Terrence Nicholson

The synthesis and characterization of [MCl3(NNC5H4NH) (HNNC5H4N) from [MO4]− (where MRe, Tc) organodiazenido, organodiazene-chelate complexes. The X-ray structure of [ReCl3 (NNC5H4NH) (HNNC5H4N)]

Abstract The reaction of Na[ReO4] with 2-hydrazinopyridine dihydrochloride in methanol gives [ReCl3(NNC5H4NH) (HNNC5H4N)] in excellent yields. The neutral, six-coordinate complex contains a pyridinium-diazenido ligand and a bidentate organodiazene ligand chelated through the pyridine nitrogen atom. The IR spectrum of this complex displays a series of strong absorptions in the 1600–1150 cm−1 region from the organohydrazide ligands. The FAB(+) mass spectrum displays the protonated parent ion of 507 m/z units and the fragment [ReCl2(NNHC5H4N) (HNNC5H4N)]+ of 470 m/z. The X-ray structure displays a meridional arrangement of chloride ligands, and the pyridine nitrogen atom of the organodiazene chelate ligand trans to the singly-bent, organodiazenido ligand. The molecular coordination geometry is distorted octahedral. The ReN bond length to the pyridine nitrogen atom of the organodiazene chelate is 2.164(7)A, while the ReN bond to the diazene α-nitrogen atom is 1.936(10) A. The NN bond length of this ligand is 1.309(11) A, indicative of multiple bonding within the chelated ligand. The ReN bond length of the pyridinium-diazenido ligand is 1.741(7) A and the NN bond length is 1.253(12) A, again reflecting the multiple bonding throughout the organodiazenido unit. The bond angle for this linkage is 168.1(8)°. Crystal data for ReCl3N6C10H10: triclinic space group P1, unit cell dimensions: a = 7.527(2), b = 7.599(2), c = 13.118(3) A , α = 106.55(3), β = 90.28(3), γ = 93.83(3)°, V = 717.4(4) A 3 , with Dcalc = 2.346 Mg m−3 to give Z = 2. Structure solution based on 2533 reflections converged at R = 3.61. The reaction of ammonium pertechnetate with 2-hydrazinopyridine-dihydrochloride in methanol gives [TcCl3(NNC5H4NH)-(HNNC5H4N)]. The 1H NMR spectrum displays inequivalent organohydrazide ligands. The IR spectrum of the technetium complex displays an extended series of absorptions in the 1600-1150 cm−1 region, analogous to the rhenium complex. The FAB(+) mass spectrum displays the protonated parent ion of 420 m/z as well as the fragment associated with the loss of HCl of 383 m/z. The reaction of the rhenium complex with stoichiometric amounts of triphenylphosphine and a proton scavenger gives [ReCl2(PPh3)(NNC5H4N) (HNNC5H4N)], an organodiazenido-organodiazene complex in which the phosphine has replaced one of the chloride ligands accompanied by the loss of the pyridium proton from the organodiazenido ligand.

The synthesis of a technetium(V) phenylimido complex from pertechnetate. The single crystal X-ray structure of [TcCl3(NPh)(PPh3)2]·CH2Cl2

