[en] The new chloro-sulfosalt Pb_3+xSb_3-xS_7-xCl_1+x (x∼0.45) has been synthesized at 500 deg. C from a mixture of PbS, PbCl₂ and Sb₂S₃. It crystallizes in the orthorhombic system (space group Pbam), with a=15.194(3) A, b=23.035(5) A, c=4.0591(8) A, V=1420.6 A³, Z=4. The crystal structure has been solved by X-ray single-crystal study, with a final R=0.0497. Deviation from stoichiometric Pb₃Sb₃S₇Cl (x coefficient) follows the substitution rule Sb³⁺+S^2-→Pb²⁺+Cl^-. Sb and Pb sub-positions within mixed (Sb,Pb) sites are discussed; Pb excess precludes any superstructure along c. A unique pure Cl position is bound only to Pb atoms with a distorted square coordination. The title compound is a rod-type structure derived from the SnS archetype, homeotypic with Pb₆Sb₆S₁₄(S₃), where the (S₃)^2- trimer is replaced by two Cl^-; this substitution is quite isovolumic. Other similar structures are: three polychalcogenides Sr₆Sb₆S₁₄(S₃), Pb₆Sb₆Se₁₄(Se₃) and Eu₆Sb₆S₁₄(S₃); KLa_1.28Bi_3.72S₈ and its Ln isotypes; dadsonite, Pb₂₃Sb₂₅S₆₀Cl. Pb_3+xSb_3-xS_7-xCl_1+x is the N=2 member of the homologous series Pb_(2+2N)(Sb,Pb)_(2+2N)S_(2+2N)(S,Cl)_(4+2N)Cl_N; the N=1 member corresponds to the previously known ∼Pb_4.3Sb_3.7S_8.7Cl_2.3 compound. Other polychalcogenide derivatives of this homologous series are K₂Pr_2-xSb_4+xSe₈(Se₄) and its Ln isotypes (N=1), as well as SrBiSe₃ (N=3). Such a comparative modular analysis allowed to propose a structural model for the previous synthetic 'Phase Y', ∼Pb₁₀Sb₁₀S₂₃Cl₄, corresponding to the combined N=(1+2) homolog. - Graphical abstract: The title compound, Pb_3+xSb_3-xS_7-xCl_1+x, is derived from the homeotypic persulfide Pb₆Sb₆S₁₄(S₃) by substituting two chlorine atoms for the S₃ trimer. This change is quite isovolumic