nido-8,7,9,10-IrC3B7H8 (15). Perfluoro-1-iodohexane (0.1 mL, 0.43 mmol) was added to a solution of 11 (100 mg, 0.18 mmol) in dichloromethane (10 mL), and the solution was then irradiated with a medium pressure mercury lamp for 3 h. The solvent was vacuum-evaporated to give 15 in 80% yield (102 mg, 0.14 mmol). Crystals were obtained upon slow evaporation of a dichloromethane solution layered with heptane. 15 was also synthesized by reacting I2 (22 mg, 0.09 mmol) with 11 (100 mg, 0.18 mmol) in a stirred dichloromethane (10 mL) solution for 12 h. The solvent was vacuum-evaporated to give 15 in 80% yield (102 mg, 0.14 mmol). 15: pale orange; mp 196−197 °C; Anal. Calcd for C22B7H34NIIr: C, 36.67; H, 4.79; N, 1.90; found: C, 37.36; H, 4.85; N, 1.98; 11B NMR (128.4 MHz, CDCl3) ppm (int, mult, J = Hz) −0.7 (1, d, 133), −6.4 (1, d, 148), −10.8 (1, d, 176), −12.2 (1, d, 137), −14.9 (1, d, 145). −20.0 (1, s), −38.4 (1, d, 138); 1H{11B} NMR (400.1 MHz, CDCl3) ppm (int, assign) 7.15−7.02 (5, Ph), 4.44 (1, BH), 4.37 (2, COD), 3.80 (2, COD), 3.44 (1, BH), 3.16 (1, BH), 2.96 (1, cage-CH), 2.55 (4, COD), 2.21 (1, BH), 2.18 (4, COD), 1.92 (9, (CH3)3), 1.41 (1, cage-CH), 1.13 (1, BH) (the remaining BH resonance was not resolvable); IR (NaCl, cm−1): 2981 (w), 2942 (w), 2886 (w), 2848 (w), 2550 (s), 2191 (s), 1492 (w), 1473 (w), 1443 (w), 1371 (m), 1086 (w), 1036 (w), 989 (m), 915 (w), 850 (m), 760 (m), 738 (m), 703 (m). Collection and Reduction of the Data. Crystallographic data and structure refinement information are summarized in the Supporting Information (Table S1). X-ray intensity data were collected on a Bruker APEXII CCD area detector employing graphite-monochromated Mo− Kα. The SHELXTL program package33 was used for data processing