Abstract The reaction of (NH4)[TcO4] with triphenylphosphine and the organohydrazine N-acetyl, N′-phenylhydrazine (PhNHNHCOCH3) in methanol with a minimal amount of HCl(aq) gives the neutral Tc(V) complex [Tc(NPh)Cl3(PPh3)2] in very good yields. The IR spectrum of this complex displays a strong band in the 1090 cm−1 region which has tentatively been assigned to v(TcN). The (+)FAB mass spectrum does not show the peak associated with the neutral parent species [TcCl3(NPh)(PPh3)2]. However, a prominent feature of 784 m/z is associated with the fragment generated from the loss of a chloride ligand, giving the cationic species [TcCl2(NPh)(PPh3)2]+. Other peaks present in the mass spectrum correspond to the fragments [TcCl2(NPh)(PPh3)]+ of 522 m/z and [TcCl(NPh)(PPh3)]·H+ of 488 m/z. The diamagnetic Tc(V) complex displays a 1H NMR spectrum with the proton signals from the imido-phenyl group resolved from those of the phosphine-phenyl groups. The complex displays distorted octahedral molecular coordination geometry, with mutually trans triphenylphosphine ligands and equatorial phenylimido and chloride ligands. The technetium-nitrogen bond length is 1.704(4) A with a technetium-nitrogen-carbon bond angle of 171.8(4)°, which reflects the sp hybridization of the phenylimido nitrogen atom. Bond lengths and angles involving the chloride and phosphine ligands are unexceptional for technetium in the +5 oxidation state. Crystal data for C43H37NP2Cl5Tc: triclinic space group P 1 , a=10.8651(9), b=12.2236(9), c=16.867(2) A, a=71.998(7)°, β=74.078(7)°, γ=80.336(7)°, V=2040.2 A3, with Dcalc=1.455 g cm−3 to give Z=2. Structure solution based on 9334 reflections converged at R=0.054, Rw=0.053, GOF=1.35. In an analogous reaction, [TcO4]− reacts with benzoylhydrazine (PhCONHNH2) and triphenylphosphine in methanol with HCl to give the Tc(V) nitrido complex [TcNCl2(PPh3)2] in excellent yields.

The characterization of technetium organohydrazide chelate complexes. The synthesis of a technetium phenylimido complex. The X-ray crystal structure of [TcO(SC6H2Pri3)2(PhNNCON2HPh)]

Abstract The reaction of the neutral technetium(V) oxo tris(thiolate) complex [TcO(SAr) 3 (C 5 H 5 N)] with (phenylazo)formic acid 2-phenylhydrazide in methanol gives the oxo technetium(V) bis(thiolato) complex [TcO(SAr) 2 (PhN 2 CONNHPh)] ( 2 ). The FAB-MS(+) of 2 shows the protonated parent ion and the organohydrazide ligand fragmenting such that the technetium-phenylimido species [TcO(SAr)(NPh)] + is generated. The X-ray crystal structure of 2 shows a distorted square pyramidal coordination geometry and the nitrogen-bound proton on the terminal exocyclic nitrogen of the singly deprotonated, chelated organohydrazide ligand. Crystal data for C 43 H 56 N 4 O 2 S 2 Tc: triclinic space group P 1 , a = 13.3613(8), b = 14.02768(6), c = 13.0857(6) A, α = 113.949(4), β = 100.265(4), γ = 76.019(4)°, V = 2166.0(4) A 3 to give Z = 2. Structure solution and refinement based on 7786 reflections converged at R = 0.040, R w = 0.045. The reaction of the cationic technetium(V) oxo complex (Bu 4 N)[TcOCl 4 ] with (phenylazo)formic acid 2-phenylhydrazide and 1,5-diphenylcarbazide yields the phenylimido complex [TcCl(NPh)PhN 2 CON 2 HPh) 2 ] ( 1 ) which incorporates a phenylimido unit. The infrared spectrum of this species shows a strong band at 1204 cm −1 which has been assigned to v (TcN). The fast atom bombardment mass spectrometric analysis shows the protonated parent ion and a fragmentation profile containing both bis(phenylimido) and tris(phenylimido) technetium species generated through the decomposition of the chelated organohydrazide ligands.

The synthesis and characterization of [TcCl3(NPh)(Ph2PCH2CH2PPh2)] and [TcCl3(NPh)(PPh3)2]. The single crystal X-ray structure of [TcCl3(NPh)(Ph2PCH2CH2PPh2)]

