Ultraviolet Photochemistry of Co^IIIL(H₂O)SO₃⁺ [L = Me₆[14]dieneN₄,[14]andN₄] Complexes. Quandaries about the Linkage Isomerization to O-Bonded Sulfite and the Photogeneration of Cobalt(I) in Sequential Biophotonic Photolysis

General Considerations.All operations were performed under N2, Ar, or vacuum, using standard Schlenk or drybox techniques.Dry, oxygen-free hexanes, benzene, and Et2O were obtained using an Anhydrous Engineering solvent purification system, and stored over Linde 4 Å molecular sieves.Methanol was distilled under N2 from Mg(OCH3)2, DMA and CH2Cl2 from CaH2.CD2Cl2, C6D6, and C7D8 were dried over activated sieves (Linde 4 Å) and degassed by consecutive freeze/pump/thaw cycles.Hydrogen (Praxair UHP grade) was purified by passage through a Deoxo cartridge and an indicating Drierite column in series.All other reagents were used as received.Solution 31 P NMR spectra were recorded on a Varian XL-300, solidstate spectra on a Bruker ASX-200 spectrometer. 1 H NMR data were measured on a Varian Gemini 200 NMR or Bruker ASX-500 spectrometer. 31P and 1 H NMR shifts are referenced to 85% aq H3PO4 or the residual protons of the deuterated solvent, respectively.Microanalytical data were obtained using a Perkin-Elmer Series II CHNS/O instrument.High-pressure hydrogenations were carried out in glass-lined Parr autoclaves.Ru(H)2Cl2(PCy3)2 (2).(a) A solution of 1 (5 mg, 6.1 µmol) in CD2-Cl2 (0.7 mL) showed clean, quantitative conversion to 2 after 24 h under H2 (1 atm). 31P{ 1 H} NMR (δ, CD2Cl2): 91.3 (s). 1 H NMR (δ, CD2Cl2): -12.4 (t, 3 J(H,P) ) 31.6 Hz, 2H, RuH), 0.9-2.3(m, 66H, Cy), 2.4 (s, 3H, toluene CH3), 7.2 (m, 5H, Ph).(b) A solution of 1 (50 mg, 60.8 µmol) in CH2Cl2 (20 mL) was stirred under 1000 psi H2 for 14 h.The orange solution was used directly in subsequent experiments.RuCl2(H2)(PCy3)2 (4).A suspension of 1 (100 mg, 122 µmol) in hexanes (10 mL) was stirred under 1000 psi H2 at 50 °C for 40 h.The resulting pale yellow solid was filtered off and dried under vacuum.Yield 60 mg (67%).Solid state 31 P{ 1 H} NMR (δ): 47.5 ppm. 31P{ 1 H} NMR (δ, C6D6, Ar): 91.3 (s, 2), 54.2 (s, 4).A third singlet appeared under H2: 40.3 (s, 7).In solution, trace impurities can be seen by 31 P-{ 1 H} NMR. 1 H NMR (δ, C6D6, Ar): -16.2 (br s, Ru(H2), 4), -12.0 (t, 3 J(H,P) ) 31.5 Hz, Ru(H)2, 2), 0.9-2.3(m, Cy).Under H2: -13.0 (br s, Ru(H2), 4), -12.0 (t, 3 J(H,P) ) 31.5 Hz, Ru(H)2, 2), -9.8 (br s, Ru(H2), 7), 0.9-2.3(m, Cy).No signal for 3 (δΗ -14.0) was observed.Hydride T1 min for 4 (C7D8, H2, 500 MHz, 268K) 18.8 ms.Anal.Calcd for C36H68Cl2P2Ru: C, 58.84; H, 9.33.Found: C, 58.91; H, 9.23.RuCl2(H2)(PCy3)2[η 1 -OdC(NMe2)Me] (6).