were vacuum-evaporated to give 9 as an oil. Crystals were obtained upon slow evaporation of a dichloromethane solution layered with heptane. 9: 62% yield (63 mg, 0.12 mmol); purple; Anal. Calcd for (9 + 3CH2Cl2) C27B7H47N3CoCl6: C, 44.76; H, 6.40; N, 5.80; found: C, 44.26; H, 6.35; N, 5.48; 11B NMR (128.4 MHz, CDCl3) ppm (int, mult, J = Hz) −3.4 (2, d, 125), −8.7 (1, d, 146), −11.1 (1, d, 137), −13.1 (1, d, 153), −17.7 (1, d, 151), −33.5 (1, d, 169); 1H{11B} NMR (400.1 MHz, CD2Cl2) ppm (int, assign) 7.76−7.05 (5, Ph), 4.38 (1, cage-CH), 4.13 (1, BH), 3.86 (1, BH), 3.13 (1, BH), 2.97 (1, cage-CH), 2.89 (1, BH), 2.82 (1, BH), 2.77 (1, BH), 1.37 (9, 3CH3), 0.93 (9, 3CH3), 0.80 (9, 3CH3) (the remaining BH resonance was not resolvable); IR (NaCl, cm−1): 3418 (m), 2983 (m), 2936 (w), 2529 (m), 2186 (m), 2128 (s), 2026 (m), 1828 (w), 1597 (w), 1490 (w), 1474 (w), 1447 (m), 1399 (w), 1372 (m), 1288 (w), 1234 (m), 1203 (s), 1071 (w), 1026 (w), 983 (w), 929 (w), 760 (s), 689 (m), 594 (s), 532 (m). 8,8,8-(CNtBu)3-9-Ph-nido-8,7,9,10-IrC3B7H9 (10). tert-Butyl isocyanide (0.07 mL, 0.63 mmol) was added to a solution of 3 (100 mg, 0.21 mmol) in dichloromethane (10 mL), and the solution then stirred at 60 °C for 20 h. The solvent was vacuum-evaporated to give 10 in 75% yield (102 mg, 0.16 mmol). Crystals were obtained upon slow evaporation of a dichloromethane solution. 10 was also synthesized by reacting tert-butyl isocyanide (0.07 mL, 0.63 mmol) with a stirred solution of 8 (100 mg, 0.20 mmol) in THF (10 mL) at 60 °C for 20 h. Following solvent evaporation, 10 was obtained in 73% yield (96 mg, 0.15 mmol). 10: pale yellow; decomposes at 180 °C; Anal. Calcd for C24B7H41N3Ir: C, 45.08; H, 6.46; N, 6.57; found: C, 45.41; H, 6.75; N, 5.92; HRMS: m/z calc for 12C1914N21H3211B7193Ir1 (10 − CNtBu): 558.2850, found: 558.2980; 11B NMR (128.4 MHz, CD2Cl2) ppm (int, mult, J = Hz) −4.9 (1, d, 132), −10.3 (1, d, 106), −13.2 (1, d, 144), −15.6 (2, d, 122), −20.8 (1, d, br), −43.4 (1, d, 147); 1H{11B} NMR (400.1 MHz, CD2Cl2) ppm (int, assign) 7.27−6.89 (5, Ph), 5.12 (1, BH), 3.84 (1, BH), 3.02 (1, BH), 2.81 (1, BH), 2.28 (1, cage-CH), 2.18 (1, BH), 2.04 (1, BH), 1.72 (9, (CH3)3), 1.43 (9, (CH3)3), 1.21 (9, (CH3)3), 1.04 (1, cage-CH), 0.69 (1, BH); IR (NaCl, cm−1): 3055 (w), 2984 (s), 2934 (s), 2526 (s), 2404 (w), 2245 (s), 2199 (s), 2158 (s), 2064 (m), 1668 (w), 1596 (m), 1575 (w), 1492 (m), 1474 (m), 1457 (s), 1399 (m), 1371 (s), 1261 (m), 1233 (s), 1205 (s), 1092 (s), 1037 (s), 990 (s), 912 (s), 801 (m), 757 (m), 733 (s), 700 (s), 663 (w), 647 (m), 585 (w), 538 (m), 519 (m). 