Abstract The reaction of (Bu4N)[TcOCl4] in methanol with 1-acetyl-2-phenylhydrazine, followed by 1,2-bis(diphenylphosphino)ethane (DPPE) gives the green technetium(V) phenylimido complex [TcCl3(NPh)(DPPE)]. The IR spectrum of this complex shows a characteristic peak at 1110 cm-1 which is assigned to v(TcN) from the linearly coordinated phenylimido unit. The 1H NMR spectrum shows a pair of coupled multiplets at 3.1 and 3.6 ppm from the aliphatic protons plus a series of six multiplets between 6.5 and 8.1 ppm from the aromatic protons of the bidentate phosphine ligand and imido-phenyl groups. The positive mode fast atom bombardment mass spectrum displays a peak at 695 m/z which corresponds to the protonated patent molecule. Also, a peak at 658 m/z corresponds to the fragment generated from the loss of one chloride from the neutral patent molecule. The X-ray crystal structure shows a facial arrangement of chloride ligands, with a TcN bond length of 1.687 A and a TcNC bond angle of 175.7° indicative of sp hybridization of the linearly coordinated phenylimido unit. Crystal data for TcCl3P2NC32H29: monoclinic space group Pc (No. 7), a=11.177(2), b=10.912(2), c=14.056(2) A, β=108.34(1)°, V=1627.3(5) A3, with Dcalc=1.414 g cm−3 to give Z=2. Structure solution based on 3069 reflections converged at R=0.051, Rw=0.072, GOF=2.32. The analogous reaction with triphenylphosphine gives the previously reported Tc(V) phenylimido complex [TcCl3(NPh)(PPh3)2]. This Tc(V) phenylimido complex reacts with pyridine in methanol to give the mixed ligand complex [TcCl3(NPh)(PPh3)(NC5H5)]. The positive mode FAB mass spectrum of this complex shows fragments which correspond to the sodium adducts of the neutral molecule minus one chloride ligand, (Na)[TcCl2(NPh)(PPh3)(C5H5N)]+ at 624 m/z, and the molecule minus two chloride ligands, (Na)[TcCl(NPh)(PPh3)(C5H5N)]+ at 589 m/z. Also present in the mass spectrum are peaks which correspond to the fragments [TcCl3(PPh3)(C5H5N)]+ at 545 m/z and [TcCl2(PPh3)(C5H5N)]+ at 510 m/z. The IR spectrum of this complex shows an absorption at 1090 cm−1 which is assigned to v(TcN) from the linearly coordinated phenylimido unit.

The synthesis and characterization of a technetium nitrosyl complex with cis-{2-pyridyl,diphenylphosphine} coligands. The X-ray crystal structure of [TcCL2(NO) (pyPPh2-P,N) (pyPPh2-P)]

Abstract The reaction of the Tc(II) nitrosyl complex (Bu 4 N) [Tc(NO)Cl 4 ] with excess pyPPh 2 in refluxing MeOH gives the bis -pyridyl-diphenylphosphine complex [TcCl 2 (NO)(pyPPh 2 - P , N ) (pyPPh 2 - P )]. The IR spectrum of the crystalline product shows a medium intensity band at 1092 cm −1 and a very strong band at 1732 cm −1 which is assigned to v (Tc=N) from the nitrosyl core. The FAB(+) mass spectrum shows the protonated parent ion of 725 m / z and the peak associated with the loss of a chloride ligand from the parent ion of 690 m / z . The 1 H NMR spectrum of the diamagnetic Tc(1) complex shows an extended series of multiples in the aryl region between 7.0 and 9.15 ppm. The X-ray crystal structure shows an unusual cis arrangement of these bulky phosphine ligands with one of these phosphine ligands coordinated in a bidentate manner. The Tc-N bond length of 1.743(5) A is consistent with the multiple bonding expected for the linearly bonded nitrosyl ligand. The Tc-N-O bond angle of 177.2(5)° reflects the sp hybridization of the nitrosyl-nitrogen atom. The Tc-P bonds are 2.400(2) and 2.405(2) A, which are unexceptional, as are the Tc-Cl bonds of 2.447(2) and 2.441(2) A. The coordination geometry of this complex is best described as a very distorted octahedron. The P-Tc-N bond angle of the chelated pyridyl phosphine ligand is 66.1(1)°, which reflects the very small bite angle imposed by the four-membered chelate ring of this phosphine. This is compensated for by a large P-Tc-P angle of 107.82(5)°, imposed by the cis -phosphine coordination of these bulky tri-aryl phosphine ligands. Crystal data for C 34 5 H 29 Cl 4 N 4 OP 3 Tc: triclinic space group P1, a=9.8440(3), b=13.4854(5), c=14.2401(5) A , α=106.406(1), β=96.013(1), γ=92.792(1) 2 V=1797.35(11) A 3 , with D calc =1.419 g cm −3 . Structure solution based on 5018 observed reflections converged at R =5.28%, for (1>2 σ (1)); GOF=1.73.

