Tautomerization of Methyldiazene to Formaldehyde-Hydrazone in Ruthenium and Osmium Complexes

Mixed-ligand hydrazine complexes [M(CO)(RNHNH2)P4](BPh4)2 (1, 2) [M = Ru, Os; R = H, CH3, C6H5; P =
P(OEt)3] with carbonyl and triethyl phosphite were prepared by allowing hydride [MH(CO)P4]BPh4 species to react
first with HBF4·Et2O and then with hydrazines. Depending on the nature of the hydrazine ligand, the oxidation of
[M(CO)(RNHNH2)P4](BPh4)2 derivatives with Pb(OAc)4 at −30 °C gives acetate [M(κ1-OCOCH3)(CO)P4]BPh4 (3a),
phenyldiazene [M(CO)(C6H5NNH)P4](BPh4)2 (3c, 4c), and methyldiazene [M(CO)(CH3NNH)P4](BPh4)2 (3b, 4b)
derivatives. Methyldiazene complexes 3b and 4b undergo base-catalyzed tautomerization of the CH3NNH
ligand to formaldehyde-hydrazone NH2NCH2, giving the [M(CO)(NH2NCH2)P4](BPh4)2 (5, 6) derivatives. Complexes
5 and 6 were characterized spectroscopically and by the X-ray crystal structure determination of the [Ru(CO)(NH2NCH2){P(OEt)3}4](BPh4)2 (5) derivative. Acetone-hydrazone [M(CO){NH2NC(CH3)2}P4](BPh4)2 (7, 8)
complexes were also prepared by allowing hydrazine [M(CO)(NH2NH2)P4](BPh4)2 derivatives to react with acetone.

含羰基与亚磷酸三乙酯配体的混合配体肼配合物[M(CO)(RNHNH₂)P₄](BPh₄)₂（编号1、2，其中M=Ru、Os；R=H、CH₃、C₆H₅；P=P(OEt)₃），通过将氢化物物种[MH(CO)P₄]BPh₄先与HBF₄·Et₂O反应，再与肼类化合物反应制得。
根据肼配体的结构性质差异，在-30℃下以四乙酸铅[Pb(OAc)₄]氧化[M(CO)(RNHNH₂)P₄](BPh₄)₂衍生物时，可得到乙酸根配合物[M(κ¹-OCOCH₃)(CO)P₄]BPh₄（3a）、苯重氮配合物[M(CO)(C₆H₅N=NH)P₄](BPh₄)₂（3c、4c）以及甲基重氮配合物[M(CO)(CH₃N=NH)P₄](BPh₄)₂（3b、4b）。
甲基重氮配合物3b与4b可发生碱催化的CH₃N=NH配体互变异构化，将配体转化为甲醛腙NH₂N=CH₂，从而得到[M(CO)(NH₂N=CH₂)P₄](BPh₄)₂（5、6）衍生物。
配合物5与6已通过光谱学方法完成表征，其中[Ru(CO)(NH₂N=CH₂){P(OEt)₃}₄](BPh₄)₂（即配合物5）的X射线晶体结构得到测定。
此外，通过使肼衍生物[M(CO)(NH₂NH₂)P₄](BPh₄)₂与丙酮反应，还制备得到了丙酮腙配合物[M(CO){NH₂N=C(CH₃)₂}P₄](BPh₄)₂（7、8）。