8,8-COD-8-CNtBu-9-Ph-nido-8,7,9,10-IrC3B7H9 (11). tert-Butyl isocyanide (0.1 mL, 0.88 mmol) was added to a solution of 8 (100 mg, 0.21 mmol) in dichloromethane (10 mL), and the mixture then stirred at room temperature for 20 h. The solution was filtered, and the solvent was vacuum-evaporated to give 11. Crystals were obtained upon slow evaporation of a dichloromethane solution. 11: 74% yield (90 mg, 0.15 mmol); pale yellow; mp 160−162 °C; Anal. Calcd for C22B7H35NIr: C, 45.44; H, 6.07; N, 2.26; found: C, 45.29; H, 5.86; N, 2.41; 11B NMR (128.4 MHz, CD2Cl2) ppm (int, mult, J = Hz) −2.6 (1, d, 147), −5.3 (1, d, 165), −11.3 (2, d, 130), −13.9 (1, d, 145), −16.4 (1, d, 150), −38.5 (1, d, 143); 1H{11B} NMR (400.1 MHz, CD2Cl2) ppm (int, assign) 7.13−6.97 (5, Ph), 4.32 (1, cage-CH), 4.22 (1, cage-CH), 4.09 (1, BH), 3.36 (1, BH), 3.15 (1, BH), 2.57 (1, COD), 2.19 (2, BH), 2.16 (1, COD), 2.14 (1, COD), 2.12 (1, COD), 1.94 (1, BH), 1.85 (9, (CH3)3), 1.81 (1, BH), 1.12 (8, COD); IR (NaCl, cm−1): 2928 (w), 2940 (w), 2882 (w), 2837 (w), 2579 (m), 2536 (s), 2493 (m), 2189 (s), 1370 (w), 1189 (w), 990 (w), 758 (m), 738 (w), 700 (m). 1-(η4-C4Ph4)-2-Ph-closo-1,2,3,4-CoC3B7H9 (12). A sample of diphenylacetylene (214 mg, 1.2 mmol) was added to a 10 mL THF solution of 1 (∼0.2 mmol), prepared in situ via the reaction of Co(CO)4I with Li+(6-Ph-nido-5,6,9-C3B7H9)−, and the mixture stirred for 5 days at 60 °C. The solvent was vacuum-evaporated to give a dark red oil that was then chromatographed with a 1:1 dichloromethane/ hexanes eluent to give 12. 12: 20% yield (49 mg, 0.08 mmol); red; oil; m/z calc for 12C171H2611 59 B7 Co1: 614, found: 614. 11B NMR (128.4 MHz, CDCl3) ppm (int, mult, J = Hz) 6.7 (1, d, br), 0.0 (1, d, br), −2.0 (1, d, br), −5.1 (1, d, ∼130), −19.1 (2, d, ∼154), −24.3 (1, d, 150); 1H NMR (400.1 MHz, THF-d8) ppm (int, assign) 7.69−7.19 (25, 5Ph), 4.10 (1, cage-CH), 2.31 (1, cage-CH). IR (NaCl, cm−1): 3456 (m), 3080 (w), 3061 (w), 1405