The reaction chemistry of a technetium(I) nitrosyl complex with potentially chelating organohydrazines: the X-ray crystal structure of [TcCl2(NO) (HNNC5H4N) (PPh3)]

The reaction of the nitrosyl complex [TcCl 2 (NO)(MeCN))(PPh 3 ) 2 ] with 2-hydrazinopyridine dihydrochloride in refluxing MeOH gives the purple complex (TcCl 2 (NO) (HN)NC 3 H 4 N) (PPh 2 ] ( 1 ) in which the neutral bidentate organodiazene ligand has replaced the acetonitrile and a phosphine ligand. The IR spectrum of 1 shows a very strong absorption at 1732 cm −1 attributed to v (NO). The FAB(+) mass spectrum of 1 displays the protonated parent ion at 570 m/z and the fragment generated by the loss of a chloride ligand from the parent ion at 533 m / z . The 1 H NMR spectrum of this diamagnetic complex displays the signal from the α-nitrogen-proton of the pyridyldiazene at 17.95 ppm as well as the aryl-protons. The X-ray crystal structure of this complex shows a distorted octahedral coordination geometry. The TcN bond length of 1.752(4) A is consistent with the multiple bonding expected for the linearly bonded nitrosyl ligand. The TcNO bond angle is 175.1(4)°. The NTcN bond angle of the chelated pyridyldiazene ligand is 73.1(2)°, which reflects the small bite angle imposed by the five-membered chelate ring of this ligand. The reaction of the nitrosyl complex [TcCl 2 (NO)(MeCN))(PPh 3 ) 2 ] with 2-hydrazino-4-trifluoromethylpyrimidine in refluxing dichloromethane gives the neutral Tc(I) complex [TcCl(NO) (NNC 4 H 2 N 2 R)(PPh 3 ) 2 ] in which the anionic bidentate organodiazenido ligand has replaced the acetonitrile and a chloride ligand. The IR spectrum of 2 shows a very strong absorption at 1717 cm −1 attributed to v (NO). The FAB(+) mass spectrum of 2 displays the parent ion at 886 m / z as well as the fragment generated by the loss of the diazenido ligand at 688 m / z . The peak associated with the loss of a phosphine ligand from the parent ion at 604 m / z is also evident.

Reactions of the technetium(V) phenylimido complex [TcX3(NPh)(PPh3)2] with aromatic thiolate ligands (where X=Cl, Br)