(a) A suspension of 1 (100 mg, 122 µmol) in Et2O-DMA (10:1, total volume 20 mL) was stirred under 1000 psi H2 for 20 h.The resulting pale yellow solid was filtered off, washed with Et2O and hexanes, and dried.Yield: 70 mg (71%).Solid state 31 P{ 1 H} NMR (δ): 32.2 (s); a small peak at 47.5 ppm is assigned to 4. Solution 31 P{ 1 H} NMR reveals only 2/4 (vide infra). 1 H NMR (δ, C6D6, Ar): -16.2 (br s, Ru(H2), 4), -12.0 (t, 3 J(H,P) ) 31.5 Hz, Ru(H2, 2), 0.9-2.6 (m, Cy, DMA).Integration vs MeOH as internal standard: hydride (2 + 4): aliphatics (Cy + DMA) ) 2:75.Hydride T1 min (C7D8, H2, 500 MHz, 268 K) 18.5 ms.IR (Nujol): ν(CO) 1630 cm -1 .Anal.Calcd for C40H77Cl2NOP2Ru: C, 58.45; H, 9.44; N, 1.70.Found: C, 58.95; H, 9.67; N, 1.66.(b) A solution of 1 (50 mg, 61 µmol) and PS (13 mg, 61 µmol) in benzene-DMA (3:1, 20 mL total) was stirred under 1 atm H2 for 16 h, until only the 31 P{ 1 H} NMR singlet for 4 was present.Removal of benzene in vacuo gave a yellow suspension, which was filtered off, washed with methanol and cold hexanes, and dried.Yield: 20 mg (44%).Some PS/DMA remained after this treatment.The C6D6 solution slowly deposited crystals of 6.Ru(H)(D)Cl2(PCy3)2 (2HD) and RuCl2(HD)(PCy3)2 (4HD).A sample of 6 (10 mg, 12 µmol) in 1 mL of C6D6 was freeze-thaw-degassed twice and then thawed under D2. 31 P{ 1 H} NMR (δ, C6D6): 90.8, 90.6 (s, two isomers of 2HD), 2a 54.2 (s, 4HD), 40.1 (s, 7HD). 1 H NMR (δ, C6D6): -11.86 (t, 3 J(H,P) ) 31.5; 2HD), -11.91 (t, 3 J(H,P) ) 31.5; 2HD), -13.1 (br t, 1 J(H,D) ) 22.5; 4HD).Deuterium splitting of the broad, low-intensity signal for 7 prevents observation of the hydride in 7HD.RuHCl(H2)(PCy3)2 (3).A solution of 1 (60 mg, 73 µmol) and PS (47 mg, 220 µmol) in CH2Cl2 (20 mL) was stirred under 1000 psi H2 for 14 h.Removal of solvent in vacuo gave an orange solid, which was extracted with cold hexanes, filtered, and washed with cold methanol and hexanes.Yield: 42 mg (82%). 31P{ 1 H} NMR (δ, C6D6): 54.2 (s). 1 H NMR (δ, C6D6, Ar): -16.3 (br s, RuH3), 0.9-2.3(m, Cy).Under H2: -14.0 (br s, RuH3), 0.9-2.3(m, Cy).A broad singlet for dihydrogen adduct 8 (δΗ -7.9) 2b is observed only on cooling to 193 K (CD2Cl2).X-ray Crystallographic Data Collection for 6.Single-crystal X-ray diffraction measurements were performed with Mo KR radiation (λ ) 0.71073 Å) on a Bruker AX SMART 1k CCD diffractometer.Crystal data: orthorhombic, space group Pnma, Z ) 4, a ) 17.831(2) Å, b ) 23.980(3) Å, c ) 9.6048(9) Å, V ) 4106.9(9) Å 3 , Fcalcd ) 1.326 gcm -3 , 1.70°e Θ e 24.71°; λ(Mo KR) ) 0.71073 Å, 0.3°ω scans with CCD area detector, T ) 203 K, 32693 reflections measured [3589 observed unique (I > 2σI) 227 parameters refined], F 2 refinement, RF(wRF 2 ) ) 0.0670 (0.1568).

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