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Pergamon: New York, 1982; Vol. 5, pp 248−258, 358−366, and 605− 611. (c) Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds. Comprehensive Organometallic Chemistry II; Pergamon: New York, 1995; Vol. 8, pp 83− 88, 167−185, and 377−393. (7) Bencze, E.; Mink, J.; Nemeth, C.; Herrmann, W. A.; Lokshin, B. V.; Kuhn, F. E. J. Organomet. Chem. 2002, 642, 246−258. (8) Nafady, A.; Costa, P. J.; Calhorda, M. J.; Geiger, W. E. J. Am. Chem. Soc. 2006, 128, 16587−16599. (9) Jina, O. S.; Sun, X. Z.; George, M. W. Dalton Trans. 2003, 1773− 1778. (10) Asbury, J. B.; Hang, K.; Yeston, J. S.; Cordaro, J. G.; Bergman, R. G.; Lian, T. J. Am. Chem. Soc. 2000, 122, 12870−12871. (11) Banister, J. A.; Cooper, A. I.; Howdle, S. M.; Jobling, M.; Poliakoff, M. Organometallics 1996, 15, 1804−1812. (12) Previous attempts to characterize the Me-analogues of 1 and 2 had also shown that these complexes rapidly decompose. Barum, B. A. Ph.D. Dissertation, University of Pennsylvania, Philadelphia, PA, 1995. (13) Nagasawa, T.; Nagata, T. Biochim. Biophys. Acta 2007, 1767, 666− 670. (14) Schumann, H.; Stenzel, O.; Dechert, S.; Girgsdies, F.; Blum, J.; Gelman, D.; Halterman, R. L. Eur. J. Inorg. Chem. 2002, 211−219. (15) For some examples, see: (a) Basolo, F. New J. Chem. 1994, 18, 19−24 and references therein. (b) Basolo, F. Polyhedron 1990, 9, 1503− 1535 and references therein. (c) O’Connor, J. M.; Casey, C. P. Chem. Rev. 1987, 87, 307−318 and references therein. (d) Schuster-Woldan, H. G.; Basolo, F. J. Am. Chem. Soc. 1966, 88, 1657−1663. (e) Rerek, M. E.; Basolo, F. J. Am. Chem. Soc. 1984, 106, 5908−5912. (f) Simanko, W.; Tesch, W.; Sapunov, V. N.; Mereiter, K.; Schmid, R.; Kirchner, K.; Coddington, J.; Wherland, S. Organometallics 1998, 17, 5674−5688. (g) Calhorda, M. J.; Gamelas, C. A.; Romão, C. C.; Veiros, L. F. Eur. J. Inorg. Chem. 2000, 331−340. (16) Williams, R. E. Adv. Inorg. Chem. Radiochem. 1976, 18, 67−142. (17) Adams, H.; Bailey, N. A.; Mann, B. E.; Taylor, B. F.; White, C.; Yavari, P. J. Chem. Soc., Dalton Trans. 1987, 1947−1951. (18) Zherikova, K. V.; Morozova, N. B.; Baidina, I. A. J. Struct. Chem. 2009, 50, 570−573. (19) (a) Malatesta, L.; Bonati, F. Isocyanide Complexes of Metals; WileyInterscience: New York, 1969. (b) Treichel, P. M. Adv. Organomet. Chem. 1973, 11, 21−310. (c) Singleton, E.; Oosthuizen, H. E. Adv. Organomet. Chem. 1983, 22, 209−310. (d) Sarapu, A. C.; Fenske, R. F. Inorg. Chem. 1975, 14, 247−253. (20) Edwards, D. A.; Tetrick, S. M.; Walton, R. A. J. Organomet. Chem. 1988, 349, 383−391. (21) Beaumont, I.; Wright, A. H. J. Organomet. Chem. 1992, 425, C11− C14. (22) Doherty, J.; Fortune, J.; Manning, A. R.; Stephens, F. S. J. Chem. Soc., Dalton Trans. 1984, 1111−1116. (23) Yang, K.; Don, M.-J.; Sharma, D. K.; Bott, S. G.; Richmond, M. G. J. Organomet. Chem. 1995, 495, 61−69. (24) See, for example: (a) Rausch, M. D.; Genetti, R. A. J. Am. Chem. Soc. 1967, 89, 5502−5503. (b) Rausch, M. D.; Genetti, R. A. J. Org. Chem. 1970, 35, 3888−3897. (c) Harrison, R. M.; Brotin, T.; Noll, B. C.; Michl, J. Organometallics 1997, 16, 3401−3412. (d) Harcourt, E. M.; Yonis, S. R.; Lynch, D. E.; Hamilton, D. G. Organometallics 2008, 27, 1653−1656. (e) Bertrand, G.; Tortech, L.; Fichou, D.; Malacria, M.; Aubert, C.; Gandon, V. Organometallics 2012, 31, 126−132. (f) Kottas, G. S.; Brotin, T.; Schwab, P. F. H.; Gala, K.; Havlas, Z.; Kirby, J. P.; Miller, J. R.; Michl, J. Organometallics 2014, 33, 3251−3264. (25) Mutseneck, E. V.; Loginov, D. A.; Perekalin, D. S.; Starikova, Z. A.; Golovanov, D. G.; Petrovskii, P. V.; Zanello, P.; Corsini, M.; Laschi, F.; Kudinov, A. R. Organometallics 2004, 23, 5944−5957. (26) Mutseneck, E. V.; Perekalin, D. S.; Holub, J.; Lyssenko, K. A.; Petrovskii, P. V.; Stibr, B.; Kudinov, A. R. Eur. J. Inorg. Chem. 2006, 1737−1742. (27) Perez-Gavilan, A.; Carroll, P. J.; Sneddon, L. G. Collect. Czech. Chem. Commun. 2010, 75, 905−917. (28) See, for example: (a) King, R. B.; Treichel, P. M.; Stone, F. G. A. J. Am. Chem. Soc. 1961, 83, 3593−3597. (b) Heck, R. F. Inorg. Chem. 1965, 4, 855−857. (c) King, R. B. Inorg. Chem. 1966, 5, 82−87. (d) King, R. B.;