Abstract The reaction of KTcO4 with triphenylphosphine and 1-acetyl-2-phenylhydrazine in methanol with HBr gives the Tc(V) phenylimido complex [TcBr3(NPh)(PPh3)2], analogous to the published reaction with HCl. The phenylimido complex reacts with unsubstituted thiophenol and a proton scavenger (R3N) in methanol to give the Tc(V) oxo complex (R3NH)[TcO(SPh)4] in excellent yield. The IR spectrum of this complex shows an absorption at 936 cm−1 associated with v(Tc=O). The Tc(V) complex [TcCl3(NPh)(PPh3)2] reacts with a four-fold excess of the sterically-hindered thiol 2,3,5,6-tetramethylbenzenethiol (TMBTH) and a proton sponge to give the Tc(V) complex [Tc(NPh)(TMBT)3(PPh3)]. The IR spectrum of this complex displays an absorption at 1100 cm−1 which is associated with v(TcN). The positive mode fast atom bombardment mass spectrum of this species displays an extensive fragmentation profile, including fragment of 947 m/z, which corresponds to the parent ion [Tc(NPh)(TMBT)3(PPh3)]+. The analogous reaction with a five-fold excess of 2,6-dimethylbenzenethiol (DMBTH) and a proton sponge gives the anionic Tc(V) complex (R3NH)[Tc(NPh)(SAr)4]. The IR spectrum of this complex displays an absorption at 1100 cm−1 which is associated with v(TcN). The positive mode fast atom bombardment mass spectrum of this anionic species displays an extensive fragmentation profile, including fragments of 998 m/z, which corresponds to {(R3NH)2[Tc(NPh)(DMBT)4]}+ and 868 m/z which corresponds to {(R3NH)[Tc(NPh)(DMBT)4]}+. The reaction of the Tc(V) complex [TcCl3(NPh)(PPh3)2] with the tetradentate phosphinetrithiol ligand [P(C6H4-o-SH)3], and a proton scavenger in methanol gives the neutral Tc(III) complex [Tc(PPh3)(PS3)]. The FAB(+) mass spectrum of this complex shows the parent ion of 716 m/z and the peak associated with the fragment generated by the loss of the triphenylphosphine of 454 m/z. The IR spectrum shows no absorptions in either the region associated with v(TcO) or v(TcN). The 1H NMR spectrum of the diamagnetic Tc(III) complex shows only narrow-line signals associated with the aryl protons.

THE SYNTHESIS AND CHARACTERIZATION OF A TECHNETIUM(III) ISODIAZENE COMPLEX. THE X-RAY CRYSTAL STRUCTURE OF TCCL3(N=NPH2) (PPH3)2

Abstract The reaction of the Te(V) complex (Bu 4 N)[TcOCl 4 ] with excess Ph 2 NNH 2 ·HCl and PPh 3 in refluxing MeOH yields [TcCl 3 (N=NPh 2 )(PPh 3 ) 2 ]. The IR spectrum of the crystalline product shows a medium intensity band at 1092 cm −1 , which is assigned to v (Tc=N) from the isodiazene core. The FAB(+) mass spectrum shows the protonated parent ion of 914 m / z and the peak associated with the loss of a chloride from the parent ion of 878 m/z . The octahedral, Tc(III) complex is paramagnetic, with no signals observed in the 1 H NMR spectrum. The X-ray crystal structure shows the mutually trans triphenyl-phosphine ligands with the isodiazene and chloride ligands in the equatorial plane. The TcN bond length is 1.738(4) A while the NN is 1.300(5) A, which is consistent with the multiple bonding expected for the linearly bonded isodiazene ligand. The TcNN bond angle of 175.6(3)° reflects the sp hybridization of the isodiazene-α-nitrogen atom. The coordination geometry of this complex is a distorted octahedron. Crystal data for C 50 H 44 Cl 7 N 2 P 2 Tc: monoclinic space group P2 1 n , a = 10.1294(1), b = 26.0792(3), c = 18.8147(3) A , β = 98.814(1)°, V = 4911.52(11) A 3 , with D calc = 1.462 g cm. Structure solution based on 6962 unique reflections converged at R = 0.0513 for (1>2 σ (1)); GOF = 1.33.

