tively. Single-crystal X-ray diffraction analysis of complex 1 showed that the structure consists of an 11-vertex nido-cobaltaborane subunit edge shared with a 10-vertex nido-borane fragment.The initial synthesis of several 19-vertex metallaborane compounds, in which nickel, cobalt, palladium, platinum, and rhodium organometallic fragments were incorporated into the macropolyhedral framework of either the anti or syn configurations of B 18 H 22 , was first reported in 1973 by Todd and Sneath. 1 These compounds were prepared by employing a synthetic pathway involving the initial deprotonation of the B 18 H 22 cage to form the [B 18 H 20 ] 2-species, followed by reaction with an appropriate organometallic reagent, such as [Co 2 (CO) 8 ], [Cl 2 Ni(Ph 2 PCH 2 CH 2 PPh 2 )], or [RhCl(CO)-(PPh 3 ) 2 ], to produce the corresponding 19-vertex metallaborane. In 1982, Greenwood and co-workers reported the synthesis of platinum derivatives of the B 18 H 22 cluster, including [(Pt-η 4 -anti-B 18 H 20 )(PMe 2 Ph) 2 ], from the reaction of anti-[B 18 H 22 ] with cis-[PtCl 2 (PMe 2 Ph) 2 ]. 2 A more compact diplatinum derivative, [(Pt 2 B 18 H 16 )(PMe 2 -Ph) 4 ], was also formed from this reaction. Sneath and Todd proposed that the structures for their 19-vertex complexes consisted of 11-vertex nido-metallaborane fragments edge-shared with 10-vertex nido-borane subunits, illustrated in Figure 1, but spectroscopic characterization and structural studies were not provided. 1 The first unsubstituted 19-vertex borane species, nonadecaborane [B 19 H 20 ] n-, was reported in 2000, 3 although some questions have recently arisen, on the basis of computational studies, as to whether this species is best formulated as a 1-or 3-anionic compound. 4,5 Nonadecaborane displays essentially the same structure as the previously described 19-vertex metallaboranes, except that a B-H unit is inserted into the anti-B 18 H 22 framework instead of an organometallic subunit.In this paper, we report the first complete spectroscopic and structural characterization of the previously reported 19-vertex metallaborane [(CH 3 ) 4 N][anti-B 18 H 20 -Co(CO) 3 ] (1). 1 In addition, we report the first example of the formation of an anti-B 18 H 21 cluster with an exobound organometallic moiety, [9-(Fe(CO) 2 (η 5 -C 5 H 5 ))anti-B 18 H 21 ] (2).
Experimental SectionPhysical Measurements. 11 B NMR spectra were recorded on a Brü ker DPX-300 NMR spectrometer operating at 96.3 MHz. Typical 11 B NMR acquisition parameters were a relaxation delay of 0.1 ms and a 90°pulse of 10 µs. Proton ( 1 H) and carbon ( 13 C) NMR spectra were recorded on a Brü ker DPX-300 spectrometer operating at 300.15 and 77.47 MHz, respectively. Mass spectra were obtained in the Mass Spectrometry Laboratory, University of Illinois. The 70-VSE mass spectrometer was purchased in part with a grant from the Division of Research Resources, National Institutes of Health (RR 04648). Unit resolution mass spectra were obtained on a HewlettPackard Model 5989B gas chromatograph/mass spectrometer (GC/M...