and structure solutions. All reflections were used during refinement. Non-hydrogen atoms were refined anisotropically, cage hydrogen atoms were refined isotropically, and all other hydrogen atoms were refined using a riding model.

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ASSOCIATED CONTENT

S Supporting Information *

X-ray crystallographic data for the structural determinations (CIF) and NMR spectra. This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected] (L.G.S.). Present Address †

Maastricht Science Programme, Maastricht University, Maastricht, The Netherlands. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The National Science Foundation is gratefully acknowledged both for the support of this research and for an instrumentation grant (CHE-0840438) that was used for the purchase of the Xray diffractometer employed in these studies.

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REFERENCES

(1) Kang, S. O.; Furst, G. T.; Sneddon, L. G. Inorg. Chem. 1989, 28, 2339−2347. (2) Ramachandran, B. M.; Carroll, P. J.; Sneddon, L. G. Inorg. Chem. 2004, 43, 3467−3474. (3) (a) Plumb, C. A.; Carroll, P. J.; Sneddon, L. G. Organometallics 1992, 11, 1665−1671. (b) Plumb, C. A.; Carroll, P. J.; Sneddon, L. G. Organometallics 1992, 11, 1672−1680. (c) Plumb, C. A.; Carroll, P. J.; Sneddon, L. G. Organometallics 1992, 11, 1681−1685. (d) Weinmann, W.; Wolf, A.; Pritzkow, H.; Siebert, W.; Barnum, B. A.; Carroll, P. J.; Sneddon, L. G. Organometallics 1995, 14, 1911−1919. (e) Barnum, B. A.; Carroll, P. J.; Sneddon, L. G. Organometallics 1996, 15, 645−654. (f) Barnum, B. A.; Carroll, P. J.; Sneddon, L. G. Inorg. Chem. 1997, 36, 1327−1337. (g) Wasczak, M. D.; Lee, C. C.; Hall, I. H.; Carroll, P. J.; Sneddon, L. G. Angew. Chem., Int. Ed. Engl. 1997, 36, 2228−2230. (h) Ramachandran, B. M.; Carroll, P. J.; Sneddon, L. G. J. Am. Chem. Soc. 2000, 122, 11033−11034. (i) Wasczak, M. D.; Wang, Y.; Garg, A.; Geiger, W. E.; Kang, S. O.; Carroll, P. J.; Sneddon, L. G. J. Am. Chem. Soc. 2001, 123, 2783−2790. (j) Ramachandran, B. M.; Trupia, S. M.; Geiger, W. E.; Carroll, P. J.; Sneddon, L. G. Organometallics 2002, 21, 5078− 5090. (k) Ramachandran, B. M.; Wang, Y.; Kang, S. O.; Carroll, P. J.; Sneddon, L. G. Organometallics 2004, 23, 2989−2994. (l) Gleeson, B.; Carroll, P. J.; Sneddon, L. G. J. Am. Chem. Soc. 2013, 135, 12407−12413. (4) (a) Ramachandran, B. M.; Carroll, P. J.; Sneddon, L. G. Inorg. Chem. 2004, 43, 3467−3474. (b) Butterick, R., III; Carroll, P. J.; Sneddon, L. G. Organometallics 2008, 27, 4419−4427. (c) PerezGavilan, A.; Carroll, P. J.; Sneddon, L. G. Organometallics 2012, 31, 2741−2748. (d) Perez-Gavilan, A.; Carroll, P. J.; Sneddon, L. G. Inorg. Chem. 2012, 51, 5903−5910. (e) Perez-Gavilan, A.; Carroll, P. J.; Sneddon, L. G. J. Organomet. Chem. 2012, 721−722, 62−69. (f) Gleeson, B.; Carroll, P. J.; Sneddon, L. G. J. Organomet. Chem. 2013, 747, 51−61. (5) (a) Butterick, R., III; Ramachandran, B. M.; Carroll, P. J.; Sneddon, L. G. J. Am. Chem. Soc. 2006, 128, 8626−8637. (b) Nafady, A.; Butterick, R., III; Calhorda, M.; Carroll, P. J.; Chong, D.; Costa, P. J.; Geiger, W. E.; Sneddon, L. G. Organometallics 2007, 26, 4471−4482. (c) Stewart, M.; Butterick, R., III; Sneddon, L. G.; Matsuo, Y.; Geiger, W. E. Inorg. Chim. Acta 2010, 364, 251−254. (6) For some reviews, see: (a) Fan, H.-J.; Hall, M. B. Organometallics 2001, 20, 5724−5730 and references therein. (b) Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds. Comprehensive Organometallic Chemistry I; 1406

DOI: 10.1021/acs.organomet.5b00141 Organometallics 2015, 34, 1396−1407

Article

Organometallics Efraty, A. J. Organomet. Chem. 1971, 27, 409−420. (e) Yamazaki, H. Bull. Chem. Soc. Jpn. 1971, 44, 582. (f) Loginov, D. A.; Vinogradov, M. M.; Starikova, Z. A.; Petrovskii, P. V.; Kudinov, A. R. Russ. Chem. Bull., Int. Ed. 2004, 53, 1949−1953. (29) See, for example: (a) McCleverty, J. A.; Wilkinson, G. J. Chem. Soc. 1964, 4200−4203. (b) Hughes, R. P.; Smith, J. M.; Liable-Sands, L. M.; Concolino, T. E.; Lam, K.-C.; Incarvito, C.; Rheingold, A. L. J. Chem. Soc., Dalton Trans. 2000, 873−879. (c) Bourgeois, C. J.; Hughes, R. P.; Husebo, T. L.; Smith, J. M.; Guzei, I. M.; Liable-Sands, L. M.; Zakharov, L. N.; Rheingold, A. L. Organometallics 2005, 24, 6431−6439. (d) GilRubio, J.; Guerrero-Leal, J.; Blaya, M.; Vicente, J. Organometallics 2012, 31, 1287−1299. (30) Loginov, D. A.; Starikova, Z. A.; Petrovskii, P. V.; Holub, J.; Kudinov, A. R. Inorg. Chem. Commun. 2011, 14, 313−315. (31) Shriver, D. F., Drezdzon, M. A., Eds. Manipulation of Air Sensitive Compounds, 2nd ed.; Wiley: New York, 1986. (32) Tasi, M.; Palyi, G. Organometallics 1985, 4, 1523−1528. (33) SHELXTL version 6.14; Bruker AXS Inc.: Madison, WI, 2003.

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