THE SYNTHESIS OF NITROSYL COMPLEXES OF TECHNETIUM WITH SULFUR-CONTAINING CORES

Abstract The reaction of [Tc(NO)Cl 2 (PPh 3 ) 2 (NCCH 3 )] with 1 equiv. of potassium alkylxanthate in CH 2 Cl 2 yields complexes of the type [Tc(NO)Cl(PPh 3 ) 2 (S 2 COiBu)], in which the weakly coordinated acetonitrile ligand and one of the chloride ligands have been replaced by the bidentate, monoanionic xanthate ligand. The 1 H NMR spectrum of this complex displays equivalent triphenylphosphine ligands, indicating mutually trans coordination geometry. The IR spectrum of this complex displays the absorption associated with ν(NO) at 1702 cm −1 from the linearly coordinated nitrosyl ligand. The FAB (+) mass spectrum of this complex contains the parent ion of 837 m / z which corresponds to [Tc(NO)Cl(PPh 3 ) 2 (S 2 COiBu)] + plus various fragments associated with the loss of the chloride and phosphine ligands. The reaction of [Tc(NO)Cl 2 (PPh 3 ) 2 (NCCH 3 )] with excess potassium alkylxanthate in CH 2 Cl 2 yields complexes of the type [Tc(NO) (PPh 3 ) (S 2 COiBu) 2 ], in which two, bidentate alkylxanthate ligands have been incorporated into the reaction product. The IR spectrum of this complex displays the absorption from ν(NO) at 1701 cm −1 which indicates a linearly coordinated nitrosyl ligand. The FAB(+) mass spectrum of the species displays the parent ion of 689 m / z which corresponds to [Tc(NO) (PPh 3 ) (S 2 COiBu) 2 ] + . The 1 H NMR spectrum of this species displays inequivalent alkylxanthate ligands which indicates that the phosphine and nitrosyl ligands are coordinated in a cis conformation. The analogous reaction chemistry of [Tc(NO)Cl 2 (PPh 3 ) 2 (NCCH 3 )] with the potentially bidentate ligand 2-mercaptopyridine is also presented.

The substitution chemistry of a useful new synthon with neutral donor ligands. Part 2. The reactions of [TcCl3(NNPh2)(PPh3)2] with neutral nitrogen and carbon ligands. The X-ray structure of [TcCl2(NNPh2)(bipy)(PPh3)][PF6], [TcCl2(NNPh2)(terpy)][BF4] and [TcCl(NNPh2)(CNCH2Ph)2(PPh3)2][PF6]

The reaction of [TcCl 3 (NNPh 2 )(PPh 3 ) 2 ] complex with 2,2′ bipyridine in MeOH yields [TcCl(OMe)(NNPh 2 )(PPh 3 )(bipy)] + which is isolated as the (BPh 4 ) − salt. The X-ray structure shows the diphenylisodiazene ligand and methoxide in the axial sites, with the bipyridyl ligand, triphenylphosphine and chloride in the equatorial plane. The methoxide ligand is introduced from the reaction solvent. The TcN(1) bond length is 1.755(3) A, while N(1)N(2) is 1.298(4) A and the TcN(1)N(2) bond angle is 171.4(2)°, which reflects the multiple bonding through out the zwitterionic isodiazene moiety. The distorted octahedral geometry results from the small bite angle associated with the bipyridine ligand which is 75.98(10)°. In the reaction of [TcCl 3 (NNPh 2 )(PPh 3 ) 2 ] with terpyridine in MeOH, [TcCl 2 (NNPh 2 )(terpy)] + is isolated as the (BF 4 ) − salt. The X-ray structure shows the isodiazene ligand and terpyridine ligands in the equatorial plane and the chloride ligands in a mutually trans orientation. The TcN(1) bond length is 1.739(3) A and the N(1)N(2) bond length is 1.301(4) A again reflecting the multiple bonding throughout the metal–nitrogen–nitrogen framework. The TcN(1)N(2) bond angle is 174.3(3)° which, along with the N(1)N(2)C bond angles of 120.3(3)° and 115.8(3)°, are indicative of sp 2 hybridization on the β-nitrogen atom. The reaction of [TcCl 3 (NNPh 2 )(PPh 3 ) 2 ] with RNC {where R=CH 2 Ph} yields [TcCl(NNPh 2 )(PPh 3 ) 2 (CNR) 2 ] + , which is isolated as the (PF 6 ) − salt. The reaction with isonitrile results in a one electron reduction of the technetium synthon, resulting in the clean isolation of the Tc(II) product. The TcN(1) bond length is 1.832(5) A and the N(1)N(2) bond length is 1.287(6) A, and the TcN(1)N(2) bond angle is 157.8(4)°. This new structural conformation approaches the ‘bent’ conformation of the isodiazene MNN linkage with sp 2 hybridization on both the α- and β-nitrogen atoms. There is no sign of an NH stretch in the IR and no evidence of a proton in the X-ray structure, so the addition of NH 4 PF 6 as counter ion did not protonate the isodiazene ligands α-nitrogen.